Despite centuries of taboo and titillation, masturbation in primates appears to serve an evolutionary purpose. A study published June 6 in the journal Proceedings of The Royal Society B, found that self-stimulating increases reproductive success and helps primates avoid sexually transmitted infections (STI), at least in males. 

[Related from PopSci+: These sex toys are designed to heal, one orgasm at a time.]

Self-pleasure is common across the animal kingdom, but is particularly frequent in primates including humans. The behavior was considered by some scientists to be either pathological or simply a by-product of sexual arousal. Recorded observations were also too fragmented to fully understand masturbation’s distribution, evolutionary history, or adaptive significance. 

In this new study, a team of researchers built a dataset on primate masturbation from close to 400 sources, including 246 published academic papers, and 150 questionnaires and personal communications from zookeepers and primatologists. To understand why and when the practice evolved in both females and males, the authors tracked the distribution of autosexual behavior across primates.

They found that masturbation has a long evolutionary history amongst primates, and was likely present in the common ancestry of all monkeys and apes, humans included. What was less clear is whether the common ancestor of other primates—lemurs, lorises and tarsiers—masturbated, largely because there was less data on these groups.

The team tested multiple hypotheses to better understand why this seemingly non-functional trait would evolve. According to the postcopulatory selection hypothesis, masturbation aids successful fertilization that can be achieved in various ways. 

Masturbation without ejaculation can increase arousal before sexual intercourse, which may be a useful tactic for low-ranking primate males that are likely to be interrupted during sex. 

Masturbation with ejaculation allows males to shed their more inferior semen, which leaves the fresh, high-quality semen available for mating. This super semen may be more likely to outcompete the semen of other males, which is necessary in primate communities with steep competition for mates. The study found support for this second hypothesis, namely that male masturbation co-evolved within multi-male mating systems where competition between males is high.

[Related: Scientists think they found a 2,000-year-old dildo in ancient Roman ruins.]

According to the pathogen avoidance hypothesis, male masturbation reduces the chance of contracting an STI by cleansing the urethra with ejaculate. The team also found evidence to support this hypothesis, with the data revealing that masturbation in males co-evolved with high STI load across the primate tree of life.

The significance of female masturbation remains less clear. While it is frequent, fewer studies and reports describe female self-pleasure.The team argues that more data on female sexual behavior is needed before understanding masturbation’s evolutionary role in females. 

“Our findings help shed light on a very common, but little understood, sexual behavior and represent a significant advance in our understanding of the functions of masturbation,” study co-author and University College London anthropologist Matilda Brindle said in a statement. “The fact that autosexual behavior may serve an adaptive function, is ubiquitous throughout the primate order, and is practiced by captive and wild-living members of both sexes, demonstrates that masturbation is part of a repertoire of healthy sexual behaviors.”

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This article was originally published on Undark.

It could have been a scene from Jurassic Park: ten golden lumps of hardened resin, each encasing insects. But these weren’t from the age of the dinosaurs; these younger resins were formed in eastern Africa within the last few hundreds or thousands of years. Still, they offered a glimpse into a lost past: the dry evergreen forests of coastal Tanzania.

An international team of scientists recently took a close look at the lumps, which had been first collected more than a century ago by resin traders and then housed at the Senckenberg Research Institute and Natural History Museum in Frankfurt, Germany. Many of the insects encased within them were stingless bees, tropical pollinators that can get stuck in the sticky substance while gathering it to construct nests. Three of the species still live in Africa, but two had such a unique combination of features that last year, the scientists reported them to be new to science: Axestotrigona kitingae and Hypotrigona kleineri.

Species discoveries can be joyous occasions, but not in this case. Eastern African forests have nearly disappeared in the past century, and neither bee species has been spotted in surveys conducted in the area since the 1990s, noted coauthor and entomologist Michael Engel, who recently moved from a position at the University of Kansas to the American Museum of Natural History. Given that these social bees are usually abundant, it’s unlikely that the people looking for insects had simply missed them. Sometime in the last 50 to 60 years, Engel suspects, the bees vanished along with their habitat.

“It seems trivial on a planet with millions of species to sit back and go, ‘Okay, well, you documented two stingless bees that were lost,’” Engel said. “But it’s really far more troubling than that,” he added, because scientists increasingly recognize that extinction is “a very common phenomenon.”

The stingless bees are part of an overlooked but growing trend of species that are already deemed extinct by the time they’re discovered. Scientists have identified new species of bats, birds, beetles, fish, frogs, snails, orchids, lichen, marsh plants, and wildflowers by studying old museum specimens, only to find that they are at risk of vanishing or may not exist in the wild anymore. Such discoveries illustrate how little is still known about Earth’s biodiversity and the mounting scale of extinctions. They also hint at the silent extinctions among species that haven’t yet been described — what scientists call dark extinctions.

It’s critical to identify undescribed species and the threats they face, said Martin Cheek, a botanist at the Royal Botanic Gardens, Kew, in the United Kingdom, because if experts and policymakers don’t know an endangered species exists, they can’t take action to preserve it. With no way to count how many undescribed species are going extinct, researchers also risk underestimating the scale of human-caused extinctions — including the loss of ecologically vital species like pollinators. And if species go extinct unnoticed, scientists also miss the chance to capture the complete richness of life on Earth for future generations. “I think we want to have a full assessment of humans’ impact on nature,” said theoretical ecologist Ryan Chisholm of the National University of Singapore. “And to do that, we need to take account of these dark extinctions as well as the extinctions that we know about.”

Many scientists agree that humans have pushed extinctions higher than the natural rate of species turnover, but nobody knows the actual toll. In the tens of millions of years before humans came along, scientists estimate that for every 10,000 species, between 0.1 and 2 went extinct each century. (Even these rates are uncertain because many species didn’t leave behind fossils.) Some studies suggest that extinction rates picked up at least in the past 10,000 years as humans expanded across the globe, hunting large mammals along the way.

Islands were particularly hard hit, for instance in the Pacific, where Polynesian settlers introduced pigs and rats that wiped out native species. Then, starting in the 16th century, contact with European explorers caused additional extinctions in many places by intensifying habitat loss and the introduction of invasive species — issues that often continued in places that became colonies. But again, scientists have a poor record of biodiversity during this time; some species’ extinctions were only recognized much later, most famously the dodo, which had disappeared by 1700 after 200 years of Europeans hunting and then settling on the island in the Indian Ocean island it inhabited.

Key drivers of extinction, such as industrialization, have ramped up ever since. For the past century, some scientists have estimated an average of 200 extinctions per 10,000 species— levels so high that they believe they portend a mass extinction, a term reserved for geological events of the scale of the ordeal that annihalated the dinosaurs 66 million years ago. Yet some scientists, including the authors of those estimates, caution that even these numbers are conservative. The figures are based on the Red List compiled by the International Union for Conservation of Nature, or IUCN, a bookkeeper of species and their conservation statuses. As several experts have noted, the organization is slow to declare species extinct, wary that if the classification is wrong, they may cause threatened species to lose protections.

The Red List doesn’t include undescribed species, which some estimate could account for roughly 86 percent of the possibly 8.7 million species on Earth. That’s partly due to the sheer numbers of the largest species groups like invertebrates, plants, and fungi, especially in the little-explored regions around the tropics. It’s also because there are increasingly fewer experts to describe them due to a widespread lack of funding and training, noted conservation ecologist Natalia Ocampo-Peñuela of the University of California, Santa Cruz. Ocampo-Peñuela told Undark that she has no doubt that many species are going extinct without anyone noticing. “I think it is a phenomenon that will continue to happen and that it maybe has happened a lot more than we realize,” she said.

Studies of animal and plant specimens in museum and herbaria collections can uncover some of these dark extinctions. This can happen when scientists take a closer look at or conduct DNA analysis on specimens believed to represent known species and realize that these have actually been mislabeled, and instead represent new species that haven’t been seen in the wild in decades. Such a case unfolded recently for the ichthyologist Wilson Costa of the Federal University of Rio de Janeiro, who has long studied the diversity of killifish inhabiting southeastern Brazil’s Atlantic Forest. These fish live in shady, tea-colored acidic pools that form during the rainy season and lay eggs that survive through the dry period. These fragile conditions make these species extremely vulnerable to changes in water supply or deforestation, Costa wrote to Undark via email.

In 2019, Costa discovered that certain fish specimens collected in the 1980s weren’t members of Leptopanchax splendens, as previously believed, but actually represented a new species, which he called Leptopanchax sanguineus. With a few differences, both fish sport alternating red and metallic blue stripes on their flanks. While Leptopanchax splendens is critically endangered, Leptopanchax sanguineus hasn’t been spotted at all since its last collection in 1987. Pools no longer form where it was first found, probably because a nearby breeding facility for ornamental fish has diverted the water supply, said Costa, who has already witnessed the extinctions of several killifish species. “In the case discussed here, it was particularly sad because it is a species with unique characteristics and unusual beauty,” he added, “the product of millions of years of evolution stupidly interrupted.”

Similar discoveries have come from undescribed specimens, which exist in troves for diverse and poorly-studied groups of species, such as the land snails that have evolved across Pacific Islands. The mollusk specialist Alan Solem estimated in 1990 that, of roughly 200 Hawaiian species of one snail family, the Endodontidae, in Honolulu’s Bishop Museum, fewer than 40 had been described. All but a few are now likely extinct, said University of Hawaii biologist Robert Cowie, perhaps because invasive ants feasted off the snails’ eggs, which this snail family carries in a cavity underneath their shells. Meanwhile, Cheek said he’s publishing more and more new plant species from undescribed herbaria specimens that are likely already extinct in the wild.

Sometimes, though, it’s hard to identify species based on individual specimens, noted botanist Naomi Fraga, who directs conservation programs at the California Botanic Garden. And describing new species is not often a research priority. Studies that report new species aren’t often cited by other scientists, and they typically also don’t help towards pulling in new funding, both of which are key to academic success, Cheek said. One 2012 study concluded it takes an average of 21 years for a collected species to be formally described in the scientific literature. The authors added that if these difficulties — and the general dearth of taxonomists — persist, experts will continue to find extinct species in museum collections, “just as astronomers observe stars that vanished thousands of years ago.”

Museum records may only represent a fraction of undescribed species, causing some scientists to worry that many species could disappear unnoticed. For some groups, like snails, this is less likely, as extinct species may leave behind a shell that serves as a record of their existence even if collectors weren’t around to collect live specimens, noted Cowie. For instance, this allowed scientists to identify nine new and already-extinct species of helicinid land snails by combing the Gambier Islands in the Pacific for empty shells and combining these with specimens that already existed in museums. However, Cowie worries about the many invertebrates such as insects and spiders that won’t leave behind long-lasting physical remains. “What I worry about is that all this squishy biodiversity will just vanish without leaving a trace, and we’ll never know existed,” Cowie said.

Even some species that are found while they are still alive are already on the brink. In fact, research suggests that it’s precisely the newly described species that tend to have the highest risk of going extinct. Many new species are only now being discovered because they’re rare, isolated, or both — factors that also make them easier to wipe out, said Fraga. In 2018 in Guinea, for instance, botanist Denise Molmou of the National Herbarium of Guinea in Conakry discovered a new plant species which, like many of its relatives, appeared to inhabit a single waterfall, enveloping rocks amid the bubbly, air-rich water. Molmou was the last known person to see it alive.

Just before her team published their findings in the Kew Bulletin last year, Cheek looked at the waterfall’s location on Google Earth. A reservoir, created by a hydroelectric dam downriver, had flooded the waterfall, surely drowning any plants there, Cheek said. “Had we not got in there, and Denise had not gotten that specimen, we would not know that that species existed,” he added. “I felt sick, I felt, you know, it’s hopeless, like what’s the point?” Even if the team had known at the point of discovery that the dam was going to wipe it out, Cheek said, “it’d be quite difficult to do anything about it.”

While extinction is likely for many of these cases, it’s often hard to prove. The IUCN requires targeted searches to declare an extinction — something that Costa is still planning on doing for the killifish, four years after its discovery. But these surveys cost money, and aren’t always possible.

Meanwhile, some scientists have turned to computational techniques to estimate the scale of dark extinction, by extrapolating rates of species discovery and extinctions among known species. When Chisholm’s group applied this method to the estimated 195 species of birds in Singapore, they estimated that 9.6 undescribed species have vanished from the area in the past 200 years, in addition to the disappearance of 58 known species. For butterflies in Singapore, accounting for dark extinction roughly doubled the extinction toll of 132 known species.

Using similar approaches, a different research team estimated that the proportion of dark extinctions could account for up to just over a half of all extinctions, depending on the region and species group. Of course, “the main challenge in estimating dark extinction is that it is exactly that: an estimate. We can never be sure,” noted Quentin Cronk, a botanist of the University of British Columbia who has produced similar estimates.

Considering the current trends, some scientists doubt whether it’s even possible to name all species before they go extinct. To Cowie, who expressed little optimism extinctions will abate, the priority should be collecting species, especially invertebrates, from the wild so there will at least be museum specimens to mark their existence. “It’s sort of doing a disservice to our descendants if we let everything just vanish such that 200 years from now, nobody would know the biodiversity — the true biodiversity — that had evolved in the Amazon, for instance,” he said. “I want to know what lives and lived on this Earth,” he continued. “And it’s not just dinosaurs and mammoths and what have you; it’s all these little things that make the world go round.”

Other scientists, like Fraga, find hope in the fact that the presumption of extinction is just that — a presumption. As long as there’s still habitat, there’s a slim chance that species deemed extinct can be rediscovered and returned to healthy populations. In 2021, Japanese scientists stumbled across the fairy lantern Thismia kobensis, a fleshy orange flower only known from a single specimen collected in 1992. Now efforts are underway to protect its location and cultivate specimens for conservation.

Fraga is tracking down reported sightings of a monkeyflower species she identified in herbaria specimens: Erythranthe marmorata, which has bright yellow petals with red spots. Ultimately, she said, species are not just names. They are participants of ecological networks, upon which many other species, including humans, depend.

“We don’t want museum specimens,” she said. “We want to have thriving ecosystems and habitats. And in order to do that, we need to make sure that these species are thriving in, you know, populations in their ecological context, not just living in a museum.”

Katarina Zimmer is a science journalist. Her work has been published in The Scientist, National Geographic, Grist, Outside Magazine, and more.

This article was originally published on Undark. Read the original article.

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Cold weather is prime time for humans to stay inside and snuggle up with loved ones. For our primate cousins, cuddling may even keep them healthy, as frosty temps and social bonds seem to go together like hot chocolate and marshmallows. Chilly temperature behavior, as it turns out, may also alter the course of evolution.

A study published June 1 in the journal Science found that a species’ long-term adaptation to life in extremely cold climates led to the evolution of successful social behaviors. Asian colobines living in colder regions saw genetic changes and adaptations to their social behaviors including extended care by mothers, which increased infant survival and the primates’ ability to live in the large complex multilevel societies we see today.

[Related: These primate ancestors were totally chill with a colder climate.]

An international team of researchers from the United States, China, the United Kingdom, and Australia studied how langurs and odd-nosed monkeys adapted over time. These members of the colobine family are leaf-eating monkeys that have been on Earth for about 10 million years. Their ancient ancestors dispersed across the planet’s continents and learned to live in tropical, temperate, and colder climates. 

“Virtually all primates are social and live in social groups,” study co-author and  University of Illinois Urbana-Champaign anthropologist Paul A. Garber said in a statement. “But the groups differ in size and cohesiveness. There are those that live in units of two or three individuals and others living in communities of up to 1,000 individuals.”

According to Garber, genomic studies suggest that the harem unit of organization—one male with two or more females and their offspring—was the ancestral norm for Asian colobines. Males are intolerant of other rival males and will fight to protect their turf. In some species, the females will stay with their natal group, while in others, both sexes leave to join or form new harems.

More complex societies formed over time. Some odd-nosed monkeys still form harems, but aren’t territorial. “This means their group territories can overlap and there are times they may come together to forage, rest and travel,” said Garber. 

Snub-nosed monkeys form a multilevel or modular society where multiple harems remain together throughout the year and create a large, cohesive breeding band. The team on this study recorded a society of about 400 individuals and breeding between individuals from different harems was common in golden snub-nosed monkeys. This inter-harem breeding happened roughly 50 percent of the time.

The study used ecological, geological, fossil, behavioral, and genomic analyses, and found that the colobine primates that lived in colder places tended to live in larger and more complex social groups. The glacial periods over the past six million years likely promoted the selection of genes that are involved in cold-related energy metabolism and hormonal regulation in the nervous system.

[Related: Baboons can recover from childhood trauma with a little help from their friends.]

Black-and-white snub-nosed monkeys in some parts of China live in low-oxygen elevations up to about 13,500 feet where night time temperatures can drop below zero on the coldest evenings. The Odd-nosed monkeys living in extremely cold locations developed more efficient pathways for dopamine and oxytocin. Oxytocin particularly is an important neurohormone for social bonding and this hormonal efficiency may lengthen the time a mother monkey takes care of her baby. This led to longer periods of breast-feeding and increase in infant survival.  

These adaptive changes appear to have further strengthened the relationships between individual monkeys, increased tolerance between males, and encouraged the evolution of more complex and larger multi level societies that go a long way. Strong social bonds can even help gut bacteria health in some monkeys.

In future studies, the team is interested in studying how changes in mating and social behavior may be the result of genetic changes from past environments and other social factors from the past. 

“With climate change becoming an hugely important environmental pressure on animals, it is hoped that this study will raise awareness for the need to investigate what course social evolution will take as the prevailing climate changes,” study co-author and University fo Western Australia biological anthropologist Cyril Grueter said in a statement. “Our finding that complex multilevel societies have roots stretching back to climatic events in the distant evolutionary past also has implications for a reconstruction of the human social system which is decidedly multilevel.”

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Over three million years ago, a 500-plus pound marsupial roamed Australia, winning the prize of the continent’s first long-distance walking champion. In a study published May 31 in the Journal of Royal Society Open Science, a team of scientists described the discovery of this new genus using advanced 3D scans and the partial remains of a 3.5 million year old specimen. 

Most earlier studies on this group have focused on its skull since other skeletal remains are rare in Australia’s fossil record. The skeleton described in this new study, found at Kalamurina Station in southern Australia in 2017, is special since it is the first that was found with associated soft tissue structures. The authors used 3D-scanning to compare the partial skeleton with other diprotodontid material housed in collections all over the world. A hard concretion that formed shortly after the animal died encased its foot, and CT scans revealed the soft tissue impressions on the outline of its footpad.

[Related: Giant wombats the size of small cars once roamed Australia.]

The new genus Ambulator, meaning “walker” or “wanderer,” had four giant legs which would have helped it roam long distances in search of food and water compared to its earlier relatives. It belongs to the Diprotodontidae family, an extinct family of big, four-legged, herbivorous marsupials that lived in New Guinea and Australia. The largest species was Diprotodon optatum, which was about the size of a car and weighed almost 6,000 pounds. Diprotodontids were an integral part of the region’s ecosystem before going extinct about 40,000 years ago. 

“Diprotodontids are distantly related to wombats – the same distance as kangaroos are to possums – so unfortunately there is nothing quite like them today. As a result, paleontologists have had a hard time reconstructing their biology,” study author and Flinders University PhD student Jacob van Zoelen said in a statement. 

Ambulator keanei lived during the Pliocene era when Australia saw an increase in grasslands and open habitats become more dry. To have enough to eat and drink, diprotodontids likely had to travel great distances. 

“We don’t often think of walking as a special skill but when you’re big any movement can be energetically costly so efficiency is key,” said van Zoelen. “Most large herbivores today such as elephants and rhinoceroses are digitigrade, meaning they walk on the tips of their toes with their heel not touching the ground.  “

Diprotodontids are plantigrade animals, which means that their heel-bone makes contact with the ground as they walk. This is similar to the way humans walk and helps distribute the weight while walking, but does use more energy when running. According to van Zoelen, diprotodontids also have extreme plantigrady in their hands. The bone of the wrist is modified into a secondary heel and this “heeled hand” may have made early reconstructions of the animal look a little bit bizarre.

“Development of the wrist and ankle for weight-bearing meant that the digits became essentially functionless and likely did not make contact with the ground while walking.” said van Zoelen. “This may be why no finger or toe impressions are observed in the trackways of diprotodontids.”

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Efficiently standing up and walking and running on two feet  stands out among the traits that separates Homo sapiens from great apes—and we can owe a lot of that to a raised medial arch. While crucial, the mechanics behind bipedal walking are still a bit of an evolutionary mystery.  A study published May 30 in the journal Frontiers in Bioengineering and Biotechnology found that helpful and spring-like arches may have evolved for the purpose of helping us walk on two feet.

[Related: Foraging in trees might have pushed human ancestors to walk on two feet.]

The team found that the recoil of a flexible arch repositions in the ankle upright for more efficient walking and is particularly effective for running. 

“We thought originally that the spring-like arch helped to lift the body into the next step,” study co-author and University of Wisconsin-Madison biomechanical engineer Lauren Welte said in a statement. “It turns out that instead, the spring-like arch recoils to help the ankle lift the body.”

The raised arch in the center of the human foot is believed to give hominins more leverage while walking upright. When arch motion is restricted, like it could be in those with more flat feet, running demands more energy from the body. Arch recoil could potentially make our species more efficient by propelling the body’s center of mass forward, essentially making up for the mechanical work that the muscles would have to do otherwise.

In this new study, the team selected seven participants with varying arch mobility and filmed their walking and running patterns with high-speed x-ray motion capture cameras. The team measured the height of each participant’s arch and took CT scans of their right feet. They also created rigid models that were compared to the measured motion of the bones in the foot. Scientists then measured which joints added the most to arch recoil and the contribution of arch recoil to center of mass and ankle propulsion.

Surprisingly, they found that a rigid arch without recoil caused the foot to prematurely leave the ground, likely decreasing the efficiency of the calf muscle. A rigid arch also leaned the ankle bones too far forward. A forward lean looks more like the posture of walking chimpanzees instead of the straight upright stance of a human gait.

A flexible arch helped reposition the ankle upright, allowing the leg to push off the ground more effectively. This effect is greater while running, suggesting that a flexible arch for more efficient running may have been a desired evolutionary trait.

The team also found that a joint between two bones in the medial arch–the navicular and the medial cuneiform–is crucial to flexibility. Investigating the changes in this joint over time could help scientists track the development of bipedalism in our own fossil record. 

[Related: The Monty Python ‘silly walk’ could replace your gym workout.]

“The mobility of our feet seems to allow us to walk and run upright instead of either crouching forward or pushing off into the next step too soon,” study co-author and Queen’s University mechanical and materials engineer Michael Rainbow said in a statement.

These findings and understanding more about arch flexibility could help people who have rigid arches due to illness or injury. Their hypothesis still needs more testing, but could help solve a plethora of modern-day foot dilemmas. 

“Our work suggests that allowing the arch to move during propulsion makes movement more efficient,” said Welte. “If we restrict arch motion, it’s likely that there are corresponding changes in how the other joints function.”

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As they creep through tropical environments appearing not to have a care in the world, sloths give off some of the chillest vibes in the animal kingdom. This relaxed and elusive nature does make studying sloths a bit difficult, but a study published May 29 in the journal PeerJ Life & Environment is shedding some new light on activity patterns and behaviors adaptations of two sloth species.

[Related: Sloths aren’t the picky eaters we thought they were.]

The team looked at Bradypus variegatus and Choloepus hoffmanni, two sloth species that live in the lowland rainforests of Costa Rica’s Caribbean coast. Costa Rica is home to six species of sloths, who have the slowest digestive system of any animal on Earth. It can take the mammals two weeks to digest an entire meal, and they sleep about 20 hours a day to conserve energy. 

Using micro data loggers, the team continuously monitored the behavior of both three-toed sloths (Bradypus) and two-toed sloths (Choloepus) for periods ranging from days to weeks. These recordings enabled the team to explore how fluctuating environmental influences sloth activity and how that correlates with their uniquely chill and low-energy lifestyle. 

Choloepus sloths are cathemeral, meaning that they have irregular variable periods of activity throughout a 24-hour cycle. Cathemeral behavior allows them to take advantage of better environmental conditions while minimizing the risk of predation. 

The study also observed a large amount of variability in activity levels between the animals and also within individual sloths. This flexibility suggests that the animals have developed diverse strategies to adapt to their surroundings, which enhances their chances of survival when the environment fluctuates. 

The team initially expected that daily temperatures, which can hit the mid-90s, would influence sloth activity, but their observations did not support that initial hypothesis. However, Bradypus sloths did increase their night time activity on colder nights and the nights that followed colder days. The authors believe that this indicates a potential correlation between sloth behavior and temperature variations.

[Related: Our bravest ancestors may have hunted giant sloths.]

While this study adds more understanding to sloth ecology, it also highlights the importance of preserving and protecting tropical rainforests and their unique inhabitants. According to Global Forest Watch, Costa Rica lost about 2.4 percent of its forest cover between 2000 and 2020, but the country has gained international recognition for its efforts to mitigate climate change and promote animal welfare.

“Understanding the drivers of sloth activity and their ability to withstand environmental fluctuations is of growing importance for the development of effective conservation measures, particularly when we consider the vulnerability of tropical ecosystems to climate change and the escalating impacts of anthropogenic activities in South and Central America,” the team wrote in the paper.

As these tropical ecosystems become more vulnerable due to human-made climate change, understanding wildlife patterns are crucial for conservation methods. While long-term observational research is a challenge, this study could pave the way for more studies on this cryptic and elusive species. 

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The armadillo is beloved for its ability to scrunch itself up in a ball with their protective flexible shells. They’ve long been considered the only living mammals with these reptilian and fish-like suits of bony or scaly armor instead of hairy mammalian skin. However, a study published May 24 in the journal iScience, shows that African spiny mice actually produce the same spiny structures beneath the skin of their tails, which has gone largely undetected by scientists.

[Related: How science came to rely on the humble lab rat.]

African spiny mice are small to medium sized rodents with spiny hairs on their upper body, large eyes and ears, and scaly tails. Some species are found in Egypt, other parts of eastern Africa, Saudi Arabia, and Pakistan and while others are native to South Africa.  

A team of scientists made this spiny discovery while conducting routine CT scanning of museum specimens for the openVertebrate program. 

“I was scanning a mouse specimen from the Yale Peabody Museum, and the tails looked abnormally dark,” co-author and director of Florida Museum of Natural History’s digital imaging laboratory Edward Stanley said in a statement. 

Stanley initially assumed the discoloration was caused by an imperfection that was introduced when the specimen was preserved, but analysis of the X-Rays revealed an unmistakable feature that he was intimately familiar with.

“My entire PhD was focused on osteoderm development in lizards,” he said. “Once the specimen scans had been processed, the tail was very clearly covered in osteoderms.”

Osteoderms are the bony deposits that form scales or plates on the skin. They are also distinct from the scales of pangolins or the quills of hedgehogs and porcupines. These parts are composed of keratin, the same tissue that makes up hair, skin, and nails.

Osteoderms on spiny mice have been observed since the mid-1970s. A 2012 study demonstrated spiny mice can regenerate injured tissue without scarring. This ability is very common among reptiles and invertebrates, but was previously unknown in mammals. While mammalian skin is particularly fragile, spiny mice can heal twice as fast as their rodent relatives.

Spiny mice belong to four genera in the subfamily Deomyinae, but other than similarities in their DNA and possibly the shape of their teeth, scientists have been unable to find a single shared feature among the species of this group that distinguishes them from other rodents.

[Related: This newly discovered gecko can literally squirm right out of its skin.]

The team scanned additional museum specimens from all four genera and found that the spiny mice tails were covered in the same sheather of bone. Gerbils are the closest relatives of Deomyinae and they do not have osteoderms, which means that this trait likely evolved only once in the ancestor of spiny mice. 

“Spiny mice can regenerate skin, muscle, nerves, spinal cord and perhaps even cardiac tissue, so we maintain a colony of these rare creatures for research,” co-author and University of Florida biologist Malcolm Maden said in a statement. 

Maden and his team are mapping the genetic pathways that give spiny mice these healing powers to hopefully find a model for human tissue regeneration. The team further analyzed the development of spiny mice osteoderms and confirmed that they were similar to those of armadillos, but likely evolved independently. 

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If Spiderman and Antman took their DNA and mixed it together in a petri dish, the result might be something like the spider species Siler collingwoodi (S. collingwoodi). This tiny, colorful, jumping spider found in China and Japan uses a combination of camouflage and some award-worthy mimicry to deter some hungry predators. In a stressful scenario, these spiders will imitate the way an ant walks to avoid being eaten.

[Related: Black widows battle their even deadlier cousins in a brutal spider war.]

A study published May 17 in the journal iScience found that the combo of camouflage and ant mimicry works to evade spiders that eat other spiders, but not hungry praying mantises. It’s advantageous to mimic an ant because they are typically not very tasty, and can have spiny defenses, chemical repellents, or venom. Not to mention, species of “exploding” ants like Colobopsis saundersi that are not afraid to fight and bite back. While scientists already knew that S. collingwoodi walked like an ant, the team on this study were curious how accurate the mimicry is, whether it imitates multiple species of ants, and how effective it is at discouraging predators. 

“Unlike typical ant-mimicking spiders that mimic the brown or black body color of ants, S. collingwoodi has brilliant body coloration,” co-author and Peking University in China ecologist Hua Zeng said in a statement. “From a human’s perspective, it seems to blend well with plants in its environment, but we wanted to test whether their body coloration served as camouflage to protect against predators.”

To better understand how these ant-inspired theatrics help the spiders avoid becoming dinner, the team collected wild ant-mimicking spiders from four spots in southern Hainan, China, and brought them back to the lab. They also collected another type of jumping spider that does not mimic ants as a comparison and five co-occurring ant species as potential models.  

The team then compared and characterized how the insects and arachnids moved in terms of how they used their individual limbs, their speed, acceleration, and whether they followed a straight path or took a more roundabout way. 

Inside of jumping like most jumping spiders, S. collingwoodi scuttle around like ants. They raise their front legs to mimic an ant’s antennae, bob their abdomens, and lift their legs to walk more ant-like. Out of the five ant species studied, the spider’s style of walking more closely resembled three of the smaller ant species that are closer in size.

“S. collingwoodi is not necessarily a perfect mimic, because its gait and trajectory showed high similarity with multiple ant species,” said Zeng. “Being a general mimic rather than perfectly mimicking one ant species could benefit the spiders by allowing them to expand their range if the ant models occupy different habitats.”

Then it was time to test these defenses against two likely predators. Portia labiata and the praying mantis. Portia labiata is a similarly sized jumping spider with color vision who specializes in preying upon other spiders. The praying mantis is a more generalist predator that has a monochromatic visual system–meaning it has trouble telling multiple colors apart. 

[Related: Jumping spiders might be able to sleep—perchance to dream.]

To see how the color camouflaging was working, they modeled how the two predators would perceive S. collingwoodi relative to the other prey species. They used a background of two plants that the spiders live on—the red-flowering West Indian jasmine and the Fukien tea tree The ant-mimicking spiders were better camouflaged from both predators on the jasmine plant than on the tea tree plant.

The predators were more likely to attack the non-mimicking spider than the ones that imitate ants. Out of 17 trials, the spider launched five attacks—all of them were launched towards a non-mimicking spider. However, praying mantises attacked both prey species with equal readiness.

“We initially thought that both predators would behave similarly in the anti predation experiments, but in fact the simulated ant locomotion of Siler collingwoodi only worked for the jumping spider predator, while the praying mantis showed indiscriminate attacks on both ants and mimics,” co-author and Peking University evolutionary ecologist Wei Zhang said in a statement. 

It is possible that this difference might be driven by each predator’s likelihood of being injured if they eat an ant. The praying mantises are much larger than their prey, and they have a better chance of eating spiny ants without risking catastrophic injury. Predatory spiders do not have this margin for error. 

“For the spider predator, a random attack on an ant could result in injury,” says Zhang, “so they are very careful predators and will only attack if they can distinguish S. collingwoodi from ants with a high degree of certainty.”

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Up until 100 million years ago, butterflies were night creatures. Only nocturnal moths were living on Earth until some rogue moths began to fly during the day. These enterprising members of the order Lepidoptera took advantage of the nectar-rich flowers that had co-evolved with bees by flying during the day. From there, close to 19,000 butterfly species were born.

[Related: Save caterpillars by turning off your outdoor lights.]

In 2019, a large-scale analysis of DNA helped solve the question of when they evolved. Now,  the mystery of where in the world colorful winged insects evolved plagues lepidopterists and museum curators. A study published May 15 in the journal Nature Ecology and Evolution found that butterflies likely evolved in North and Central America, and they forged strong botanical bonds with host plants as they settled around the world.

Getting to this conclusion took a four-dimensional puzzle that makes 3D chess look like a game of Candyland. Scientists from multiple countries had to assemble a massive “butterfly tree of life” using 100 million years of natural history on their distribution and favorite plants, as well as the DNA of more than 2,000 species representing 90 percent of butterfly genera and all butterfly families. 

Within the data were 11 rare butterfly fossils that proved to be crucial pieces to the story.  Butterflies are not common in the fossil record due to their thin wings and very threadlike hair. The 11 in this study were used as calibration and comparison points on the genetic trees, so the team could record timing of key evolutionary events.

They found that butterflies first appeared somewhere in central and western North America. 100 million years ago, North America was bisected by an expansive seaway called the Western Interior Seaway. Present day Mexico was joined in an arc with the United States, Canada, and Russia. North and South America were also separated by a strait of water that butterflies had little difficulty crossing.

The study believes that butterflies took a long way around to Africa, first moving into Asia along the Bering Land Bridge. They then radiated into Southeast Asia, the Middle East, and eventually the Horn of Africa. They were even able to reach India, which was an isolated island separated by miles of open sea at this time. 

[Related: The monarch butterfly is scientifically endangered. So why isn’t it legally protected yet?]

Australia was still connected to Antarctica, one of the last remnants of the supercontinent Pangaea. Butterflies possibly lived in Antarctica when global temperatures were warmer, and made their way north towards Australia before the landmasses broke up. 

Butterflies likely lingered along the western edge of Asia for up to 45 million years before making the journey into Europe. The effects of this pause are still apparent today, according to the authors. 

“Europe doesn’t have many butterfly species compared to other parts of the world, and the ones it does have can often be found elsewhere. Many butterflies in Europe are also found in Siberia and Asia, for example,” study co-author and curator of lepidoptera at the Florida Museum of Natural History Akito Kawahara said in a statement. 

Once butterflies were established all over the world, they rapidly diversified alongside their plant hosts. Nearly all modern butterfly families were on Earth by the time dinosaurs went extinct 66 million years ago. Each butterfly family appears to have had a special affinity for a specific group of plants.

“We looked at this association over an evolutionary timescale, and in pretty much every family of butterflies, bean plants came out to be the ancestral hosts,” Kawahara said. “This was true in the ancestor of all butterflies as well.”

Over time, bean plants have increased their roster of pollinators to include multiple types of bees, flies, hummingbirds, and mammals, while butterflies have similarly expanded their palate. These botanical partnerships helped make butterflies blossom from a minor offshoot of moths to one of the world’s largest groups of insects, according to the study.

“The evolution of butterflies and flowering plants has been inexorably intertwined since the origin of the former, and the close relationship between them has resulted in remarkable diversification events in both lineages,” study co-author and Florida Museum curator Pamela Soltis said in a statement. 

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After an asteroid that wiped out the dinosaurs struck the Earth, the prehistoric giants lost their dominion over the planet. The mammals that rose up about 66 million years ago during the Eocene Epoch had some big shoes to fill—and they certainly grew into the challenge over time.

[Related: We’re one step closer to identifying the first-ever mammals.]

In a study published May 11 in the journal Science, found that a family of extinct rhinoceros-like herbivores called brontotheres began their time on Earth about the size of a dog, but evolved to reach elephant size over a relatively short amount of time. Brontotheres also may have not reached its full size potential before it went extinct roughly 34 million years ago due to changes in their environment.

With the dinosaurs gone at the end of the Cretaceous period (145 million to 66 million years ago), the mammals of the world had significantly less competition for resources, and scientists believe this led to their success as a family. Brontotheres was one of the biggest winners among mammals, and grew from about coyote-sized, 40 pound creatures into 2,000 pound goliaths. According to the study, they did this over a period of only 16 million years, which is very quick in evolutionary terms.

Brontothere means “thunder beasts,” and their powerful name was inspired by Lakota oral histories of violent thunderstorms accompanied by giants, according to the National Park Service.The animals lived in Asia, Europe, and North America. Most species weighed over a ton, but the biggest roamed what is now the South Dakota Badlands. These giants clocked in at about 8 feet tall and 16 feet long. They are the relatives of modern tapirs, horses, and rhinos, and were equipped with Y-shaped horns on their noses. 

The team of researchers on this brontothere size evolution study peered back at the evidence from the family’s fossil record and a family tree of 276 known brontothere individuals. They were fortunate that the fossil record shows most of their evolutionary record, and the team generated computer models to track how the genetic traits of different brontothere species changed. 

They also conducted phylogenetic analysis, or an evaluation of the evolutionary avenues that causes a new species to take shape. This helped them determine how such evolutionary changes may be linked or connected to their increase in body size. 

The data showed that body size actually evolved in both directions across brontothere species. Some would evolve bigger, while other times a species would evolve smaller. They found that the smaller species were more prone to extinction compared to their bigger cousins, and a trend of bulkier brontotheres persisted longer than the smaller species emerged.  

[Related from PopSci+: An ancient era of global warming could hint at our scorching future.]

Towards the end of the Eocene, the remaining brontotheres were true thunder beasts. Their status as megaherbivores likely benefited the beasts, with the smaller animals being more vulnerable to become a carnivore’s dinner. Competition from other big and small herbivores could hardly stand up to the beasts, according to the study.

Unfortunately, at this same time, the climate drastically changed from a more humid herbivore’s paradise to something much more dry. The brontotheres thus lost their evolutionary advantages when the previously lush and green ecosystem dried up. They eventually went extinct about 34 million years ago.

Further research into this family could model the ecological factors like ancient climate shifts that affected how much edible vegetation covered the planet and how it led to the demise of these megaherbivores.

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The humble sea star is an ancient marine creature that possibly goes back about 480 million years. They are beloved in touch tanks in aquariums for their celestial shape, spongy skin, and arm suckers. These beautiful five-limbed echinoderms are also helping scientists figure out a crucial life process called tubulogenesis. 

[Related: What’s killing sea stars?]

A study published May 9 in the journal Nature Communications, examined this process of hollow tube formation in sea stars that provides a blueprint for how the organs of other creatures develop.

Tubulogenesis is the formation of various kinds of hollow, tube-like structures. in the body. These tubes eventually form blood vessels, digestive tracts, and even complex organs like the heart, kidneys and mammary glands. It is a basic and crucial process that occurs in the embryo stage, and abnormalities during these processes can cause dysfunctional, displaced, or non-symmetrical organs and even regeneration defects in structures like blood vessel. 

Little is known about the general mechanisms of the hollow tube formation during embryogenesis since animals all use very different strategies to form these tubular structures.

That’s where the sea star comes in. Their process of tubulogenesis is relatively easy to observe since their embryos are very transparent and can be observed without disturbing them. Not to mention, they breed in large numbers year round. This new study reveals the initiation and early stages of tube formation in the sea star Patiria miniata or bat star.

“Most of our organs are tubular, because they need to transport fluids or gasses or food or blood. And more complex organs like the heart start as a tube and then develop different structures. So, tubulogenesis is a very basic step to form all our organs,” study co-author and cell biologist Margherita Perillo of the University of Chicago-affiliated Marine Biological Laboratory said in a statement. 

Not only is the sea star an ideal because of its translucence, the researchers needed an animal that was along the base of the tree of life and evolved before the phylum Chordata– vertebrates including fish, amphibians, reptiles, birds, and mammals, Perillo adds.

Perillo and her colleagues used CRISPR gene editing and other techniques to analyze the gene functions in the sea stars and long time-lapse videos of developing larvae. The team worked out how the sea star generates the tubes that branch out from its gut. From these observations, they could define the basic tools needed for more advanced chordate tubular organs that may have developed. Now, they are getting closer to answering how organisms developed up from one cell into the more complex 3D tubular structures that make up various organisms. 

According to Perillo, in some organisms such as flies, “there is a big round of cell proliferation before all the cells start to make very complex migration patterns to elongate, change their shapes, and become a tube.”

[Related: These urchin-eating sea stars might be helping us reduce carbon levels.]

In other animals, including mammals, cell proliferation and migration occur together. The team found that in sea stars, cells can also proliferate and migrate at the same time in order for the tubes to form the way they do in vertebrate formation. The mechanism behind making organs must have already been established at the base or root of chordate evolution, according to the team. 

Beyond providing evolutionary insights into organ formation, sea stars can also aid in biomedical research. Perillo found that a gene called Six1/2 is a key regulator of the branching process in tube formation. If Six1/2 is taken out of mice, their kidneys form abnormally, but the mice that lack the gene also resist tumor formation, even if they are injected with tumor cells. Understanding this gene, that is overexpressed in cancer cells, may lead to new ways to study disease progression.  

“I can now use this gene to understand not only how our organs develop, but what happens to organs when we have a disease, especially cancer,” said Perillo. “My hope is that, in five to 10 years maximum, we will be able to use this gene to test how organs develop cancer and how cancer becomes metastatic.”

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Before being outbred by Homo sapiens, Neanderthals could have been many things: including the world’s first weavers, artists, and even crab chefs. Their contributions may even go deeper—even to modern day faces. Genetic material from this now extinct crew  influences the shape of human noses today, according to new research. 

In a study published May 8 in the journal Communications Biology, an international team of researchers found a particular gene that leads to a taller nose (top to bottom) might be the product of natural selection when sentient humans adapted to colder climates after leaving the African continent.

[Related: Humans and Neanderthals could have lived together even earlier than we thought.]

“In the last 15 years, since the Neanderthal genome has been sequenced, we have been able to learn that our own ancestors apparently interbred with Neanderthals, leaving us with little bits of their DNA,” Kaustubh Adhikari, a co-author and statistical geneticist at University College London, said in a statement. “Here, we find that some DNA inherited from Neanderthals influences the shape of our faces. This could have been helpful to our ancestors, as it has been passed down for thousands of generations.”

The research team used data from over 6,000 volunteers from Brazil, Colombia, Chile, Mexico, and Peru with mixed European, Native American, and African ancestry. They compared their genetic information to photographs of their faces, and examined the distances between points on the face, like the edge of the lips to the tips of the nose to see how different facial traits might be associated with different genetic markers.

“Most genetic studies of human diversity have investigated the genes of Europeans; our study’s diverse sample of Latin American participants broadens the reach of genetic study findings, helping us to better understand the genetics of all humans,” Andres Ruiz-Linares, co-author and geneticist at University College London, said in a statement.

They found 33 new genome regions that are associated with face shape, and they could replicate 26 of them in comparisons with data from other ethnicities using participants in east Asia, Europe, or Africa.

[Related: Europeans looked down on Neanderthals—until they realized they shared their DNA.]

They looked at a genome region called ATF3, and found that many of those in the study with Native American ancestry had genetic material inherited from Neanderthals that contributes to nasal height. They compared that same genome region with those of east Asian ancestry from a different cohort and saw the same genetic material.  This gene region also has signs of natural selection, suggesting that it has an advantage for those carrying the genetic material.

“It has long been speculated that the shape of our noses is determined by natural selection; as our noses can help us to regulate the temperature and humidity of the air we breathe in, different shaped noses may be better suited to different climates that our ancestors lived in,” Qing Li, a co-author and scientist at China’s Fudan University, said in a statement. “The gene we have identified here may have been inherited from Neanderthals to help humans adapt to colder climates as our ancestors moved out of Africa.”

In 2021, this same team also found that genes influencing facial shapes were inherited from another extinct human species called the Denisovans. In that study, they found 32 gene regions that influence facial features like nose, lip, jaw, and brow shape.

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There is truly no shortage of interesting courting and mating rituals throughout the animal kingdom. From trilobites “jousting” to win mates to the important pee sniffing rituals of giraffes, getting it on is serious business. And so is winning over a mate. 

[Related: Male California sea lions have gotten bigger and better at fighting.]

For the first time, scientists have found direct evidence that adult male woolly mammoths experienced an event called musth. Musth comes from the Hindi and Urdu word for intoxicated, and in the case of giant mammals like adult elephants, this is a testosterone-fueled event where the male sex hormone surges and aggression against rival males is heightened. 

The study, published online May 3 in the journal Nature, found evidence that testosterone levels are recorded within the growth layers of both elephant and mammoth tusks. In living male elephants, blood and urine tests recognized the elevated testosterone, but musth battles from its extinct relatives has only been inferred from to fossilized consequences of testosterone-fueled battle, such as pieces of tusk tips and skeletal injuries. 

In the study, an international team of researchers report the presence of annually recurring testosterone surges (up to 10 times higher than baseline levels) are present within a permafrost-preserved woolly mammoth tusk. 

The team sampled tusks from one adult African bull elephant from Botswana and two adult woolly mammoths: a male who roamed Siberia over 33,000 years ago and a roughly 5,597 year-old female that was discovered on Wrangel Island. This Arctic Ocean island used to be connected to northeast Siberia and is the last place where woolly mammoths survived up until about 4,000 years ago. 

“This study establishes dentin as a useful repository for some hormones and sets the stage for further advances in the developing field of paleoendocrinology,” study co-author and paleontologist at the University of Michigan Museum of Paleontology Michael Cherney said in a statement. “In addition to broad applications in zoology and paleontology, tooth-hormone records could support medical, forensic and archaeological studies.”

Hormones are signaling molecules that help regulate physiology and behavior. Testosterone in male vertebrates is part of the steroid group of hormones. Testosterone circulates throughout the bloodstream and accumulates in various tissues.   

[Related: How much acid should you give an elephant? These scientists learned the hard way.]

According the authors, their findings demonstrate that steroid records in teeth can provide scientists with meaningful biological information that can even persist for thousands of years.

“Tusks hold particular promise for reconstructing aspects of mammoth life history because they preserve a record of growth in layers of dentin that form throughout an individual’s life,” study co-author and U-M Museum of Paleontology curator Daniel Fisher said in a statement.  “Because musth is associated with dramatically elevated testosterone in modern elephants, it provides a starting point for assessing the feasibility of using hormones preserved in tusk growth records to investigate temporal changes in endocrine physiology.”

They team used CT scans to find the annual growth increments deep within the tusks, like tree rings. Modern elephant and ancient mammoth tusks are elongated upper incisor teeth, and only hold on to traces of testosterone and other steroid hormones. The chemical compounds are all incorporated into dentin, which is the mineralized tissue that makes up the interior portion of teeth. 

The study also required new methods to extract steroids from the tusk dentin with a mass spectrometer. Mass spectrometers identify chemical substances by sorting the ions present by their mass and charge. 

“We had developed steroid mass spectrometry methods for human blood and saliva samples, and we have used them extensively for clinical research studies. But never in a million years did I imagine that we would be using these techniques to explore ‘paleoendocrinology,'” study co-author and U-M endocrinologist Rich Auchus said in a statement. 

The results and the new measuring technique will likely further new approaches to investigating reproductive endocrinology, life history, and even disease patterns in modern and prehistoric context.

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The tiny country of Wales on the western coast of Great Britain may now be home to one of the world’s most unexpected fossil sites. Scientists found an “unusually well-preserved”  deposit of over 150 species from 462 million years ago. Interestingly enough, many of them have miniature bodies. The findings by an international team of scientists from the United Kingdom, China, Sweden are detailed in a study published May 1 in the journal Nature Ecology & Evolution.

[Related: These weird marine critters paved the way for the ‘Cambrian explosion’ of species.]

The “marine dwarf world,” as dubbed by the research team, is located in Castle Bank near Llandrindod, central Wales. Two of the study’s authors, Joe Botting and Lucy Muir,  found the site in 2020. Castle Bank is a rare site where the soft tissues and complete organisms are preserved. These specimens help scientists observe how life evolved over time. 

Similar fossil sites like the Burgess Shale fossil deposits in Canada date back 542 to 485 million years ago during the Cambrian period, when recognizable animals first appear in the fossil record. This period is known for a huge explosion of life on Earth. During the Cambrian, the origins of major animal groups still around today, such as mollusks, arthropods, and worms, occurred in what scientists call the Cambrian Explosion. 

The fossilized time capsule from Castle Bank is from the middle of the succeeding Ordovician Period, about 462 million years ago. The Ordovician was a critical time in the history of life when extraordinary diversification of animals occurred and more familiar ecosystems like coral reefs began to appear at the end of the period. Until now, a big gap has existed between thes Cambrian and Ordovician eras. Some of the fauna found at Castle Bank dating back to the middle of this time interval will help fill in evolutionary mysteries about animal shifts over time. 

The more than 150 species found at Castle Bank are almost all new. Many are less than an inch long, but contain tiny details in their bodies. They range from arthropods like crustaceans and horseshoe crabs to worms, sponges, starfish, and more. 

In some animals in the study, internal organs like digestive systems, the limbs of tiny arthropods, delicate filter-feeding tentacles, and even nerves have been preserved. According to the authors, exquisite detail like this is known from Cambrian specimens, but not previously from the Ordovician.

The range of fossils also includes several unusual discoveries, including unexpectedly late examples of animals from the Cambrian that look like the strange looking proto-arthropod opabiniids and slug-like wiwaxiids. Some of the early fossils also resemble modern goose barnacles, possible marine relatives of insects and cephalocarid shrimps, which have no fossil record at all.

[Related: This fossilized ‘ancient animal’ might be a bunch of old seaweed.]

“It coincides with the ‘great Ordovician biodiversification event’, when animals with hard skeletons were evolving rapidly,” Muir, a paleontologist and research fellow from the National Museum Wales, told the BBC. “For the first time, we will be able to see what the rest of the ecosystem was doing as well.”

These findings also have important implications for the evolution of sponges, particularly Hexactinellida. Also called a glass sponge, this animal is considered a transitional interval between sponges that the team have been studying for years. 

“Despite the extraordinary range of fossils already discovered, work has barely begun,” Botting, a paleontologist and research fellow at the National Museum Wales and Nanjing Institute of Geology and Paleontology Chinese Academy of Sciences, told the BBC. “Every time we go back, we find something new, and sometimes it’s something truly extraordinary. There are a lot of unanswered questions, and this site is going to keep producing new discoveries for decades.”

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BUMS. HEINIES. FANNIES. DERRIERES. Few muscles in the human body carry as much cultural clout as the gluteus maximus. “Butts are a bellwether,” writes journalist Heather Radke in her 2022 book Butts: A Backstory. Radke goes on to explain that our feelings about our hindquarters often have more to do with race, gender, and sex than with the actual meat of them. Unlike with a knee or an elbow, Radke argues, when it comes to the tuchus, we’re far more likely to think about form than function—even though it features the largest muscle in the human body. 

For all the scrutiny we spare them (outside of when we’re trying on new jeans) our butts aren’t mere aesthetic flourishes. A booty is, in fact, a unique feat of evolution: Out of any species, humans have the most junk in their trunks. Many other creatures have muscle and fat padding their backsides, and some even have butt cheeks. But none pack anything close to the same proportions as us.

So why did our ancestors develop such a unique cushion? Evolutionary biologists’ best guess is that our shapely rears help us walk upright. The curved pelvic bone that gives the butt its prominence likely developed as our weight moved upward and our muscular needs shifted. Research increasingly suggests that more massive muscles in the vicinity of the buttocks make for faster sprinting and better running endurance too. “The butt is an essential adaptation for the human ability to run steadily, for long distances, and without injury,” Radke writes. 

That said, the gluteus maximus does more than just keep us on our feet. The fat that sits atop it affects how we feel whenever we sit or lie down. The organs nestled behind those cheeks also have a massive influence on our health and wellbeing. Here are a few of the ways our bums factor into scientific understanding, lifesaving medicine, and the future of engineering. 

Digging deep for ancient backsides 

For as long as humans have been making art, they’ve been thinking about bodacious butts. The 30,000-year-old Venus of Willendorf is a famous pocket-size figurine carved by a Western European civilization during the Upper Paleolithic. The statuette, which some archaeologists suspect served as a fertility charm, immortalizes a body too thick to quit.

Scientists also love peeping at the actual posteriors of our early ancestors, which hold a broader archaeological significance in telling the stories of ancient people and their lifestyles. Differences in the pelvis and other sat-upon bones have long been used to determine the sex of unearthed skeletal remains, though we know now there isn’t as clear-cut a binary as researchers long assumed. In 1972, anthropologist Kenneth Weiss flagged that experts were 12 percent more likely to classify skeletons found at dig sites as men versus women, which he blamed on a bias for marking indeterminate skeletons as male. Recent research bears that out, with anthropologists now designating many more remains as having a mix of pelvic characteristics (or simply being inconclusive) than they did historically. Still, while the distinction isn’t completely black and white, the signs of a body primed for or changed by childbirth are useful in figuring out the age and sex of ancient remains. Butt bones can also tell us about how people lived: This March, archaeologists published the oldest known evidence for human horseback riding in the journal Science Advances. They identified their 5,000-year-old equestrians—members of the Yamnaya culture, which spread from Eurasia throughout much of Europe around that same time—with the help of signs of wear and tear to hip sockets, thigh bones, and pelvises. 

Supporting heinies of all shapes and sizes

As Sharon Sonenblum, a principal research scientist at the School of Mechanical Engineering at Georgia Tech, puts it, “What could be better than studying butts?” The Rehabilitation Engineering and Applied Research Lab that she’s part of is perhaps more aptly referred to by its acronym: REAR. 

Stephen Sprigle, a Georgia Tech professor in industrial design, bioengineering, and physiology, started REARLab with better solutions for wheelchair users in mind. A decade ago, he and Sonenblum saw the potential for an engineering-minded solution to the serious clinical problem of injuries from sitting or lying down for extended periods. Pressure sores and ulcers are a risk whenever soft tissue presses against a surface for a prolonged time, and they become more dangerous in hospital settings—where antibiotic-resistant bacteria often lurk—and in people with conditions that hinder wound healing, like diabetes. 

Sonenblum recalls that they set out to answer a deceptively simple question: What makes one backside different from another? To answer it, they had to put a whole lot of booties into an MRI scanner. Those imaging studies and others (including some done on supine patients) have provided an unprecedented amount of data about butt cheeks and the stuff inside them. 

The big headline, Sprigle says, is that “we’re big bags of water. What the skeleton does in that big bag of goo is totally fascinating.” 

The work proved particularly humbling for Sonenblum, who’d intended to spend her career studying how the gluteus maximus affects seating. Instead, she and her colleagues figured out that humans don’t rest on muscle at all—the fat is what really counts. Sonenblum and the rest of the REARLab team are investigating how the natural padding in our rears changes over time, particularly in people who spend a lot of time sitting or supine.

Today, REARLab creates more precise computer models and “phantoms” to help cushion testing—mainly for wheelchair seats, but also for ergonomic chairs of all stripes—better account for real-world bums. Phantoms aren’t quite faux butts; they’re simple and scalable geometric shapes, almost like the convex version of a seat cushion designed for your tuchus to nestle into. They don’t account for bodies’ individual differences either. 

“Phantoms are always a tricky balance between time and representation,” Sonenblum says. “You want to represent the population well, but you can’t have too many or you’ll spend your entire life running tests.”

REARLab’s current approach is to use two shapes—elliptical and trigonometric—to represent a fuller backside and one more likely to pose biomechanical problems when seated, respectively. It would be reasonable to assume the trigonometric butt is the bonier of the two, Sonenblum says, but the reality isn’t so simple. Large individuals with lots of adipose tissue can still lose the round cushioning when they sit. 

“I’ve seen scans of butts that look like this, and when I do, I think, Wow, that’s a high-risk butt,” Sonenblum explains. It comes down to the quality of the tissue, she adds. “If you touch a lot of butts, you’ll find that the tissue changes for people who are at risk [of pressure injuries]. It feels different.”

Sonenblum and Sprigle hope that continued work on backside modeling, cushion-testing standards, and adipose analysis will help wheelchair users and patients confined to their beds for long stretches stay safer and more comfortable. But their work has implications for absolutely anyone who sits down. When asked what folks should take away from their studies, they’re both quick to answer: Move. People with limited mobility may not be able to avoid the loss of structural integrity in their butt tissue, but anyone with the ability to get up often and flex their muscles can keep that natural padding in prime health. 

Finding better bellwethers for bowel cancer

When it comes to protecting your posterior, it’s not just the bodacious bits of the outside that count. One of the biggest backside-related issues scientists are tackling today is the sharp rise in colorectal cancer, which starts with abnormal cell growth in the colon or rectum. It’s already the third most common cancer and second leading cause of cancer death, but it represents a mounting threat, especially for millennials. New cases of young-onset colorectal cancer (yoCRC)—defined as a diagnosis before age 50—have gone up by around 50 percent since the mid-1990s. 

Blake Buchalter, a postdoctoral fellow at Cleveland Clinic Lerner Research Institute focused on cancer epidemiology, says that the most troubling thing about this recent uptick in cases is how little we know about what’s causing it. He and his colleagues suspect that 35- to 49-year-olds who die from colorectal cancer may share many of the same demographics and risk factors—higher body weight, lower activity levels, smoking, alcohol use, and diets high in processed and red meats—seen in patients aged 50 and older. But those under the age of 35 don’t follow those patterns as closely as expected. 

“This indicated to us that mortality among the youngest colorectal cancer patients may have different drivers than among older populations,” Buchalter says. “Our future work in this space aims to identify underlying factors that might be driving higher incidence and mortality among certain age groups in particular geographic regions.” 

Buchalter hopes that more granular data will encourage more granular screening guidelines too. While he was heartened to see the US Preventative Services Task Force shift the recommended colon cancer screening age down from 50 to 45 in 2021, it’s clear that some populations are at risk for the disease earlier, he says. Buchalter and his colleagues hope to zero in on who should be getting screened in their 20s and 30s. 

But colonoscopies, the most commonly recommended form of detection, present a major hurdle in themselves. A 2019 study found that only 60 percent of age-eligible US adults were up to date on their colorectal cancer screenings, with others citing fear, embarrassment, and logistical challenges such as transportation to explain their delayed colonoscopies. At-home fecal tests offer a less invasive alternative, but research shows that fear of a bad diagnosis and disgust with the idea of collecting and mailing samples still keep many folks from using them. Blood tests and colon capsule endoscopy (CCE), in which patients swallow a pill-size camera to allow doctors to examine the gastrointestinal tract, both show promise in supplementing, and perhaps someday replacing, the oft-dreaded colonoscopy.

For now, it’s worth going in for the physical screening if you can manage it. While blood and stool tests can accurately detect signs of the cancer, colonoscopies can actually help prevent it. During a standard colonoscopy, gastro­enterologists are able to identify and remove potentially precancerous polyps known as adenomas on the spot. No DIY kit can manage that.  

Tracking microbiomes with futuristic commodes

Meanwhile, other researchers are uncovering health secrets from long-ago water closets. In 2022, archaeologists uncovered what they believe to be the oldest flush toilet ever found, in Xi’an, China. The 2,400-year-old lavatory features a pipe leading to an outdoor pit. Researchers believe the commode, which was located inside a palace, allowed servants to wash waste out of sight with buckets of water. Flush toilets wouldn’t appear in Europe until the 1500s, and wouldn’t become commonplace until the late 19th century. Up until that point, major US cities employed fleets of “night soil men” to dig up and dispose of the contents of household privies and public loos.

As far as we’ve come from the days of night soil, the future of the humble toilet looks even brighter. Sonia Grego, an associate research professor in the Duke University Department of Electrical and Computer Engineering, says she’s “super-excited” to see commodes enter the 21st century. 

“Smart” toilets boast everything from app-controlled heated seats to detailed water-usage trackers, and could grow into a $13.5 billion industry by the end of the decade. But Grego’s team—the Duke Smart Toilet Lab at the Pratt School of Engineering—is focused on turning waste flushed down porcelain bowls into a noninvasive health tool. She envisions a future in which your toilet can warn you of impending flare-ups of gut conditions like irritable bowel syndrome, flag dietary deficiencies, and even screen for signs of cancer. 

“When we first started to work on the smart toilet for stool analysis, laboratory scientists were skeptical that accurate analytical results could be obtained from specimens that had been dropped in a toilet instead of a sterile collection container,” Grego recalls. “The perspective is very different now.”

Drawing inspiration from wild butts 

Humans may be unusually blessed in the butt-cheek department, but that doesn’t mean other animals’ rears hold less scientific appeal. From modeling the evolution of the anus to cracking the code on climate-friendly gut microbes, scientists are keeping close tabs on all sorts of animal bottoms. Some researchers are even hoping to harness the power of butt breathing—yes, actually breathing through your butt—for future applications in human medicine. 

We’ll circle back to backside breathing in a moment. First, let’s consider the wombat. While it’s true enough that everybody poops, these marsupials are the only animals known to drop cubes. For years, no one was quite sure how they managed to get a square peg out of a round hole. Some even assumed the wombat must have an anus designed for squeezing out blocks instead of cylinders. In 2020, mechanical engineers and wildlife ecologists at Georgia Tech teamed up to publish a surprising new explanation for the shape in the aptly named journal Soft Matter. They’d borrowed roadkill from Australia to do the first-ever close examination of a wombat’s intestines. By inflating the digestive tract and comparing it to more familiar pig intestines, they were able to show that the marsupial’s innards have more variation in elasticity: Instead of being fairly uniform throughout, the organs have some inflexible zones. The team’s findings suggest that a few nooks within the digestive system—some stretchy, others stiff—provide a means to shape the refuse into a square. 

Wombat butts themselves, by the by, are veritable buns of steel. Their rumps contain four fused bony plates surrounded by cartilage and fat and can be used to effectively plug up the entrance to a burrow when potential predators come sniffing around. While this has yet to be caught happening live, some scientists think wombats can even use their powerful bums to crush the skulls of intruders like foxes and dingoes who manage to make it inside. 

So now we have more clarity on how wombats poop cubes, but the question of why remains unanswered. Experts have posited that wombats communicate with one another by sniffing out the location of poop cubes, making it advantageous to produce turds less likely to roll out of place. Others argue that the unusual shape is a happy accident: Wombats can spend as long as a week digesting a single meal, with their intestines painstakingly squeezing out every possible drop of moisture to help them survive the arid conditions Down Under. Their entrails, when unwound, stretch some 33 feet—10 feet more than typical human guts—to help facilitate the frugal squeezing. When the species is raised in captivity with loads of food and water, their poops come out moister and rounder. 

Elsewhere in the world of scat science, folks are working to understand the secrets of nonhuman gut microbiomes. Earlier this year, biotechnologists at Washington State University showed that baby kangaroo feces could help make beef more eco-friendly. Joey guts contain microbes that produce acetic acid instead of methane, which cows burp out in such abundance that it significantly worsens climate change. By reseeding a simulated cow stomach with poop from a newborn kangaroo, researchers say they successfully converted the gut to a factory of acetic acid, which doesn’t trap heat in the atmosphere. They hope to try the transfer out in a real bovine sometime soon. 

Going back to the butt breathing, scientists are hoping to suss out how to give humans a superpower already exhibited by catfish and sea cucumbers. In 2021, Japanese researchers reported in the journal Med that they’d been able to keep rodents alive in oxygen-poor conditions by ventilating them through their anuses. Inspired by loaches—freshwater fish that can take in oxygen through their intestines—the scientists are trying to find new ways to help patients who can’t get enough air on their own. They’ve moved on to study pigs, which they say do wonderfully with a shot of perfluorodecalin (a liquid chemical that can carry large amounts of oxygen) up the bum. 

From an evolutionary standpoint, it’s not all that surprising that our outbox can handle the same duties as our inbox. Though it’s still not clear which came first, it’s well established that the anus and the mouth develop out of the same rudimentary cell structures wherever they appear. Some of the most basic animals still use a single opening for all their digestive needs. And one creature—just one, as far as we know—has a “transient anus.”

In 2019, Sidney Tamm of the Marine Biological Laboratory in Woods Hole, Massachusetts, demonstrated that the warty comb jelly creates new anuses as needed. Whenever sufficient waste builds up—which happens as often as every 10 minutes in young jellies—the gut bulges out enough to fuse with the creature’s epidermis, creating an opening for defecation. Then it closes right back up. It’s possible that the world’s first anuses followed the same on-demand model, proving yet again that the butt and its contents are worthy of our awe, curiosity, and respect.  

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It’s hard to imagine life without the nightshade family. It includes the likes of tomatoes, potatoes, peppers, and eggplants—some of the essential ingredients for a healthy diet–and delicious recipes. But, it turns out one of these tasty flowering plants has a longer history in North America than scientists previously believed. 

According to a March paper in the journal New Phytologist, the chili pepper may have been growing roots in present-day Colorado at least 50 million years ago—quite a bit earlier than scientists originally believed.  Previously, the chili pepper’s origin was placed 15 million years ago in South America. The newest theory emerged when a postdoc and an undergraduate student at University of Colorado-Boulder discovered a fossil of a plant that uncannily resembles the chili pepper, notably through its spiky ends on a fruiting stem called the calyx. 

“The world has maybe 300,000 plant species. The only plants with that kind of calyx is this group of 80 or 90 species,” Stacey Smith, senior author of the paper and associate professor of evolutionary biology at CU Boulder, said in a press release.

[Related: 5 heirloom foods that farmers want to bring back from obscurity.]

The well-preserved specimen was revealed in the Green River Formation, a site chock full of Eocene fossils and discoveries. But, it ended up not being as rare as the authors thought at first—two more similar chili pepper deposits from Green River were hidden in the CU Boulder collections and another at the Denver Museum of Nature and Science. These fossils were uncovered in the 1990s, but it certainly isn’t unheard of for discoveries to lay in wait until the right scientists come along. 

The Green River Formation is a marvel for capturing the Eocene, which lasted from around 34 to 56 million years ago and marked the beginning of the era of mammals. During this epoch, the amount of carbon in the atmosphere was around double that of today, paving the way for palm trees to grow in Alaska and a lack of ice driving sea levels 500 feet higher than they are currently. 

So what could’ve happened that caused the gap between when chili peppers were evolving in Colorado and when they appeared in South America during the Miocene? The authors theorize that modern birds, which have been able to fly long distances for some 60 million years, could’ve carried seeds and plants in their poop or stuck to their bodies. 

Through birds, chili peppers would’ve made their way to South America. Since the latest discovery puts the evolution of chili peppers back to the days of Gondwana, transoceanic travel may have been unnecessary. Birds could simply fly across shorter watery distances or via a chain of volcanic islands, the scientists wrote in the new paper. 

[Related: Oldest evidence of digested plants in a roughly 575-million-year-old creature’s gut.]

Nevertheless, this discovery puts the oldest chili peppers in a place that no longer has many native nightshades or any chili peppers at all. “These chili peppers, a species that we thought arose in an evolutionary blink of an eye, have been around for a super long time,” Smith added. “We’re still coming to grips with this new timeline.”

So next time you break out a meal of Colorado-style chili, that bowl of goodness might have even more local roots that anyone realized.

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From the brightly colored poison frogs of South America to the prehistoric-looking newts of the Western US, the world is filled with beautiful, deadly amphibians. Just a few milligrams of the newt’s tetrodotoxin can be fatal, and some of those frogs make the most potent poisons found in nature.

In recent years, scientists have become increasingly interested in studying poisonous amphibians and are starting to unravel the mysteries they hold. How is it, for example, that the animals don’t poison themselves along with their would-be predators? And how exactly do the ones that ingest toxins in order to make themselves poisonous move those toxins from their stomachs to their skin?

Even the source of the poison is sometimes unclear. While some amphibians get their toxins from their diet, and many poisonous organisms get theirs from symbiotic bacteria living on their skin, still others may or may not make the toxins themselves — which has led scientists to rethink some classic hypotheses.

Deadly defenses

Over the long arc of evolution, animals have often turned to poisons as a means of defense. Unlike venoms — which are injected via fang, stinger, barb, or some other specialized structure for offensive or defensive purposes — poisons are generally defensive toxins a creature makes that must be ingested or absorbed before they take effect.

Amphibians tend to store their poisons in or on their skin, presumably to increase the likelihood that a potential predator is deterred or incapacitated before it can eat or grievously wound them. Many of their most powerful toxins — like tetrodotoxin, epibatidine and the bufotoxins originally found in toads — are poisons that interfere with proteins in cells, or mimic key signaling molecules, thus disrupting normal function.

That makes them highly effective deterrents against a wide range of predators, but it comes with a problem: The poisonous animals also have those susceptible proteins — so why don’t they get poisoned too?

It’s a question that evolutionary biologist Rebecca Tarvin took up when she was a graduate student at the University of Texas at Austin. Tarvin opted to study epibatidine, one of the most potent poisons of the thousand-plus known poison frog compounds. It’s found in frogs such as Anthony’s poison arrow frog (Epipedobates anthonyi), a small, ruddy creature with light-greenish-white splotches and stripes. Epibatidine binds to and activates a receptor for a nerve-signaling molecule called acetylcholine. This improper activation can cause seizures, paralysis and, eventually, death.

Tarvin hypothesized that the frogs, like some other poisonous animals, had evolved resistance to the toxin. She and her colleagues identified mutations in the genes for the acetylcholine receptor in three groups of poison frogs, then compared the activity of the receptor with and without the mutation in frog eggs. The mutations slightly changed the receptor’s shape, the team found, making epibatidine bind less effectively and limiting its neurotoxic effects.

That helps to solve one problem, but it presents another: The mutations would also prevent acetylcholine itself from binding effectively, which would disrupt normal nervous system functions. To address this second problem, Tarvin found, the three groups of frogs each have another mutation in the receptor protein that again changes the receptor’s shape in a way that allows acetylcholine to bind but still rejects epibatidine. “This is a series of very slight tweaks,” Tarvin says, which make the receptor less sensitive to epibatidine while still allowing acetylcholine to perform its usual neural duties.

Tarvin, now at the University of California, Berkeley, is researching how animals evolve to cope with toxins, using a more tractable experimental organism, the fruit fly. To that end, she and her colleagues fed food containing toxic nicotine to two lineages of fruit flies that differed in their ability to break down nicotine.

When the researchers exposed fly larvae to predators — parasitic wasps that laid eggs in the flies — both groups of flies were protected by the nicotine they ate, which killed off some of the developing parasites. But only the faster-metabolizing flies benefited from their toxic diet, because the slower-metabolizing flies suffered more from nicotine poisoning themselves.

Tarvin and her students are now working on an experiment to see if they can induce the evolution of adaptations, such as those she identified in the frogs’ proteins, by exposing generations of flies to nicotine and wasps, then breeding the flies that survive.

Fishing for poisons

Poisonous animals must do more than survive their own toxins; many of them also need a way to safely transport them in their bodies to where they’re needed for protection. Poison frogs, for instance — which obtain their toxins from certain ants and mites in their diet — must ship the toxins from their gut to skin glands.

Aurora Alvarez-Buylla, a biology PhD student at Stanford University, has been trying to nail down which genes and proteins the frogs use for this shipping. To do so, Alvarez-Buylla and her colleagues used a small molecule she describes as a “fishing hook” to catch proteins that bind to a toxin — pumiliotoxin — that the frogs ingest. One end of the hook is shaped like pumiliotoxin, while the other end bears a fluorescent dye. When a protein that would normally bind to pumiliotoxin instead latches onto the similar hook, the dye allows the researchers to identify the protein.

Alvarez-Buylla expected her hook to catch proteins similar to saxiphilin, which is thought to play a role in transporting toxins in frogs, or other proteins that transport vitamins. (Vitamins, like toxins, are usually scavenged from the diet and then moved around the body.) Instead, she and her fellow researchers found a new protein, similar to a human protein that transports the hormone cortisol. This new transporter, they found, can bind to multiple different toxic alkaloids found in different species of poison frogs. The similarity suggests that the frogs have borrowed the hormone-transporting system to also transport toxins, says Lauren O’Connell, Alvarez-Buylla’s PhD advisor at Stanford and a coauthor of the paper, which is still to be formally peer-reviewed.

This may explain why the frogs aren’t poisoned by the toxins, O’Connell says. Hormones often become active only when an enzyme cleaves their carrier, releasing the hormone into the bloodstream. Similarly, the new protein may bind to pumiliotoxin and other toxins and prevent them from coming into contact with parts of the frog nervous system where they could cause harm. Only when the toxins reach the right spot in the frogs’ skin would the toxin-carrying protein release them, into skin glands where they can be safely stored.

In future work, the scientists aim to understand exactly how the new protein can bind to several different types of toxins. Other known toxin-binding proteins, like saxiphilin, tend to bind tightly to just a single toxin. “What’s special about this protein is that it’s a little bit promiscuous in who it binds to, but also there’s some selectivity there,” says O’Connell. “How does that work?”

Turning toxic

While poison frogs definitively get their toxins from the food they eat, the source of toxins used by other poisonous amphibians is not always clear-cut. Amphibians such as toads, it appears, may make their own poisons.

To show this, TJ Firneno, an evolutionary biologist at the University of Denver, and his colleagues manually emptied the toxin glands of 10 species of toads by squeezing the glands (“It’s like popping a zit,” Firneno says, and is harmless to the toads), then looked at which genes were most active in those glands 48 hours later. The hypothesis, says Firneno, was that genes especially active after the glands are emptied could be involved in toxin synthesis.

Firneno and his colleagues identified several activated genes that are known to be part of metabolic pathways for creating molecules related to toxins in plants and insects. The genes they identified, Firneno says, can help point scientists in the right direction for further investigations into how toads may make their toxins.

Other amphibians may rely on symbiotic bacteria for their toxins. In the United States, newts of the genus Taricha are among the country’s most toxic animals. Though they look harmless, individual newts from some populations of these ancient creatures contain enough tetrodotoxin to kill numerous people. Many scientists believed the newts made the toxin themselves. But when a team of researchers collected bacteria from the newts’ skin, then cultured individual microbial strains, they found four types of tetrodotoxin-producing bacteria on the amphibians’ skin. That’s similar to other tetrodotoxin-containing species, such as crabs and sea urchins, where scientists agree that bacteria are the source of the toxin.

The origin of the toxin in these newts has broader ramifications, because they — and the garter snakes that eat them — are poster animals for what has been considered a classic example of coevolution. The snakes’ ability to eat the highly toxic newts is evidence that they have coevolved with the newts, gaining resistance so that they can continue to eat them, some scientists think. Meanwhile, the newts, the idea goes, have been evolving ever-greater toxicity to try and keep the snakes at bay. Scientists refer to this kind of escalating competition as an evolutionary arms race.

But in order for the newts to participate in such an arms race, they have to have genetic control of the amount of toxin they produce so that natural selection can act, says Gary Bucciarelli, an ecologist and evolutionary biologist at the University of California, Davis, who coauthored a re-evaluation of the arms race idea in the 2022 Annual Review of Animal Biosciences. If the tetrodotoxin actually comes from bacteria on the newts’ skin, it’s harder to see how the newts could turn up the toxicity. The newts could conceivably coerce the bacteria to pump out more tetrodotoxin, Bucciarelli says, but there’s no evidence that this happens. “It’s certainly not this very tightly linked, antagonistic relationship between newts and garter snakes,” he says.

Indeed, at the field sites where Bucciarelli works in California, he’s never actually witnessed a garter snake eating a newt. “If you follow the literature, you’d think that there are snakes just picking off newts like crazy at the edge of a stream or a pond. You just don’t see that,” he says. Instead, the snakes’ resistance to tetrodotoxin could have arisen for some other reason, or even by evolutionary happenstance, he says.

The newts’ toxin source is far from nailed down, though. “Just because you have bacteria that do something that live on your skin, doesn’t mean that’s the source in newts,” says biologist Edmund Brodie III, who was among the scientists that first put forward the arms race hypothesis between the snakes and newts more than 30 years ago. Brodie notes that other researchers have found that newts contain molecules that, based on their structures, may be part of a biological pathway for newts to synthesize their own tetrodotoxin. Still, Brodie says of the study showing that bacteria found on the newts can produce tetrodotoxin, “it’s the best thing we have so far.”

Brodie’s instinct is that one way or the other, the newts control their tetrodotoxin production, whether that’s by making the tetrodotoxin themselves or somehow manipulating their bacteria. The presence of bacteria as a third player in the newt-snake war would just make it an even more interesting system, he says.

One major barrier in determining whether the newts can make tetrodotoxin on their own is that no full genome has been published for Taricha newts. “They have one of the largest genomes of any animal we know of,” says Brodie.

Studying the ways that poison animals adapt and use toxins, just like much basic science research, has inherent interest for researchers who seek to understand the world around us. But as climate change and habitat destruction contribute to an ongoing loss of biodiversity that has hit amphibians especially hard, we’re losing species that not only have intrinsic importance as unique organisms but are also sources of potentially lifesaving and life-improving medicines, says Tarvin.

Epibatidine, tetrodotoxin and related compounds, for example, have been investigated as potential non-opioid painkillers when administered in tiny, controlled doses.

“We’re losing these chemicals,” Tarvin says. “You could call them endangered chemical diversity.”

This article originally appeared in Knowable Magazine, an independent journalistic endeavor from Annual Reviews. Sign up for the newsletter.

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In response to climate change, a lot of animals—such as polar bears and birds like sparrows—appear to be getting smaller in size. However, male California sea lions have increased their average body size even as their population has grown and the competition for food and resources has increased. 

In a study published April 27 in the journal Current Biology found that sex selection was a strong driving force for the male sea lions to strengthen the neck and jaw muscles that they use to fight for mate and to grow larger. Additionally, both male and female sea lions responded to food shortages by diversifying their diets and foraging further from the shore in some cases.

[Related: Fish populations thrive near marine protected areas—and so do fishers.]

Numerous marine species have rebounded a bit since the Marine Mammal Protection Act was passed in 1972, but California sea lions are notable for the size and duration of their population increase. The number of breeding females have tripled since the 1970s and the population growth is only beginning to plateau now. 

“Body size reduction is not the universal response to population increase in marine predators,” co-author and University of California Santa Cruz and the Smithsonian Institution paleoecologist  Ana Valenzuela-Toro said in a statement. “California sea lions were very resilient over the decades that we sampled and were able to overcome increasing competition thanks to prey availability. They’re like the raccoons of the sea: they can consume almost everything, and they can compensate if something is lacking.”

In the study, the team analyzed museum specimens of adult male and female California sea lions that were collected between 1962 and 2008. To estimate changes in body size, they then compared the overall size of over 300 sea lion skulls, taking into account other skull features like the size of muscle attachment points, to assess the changes made in both neck flexibility and biting force.

To get an idea of where the sea lions were foraging and what they were eating, the team took tiny bone samples from the skulls and measured their stable carbon and nitrogen isotope composition. “Carbon provides information about habitat use—whether they’re foraging along the coast or offshore—and nitrogen provides insights about the trophic level of their prey, for example if they’re consuming smaller or larger fish,” said Valenzuela-Toro.

The team found that overall the male sea lions have increased in size, while females have remained stable. They believe that the sex difference is likely due to the fact that size matters more for a male in terms of mating success. “One male can breed with many females, and males in the breeding colony fight with each other to establish their territory,” said Valenzuela-Toro. “Bigger males are more competitive during physical fights, and they can go longer without eating, so they can stay and defend their territory for longer.”

[Related: For marine life to survive, we must cut carbon emissions.]

The male sea lions also increased their biting force and neck flexibility over this same time period. This allows them to move their heads more with greater agility and bite harder when fighting other males. 

The isotopic analyses showed that both sexes managed to meet nutritional needs through diet diversification and going further north for food. Female sea lions consistently had a more diverse diet than the male sea lions, and the authors suggest that this flexibility in food choice may be what allowed females to maintain average body size. 

The flexibility can only take sea lions so far, however, and climate change is putting their future in jeopardy. The dynamics that allowed for this growth occurred when their prey of sardines and anchovies were plentiful, and the populations of both fish have collapsed in recent years. The California sea lions have continued to diversify their diets to compensate, but are struggling. 

“As climate change progresses, prey availability of sardines and anchovies will decrease even more, and eventually we will have more permanent El Niño-like warming conditions, reducing the size and causing a poleward shift of these and other pelagic fishes,” said Valenzuela-Toro “It will be a really hostile environment for California sea lions, and eventually we expect that their population size will stop growing and actually decline.”

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Humans and chimpanzees share a common ancestor, but 4 to 6 million years ago they split off on different evolutionary paths. Chimps continued to walk on all fours and live in trees, while we lost our fur and grew past the need for a tail. But it was our large brains that set us the most apart from our closest relatives. The human brain (about the size of 10 tennis balls) is three times bigger than a chimp’s.

There are multiple theories for why we evolved large and complex brains. Some evolutionary biologists think humans developed bigger bodies as a response to environmental pressures such as living in open, unforested habitats that required more cooperation and thinking to catch prey. Others speculate our brains needed to grow to handle the information needed to manage social relationships. And in a new study published in Science today, geneticists offer a third explanation: We just got lucky.

Lead author Katie Pollard, the director of the Gladstone Institute of Data Science and Biotechnology in California, likes to think of it as rolling dice. Every time another member of a species is born, there’s a chance that mutations will spring up in their genome. Each new generation gets more opportunities to score big with tweaks in the gene pool that increase the odds of survival. These beneficial mutations are more likely to stick around as organisms thrive and pass them on to offspring. In the case of humans and brain size, eventually, the buildup of mutations would be reflected in changes in the overall genome, Pollard says.

These random mutations could have contributed to the 49 short DNA sequences in our genome called human accelerated regions (HARs). Pollard and her team were the first to find these segments back in 2006 when comparing the genomes of humans to chimpanzees. HARs work as gene enhancers, controlling which genes are turned up or down during embryonic development, especially for brain formation. 

[Related: Eating meat may not have been as crucial to human evolution as we thought]

HARs in humans are very similar in each individual but vary when compared to accelerated regions in other vertebrates like chimps, frogs, and chickens. Since the initial discovery, research has found a connection between HARs and multiple traits that make our species distinct. And while Pollard has spent a lot of time understanding how HARs helped humans evolve, the current study focuses on why HARs emerged in the first place. 

The team collected data from 241 mammalian genomes (in concert with the larger Zoonomia project) and identified 312 accelerated regions across all of them. Most of the accelerated regions identified acted as neurodevelopmental enhancers, indicating a connection to brain development. But when comparing human and chimp DNA sequences, 30 percent of HARs were in areas of the genome where the DNA was folded differently. This suggests the structural variations in the human genome likely came from a random mutation during reproduction. “Mutations happen all the time and everytime sperm and eggs get made, there are some mistakes that cause cuts, deletions, and other edits to the DNA,” explains Pollard. “Many of the mutations don’t make any difference, but now and then some have a positive effect and that’s actually very rare.” 

In this case, scrunching and folding up DNA in different ways seemed to help with fitting a copy of the genome in every cell of the body. “It’s a big surprise that genome folding is involved since it hadn’t been on anyone’s radar when studying human accelerated regions,” says Pollard. “We had been thinking of DNA as a text file in a big folder full of A, C, T, and G’s, and looking for patterns as you move linearly through the sequence.”

The folding change would have affected how enhancers regulated gene activity in early humans. Depending on how the DNA was folded, enhancers could have been situated near new sequences, giving them different genes to target and boost. In humans, it just so happened that most of the adjacent genes were involved in brain development. In other words, we won the mutation lottery.

“The main achievement of this study is the discovery that the evolutionary history of HARs is connected in some way with the complex dynamics of structural configurations of the human genome,” says Anastasia Levchenko, a genetic researcher for the Institute of Translational Biomedicine at Saint Petersburg State University in Russia who has previously studied HARs’s role in brain development. However, she would like to see more research on the sequence of events in the evolution of the human genome. For example, it’s possible that HARs appeared way earlier than the changes in our DNA folds, or that DNA folding is only one factor contributing to the creation of HARs.

[Related: This is the most complete map we have of the human genome]

What’s more, humans might have used other genetic pathways to develop different features from other animals. Pollard’s study is one of 11 papers published in Science today as part of the Zoonomia Project, an international collaboration that aims to understand the codes behind shared and specialized traits across hundreds of mammalian species. For example, Zoonomia researchers identified the distinct parts of Balto’s genome that helped the sled dog deliver a serum to a remote Alaskan village, as well as genetic variants in early humans that could play a role in modern-day diseases. Another paper focuses on using information from DNA to predict which species are more likely to face extinction. All together, identifying the different genomes will open the door to understanding mammalian evolution and what exactly makes us uniquely human. 

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The unusual looking mudskipper has a startling face, and a fascinating backstory. The fish is actually amphibious and has evolved traits that ensure its survival in both water and on land. They have eyes on the top of their heads for better aerial vision and also use oxygen from their water stored in their gill chambers to breathe on land. However, the mudflat-dwelling fish’s ability to blink its eyes is shedding light on how our own ancestors evolved from living in the water to walking on land.

A study published April 24 in the Proceedings of the National Academy of Sciences (PNAS) found that the blinking behavior serves many of the same functions of our blinking, and it may be part of that suite of traits that allowed tetrapods to evolve on land. Tetrapods are the group of animals, including today’s amphibians, birds, reptiles and mammals, that evolved to exist on land in a rapid turn of events roughly 375 million years ago.

[Related: Our four-legged ancestors evolved from sea to land astonishingly quickly.]

Animals blink to keep the eyes wet and clean and protect them from injury. Sometimes, blinking can even be a form of communication. Humans and other tetrapods blink constantly through the day and despite it being a subtle action, it is quite complex. Strangely enough, mudskipper’s blink lasts roughly the same length of time as a human’s. 

“Studying how this behavior first evolved has been challenging because the anatomical changes that allow blinking are mostly in soft tissues, which don’t preserve well in the fossil record,” co-autor and Penn State University biologist Thomas Stewart said in a statement. “The mudskipper, which evolved its blinking behavior independently, gives us the opportunity to test how and why blinking might have evolved in a living fish that regularly leaves the water to spend time on land.”

To better understand how mudskippers evolved the ability to blink, the team analyzed blinking using high-speed videos. They compared the mudskippers’ anatomy with a closely related water-bound fish that doesn’t blink. Mudskippers blink with eyes that bulge out of the top of their heads, similar to a frog’s eyes. They momentarily retract their eyes down into the sockets, when they are covered by a sketchy membrane called a dermal cup. 

“Blinking in mudskippers appears to have evolved through a rearrangement of existing muscles that changed their line of action and also by the evolution of a novel tissue, the dermal cup,” co-author and Seton Hall University biologist Brett Aiello said in a statement. “This is a very interesting result because it shows that a very rudimentary, or basic, system can be used to conduct a complex behavior. You don’t need to evolve a lot of new stuff to evolve this new behavior — mudskippers just started using what they already had in a different way.”

To understand why the mudskippers blink on land, the team looked to the roles that blinking plays in other tetrapods. Tears in humans are critical to keeping the eye’s cells oxygenated and healthy, so the team looked to see if mudskippers blink to keep their eyes wet when exposed to the air.  

[Related: Tiktaalik’s ancient cousin decided life was better in the water.]

“We found that, just like humans, mudskippers blink more frequently when confronted with dry eyes,” said Aiello. “What’s incredible is that they can use their blinks to wet the eyes, even though these fish haven’t evolved any tear glands or ducts. Whereas our tears are made by glands around our eyes and on our eyelids, mudskippers seem to be mixing mucus from the skin with water from their environment to produce a tear film.”

They also found that blinking in mudskippers is triggered to protect the eye from injury as well as  clearing their eyes from possible debris. The finding suggests that mudskipper blinking appears to fulfill blinking’s three major functions—protecting, cleaning, and maintaining moisture.

“Based on the fact that mudskipper blinking, which evolved completely independently from our own fishy ancestors, serves many of the same functions as blinking in our own lineage, said Stewart. “We think that it was likely part of the suite of traits that evolved when tetrapods were adapting to live on land.”

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Is the phase “nice guys finish last” actually true? Unfortunately for all the soft-hearted among us, brutish behavior can be an effective path to power and dominance in both humans and chimpanzees. A study published April 24 in the journal PeerJ Life and Environment found that the male chimpanzees who exhibited greedy, irritable, and bullying personalities reached a higher social status. These rascals were also more successful at producing offspring. 

[Related: Adolescent chimpanzees might be less impulsive than human teens.]

However, the team is still plagued by a puzzling question from these findings: if being mean is the key to success, why isn’t every chimp a bully? 

For the study, the team followed 28 male chimpanzees living in Tanzania’s Gombe National Park. A previous study had found that  these particular chimpanzees had a few members that  are more sociable whereas others are loners. Some of the chimps had overbearing personalities, and some were more easy-going. And, of course, there are a handful that are more quick to pick fights with others. 

Tanzanian field researchers performed personality assessments on the chimpanzees based on years of near-daily observations of how each animal interacted with others and behaved among the group. They found that a personality combination of high dominance and low conscientiousness helped the male chimpanzees fare better in life than the others, but it still doesn’t answer the evolutionary puzzle of why personality differences exist at all. 

A long held theory is that different personality traits matter at different points in an animal’s life or that certain traits that are a liability when an animal is young may pay off in old age. 

“Think of the personality traits that lead some people to peak in high school versus later in life,” Alexander Weiss, co-author and comparative psychologist at the University of Edinburgh, said in a statement. “It’s a trade-off.” 

The team tested the theory using almost 40 years of data that goes back to famed primatologist Jane Goodall’s early research at Gombe. Across the lifespan, the same personality traits were linked to both high reproductive success and high social rank. 

[Related: Popular chimpanzees set hand-holding trends for the whole group.]

Something else must be behind the diversity of chimpanzee personality. The “best” personality to have could depend on social or environmental conditions. Gender could matter too—a trait that is beneficial to males could cost a female. If this is true, then “genes associated with those traits would be kept in the population,” Weiss said. Further study is needed to confirm this idea. 

The suggestion that animals have distinct personalities was considered taboo not too long ago, with Goodall herself accused of anthropomorphism with her descriptions. Scientists have studied animals ranging from squid to birds, finding evidence of distinct personalities. These quirks, idiosyncrasies, and ways of relating to the world around them remain reasonably stable over time and across situations.

Like with measures of human personality, personality ratings for animals have also been proven to be as consistent from one observer to the next. “The data just doesn’t support the skepticism,” Weiss said.

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Carnivorous plants come in a variety of shapes and colors—and it’s often their looks that help them attract their prey. However, these floral tricksters may use a different scene to attract their dinner: smell. A small study published this month in the journal PLOS One found evidence that different species of Sarracenia, a genus of North American pitcher plant, produces scents that are directed at certain groups of prey.

[Related: Two newly discovered Andes Mountain plant species have an appetite for insects.]

Sarracenia pitcher plants typically make their home in bogs and in poor soil throughout North America. Their signature purple or reddish flowers are actually leaves which form a cup called the “pitcher”  filled with digestive enzymes.  If an insect gets too close to the plant, the pitcher traps it and digests the insect to help supplement their diet in a nutrient-poor home. 

The odor of carnivorous plants hasn’t been well-studied by humans, but has been suspected for over a century. Charles Darwin wrote about the unique plants about 150 years ago, but it’s been more difficult to find concrete evidence of its olfactory mechanisms. 

“Of the signals involved in communication, odor is probably the most cryptic to humans,’ co-author and carnivorous plant expert French National Centre for Scientific Research Laurence Gaume said in a statement. “In plants, it is often correlated with other plant characteristics such as nectar, shape and visual signals, which make it difficult to disentangle its effect from others.”

In this new study, a team identified the odor molecules emanating from four types of pitcher plants. The scents appear to correlate with the types of incense that wound up inside of the pitchers. The chemicals that make up some of the scents are similar to ones known to act as signals to certain insects, which may mean the pitcher plants have evolved to take advantage of their prey’s senses.

“It offers potentially interesting avenues in the field of biological control, and one can imagine drawing inspiration from the olfactory cues of these pitcher plants to control plant pests, for example,” said Gaume.

The team grew Sarracenia purpurea and three of its hybrids with other pitcher plants in a lab.  

They found that all of the pitchers produced a scent that was similar to more generalist plants that are pollinated by many different species. This can allow them to cast a wide net for prey, but they noted that there were subtle differences in the volatile organic compounds that they produced. 

[Related: Dying plants are ‘screaming’ at you.]

The pitchers attracting butterflies and bees were rich in compounds like limonene, a chemical that gives citrus fruits their unique smell. The aroma comes from a class of chemicals found in the scents of around two thirds of flowering plants which attract these pollinators.

Meanwhile, S. purpurea also had an odor that was high in fatty acid chemicals known to attract parasitoid wasps and possibly other insect predators. Wasps and insects made up a large part of the plant’s diet, which suggests that the scent could be targeting them directly. 

The team found that both the odor of a pitcher and its dimensions could help predict the prey caught by a plant about 98 percent of the time. This is not definitive proof, but it suggests a possible link between a pitcher plant’s scent and its prey. 

Since carnivorous plants cannot move to hunt for their prey like a lion or a shark, smells can help them not only find food, but communicate with other plants. Plants being eaten can release scents that tell other plants nearby to get their defenses ready or produce a smell that attracts predators. 

Plants that are pollinated by animals often rely on scents to attract pollinators, like bees. Anything that hides their scent–like air pollution–can cause a drop in the number of pollinators that can find them. 

Further studies could help explain how carnivorous plants that are pollinated by insects can attract some for pollination and other for food. For example, the most important pollinators of Venus fly traps are never found inside its traps, and scent could play a role in this. 

 “However, we remain cautious because our results are currently based on correlations. Even with strong correlations, further tests are necessary to investigate whether the different insect types are indeed attracted to particular scents,” said Gaume.

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Today is a very special holiday where a skunky smell permeates the air. If you’re celebrating 4/20, Popular Science has the perfect lineup of dope science stories to make you everyone’s favorite bud. Don’t puff puff pass on this one!

Essential cannabis accessories

First things first, everyone needs some cannabis supplies before lighting up. But with so many twists on glassware and other options, how do you decide? From vaporizers to grinders to pen batteries, PopSci’s roundup of essential cannabis accessories will walk you through the choices.

A step-by-step guide to rolling a joint

Rolling a joint can’t be that hard, right? Wrong. Thankfully, in honor of 4/20, our DIY step-by-step guide will explain both the art and the science of rolling a joint, with advice straight from some of New York City’s expert budtenders. It’s the perfect refresher for veterans and crash course for newbies, complete with photos, detailed instructions, and material recommendations.

Can CBD help you chill? Here’s what we know so far.

CBD, THC’s sister molecule, has been working its way into various products as part of a budding industry. CBD is legal in more US states than cannabis, and can be added to almost any product as long as it has less than 0.3 percent THC. It’s a great alternative for those looking for stress relief, or don’t want the psychoactive effects of cannabis itself. Still have some questions about CBD? It’s not a panacea, but it may be worth trying out.

Is growing weed sustainable? The answer is complicated.

Using cannabis products to ease climate anxiety might be a Catch-22. Researchers say it’s hard to measure the environmental impact of today’s celebrated plant: Grow operations across the US take up a lot of water, land, and energy. Here’s what we know about the sustainability of cannabis.

Can you overdose on weed?

All substances have their risks, what about weed? Well, thankfully its not possible to overdose in the traditional sense, but overdoing it does pose some safety threats. Before you celebrate 4/20, listen to this Ask Us Anything podcast on the side effects of weed to gain some insights on responsible consumption.

The tasty chemicals flavoring the edible cannabis boom

Cannabis may have a distinctive smell, but a little-known aspect to users and non-users alike is that each strain has a special chemical composition. Like wine with its various aromas (such as floral, fruity, or earthy) different strains of cannabis possess a signature scent and taste. What makes them unique? Terpenes, or “terps,” are aromatic compounds found in many herbs and flowers. There are hundreds of known kinds that yield diverse flavors and effects. PopSci reported a comprehensive overview on the science of terpenes, ending with a list of the most buyable varieties.

Is marijuana a performance-enhancing drug? The best evidence says no.

Unfortunately for many athletes, cannabis use still falls on the list of prohibited substances. These regulations are in place to prevent the use of performance-enhancing drugs and ensure fair competition, but does cannabis really belong on the same list as steroids? Learn why the scientific reasoning behind cannabis regulations in sports might be lacking.

Cannabis gets its high-inducing power from ancient viruses

The next time a friend thanks a higher power for cannabis, remind them to appreciate viruses for their genetic contributions. (At the very least, it was a joint effort.) The psychoactive and medicinal effects of cannabis probably evolved from ancient viruses Mapping the genome of the plant posed a challenge to researchers as an illicit substance, but as it slowly became legal in different states over the past two decades, they dove deep into its background. What better time than 4/20 to learn the evolutionary history of cannabis.

Why German scientists got cows stoned

Nobody wants animals to get high on our supply, but these German scientists did it on purpose with cows. Not to laugh at the animals’ “pronounced tongue play,” as researchers described: They wanted to test if leftover organic matter from the hemp industry could be fed to livestock, reducing waste and curbing methane emissions from regular hay and soy. The German study led to some especially silly bovine behavior and THC-spiked milk.

Does CBD show up on a drug test?

Using cannabis products might lead to a positive drug test that could cost you a job or other opportunities. For those that want the stress-reducing effects of cannabis, but have to keep off the grass, consider quality products with this CBD drug test and product guide.

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For spiders, spinning their silky webs is a matter of survival. Those that don’t weave good enough silk to spin an insect-trapping web will have a much tougher, or even impossible, time getting enough food to eat. Since spiders are found throughout world, the more fine-tuned their webs are to their environment, the better they will work. 

In a study published April 18 in the journal Frontiers in Ecology and Evolution, biologists found that the glue that makes orb weaver spiders’ webs so sticky actually evolves faster than the spiders’ genes. 

[Related: Black widows battle their even deadlier cousins in a brutal spider war.]

“Discovering the sticky protein components of biological glues opens the doors to determining how material properties evolve,” study co-author and Washington and Lee University biologist Nadia Ayoub said in a statement. “Spider silk fibers and glues represent a fantastic model for answering such questions since they are primarily made of proteins and proteins are encoded by genes.”

Like the individual threads of a tapestry, each strand in an orb weaver spider’s web works to capture food. The web’s stiff frame absorbs the impact of the prey before it is trapped by the sticky lines so that the spider can tackle its food. A special glue that is synthesized in the spider’s aggregate glands makes the lines of the web sticky by absorbing water from the atmosphere. The glue should be altered to achieve the best stickiness for the amount of humidity in the air in the region where the spider lives. Since there are numerous species of orb weaver spiders living in many environments, the team on this study believed their glue must adapt to humidity levels. 

To investigate this glue adaptation strategy, the team focused on two species– Argiope argentata (A. argentata) and Argiope trifasciata (A. trifasciata). A. argentata lives in dry environments and is native to Southern California. The team had them build webs in a lab, but were fed a diet comparable to their prey and compared the glue droplet volume found in nature to make sure they were equivalent to what they weave in nature. A. trifasciata lives in humid environments all over the world and the team collected webs from them in the wild. 

They analyzed the proteins in the glue and the droplets’ material properties and found that the droplets from the dry-living A. argentata spiders are smaller than those from the more humidity prone A. trifasciata, and also absorb less water as local humidity increases. A. argentata’s glue also had smaller protein cores that occupied a smaller proportion of the droplet’s volume and absorbed less water from the atmosphere. 

[Related: How researchers leveled up worm silk to be tougher than a spider’s.]

The stiffness of these protein cores in the droplets affected the toughness of the glue droplets and the toughness of A. argentata’s protein core decreased as the humidity went up. A. argentata thread glue droplets were generally sticker and  more closely spaced.

When the team analyzed the proteins in the glue to understand how these differences in their material properties arise from these proteins, they found that the proteins appeared in different proportions, even though they were similar. A. argentata glue had the protein products of four genes which didn’t appear in A. trifasciata glue. The extra proteins and a more balanced ratio of the glue’s key AgSp1 and AgSp2 proteins may explain the greater toughness of this glue and its lower capacity for water absorption.

“Despite the dramatic differences in material properties, the two species share most of their protein components,” co-author and Virginia Tech biologist Brent Opell of Virginia Tech said in a statement. “The sequences of these proteins are also similar between species, but the relative abundance of individual proteins differs. Modifying the ratios of proteins is likely a rapid mechanism to adjust material properties of biological glues.”

According to the team, one of the limitations to this study includes that it only looked at two species, and the relationship between proteins and web material properties are not quite to scale yet. To address this, the team is documenting protein components and the material properties of a diverse set of species.

More study on spider silk and their properties could also have some wider scientific and technological applications. “Spider silks and glues have huge biomimetic potential. Spiders make glues with impressive properties that would have applications in industry, medicine, and beyond,” said Opell.

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Since its discovery nearly 70 years ago, paleontologists have debated the lineage of the mysterious “Tully monster.” The six-inch-long, stalk-eyed creature lived over 300 million years ago in the seas of modern-day Illinois. Its unique anatomy has long challenged researchers, making it difficult to identify as either a vertebrate or invertebrate–one of the first steps of classification. 

Vertebrates are animals with spines, including mammals, birds, reptiles, amphibians, and fish. Invertebrates are animals without spines, including insects, arachnids, crustaceans, mollusks, annelids, and more. The Tully monster, or Tullimonstrum gregarium, was a soft-bodied marine animal, so its fossilized remains do not show clear evidence of a backbone. In 2016, researchers claimed to have identified a pale gut-like structure as a notochord, a primitive spine, signaling a vertebrate affinity. 

Now, researchers at the University of Tokyo believe they have solved the mystery of Tullimonstrum gregarium’s lineage, finding characteristics that point to an invertebrate identity. Their findings were published in the journal Palaeontology on April 17, 2023.

Amateur collector Francis Tully found the first fossils in Illinois’ Mazon Creek formation in 1955, a fossil bed known for its treasure trove from the Carboniferous period. He then took his unidentified ‘monster’ to the Field Museum of Natural History, where it confounded paleontologists and opened up a debate that would last decades. It was first described in a paper in 1966 and became the Illinois state fossil in 1989.

[Related: A gator-faced fish shaped like a torpedo stalked rivers 360 million years ago]

So far, researchers have been unable to determine whether the fossil was a vertebrate or invertebrate, one of the first bases of taxonomic identification. Invertebrates emerged first in the form of soft-bodied organisms, such as sponges, jellyfish, and worms over 600 million years ago. Vertebrates evolved after, during the Cambrian explosion about 540 million years ago. Both sides of the debate have evidence to support them, and it is still an open discussion. If found to be a vertebrate, the Tully monster would fill a gap in evolutionary history, connecting jawless fish (such as lampreys and hagfish) to jawed fish. 

Recent findings suggest the opposite. Researchers at the University of Tokyo analyzed 3D imaging of 153 Tully monster fossils from Mazon Creek. They found structures that point to it being an invertebrate chordate, like a lancelet, a small eel-like marine invertebrate which evolved 500 million years ago. The Tully monster could also potentially be a radically modified protostome, a clade of animals encompassing insects and crustaceans, which first evolved around 540 million years ago along with vertebrates during the Cambrian explosion. 

“The most important point is that the Tully monster had segmentation in its head region that extended from its body. This characteristic is not known in any vertebrate lineage, suggesting a nonvertebrate affinity,” Tomoyuki Mikami, a doctoral student in the Graduate School of Science at the University of Tokyo at the time of the study and currently a researcher at the National Museum of Nature and Science, said in a press release. 

The researchers found structures consistent with those of invertebrates, such as body segmentation, vertical tail fins and head shape. They also analyzed body parts thought to prove similar to those of vertebrates, such as a tri-lobed brain, tectal cartilage (supporting the eyes and optic nerves) and fin rays. They found that these structures, though similar, are not comparable to those of vertebrates.

[Related: One wormy Triassic fossil could fill a hole in the evolutionary story of amphibians]

Using three-dimensional imaging techniques, the authors described the morphology of the Tully monster’s proboscis and its stylets—thin, needle-like structures with a similar function as teeth, in depth. According to the research, these structures are inconsistent with the keratinous teeth found in lampreys and hagfish, two vertebrates thought to be distant relatives.

In one of the earliest studies on the unique animal published in 1969, researchers stated that “our conception of the diversity of the organic world is based upon a small sample consisting almost entirely of animals with preservable hard parts.” The Tully monster, however, has few of such parts—not unlike jellyfish and worms, which lack hard skeletal structures and leave only impressions in sediment as they are fossilized. Studying what little evidence we have of ancient soft creatures is crucial for reconstructing the history of life, as a significant number of Earth’s creatures became extinct without leaving any fossils behind.

“More and more research is needed to extract important clues from Mazon Creek fossils to understand the evolutionary history of life,” Mikami said.

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Two new studies are shedding light on not only early hominid evolution, but are turning back the evolutionary clock on how early grassy woodlands appeared on the African continent.

The first new study, published April 13 in the journal Science, suggests that life in the open woodlands of Africa and a leafy diet may have influenced the upright stature of humans’ ape ancestors. 

[Related: Ancient DNA confirms Swahilis’ blended African and Asian ancestry.]

Anthropologists had long believed that our ancestors evolved an upright torso to pick fruit in forests, since some of our favorite produce grows on the spindly peripheries of trees. Large apes would have needed to distribute their weight on the branches stemming up from the trunk and then reach up with their hands to grab the fruit. Performing this task is easier if an ape is upright, since it can grab the branches better with their hands and feet. If an ape’s back is horizontal, the hands and feet are typically underneath the body, which makes it harder to move outward to the smaller branches of the tree. 

However, new research using a 21-million-year-old fossilized ape called Morotopithecus suggests that early apes actually ate the leaves in a seasonal woodland with a broken tree canopy and open grassy areas. The team believes that this landscape, and not fruit in closed canopy forests, possibly drove the ape’s upright structure.   

“The expectation was: We have this ape with an upright back. It must be living in forests and it must be eating fruit. But as more and more bits of information became available, the first surprising thing we found was that the ape was eating leaves. The second surprise was that it was living in woodlands,” co-author and University of Michigan paleoanthropologist Laura MacLatchy said in a statement.

Both papers grew out of a collaboration of international paleontologists called the Research on Eastern African Catarrhine and Hominoid Evolution project (REACHE). MacLatchy’s study focused on the a 21-million-year-old site in eastern Uganda called the Moroto site. Here, the team found fossils in a single rock layer. Fossils of other mammals and evidence of plant life were found in this layer and these lines were used to recreate Morotopithecus’ environment.

In a companion paper, also published April 13 in Science, another team used environmental proxies to reconstruct nine fossil ape sites across Africa, including the Moroto site during the early Miocene. The proxies revealed that grasses were actually all over the area 21 million years ago, instead of the previously determined 7 to 10 million. 

The team then found that the plants in this landscape were “water stressed,” which means that they lived in seasonal periods of rain and of aridity. These shifts mean that apes would have had to rely on something other than fruit to survive. These findings indicate that Morotopithecus likely lived in an open woodland that was punctuated by broken canopy forests made up of shrubs and trees. 

[Related: The ‘granddaddy’ of all early hominins walked on Earth a lot longer than we thought.]

“For the first time, we’re showing that these grasses are widespread, and it’s this general context of open seasonal woodland ecosystems that were integral in shaping the evolution of different mammalian lineages, including and especially in our case, how different ape lineages evolved,” study co-author and University of Michigan biological anthropologist John Kingston said in a statement.

The nine sites in both studies are scattered across eastern equatorial Africa, which is an area large enough for the team to develop a better regional picture of what these landscapes looked like 23 million to 16 million years ago during the early Miocene. At this time, the East African Rift forming the region saw huge change in topography. This upheaval as the Earth was pulling apart resulted in regional climate and its vegetation.  

“These open environments have been invoked to explain human origins, and it was thought that you started to get these more open, seasonal environments between 10 and 7 million years ago,” MacLatchy said. “Such an environmental shift is thought to have been selected for terrestrial bipedalism—our ancestors started striding around on the ground because the trees were further apart. Now that we’ve shown that such environments were present at least 10 million years before bipedalism evolved, we need to really rethink human origins, too.” 

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A team of scientists from the United States and the Netherlands have discovered a new species of bat based on the oldest bat skeletons ever discovered. The findings are described in a study published April 12 in the journal PLOS One. 

The new species is named Icaronycteris gunnelli (I. gunnelli) in honor of the late Gregg Gunnell, a Duke University paleontologist who died in 2017 and is remembered for his contributions to understanding fossil bats and evolution. 

[Related: How killing vampire bats to slow rabies can go wrong.]

The now extinct I. gunnelli lived in Wyoming roughly 52 million years ago and the current scientific consensus is that bats rapidly diversified on multiple continents during this time in history. There are currently over 1,460 living bat species  found almost all over the world, except for the Earth’s polar regions and a few remote islands. 

The bat skeletons are about 1.5 inches long and were found near Kemmerer, Wyoming in the Green River Formation. The formation spans parts of Wyoming, Colorado, and Utah and is home to an extensive fossil deposit from the early Eocene—about 56 million to 47.8 million years ago.  Scientists have found more than 30 bat fossils in the last 60 years within the formation. Until finding this new species, however, they believed all of them were from the same two extinct species, Icaronycteris index and Onychonycteris finneyi.

“Eocene bats have been known from the Green River Formation since the 1960s. But interestingly, most specimens that have come out of that formation were identified as representing a single species, Icaronycteris index, up until about 20 years ago, when a second bat species belonging to another genus was discovered,” study co-author Nancy Simmons, curator-in-charge of the American Museum of Natural History’s (AMNH) Department of Mammalogy said in statement. Simmons helped describe the second species named Onychonycteris finneyi in 2008, but always thought that there might be even more Eocene bats out there. 

Recently, scientists from the Naturalis Biodiversity Center in the Netherlands began to look closely at Icaronycteris index by collecting measurements and other data from museum specimens to put together a dataset.

“Paleontologists have collected so many bats that have been identified as Icaronycteris index, and we wondered if there were actually multiple species among these specimens,”  co-author and evolutionary biologist Tim Rietbergen said in a statement. “Then we learned about a new skeleton that diverted our attention.”

[Related: Both bats and humans test out talking as infants.]

The well-preserved I. gunnelli skeleton in this study was purchased by a private collector in 2017 and was subsequently purchased by AMNH. The team compared the skeleton with Rietbergen’s extensive bat dataset and saw that it clearly stood out as a new species.

A second fossilized Icaronycteris gunnelli skeleton that was discovered at this same quarry in 1994. It eventually made its way to the Royal Ontario Museum in Toronto and was also identified as this new species. 

While there are fossilized bat teeth from Asia that are slightly older than these skeletons, the two I. gunnelli fossils represent the oldest bat skeletons ever found, according to the team. The I. gunnelli skeletons are also the oldest bat fossils that have been recovered from the Green River Formation, but they are not the most primitive, meaning not the earliest on the bat evolutionary tree. According to the team, this supports the idea that the bats in the region evolved separately from other Eocene era bats.

“This is a step forward in understanding what happened in terms of evolution and diversity back in the early days of bats,” said Simmons.

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Plenty of species have traits evolved for more than one purpose. Deer antlers are built-in weapons as well as seductive doe-magnets. Octopus suckers can trap prey in their suction but also taste and smell. Bright colors in frogs signal danger to predators while flaunting reproductive viability to potential mates. The Luna moth has uniquely shaped wings that thwart predation from bats, but what else might they be good for? How does one determine the evolutionary role of a trait? 

In two recent complementary studies published in Behavioral Ecology and Biology Letters earlier this year, researchers expanded our understanding of the adaptation by testing the role of wing tails against sexual selection and bird predation.

Luna moths are native to the Eastern half of North America. Like all silk moths, they have distinctive long, trailing tails on their hindwings, or “twisted, cupped paddles” as lead author of both studies and doctoral student at the Florida Museum of Natural history Juliette Rubin said in a statement. Bats use echolocation to detect the position of objects with reflected sound, but the moth’s wing shape reflects sound waves in a way that makes the flying mammals aim for the ends of their wings. In a flap of a wing, the moth just barely dodges their predators. 

[Related: What bats and metal vocalists have in common]

First, the researchers wanted to see if the wing tails also played a role in sexual selection. When female Luna moths are ready to mate, they perch in one spot and release pheromones. Males, with extremely sensitive antennae, can detect and follow a pheromone trail, according to the University of Florida’s entomology department. Then, the female has her pick of suitors. 

In the first experiment, researchers placed a female moth in a flight box with two males: one with intact wings and one with the wing tails removed. Initial data suggested that females preferred tails over no-tails, but further trials demonstrated otherwise. When researchers removed tails by clipping them, the resulting damage may have hindered these males’ performance in the first trial, allowing the intact males to mate successfully.

They recreated the tail/no-tail experiment by removing tails from both males, and re-gluing them to one male, while placing glue only on the hindwings of the other. Researchers found no significant difference in mating success between them. 

To ensure the glue did not confound the results, researchers conducted an additional experiment with two intact males, one with glue on the hindwings. Similarly, they had equal mating success.

Though their elegance is attractive to us humans, the experiment revealed that Luna moth wing tails aren’t the result of sexual selection. 

Then, researchers wanted to see if the moths’ tails had any obvious drawbacks. They help moths to survive bats, a species that relies on echolocation, but what about visually-oriented predators? 

Luna moths sit still during the day, since flying in broad daylight with their large bright green wings would make them easy targets. To test whether or not their tails would have any impact on daytime predation, researchers wrapped pastry dough around mealworms and molded them to the size and shape of real Luna moths. They attached full wings and wings without tails to each half. They placed the replicas around branches and leaves in an aviary, and introduced Carolina wrens. 

The wrens ate the fake moths at the same rate regardless of wing type, indicating that the tails had no effect on whether or not birds could locate them. Some research suggests that birds rely on search images, mental representations of objects, when they are searching for prey. They use visual cues, such as the shape of moth wings, to distinguish between the prey from patterns in the background. So, the wrens may ignore the hindwing tails, using the overall shape of Luna moths to identify food, according to the press release.

[Related: A new technique reveals how butterfly wings grow into shimmery wonders.]

These experiments show that despite being a noteworthy feature to humans, the Luna moths’ tails do not play a role in attracting a mate, nor do they affect predation by birds.

“When we see these really obvious physical features in animals, we’re often drawn into stories we’ve heard about them,” Rubin said in the statement. “A trait that’s obvious to us, as visual creatures, might not stand out to the predators that hunt them, and the traits that we think are dynamic and alluring might not seem that way to a potential mate.”

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While the extinct woolly mammoth and present day elephants may be similar in size and many physical features, scientists are still learning more about what makes the giant elephant ancestors stand apart. The Woolly mammoth went extinct around 4,000 years ago, possibly due to changes in the Earth’s climate, when the vegetation that they survived on became too wet to consume when ice melted, but scientists have uncovered samples of its DNA from specimens preserved in ice and other fossils. 

Scientists found that many of the animal’s trademark features–like large fat deposits and woolly coats–were genetically encoded in the earliest woolly mammoths, but became more defined over 700,000 years of evolution. While woolly mammoths lived in northern parts of America and Eurasia, the specimens in this study came from an area now known as Siberia. The study published April 7 in the journal Current Biology also located a gene with several mutations that may have been responsible for the woolly mammoth’s tiny ears.

[Related: This is the most-complete woolly mammoth ever found in North America.]

“We wanted to know what makes a mammoth a woolly mammoth,” said study co-author and paleogeneticist David Díez-del-Molino of the Centre for Palaeogenetics in Sweden in a statement. “Woolly mammoths have some very characteristic morphological features, like their thick fur and small ears, that you obviously expect based on what frozen specimens look like, but there are also many other adaptations like fat metabolism and cold perception that are not so evident because they’re at the molecular level.”

The team compared 23 Siberian woolly mammoth genomes with 28 modern-day Asian and African elephant genomes. Though woolly mammoths are hypothesized to have been on Earth as long as 2.4 million years ago, their genes had accrued a large number of mutations specifically during those 700,000 years in Siberia. Twenty-two of the woolly mammoths in the study had relatively “modern” genomes, meaning that they had lived within the past 100,000 years. One sample named Chukochya was from an animal that lived roughly 700,000 years ago and is one of the oldest known woolly mammoths scientists have discovered.

[Related: Scientists made a woolly mammoth meatball, but don’t grab your fork yet.]

“Having the Chukochya genome allowed us to identify a number of genes that evolved during the lifespan of the woolly mammoth as a species,” study co-author and evolutionary geneticist Love Dalén from the the Centre for Palaeogenetics said in a statement. “This allows us to study evolution in real time, and we can say these specific mutations are unique to woolly mammoths, and they didn’t exist in its ancestors.”

The team found highly evolved genes related to fat storage and metabolism, like the ones modern-day polar bears and reindeer have, even though those animals are not related to woolly mammoths. According to Díez-del-Molino, this is a sign of convergent evolution–the evolution of two lineages that are similar, but it is not linked to a common ancestor–for the genes in cold-weather adapted mammals. 

[Related: Researchers retraced a woolly mammoth’s steps 17,000 years after it died.]

The relatively large woolly mammoth genome sample size helped the team pinpoint the genes that were common across the species. These genes were likely adaptive–which arise in response to a specific situation–instead of a naturally occurring variation. These genes also may have only been present in the single individual animal studied.

“We found that some of the genes that were previously thought to be special for woolly mammoths are actually variable between mammoths, which means they probably weren’t as important,” said Díez-del-Molino.

Compared with the newer woolly mammoth genomes, the Chukochya genome shared roughly 91.7 percent of the mutations that caused protein-coding changes in the more modern woolly mammoths. This high overlap shows evidence that their thick fur, fat metabolism, and cold-perception abilities were likely already present when the woolly mammoth first diverged from its ancestor the steppe mammoth, between 800,000 to 600,000 years ago.

Older woolly mammoths like Chukochya also likely had larger ears and a different wool type and texture and those traits continue to develop over time. The more modern genomes also had several immune mutations in T cell antigens that were not present in Chukochya. The team believes that these mutations were likely related to developing better immune responses to emerging viruses. 

All the woolly mammoth genomes were from specimens collected in Siberia, but the researchers hope to branch out and compare them with North American specimens. “We showed a couple of years ago that there was gene flow between woolly mammoths and the ancestors of Colombian mammoths, so that’s something that we will need to account for because North American woolly mammoths might have been carrying non-woolly mammoth genes as well,” said Dalén.

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THE FIRST TIME I had cilantro, I sat in the car with my mother, eating tacos from her favorite spot. As I settled in and took my first bite, I was immediately disgusted and spit it out. After repeated insistence that her food tasted fine and a quick Google search, we deduced that the problem was the cilantro and that I was, sadly, someone to whom it tasted like soap—Dove Sensitive Skin Beauty Bar, to be specific.

“You must get that from yo’ daddy,” she said, laughing. 

The dislike of cilantro is a commonly known food aversion, though it affects only a small section of the population. A 2012 study on young adults in Canada found that, generally, dislike of cilantro ranges between 3 and 21 percent of the population, with varying ethnocultural specificities. Nevertheless, my mama isn’t wrong. There’s a strong chance that I did inherit this distaste for cilantro from my father or someone else in my direct lineage. But before we get into the genetic variations, it’s essential to understand the difference between literal taste and the perception of flavor. 

Taste, scientifically, covers only salt, sweet, sour, bitter, and umami, which are chemical cues picked up by the tongue, explains James N. Palmer, the director of the division of rhinology at the University of Pennsylvania’s School of Medicine. “Flavor is the combination of taste and smell,” he says. “So what people will call taste isn’t really taste: It’s flavor.” 

Our food is broken down with our teeth and the enzymes in our saliva when we eat. Next, the chomped-up bits glide over our papillae, the thousands of little bumps on the tongue, the roof of the mouth, and the throat. Those bumps contain taste buds, which each have between 50 to 100 chemical receptors that identify the five tastes. 

“We use our taste system simply to identify specific chemicals in our food,” says Kathryn Medler, a professor in the University of Buffalo’s biological sciences department. “There are things that we need in our diet, so we prefer them. We eat things that are sweet, salty, or umami [because] those are [nutrients] that we need in our diet in order to be healthy. And we innately avoid sour things, which are going to potentially identify spoiled foods, as well as bitter, which are going to identify potential toxins.” (The cool thing about your taste buds, however, is that you can train them to acquire a taste for sour and bitter flavors.) 

The chewing process also releases odorants. These smells travel up the back of the nasopharynx and into the back part of the nose, resulting in retronasal olfaction, which is how we process odors while consuming food. As we chew, our brains combine these signals to determine the flavor of a food or drink. (Our brains also pick up on mouthfeel–like stringiness or crispiness–as we chew, but that is a separate sensory process.) For instance, Palmer says that steak sauce and chocolate have the same levels of bitterness, sour, and sweet, and that it’s our sense of smell that makes us perceive them as different flavors.

Once the distinction between taste and flavor is clear, it’s easier to understand how DNA affects how we enjoy—or don’t enjoy—certain foods. Our genes influence how we experience flavor, not taste itself. Cilantro will always have a fresh, citrusy smell. But due to a variation in a cluster of olfactory receptor genes that makes them more sensitive to the scents of aldehyde chemicals—found in cilantro and used in soap making—eating cilantro can feel like chewing on a sudsy washrag to some people because the scent of aldehyde is released during chewing.

There are other factors—such as the foods we grew up eating—at play when it comes to why we love or hate certain tastes and flavors. 

Most taste preferences and differences are not necessarily related to genes, says Medler; some can also be related to the cultures or regions we were raised or live in. Take okra, for instance. Medler and I both grew up eating fried okra because we’re Southerners, and we remain very fond of it because it reminds us of home. However, her husband, who grew up in New England, could take it or leave it. “It’s not that he inherently tasted something different than I tasted, but he doesn’t have the positive associations with it,” she explains. 

But both Medler and I lose our affection for okra when it’s cooked in a way that makes it become slimy. The vegetable’s texture is crispier when it’s fried, because frying eliminates most of the gumminess. When it’s included in gumbo or the Nigerian soup obe ila, though, the slippery nature is more pronounced. Enjoying that mouthfeel is typically learned: A friend who grew up eating obe ila loves okra as a stew or fried—in part because it has positive associations for him and because he’s familiar with its textures.

Still, some food experiences, like my soapy-taco debacle, are genetically set in stone. “Everybody’s genetics are slightly different, which means their taste receptors are slightly different, which means [everyone is] going to have different powers in terms of tasting things,” says Palmer. 

“I smile when my patients say, ‘Well, why do things taste different to me than they do to somebody else?’” he continues. “You’re a different height than everybody else. … You have all sorts of other genetic characteristics that differ. So you would expect taste genetics and smell genetics, and therefore flavor genetics, to be different for every person.”

Read more PopSci+ stories. 

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Wild elephants could be the next animals to join an exclusive list of species that show signs of self-domestication. A study published April 3 in the journal Proceedings of the National Academy of Sciences (PNAS) found that elephant self-domestication may have led to some of their advanced traits, such as mourning their dead, helping sick or injured elephants, and even recognizing themselves in mirrors. 

According to  the self-domestication hypothesis, humans have gone through a process of “selection against aggression,” that was self-induced and not forced.  

“The theory of self-domestication is hard to test,” study co-author and Max Planck Institute evolutionary biologist Limor Raviv said in a statement. “This is because only one other species besides humans has been argued to be self-domesticated: bonobos.”

[Related: A DNA tool designed to solve murders is exposing elephant poachers.]

Raviv and her colleagues looked at how African savannah elephants compared with humans and bonobos on 20 different measures. They found that all three species share some of the same physical features and display the same habits. Elephants play, are social, have a long childhood, and “babysit” for the offspring of other members of their groups. Both bonobos and humans also do this. Additionally, wild African elephants’ have a shortened jawbone, which is a trait shared by domesticated animals such as cats.  They also appear to be able to restrain themselves from being aggressive to others.

Elephants can also learn from each other. Knowledge like what to eat and how to raise their young are socially transmitted, versus being innate like they are in other animals. For example, spiders are born knowing how to spin silk, same goes with birds building nests. Elephants also have a sophisticated and varied communication system. Their extensive vocal repertoire ranges from roars to low-frequency rumbles to trumpets and roars to low-frequency rumbles. Elephants in Kenya even have a different alarm call for bees than they do for humans. 

The team also found several candidate genes associated with domestication in elephants. They compared the genomes of wild elephants with studies of 261 domesticated mammals and created a list of the genes that are frequently associated with domestication. Of the 674 genes that the team says have a high likelihood of being passed down from earlier elephant generations, 79 genes were associated with domestication in other species. This could suggest that domestication can evolve in multiple branches of the mammal evolutionary tree. 

[Related: ‘Zombie genes’ could be why so few elephants die of cancer.]

The team hypothesizes that self-domestication in elephants might be related to their large size and relative strength. “This means that elephants are generally less worried about evading or fighting other animals for their survival,” Raviv said. “This kind of ‘safe environment’ could relax selective pressures for aggression, free cognitive resources, and open up more opportunities for exploration, communication, and play.”

Some scientists remain wary about self-domestication in general and future studies are needed to further test this hypothesis. Melinda Zeder, an emeritus archaeologist and domestication expert at the Smithsonian Institution told Science, “it’s nice to see the correlations with bonobos and humans and the genetic similarities tied to the reduction of aggression,” but she is still skeptical of the self-domestication idea in general. She adds that self-domestication is a “meaningless term that muddies the waters,” and that domestication requires “two to tango,” meaning a domesticator and a domesticate.

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Watching a bird leap around on its crooked legs before it takes off into the air is kind of  like turning back the evolutionary clock and watching a theropod dinosaur. Numerous paleontologists believe that theropod group, which includes the spinosaurus, tyrannosaurus rex, and velociraptor, evolved into the birds we see on Earth today. This would make them the only dino-descendants that survived catastrophic extinction 66 million years ago.

Like birds, theropod dinos also laid eggs, and scientists are beginning to fill in evolutionary gaps by studying the shelly remains. A study published April 3 in the journal Proceedings of the National Academy of Sciences (PNAS) examined the calcium carbonate left behind in the eggs of a funky theropod called Troodon and found that the dinosaurs laid four to six eggs in communal nests. 

[Related: Newly found titanosaur eggs reveal dino nurseries once teemed with baby giants.]

Troodon was a carnivorous dinosaur over six feet long that lived in North America about 75 million years ago. It had some bird-like features, particularly its light and hollow bones, two legs, and fully developed feathery wings. However, the dinosaur’s relatively large size kept it from flying, but it likely ran very fast and caught prey in strong claws. 

Troodon females also laid eggs that are more similar in shape to the asymmetric eggs laid by  modern birds than to the round reptile eggs. Their eggs were blue-green colored like other theropod eggs, and they have been found half buried into the ground. The international team of scientists on this study believes that mother Troodons sat and brooded on them.

To learn more, the team examined the calcium carbonate left behind in some well-preserved Troodon eggshells. They used a method developed in 2019 called “dual clumped isotope thermometry.” 

With this technique, they could measure the extent to which heavier isotopes of oxygen and carbon clump together in carbonate minerals. Isotopic clumping is temperature-dependent, and the prevalence of this clumping helped the team determine the temperature at which the carbonates crystallized. The eggshells were likely produced at temperatures of 107 degrees Fahrenheit and then deduced down to 86 degrees, which is very similar to modern birds. 

[Related: A fossilized egg laid by an extinct, human-sized turtle holds a rare jackpot.]

The team then compared  the isotopic compositions of reptile egg shells (alligator, crocodile, and multiple turtle species) with modern birds (chicken, sparrow, wren, emu, kiwi, cassowary, and ostrich) to see if Troodon was closer to either birds or reptiles. Two different isotopic patterns were revealed. The reptile eggshells have isotopic compositions matching the temperature of the surrounding environment, since they are cold-blooded and form their eggs slowly. Birds leave a recognizable non-thermal signature in the isotopic composition, which is evidence of quick eggshell formation. 

“We think this very high production rate is connected to the fact that birds, unlike reptiles, have a single ovary. Since they can produce just one egg at the time, birds have to do it more rapidly,” study author and geochemist from Goethe University Frankfurt in Germany Mattia Tagliavento said in a statement. 

The team compared these results to the remains of Troodon eggshells and did not not detect the isotopic composition which is typical for birds. According to Tagliavento,  “this demonstrates that Troodon formed its eggs in a way more comparable to modern reptiles, and it implies that its reproductive system was still constituted of two ovaries.”

As a last step, the researchers combined their results with existing knowledge about body and eggshell weight and determined that Troodon only produced only four to six eggs per reproductive phase. They found this observation particularly notable because Troodon nests are typically large and have up to 24 eggs, so the team believes that this means they laid their eggs in communal nests. This communal egg nesting behavior is seen in modern day ostriches.  

“Originally, we developed the dual clumped isotope method to accurately reconstruct Earth’s surface temperatures of past geological eras,” study co-author, geochemist, and developer of the new thermometry method Jens Fiebig, said in a statement. “This study demonstrates that our method is not limited to temperature reconstruction, it also presents the opportunity to study how carbonate biomineralization evolved throughout Earth’s history.”

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Real predatory dinosaurs like the infamous Tyrannosaurus rex may have looked quite a bit different than their movie star counterparts—and not just because they had feathers. Theropods like the T. rex may have also had completely different mouths. Instead of a lipless grin and permanently exposed teeth with their upper jaw hanging over the lower jaw like a crocodile, the T. rex may have boasted scaly lips covering up their teeth.

The details of this possible oral makeover are described in a new study published March 30 in the journal Science. An international team of researchers say that these lips were more similar to lizards and their relative, the tuatara. The tuatara, the last survivors of an order of reptiles that thrived during the age of the dinosaurs, is a rare reptile that is found only in New Zealand that can live up to 100 years.

[Related: What are dinosaur feathers like?]

The team examined the tooth structure, wear patterns, and jaw morphology of reptiles from both lipped and lipless groups. They found that the theropod mouth functionality and anatomy actually resembled lizards more than crocodiles. The study says this similarity implies the T. rex had lizard-like oral tissues, with scaly lips covering up their teeth.   

“Paleontologists often like to compare extinct animals to their closest living relatives, but in the case of dinosaurs, their closest relatives have been evolutionarily distinct for hundreds of millions of years and today are incredibly specialized,” study co-author and Canada’s Royal BC Museum paleontology collections manager and researcher Derek Larson, said a statement. “It’s quite remarkable how similar theropod teeth are to monitor lizards. From the smallest dwarf monitor to the Komodo dragon, the teeth function in much the same way. So, monitors can be compared quite favorably with extinct animals like theropod dinosaurs based on this similarity of function, even though they are not closely related.”

Additionally, therapod lips were likely not muscular, as seen in mammals. Most reptiles have lips that cover up teeth, but can’t be moved independently. Humans and mammals can make all sorts of movements with their lips, like curling them into a snarl or posing with “duck face” in a selfie, but reptile lips can’t. 

The study also found that the tooth wear in lipless animals was different from what has been seen in carnivorous dinosaurs. Dinosaurs also had teeth that were no larger than modern lizard teeth when compared to their relative skull size. The teeth were likely not too big to be covered up by scaly lips. 

[Related: Is T. rex really three royal species? Paleontologists cast doubt over new claims.]

Another more lizard-like feature in theropods was the distribution of small holes around the jaws that supply blood and nerves to dinosaur gums and tissues in the mouth. When modeling mouth closure in lipless theropod jaws, the team found that the lower jaw either had to crush jaw-supporting bones or disarticulate the jaw joint to seal the mouth.

“As any dentist will tell you, saliva is important for maintaining the health of your teeth. Teeth that are not covered by lips risk drying out and can be subject to more damage during feeding or fighting, as we see in crocodiles, but not in dinosaurs,” said co-author Kirstin Brink, a vertebrate paleontologist at the University of Manitoba, in a statement.

According to the team, this prehistoric lip debate has roots all the way back to the nineteenth century, when scientists began restoring dinosaur fossils. It became more prominent when blockbuster films like Jurassic Park and documentaries took to the screen and have since become deeply rooted in popular culture. 

“Curiously, there was never a dedicated study or discovery instigating this change and, to a large extent, it probably reflected preference for a new, ferocious-looking aesthetic rather than a shift in scientific thinking,” paleontologist and co-author Mark Witton from the University of Portsmouth, said in a statement. “We’re upending this popular depiction by covering their teeth with lizard-like lips. This means a lot of our favorite dinosaur depictions are incorrect, including the iconic Jurassic Park T. rex.”

This study provides new insights into how paleontologists can reconstruct both the soft tissues and appearance of extinct species, so that scientists can learn more about how they fed, maintained their tooth health, and even more broad patterns in their evolution. 

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Windows can be a death trap for birds—after all, their eyesight makes it difficult or impossible to distinguish between glass and clear flying space. Millions of birds crash into windows along their annual migratory paths and the collisions kill somewhere between 365 million to nearly one billion birds in the United States alone each year. 

Volunteers and scientists throughout the years have collected the fallen birds around the country every spring and fall to rehabilitate  injured birds and document the dead.  The bodies contain valuable scientific information, especially when they are compared over time.

[Related: How to help birds avoid crashing into your windows.]

A study published March 28 in the journal Molecular Ecology is helping scientists better understand the relationship between birds and the multiple microbes in their guts by using these unique specimens.

“In humans, the gut microbiome—the collection of bacteria, fungi, and other microbes living in our digestive tracts—is incredibly important to our general health and can even influence our behavior. But scientists are still trying to figure out how significant a role the microbiome has with birds,” co-author Heather Skeen, a biologist and research associate at Chicago’s Field Museum, said in a statement.

Different mammal species tend to have their own signature microbes living in their gut. The microbes help them digest food and fight disease, with evidence that these relationships can go back millions of years. Researchers have been finding that bird microbiomes likely play by a whole different set of rules.

“Bird gut microbiomes don’t seem to be as closely tied to host species, so we want to know what does influence them,” said Skeen. “The goal of this study was to see if bird microbiomes are consistent, or if they change over short time periods.”

Skeen focused on four common species of songbirds called thrushes, but there are dozens of species found throughout Chicago after crashing into the city’s buildings. She took samples from 747 birds over three years and included samples from the thrushes summer breeding grounds in Manitoba in Canada and the Midwestern states of Michigan and Minnesota.

To get inside of the bird bellies, she made a small incision into the abdomen to reach the bird’s intestines and squeezed out what was inside.  She then transferred bird poop from the intestines to specialized filter paper cards that preserve DNA. The genetic material was then sent away for bacteria classification. 

[Related: Puffy unicorn stickers could save millions of migrating birds each year.]

“Analyzing the bacterial DNA present in the poop allowed us to determine exactly what kinds of bacteria were present,” said Skeen. “It turns out, there were about 27,000 different types of bacteria present.”

The team looked for trends in the bacteria present across the whole sample, and found that the different bird species didn’t seem to have their own unique set of microbes—unlike mammals. Instead, time was the clearest link between the birds and the bacteria present in their microbiomes. Gut microbiomes had significant differences in the composition of the bacteria season to season and year to year.

The results suggest that bird microbiomes might have more to do with their environment than the inborn, consistent relationship that is seen in most mammal species. 

Shannon Hackett, associate curator of birds at the Field Museum and a co-author of the paper, says the museum has been scooping birds killed by buildings for 40 years and that this study helps show why museum collections are valuable for research

“At the time, people were like, ‘What the hell are you doing?’ But the fact that he’s been doing this for forty years means we have a unique opportunity to study birds across fairly short periods of time. We have more than 100,000 window-killed birds at this point, it’s an incredibly rich resource,” Hackett said in a statement. “And as technology evolves and new scientists like Heather come up, we broaden what we’re able to do with these resources.”

Some ways to help birds avoid crashing into your windows include using decals and films on them that are invisible to birds while also letting light in, supporting bird-safe buildings, and turning off interior lights at night.

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As the saying goes, “everything’s bigger in Texas.” That extends to one of the state’s famed roadside shopping hubs. Buc-ee’s boasts the world’s largest convenience store, largest car wash, and even the world’s cleanest restrooms among its numerous offerings to motorists traveling the Lone Star and six other states.

The travel center selling everything from jerky to gas grills can now boast that it has a species of ancient beaver named after its smiling cartoon beaver  mascot. A team of researchers at The University of Texas at Austin (UT)  found the fossilized beaver specimen in the school’s collection and named it Anchitheriomys buceei (A. buceei) after Buc-cee’s semi aquatic salesman. 

[Related from PopSci+: Beavers, snails, and elephants are top grads from nature’s college of engineering.]

“Buc-ee’s was founded in 1982, but we may need to rethink our beginnings,” Arch “Beaver” Aplin III, the founder and CEO of Buc-ee’s, said in a statement regarding the company mascot’s place in Texas’ history.

The new species is described in a study published in the March issue of the journal Palaeontologia Electronica.

While driving down a highway in 2020, UT research associate and study co-author Steve May spotted a Buc-ee’s billboard that said “This is Beaver Country.” May thought back to fossils of the beaver fossils he studied at the university’s Texas Vertebrate Paleontology Collections.

“I thought, ‘Yeah, it is beaver country, and it has been for millions of years,’” May said in a statement.

The new paper describes A. buceei and another much smaller species of beaver and provides an overview of beaver occurrences along the Texas Gulf Coast from 15 million to 22 million years ago.

A. buceei roamed Texas about 15 million years ago during the Miocene. A previous study described the “Texas Serengeti” at the time, where large elephant-like animals, alligators, antelopes, and rhinos roamed the state. A. buceei was about 30 percent larger than the modern beavers scurrying across current-day Texas. 

The UT collections includes A. buceei fossils from six sites in Texas, but most of what the researchers could learn about the old beaver comes from a unique partial skull from the eastern town of Burkeville, Texas. That fossil is a fusion of bone and brain cast that formed when sediment naturally seeped into the beaver’s brain cavity. This created a rock replica of the animal’s brain as a specimen fossilized. 

[Related: Wolves and beavers can have magical ecosystem effects—if they have space to thrive.]

The team took high-resolution X-ray images of the skull to get a better look at the small anatomical details of the skull which  helped May and co-author  Matthew Brown, a paleontologist at UT, confirm that the skull belonged to a new species. 

However, this team was not the first to suspect that this was a distinct new species of ancient beaver.  When the skull was originally collected in 1941, a museum curator named Curtis Hesse from Texas A&M University noted that he intended to name it a new species. However, Hesse died in 1945 before he could complete his study and publish his findings. Eighty years later, a team equipped with new technology and more understanding of the fossil record picked right up where Hesse left off.  

“New discoveries in the field capture lots of attention, but equally as valuable are the discoveries made in existing museum collections,” Brown said in a statement. “We know that these opportunities are littered throughout the drawers in these cabinets.”

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For decades, scientists have been studying a South African daisy’s (Gorteria diffusa) deceptive way to attract pollen. It uses its petals to trick male flies into believing the flower is actually a female fly. When a male insect approaches the flower, it jiggles around trying to mate, and typically buzzes off after a few unsuccessful attempts, leaving pollen behind.

In a study published March 23 in the journal Current Biology, scientists have identified three sets of genes that help build the fake fly appearance on the daisy’s petals. To determine what these genes do, the team compared which genes were ‘switched on’ in petals that had fake flies compared to petals without. They then compared the petals to a different type of daisy that produces a simple spot pattern on its petals, to figure out which genes were specifically involved in making the more deceptive fake fly spots.

According to the team, the surprising find is that all three sets of insect lookalike-creating genes already have other functions in the plant. One set moves iron around, one controls when flowers are made, and one makes hairs on the roots grow. 

[Related: Ecologists have declared war on this popular decorative tree.]

“This daisy didn’t evolve a new ‘make a fly’ gene. Instead it did something even cleverer – it brought together existing genes, which already do other things in different parts of the plant, to make a complicated spot on the petals that deceives male flies,” said study co-author and University of Cambridge plant biologist Beverley Glover, in a statement.

To make this work, the ‘iron moving’ genes add iron to the flower petal’s typically reddish-purple pigments, which changes the color to a more fly-like hue of blue-green. The root hair genes create hairs that expand the petal and give it more texture, making  the fake flies appear in different positions on the petals.

According to the team, this method of attracting more male flies to pollinate gives the plant an evolutionary advantage. The daisies grow in a harsh desert environment with a short rainy season, with makes for a  compressed flower producing, pollination, and seeding schedule. There’s intense competition for the plants to attract pollinators, and these fake lady flies help the daisies stand out. 

By evolutionary standards, this daisy is fairly young at 1.5 to two million years old. These fake fly spots were not on the planet’s oldest daisies, so they likely appeared on petals early on in their evolution. 

“We’d expect that something as complex as a fake fly would take a long time to evolve, involving lots of genes and lots of mutations. But actually by bringing together three existing sets of genes it has happened much more quickly,” said study co-author and plant evolution specialist Roman Kellenberger, in a statement. 

[Related: Bees can sense a flower’s electric field—unless fertilizer messes with the buzz.]

The authors add that this is the only example of a flower producing multiple fake flies on top of its petals. Other daisies make simpler spots like those around the petals, but they are not as convincing to real flies. Orchids can also use sexual deception to trick males into mating with its petals.
“It’s almost like evolving a whole new organ in a very short time-frame,” said Kellenberger.“Male flies don’t stay long on flowers with simple spots, but they’re so convinced by these fake flies that they spend extra time trying to mate, and rub off more pollen onto the flower – helping to pollinate it.”

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As winter melts into the spring, flowers start to bloom and  some unique animals also begin to change color. The white-tailed jackrabbit is one of close to 20 species of animals and birds that have evolved to change colors with the seasons. The rabbit is not white all year, changing from its winter white into spring and summer brown with the season. It’s a survival tactic, as darker hued animals stand out to predators in snowy climates. 

A team of researchers from the United States and Portugal sought out to learn more about the genetics involved in these colorful seasonal changes. Their study, published today in the journal Science, details the evolution of winter camouflage in white-tailed jackrabbits. They uncovered how the genes that control this winter color variation could be a key to their survival as the planet warms and snow cover reduces.

[Related: How a peculiar parasitic plant relies on a rare Japanese rabbit.]

“Several members of the research team live and work in the Rocky Mountains, with a close connection to nature and the incredible changes that we are all experiencing year to year in the intensity of extreme weather and climate,” study co-author and ecologist/evolutionary biologist Jeffrey Good from the University of Montana, told PopSci. 

When beginning this research over a decade ago, Good said that a team member discovered a natural history study from 1963 which described more complicated, but intriguing patterns of continuous color variation in a white-tailed jackrabbit population in Colorado.

Study lead author and evolutionary biologist Mafalda Sousa Ferreira from BIOPOLIS-CIBIO at the University of Porto in Portugal was conducting this research as part of her PhD and took a closer look. “This made this part of my PhD project a bit risky,” Sousa Ferreira told PopSci. “If the paper was correct, we could explain something very unique, but if we couldn’t sample the specimens to characterize it, I might have to rethink part of my thesis.” 

With this half a century old clue in tow, they used museum specimens collected over the years to characterize the variations in color. The oldest of their 196 specimens dated back from 1906, sourced  from multiple museums including the Denver Museum of Nature & Science and the American Museum of Natural History in New York. Importantly, they confirmed the study from 1963 on color variation in white-tailed jackrabbits.

“It is very exciting to see something described years earlier materialize like that before your eyes. The high-risk project was actually possible, and eventually successful!” said Sousa Ferreira.

[Related: This hybrid hummingbird’s colorful feathers are a genetic puzzle.]

After categorizing the fur color variation, the team then used genetic sequencing and determined that the jackrabbits’ color variation in winter is primarily determined by three genes (EDNRB, CORIN, and ASIP) that control the production and localization of melanin pigments.

“Fur coat color is determined by pigments that are produced in special cells in the skin (melanocytes). You can think of these cells as pigment factories. How active these factories are—what type of pigment (black and brown, red and yellow) and how much is produced determines the color of hair,” explained Good. 

This process is quite common across mammals and are the same pigments that determine the color and darkness of hair in humans. Jackrabbits can display white, brown, or more intermediate-colored coats depending on what versions they get from their parents. 

After establishing how winter color variation, the environment, and the rabbit’s genetics were related, they combined these results with climate projections on expected snow loss due to climate change.

Surprisingly, they found that rabbit populations with higher variability in their color genes should be well prepared to face snow loss over the next 100 years. These projections indicate that the winter-brown jackrabbits will actually expand their range and could even help rescue the whole species from decline. 

It was a welcome bit of positive news, but the team still cautions that human-caused threats (disease, habitat loss, etc.) put this adaptability in jeopardy and highlights the importance of conservation at the species level.

“The jackrabbits and their coat colors show how understanding and preserving the genetic diversity of a species is just as important, particularly in this rapidly changing natural world,” said Good.

The post Jackrabbit’s color-changing fur may prepare them for climate change appeared first on Popular Science.

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Everything we’ve learned about dinosaurs essentially comes from fossils. But million-year-old rocks and bones have left a few hulking gaps in our understanding of the prehistoric world. Dinosaur Mysteries digs into the more secretive side of the “terrible lizards,” and all the questions that keep paleontologists up at night.

DINOSAURS DOMINATED EARTH. We all know the trope. The stupendous reptiles were so numerous and unique that they claimed a 150-million-year-long chunk of Earth’s history as the Age of Dinosaurs. 

But talking about a single group of organisms “dominating” the planet is silly. For one thing, the only dinosaurs bobbing in the ocean waves were carcasses, washed out by coastal storms.

Oceans have covered the vast majority of our planet for billions of years and contain more than 96 percent of Earth’s water at present. Dinosaurs, so far as we can tell, never made the sea their home. And paleontologists still don’t know why.

If there’s anything more challenging than understanding why a species evolved a particular way, it’s trying to backtrack on the evolutionary roads it didn’t take. Nature is full of invisible barriers and bottlenecks that open and close based on previous change. We usually don’t perceive these biological constraints until we run into a “Why not?” question. And even then, it can be difficult to distinguish between what’s actually impossible and what simply didn’t happen due to coincidence. In the case of the dinosaurs, though, we have a few clues as to why the seas remained beyond their domain.

For the most part, dinosaurs were atrocious swimmers. But it took decades for paleontologists to figure this out as they waited for the right fossil tracks, analyses of dinosaur bone structure, and computer methods capable of estimating the buoyancy of dinosaurs. During much of the 20th century, when experts insulted living reptiles and dinosaurs alike by characterizing the extinct saurians as dimwitted slowpokes, some paleontologists thought long-necked sauropods like Brachiosaurus could only support their weight in water. They also posited that the “duck-billed” dinosaurs, or hadrosaurids, plunged into lakes when tyrannosaurs stalked too near—the only defense herbivores that weren’t covered in armor or horns could have, apparently. Starting in the 1970s, paleontologists realized that fossilized tracks and other clues about the sauropods and duck-bills indicated they lived in terrestrial environments and weren’t adept in water. Not only that, but the relatively few trace fossils made by swimming dinosaurs—scrapes in the sediment from when they kicked their feet—were created by carnivorous dinosaurs, undercutting the idea that water was a refuge for plant eaters. 

A key dinosaurian trait may have prevented the reptiles from getting cozy in the water. The bony respiratory systems of sauropods and theropods show evidence of a unique set of air sacs connected to the lungs and other parts of the respiratory system. These soft-tissue pockets allowed the creatures to breathe more efficiently than mammals by keeping new air constantly flowing instead of relying on distinct inhales and exhales. (Birds have the same feature, with the added benefit that it keeps their skeletons light by filling bony spaces with air.) But when modeling how these air pockets would have affected dinosaurs’ swimming ability, paleontologists found that even large species would have acted like inflatable pool toys—too light for their size to be stable in the water. Adaptations to a life aquatic usually involve denser bones as a form of natural ballast—too much internal air would make dinosaurs work too hard to stay submerged. So much like us, while some dinosaurs could swim, they certainly weren’t diving neck and neck with the prehistoric sea turtles and plesiosaurs.

The same problem comes up for dinosaurs that were once considered skilled swimmers. The sail-backed, roughly 50-foot-long Spinosaurus has a few anatomical hallmarks associated with dipping and diving: Some of its bones seem extra dense, like those of other semiaquatic animals, and its tail is long and eel-esque, like a giant hitched-on paddle. But recent studies have found that Spinosaurus’ airy skeletal structure would have made it unstable in water too, and that the huge sail would have hampered the dinosaur’s ability to chase after prey while submerged. It’s more likely that the creature, once heralded as the world’s first swimming dinosaur, was more of a wader that plodded through the shallows as it tried to ambush fish. While additional evidence might alter the picture, especially because no one has found anything close to a complete Spinosaurus skeleton, for now the dinosaur most closely associated with the water was less aquatic than an alligator.

In all, after more than two centuries of searching, paleontologists have not identified a single dinosaur fossil that definitely spent most of its life at sea. The few specimens dug up from marine sediments—like the beautifully preserved armored Borealopelta from Alberta—represent dinosaurs that perished inland or along the coasts and were washed out to sea by storms or local flooding. Some became food for sharks and marine reptiles; some formed temporary reefs; and some quickly got buried under rock and soil, preserving their scales in place. But there were plenty of other reptiles in the sea—fish-like ichthyosaurs, long-necked plesiosaurs, and mosasaurs that were the ocean equivalent of Komodo dragons—that prove the dominion of dinosaurs was exaggerated. 

Of course, we know that dinosaurs eventually did wander into the water. For example, about 5 million years after the asteroid impact that ended the Cretaceous, the first ancestors of penguins took the plunge. Today, these water-savvy birds “fly” by flapping their wings underwater and sport a variety of adaptations, from hydrophobic feathers to salt-excreting vessels in their bills, that allow them to spend a great deal of their time in the ocean. But they still reproduce on land, shedding yet another clue to why extinct dinosaurs never hit the deep blue.

So far as we know, all dinosaurs laid eggs—from the very first terrible lizard (“dinosaur” translated into Greek) 243 million years ago to the chickadees bouncing around on the sidewalk in the present. Whereas other marine reptiles repeatedly evolved ways to give birth, likely starting with the soft-shelled eggs that some snakes and lizards retain today, dinosaurs don’t seem to have ever evolved a different capability. Or perhaps they did but were so late to the party that the seas were already full of nimble, sharp-toothed reptiles ready to munch on any awkward dino-paddlers. The ancient world of the dinosaurs was one that ended at the shoreline, leaving plenty of space for other creatures to rule the water.

We hope you enjoyed Riley Black’s column, Dinosaur Mysteries. Check back on PopSci+ in May for the next article.

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Thom van Dooren is a field philosopher at the University of Sydney and the University of Oslo. He is the author of several books, including “Flight Ways: Life and Loss at the Edge of Extinction, “The Wake of Crows: Living and Dying in Shared Worlds,” and “A World in a Shell: Snail Stories for a Time of Extinctions,” from which this article is adapted.

This excerpt was originally featured on MIT Press Reader.

There have been surprisingly few experimental efforts to explore the possible avenues by which Hawai‘i’s snails might have crossed oceans to arrive in their new home. In fact, to date there has been precisely one study on this topic of which I am aware. In 2006, Brenden Holland, a researcher in the biology department at Hawai‘i Pacific University, placed a piece of tree bark with 12 live snails of the species Succinea caduca into a saltwater aquarium. This is one of Hawai‘i’s nonendangered snail species; in fact, it is one of the few species that is found on multiple islands and seems to be doing okay. It is a coastal species, and the individuals enrolled into the study were from populations living as little as 10 meters from the beach. Brenden explained to me: “After heavy rain, they are commonly seen in gullies by the coast so there’s no question that they are going to get washed down pretty frequently.”

The purpose of Brenden’s experiment was to determine whether, when this happens, it might be possible for these snails to move around by sea and successfully establish themselves in new places. The answer, it seems, is yes. Brenden and his colleague Rob Cowie reported that: “After 12 h of immersion, all specimens were alive, indicating that sea water is not immediately lethal and suggesting the potential for rafting between islands on logs and vegetation.”

Why, you might wonder, does this matter? Far from being an abstract, albeit fascinating, scientific curiosity, I am convinced that attending to snail biogeography and evolution is particularly important at our present juncture. Hawai‘i was once home to one of the most diverse assemblages of land snails found anywhere on the planet, over 750 species. Today, however, the vast majority of these species are extinct, and most of those that remain are headed in the same direction. As they disappear from their island homes en masse, my hope is that paying attention to the deep-time processes of snail movement that brought them all here in the first place could help us to understand and appreciate these snails in new ways. As the writer Robert Macfarlane has argued, a deep time perspective can offer “a means not of escaping our troubled present, but rather of re-imagining it; countermanding its quick greeds and furies with older, slower stories of making and unmaking.”

Beyond Hawai‘i’s shores there have been numerous efforts to experimentally explore or otherwise interrogate the puzzle that is the evolution and distribution of island land snails. Charles Darwin, in a letter to Alfred Russel Wallace in 1857, summed up the situation succinctly: “One of the subjects on which I have been experimentising and which cost me much trouble, is the means of distribution of all organic beings found on oceanic islands and any facts on this subject would be most gratefully received: Land-Molluscs are a great perplexity to me.” Or, as he put it in a letter to another correspondent a year earlier: “No facts seem to me so difficult as those connected with the dispersal of land Mollusca.”

“No facts seem to me so difficult as those connected with the dispersal of land Mollusca,” Darwin wrote in 1857.

In an effort to address this perplexity, Darwin submerged land snails in saltwater to discover whether and how long they might survive. Among his other findings was the fact that estivating snails of the species Helix pomatia recovered after 20 days in seawater. The fact that these snails were estivating is important. During these periods snails can create a thin layer of mucus to cover their aperture and prevent them drying out. As long as they are sealed up inside their shells in this way, it seems that many snails can survive being submerged in saltwater for weeks at a time.

Inspired by Darwin, a French study in the 1860s placed 100 land snails of 10 different species in a box with holes and immersed it in seawater. Roughly a quarter of the snails, from six different species, survived for 14 days — which was calculated to be about half the time it would take for an object like a log to float across the Atlantic.

All of these years of submerging snails — of gastropods drowned and survived — have produced one primary, albeit tentative, finding: It is at least possible that land snails are floating around the world to establish themselves in distant places. We just don’t know enough about Hawai‘i’s snails to know how likely a vector this is for their movements; we have a single, short-term study on one of the over 750 known species.

But floating is by no means the only mode of transportation open to snails. In fact, most of the biologists I spoke to were of the view that it probably isn’t the primary way in which they have moved across large distances. While snails have possibly floated around within the Hawaiian archipelago, between islands, it is thought to be unlikely that the first snails to arrive did so in this way: The distances of open ocean are just too vast. But here, things get even stranger, and even less amendable to experimentation.

As we walked along a winding path around the summit of Pu‘u ‘Ōhi‘a on a cool, rainy, afternoon, Brenden Holland and I discussed some of these other potential modes of snail movement across oceans. He explained to me that not all of these possibilities are immediately obvious if we look only at organisms in their current forms. Many species change after arriving on islands; some, for example, undergo processes of “gigantism” or “dwarfism” in which their new environmental conditions lead to a significantly increased or decreased body size. Alongside these kinds of changes, many entirely new species evolve on islands after initial arrival events. In the case of Hawai‘i’s snails, phylogenetic analysis indicates that the vast majority of species evolved in the islands in this way, a single arrival giving rise to multiple new species over a few million years (these analyses compare genetic material to determine how closely related species on different islands are to one another, and in this way piece together their histories of arrival and evolutionary divergence). Some of these new island species will continue to look a great deal like the ancestor that made that initial oceanic crossing; others will not.

As we walked that day, Brenden pointed out to me tiny snails of the species Auriculella diaphana, moving around among the introduced ginger plants. It was these snails he had brought me here to see. He explained that despite their very different appearance, these snails are actually close relatives of the much larger, brightly colored, Achatinella tree snails that have become the poster-children of endangered snail conservation in Hawai‘i. The former is about 7 millimeters in length, the latter about 2 centimeters. But, Brenden told me, Auriculella and Achatinella have a smaller common relative still, and phylogenetic analysis indicates that it is an even more likely candidate for having made the initial trip to the islands. There, among the ginger leaves, we were lucky enough to also encounter some of these tiny beings, members of the subfamily Tornatellidinae.

The Tornatellidinae snails we saw that day, along with some other species within this subfamily, reach a maximum size of about 2 millimeters in length, roughly the size of a grain of rice. But this size difference is more significant than these simple length measurements imply. As Rob Cowie explained to me, the mass of a snail is roughly equivalent to the cube of its length. As such, one of the tiny Tornatellidinae snails might be as much as 1,000 times lighter than its Achatinella brethren. If a minute creature similar to these tiny snails was the ancestor that first made its way to the Hawaiian Islands, then it might have had many other modes of transportation open to it. It might even have arrived by bird.

At some point in the distant past, a tiny snail climbed on board a migratory bird, perhaps a golden plover, as it perched or nested overnight.

In numerous conversations with biologists, again and again I was told with varying degrees of confidence that the most likely answer to the puzzle of Hawai‘i’s snails is that the first ones flew here. Everybody narrated this hypothetical scene a little differently, but the main events remained the same. At some point in the distant past, a tiny snail climbed on board a migratory bird, perhaps a golden plover, as it perched or nested overnight. As snails are nocturnal, it makes sense that they might encounter a perched bird in this way, and that this wayward passenger might then be able to hunker down, deep in the bird’s feathers, sealing itself up. Days or weeks later, having rested through the exhausting crossing, the snail then climbed off the bird in its new home.

I must admit that on first hearing this explanation I was somewhat dubious. This sequence of events just seemed so horribly unlikely. I reminded myself, though, that in the vastness of evolutionary time, “horribly unlikely” is actually pretty decent odds. But as I continued to talk to scientists and read the literature, I discovered an unseen world of surprising snail journeys. For the most part, scientists have not deliberately gone looking for snails on birds, but in a handful of articles published over the last several decades they have nonetheless reported on their accidental encounters with them, usually in the course of routine bird banding or observation. In these cases, it seems, snails have sometimes been present with surprising regularity and abundance.

Across several studies, the snail Vitrina pellucida has been found on a variety of migratory birds in Europe, while Succinea riisei has been found on three different types of birds in North America, with anywhere from one to 10 snails on a single bird. In one particular study, focused on migratory birds in Louisiana, snails were found on three different bird species. The main focus of the research was the woodcock, and it was only on these birds that the researchers really monitored snail presence: “Of the 96 woodcock checked, 11.4% had snails present,” they report. “Of those, the average number of snails per bird was 3.”

In Hawai‘i, there has never been a targeted scientific search for snails on birds, so it is hard to know which species might be climbing on board and with what kinds of frequency. Partway through my research, however, Nori Yeung at the Bishop Museum came across and shared with me a tantalizing snippet from a field notebook. The collecting note was made in 1949 by Yoshio Kondo who was at the time in Nori’s current position as curator of the museum’s malacology collection. There at the top of a grid-lined page, in neat cursive writing, he reported: “a juvenile sooty tern on which were Succinea and Elasmias. Brought bird back. Unfortunately, did not keep shells on bird separate.”

But there is another fascinating, albeit equally speculative, avenue by which tiny snails might move around the globe. They might fly without the aid of birds, blown on leaves and other debris, or just on their own, sealed up in their shells. Indeed, there is significant evidence from sampling, conducted with nets attached to airplanes, that rock particles the size and weight of some of these tiny snails can move around in this way, sometimes being found at altitudes of more than 2,000 meters. Drawing on these findings, some scientists have argued that it is not at all unreasonable to think that snails might travel in similar ways, definitely over shorter distances but perhaps also for transoceanic journeys. At least a couple of the scientists I spoke to, including Brenden and Rob, were holding open the possibility that the progenitors of at least some of Hawai‘i’s snail families may have blown to the islands in this way, perhaps even carried by the winds of a hurricane.

Of course, once a snail species has made that first giant leap across oceans, a range of other options open up for the shorter, inter-island, movements that genetic analysis indicates have taken place at various points in the past. As we have seen, some snails might survive a floating journey between islands. Others, it seems, might be making these briefer trips inside birds: studies in various parts of the world have now shown that a variety of snail species — including as least one species of the Tornatellidinae — can survive passage through avian digestive tracts at a relatively high frequency.

These are, undoubtedly, all rather unreliable ways to travel. For every snail that successfully arrived in a strange new land on a bird or a floating branch, countless millions must have been washed, blown, or flown out to sea without such luck. The odds must be slightly better traveling by bird than log: At least in theory, if you hop onto or into a migratory bird in a forest, you are reasonably likely to be taken to another forest. Of course, for those snails unfortunate enough to be traveling inside the bird, they would have to survive the journey through the digestive system too.

However they travel, snails are largely at the whim of external forces in these movements, subject to what biologists call “passive dispersal.” As Brenden helpfully summed it up for me: “biogeographically, snails are plants” — both groups share many of the same vectors for movement, the latter usually by seed or spore. This is clearly a “system” of island dispersal that can hope to achieve results only with immense periods of time at its disposal. Over millions of years, a few lucky snails made these journeys successfully. We can’t know for certain how many times this happened in the Hawaiian Islands. But by tracing species back to their common ancestors in Hawai‘i and beyond its shores, Brenden and Rob have estimated that things must have worked out for around 20, and likely fewer than 30, intrepid travelers, or groups of travelers, over roughly the past 5 million years (when Kaua‘i, the oldest of the current high islands with suitable snail habitat, formed). All of the rest of Hawai‘i’s incredible gastropod diversity is thought to have evolved in the islands from this small number of common ancestors.

While there is undoubtedly something very “passive” about this dispersal of snails — always at the whim of others, be they birds, storms, or tides, traveling under their steam and direction — this isn’t the whole of the story. Deep evolutionary histories have produced these possibilities. Snails’ modes of passive movement only “work” because they have evolved some remarkable traits for dispersal, survival, and reproduction, across and into isolated new lands: from epiphragms that seal them up inside their shells and sticky eggs that can attach themselves to birds and debris, to hermaphroditism, sperm storage, and self-fertilization which all potentially allow a single snail introduced to a new land to begin reproducing. While not all snails can do all of these things, where these traits are present, they are surely a huge advantage. Millions of years and countless generations of more or less successful journeying have selected for those individuals that survived and established themselves best.

There is a profound kind of evolutionary agency at work here, a creative, experimental, adaptive working-out of living forms with particular capacities and propensities. For the most part, individual snails are indeed relatively passive in all this. They’re not, however, irrelevant. The particular actions of those snails that crawled onto a bird, that opted to seal up their apertures, that safely stored away sperm for future use, mattered profoundly. But neither are snails involved in the more active, sometimes even deliberate, dispersal undertaken by many other animals.

Instead, if we pay attention, snails amaze with their capacity to move so far, to spread so widely, while doing so little. This, it seems to me, is one of the real marvels of snail biogeography. Individuals do not need to exert great effort because natural selection has acted for them, acted on them, acted with them, to produce these beings that are so unexpectedly but uniquely suited to a particular form of deep time travel, drifting. From such a perspective, rather than being any kind of deficiency, the highly successful passivity of snails might be seen as a remarkable evolutionary achievement.

It’s likely that in the history of these islands, on average one successful snail arrival event has taken place every few hundred thousand years.

There is so much more to learn here, so much to learn about not just the vectors but the patterns under which dispersal takes place: Are they laid down by atmospheric and oceanic currents, or by the inherited paths of avian migration? And yet to some extent this must remain a space of uncertainty and even mystery. How can one really study processes of biogeography that take place across such vast periods of time and space? As Brenden reminded me, it’s likely that in the history of these islands, on average one successful snail arrival event has taken place every few hundred thousand years. Put simply, it’s not something that any of us are likely to ever see, let alone study, firsthand.

It is hard to really make sense of the vast, deep-time assemblage of Hawaiian snail life. I imagine it as something like a giant network with strands stretching out across the Pacific Ocean and beyond, extending back over evolutionary and geological time frames. Each strand represents one of hundreds of unique species. Millions of years of unlikely journeys — nestled into a bird’s feathers, or perhaps tucked away in the crevice of a floating log — heading to destinations unknown. Millions of years that have produced these intrepid, even if somewhat unlikely, island dispersers with the reproductive and other adaptations that made these movements possible. These are at least some of the processes that have produced the breathtakingly diverse, utterly unrepeatable assemblage of snail life in Hawai‘i.

To labor to hold this network in mind, however imperfectly, however impossibly, might offer us a glimpse into one of the reasons why these snails matter, and so the significance of what is being lost in their extinction. Doing so might remind us that each of the fragile, fleshy, little individuals of Auriculella diaphana or Achatinella mustelina is not so much a “member” of a species as it is a “participant” in a lineage, one link in a vast, improbable, intergenerational project. These are projects — made up of the lives, histories, and possibilities of diverse snail species — that are today being radically truncated, or simply shorn off, all within the space of a few generations of human life. With them is disappearing countless unique ways of life and the vast evolutionary heritage — to borrow Loren Eiseley’s apt term, the “immense journey” — that they together comprise.

The post It’s still a mystery how snails ended up scattered around the globe appeared first on Popular Science.

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Starting around seven million years ago, the Thylacosmilus atrox, also known as the “marsupial sabertooth,” prowled South America with canine teeth so large that they reached the top of their skull. The hypercarnivore, meaning it had a diet of at least 70 percent meat, and possibly used its tongue to slurp out the innards of its prey. Thylacosmilus went extinct about 3 million years ago and was a member of Sparassodonta, a group of carnivorous mammals that related to living marsupials.

The 200 pound beast had wide-set eyes like a cow, which are considerably different compared to the forward facing eye sockets of cats.  The strange setup helped the creature see in stereoscopic vision (or 3D).

[Related: Giant wombats the size of small cars once roamed Australia.]

With eyes like this, objects do not overlap sufficiently for the brain to integrate them in three-dimensions. Scientists have long been perplexed as to why the ferocious hunter would evolve such a strange adaptation in its skull. 

Now, a study published March 21 in the journal Communications Biology answers a few questions on how this extinct animal with a unique skull could see and hunt in its ancient world. 

Scientists from Argentina and the US used CT scanning and 3D virtual reconstructions to assess how the nasal cavities were organized in both modern and fossilized mammals.  The scans and reconstructions enabled the team to compare Thylacosmilus’ visual system with other carnivores or other mammals in general and study orbital convergence. This is the way the eyes move together and point inward when they look at objects that are close by. 

Thylacosmilus had an orbital convergence value as low as 35 degrees, which is pretty extreme compared to that of a typical predator at around 65 degrees. 

“Thylacosmilus was able to compensate for having its eyes on the side of its head by sticking its orbits out somewhat and orienting them almost vertically, to increase visual field overlap as much as possible,” said co-author Analia M. Forasiepi, from Instituto Argentino de Nivología, Glaciología, y Ciencias Ambientales (INAGLIA) and a researcher at the Argentinian science and research agency, in a statement. “Even though its orbits were not favorably positioned for 3D vision, it could achieve about 70 percent of visual field overlap—evidently, enough to make it a successful active predator.”

According to the team, how Thylacosmilus was able to compensate for low orbital convergence appears to be the key to understanding how this extinct marsuipial’s skull was put together. The growth patterns in their canines during early stages of development would have moved the eye sockets away from the face, resulting in the wide-set eyes seen in adults. 

“You can’t understand cranial organization in Thylacosmilus without first confronting those enormous canines,” said Charlène Gaillard, a Ph.D. student also at INAGLIA and study co-author, in a statement. “They weren’t just large; they were ever-growing, to such an extent that the roots of the canines continued over the tops of their skulls. This had consequences, one of which was that no room was available for the orbits in the usual carnivore position on the front of the face.”

[Related: Koalas use their noses to find friends and avoid enemies.]

The strange placement of the eye sockets was not the only modification that Thylacosmilus developed to accommodate its enormous canines. Since their eyes are much closer to their chewing muscles, these muscles risk getting deformed while eating. The eyes on the side of the skull also brings them closer to the mouth’s chewing muscles, possibly resulting in a deformation of the mouth muscles. Some mammals, including primates and Thylacosmilus, have developed a bony structure that closes off the eye sockets from the side as a way to control this. 

Now, a new question remains—why would the animal develop huge, constantly growing teeth that required its whole skull to be re-engineered? 

“It might have made predation easier in some unknown way,” said Gaillard. “The canines of Thylacosmilus did not wear down, like the incisors of rodents. Instead, they just seem to have continued growing at the root, eventually extending almost to the rear of the skull.”

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Over 60,000 years ago, an eagle relative with an almost 10 foot wingspan stalked the skies over southern Australia. Dynatoaetus gaffae (Gaff’s powerful eagle) had talons that could even snatch a koala or small kangaroo for dinner. The massive bird of prey was likely the largest continental eagle the world had ever seen. 

A study published March 16 in the Journal of Ornithology details how a team of fossil hunters from Flinders University in Australia put together this bird’s story. Four large fossilized bones were collected in Mairs Cave southern Australia’s Flinders Ranges  as far back as 1956 and 1969. The authors found an additional 28 bones scattered among the boulders in the site whoch helped them create a better picture of this giant extinct bird. 

[Related: This dragon-like reptile once soared over Australia.]

This now extinct raptor is closely related to Old World vultures that prowled Africa and Asia during the Pleistocene. In today’s fauna, its closest relative is likely the critically endangered monkey-munching Philippine Eagle. During the late Pleistocene Epoch, when giant megafauna like the mammoth roamed the Earth and ice sheets and glaciers were growing, Dynatoaetuswas likely the top avian predator on the planet. 

“It’s often been noted how few large land predators Australia had back then, so Dynatoaetus helps fill that gap,” said study author and Flinders University paleontologist Ellen Mather, in a statement.  “This discovery reveals that this incredible family of birds was once much more diverse in Australia, and that raptors were also impacted by the mass extinction that wiped out most of Australia’s megafauna.”

Dynatoaetus and another recently described smaller bird named Cryptogyps represent a new genera of raptors that are unique to Australia. 

“[Dynatoaetus] was humongous. Larger than any other eagle from other continents, and almost as large as the world’s largest eagles once found on the islands of New Zealand and Cuba, including the whopping extinct 13kg [28 pound] Haast’s eagle of New Zealand,” said Trevor Worthy, a study co-author and paleontologist at Flinders University, in a statement. 

[Related: Giant wombats the size of small cars once roamed Australia.]

Dynatoaetus also coexisted with the Wedge-tailed Eagle, a species that currently lives in Australia. The team says that this has interesting implications.

“Given that the Australian birds of prey used to be more diverse, it could mean that the Wedge-tailed Eagle in the past was more limited in where it lived and what it ate,” said Mather. “Otherwise, it would have been directly competing against the giant Dynatoaetus for those resources.”

Most of Australia’s eagles and vultures like the Dynatoaetus went extinct about 50,000 years ago, along with most of the continents’s megafauna.  One 2020 study found that a possible explanation is extreme environmental change and deterioration (loss of water, increased burning of trees and grass, etc.) that wiped out at least 13 super-sized megafauna species, including the world’s largest wombats and kangaroos.

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Deep in the South American rainforest lives one of the brightest colored amphibians in the world: the poison dart frog. But don’t take their dazzling appearance as an invitation to come closer. These hues are a warning that they are not worth attacking. Touching the skin of a poison dart frog—among the most toxic animals in the world—can induce nausea, swelling, and paralysis, even in humans. 

Predators to these frogs have learned to see bright shades as poisonous or unappetizing. But associating color with danger takes time, leaving evolutionary biologists with a paradoxical problem. How did prey species survive long enough to evolve colors as warning signals while living among predators who can better spot them and had not yet learned to avoid them?

[Related: These buff frogs never skip arm day]

One theory is that colorful warning signals, also known as aposematism, evolved indirectly and through gradual stages. A study published today in the journal Science suggests some creatures permanently adapted to vivid skins, by first using hidden signals to give predators plenty of time to learn that these colors should be treated with caution. These colors were often concealed in their bellies or undersides.

“If you’re the first conspicuous individual in a chemically defended lineage, it will be very difficult for that mutation to take hold in the population, because predators have no way of knowing your coloration is associated with chemical defense,” says Changku Kang, an assistant professor at Seoul National University in South Korea and study coauthor.

To study how colors evolved in animals, the study authors ranked over 1,000 species of frogs and salamanders into five groups. Most studies on the evolution of animal coloration try to place animals in one of two categories—either conspicuous or camouflaged—which limits the complex understanding of animal coloration, says Karl Loeffler-Henry, a postdoctoral fellow at Carleton University in Canada who served as lead study author. 

Instead, this research looked at those two extremes as well as other adaptations animals could have developed. Animals with colors that make them stand out like reds, yellows, and bright blue skins were classified as conspicuous. Animals that developed colors meant to camouflage into the environment were cryptic. Partially conspicuous animals were those with colors that were somewhat hidden in limbs and other body areas. Fully conspicuous critters had bright colors fully tucked away in their underbellies and other hidden regions. Amphibians with both cryptic and conspicuous forms were placed under the polymorphism category.

The biologists then tested nine different evolutionary models to reconstruct the evolutionary pathways their ancestors took, including when they developed both aposematism and toxicity as a defense strategy. 

The path to aposematism was not a straight line. Instead of evolving directly from a camouflage strategy, aposematism had an important transitional state. “The conditions favoring the evolution of this type of coloration are likely to be much less restrictive, and yet they provide a clear pathway to the evolution of overall bright coloration,” says Kyle Summers, an evolutionary biologist at East Carolina University who was not involved in the study. When animals first developed vivid pigments, they initially concealed them in body parts such as the limbs or the underbelly. 

[Related: Could reptiles and amphibians hold the key to the fountain of youth?]

If threatened, these animals would lift up their limbs or bodies to expose the colors that eventually served as warnings to predators who naively ate these creatures. “Aposematism has evolved independently many times in separate lineages of amphibians,” explains Loeffler-Henry. “Hidden signals give an answer to how this is happening and unravel a fascinating story of how the evolutionary process took place.”

“The study offers a novel solution to the long-standing paradox of evolution of conspicuous antipredator warning signals,” adds Alice Exnerová, an assistant professor of zoology at Charles University in Prague who was also not affiliated with the research. What’s more, she says the findings show the value of exploring alternative and overlooked evolutionary strategies, which can advance our understanding of diverse antipredator defense strategies in the natural world.

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Dinosaurs came in all shapes and sizes, but we know they could get pretty darn big. For sauropods, a clade of dinos that roamed the planet from the Early Jurassic all the way to the Cretaceous–Paleogene extinction event, their size was largely reflected in their long necks. But according to new findings, the Mamenchisaurus sinocanadorum uncovered in modern-day China may have been the longest-necked of them all.

In a study published today in The Journal of Systematic Paleontology, an international team of scientists determined that this particular specimen of sauropod had a 49-foot-long neck—that’s six times as long as a giraffe neck. 

“It would require a lot of muscles to hold up a neck that size, and then there’s the question of how it gets air down to the lungs and back up again,” Paul Barrett, a professor at the Natural History Museum in London, said in a press release. “This could support the theory that these necks were a sexually selected feature where only the strongest and fittest dinosaurs that were able to hold up these giant necks in impressive displays were able to mate.” 

[Related: Feisty ankylosaurs clubbed each other with their tails.]

This took paleontologists quite a bit of puzzling—there’s only one Mamenchisaurus sinocanadorum specimen to analyze, discovered in 1987 at a site in the Shishugou Formation in northwestern China. The skeleton only includes the front end of the neck, a rib, some skull bones, and a lower jaw. 

So, how do you measure the entire length of a neck from just a few bones? Well, you have to find a similar species to compare it to. In 2012, the giant sauropod Xinjiangtitan was uncovered in China with an intact 43-foot-long neck. Using an “elementary bit of maths,” Barrett explained, the team was able to look at proportions of the relative’s vertebrae and scale up the incomplete skeleton. What they found was a specimen that could very well be a record-breaker. 

But the team didn’t just figure out how long the dinosaur’s neck was—they prodded at the biomechanics of how such a body part could even exist. Using computer-tomography scanning, the authors found that the hollow vertebrae of the massive sauropod was around 69- to 77-percent air, which is similar to modern-day storks. The authors determined that to protect such a lightweight neck from getting hurt, the dinosaur had 13-foot-long rod-like cervical ribs on either side for stability. 

“Biomechanical studies of the [Mamenchisaurus] neck suggest that it was elevated at only a relatively shallow angle above the horizontal (20 to 30°). However, even at this relatively shallow angle, the extreme length of the neck would still mean that the animal’s head could reach heights of around [25 to 33 feet] above ground level,” co-author Paul Upchurch, a professor of palaeobiology from the University College London, said in a press release. 

[Related: Move over, Stegosaurus, there’s a new armored dino in town.]

The reasons for the long neck—and exact mechanics of how it worked—are still a mystery, but some paleontologists believe they could have evolved so the giant creatures could sit still in one spot and still have access to lots of leafy trees to eat. They could have also allowed the sauropod to shed extra heat by increasing their surface area. 

“It could have also been to do with sexual display or used for neck-butting contests between males fighting over mates and territory, similar to how giraffes behave today,” Barett said. “But we can’t say for sure. At this point, it’s pure speculation as to why they evolved necks of this length.”

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Humans have been experimenting with mind-altering plants for many millennia now. . Modern-day drugs such as opium were being used in Europe around 5,700 BCE, and cannabis seeds started showing up in archeological digs in Asia some 10,000 years ago. Some studies have shown that ancient hominids have been using psychotropic plants and drugs as far back as 200 million years ago.

While tripping might seem like an exclusively human desire, it turns out that some of our closest great ape relatives might also find ways to switch up their state of mind—but instead of using plants and other substances, they just twirl around really quickly. For  research published today in the journal Primates, researchers watched 40 videos of great apes spinning around just to get dizzy. And they think these actions could have some clues into why people have often seeked innovative ways to get a little high, drunk, and what have you.

[Related: Why do humans talk? Tree-dwelling orangutans might hold the answer.]

“Every culture has found a way of evading reality through dedicated and special rituals, practices, or ceremonies,” study author Adriano Lameira, an associate professor of psychology at the University of Warwick, said in a press release. “This human trait of seeking altered states is so universal, historically, and culturally, that it raises the intriguing possibility that this is something that has been potentially inherited from our evolutionary ancestors.”

Inspired by a viral video of a male gorilla spinning in a pool, the team found dozens of videos of gorillas, chimpanzees, bonobos, and orangutans going round and round, often using ropes or vines. The researchers then analyzed the movements, finding that on average the apes spun 5.5 times per session, with an average speed of 1.5 revolutions per second. Most animals then repeated the session three times in a row. This is about as fast as professional dancers, circus artists, and Dervish Muslims twirl, according to the authors. 

The apes themselves would often be so dizzy after a bout of twirling that they were noticeably dizzy and likely to lose their balance. To understand the feeling of euphoria after such a feat, the team tested out twirling at the same speed and intensity themselves, and actually struggled to get to the third round due to dizziness. 

[Related: These long-fingered lemurs pick and eat their boogers, just like humans.]

Previous studies on why humans crave self-induced dizziness have focused on alcohol and drug use, but the authors of this study argue that simple spinning could be worth a deeper look. After all, the ability to make or find mind-altering substances requires knowledge, skills, and tools that we aren’t sure humans or pre-humans had access to, Lameira added. Additionally, there could be links with mental state and boredom, as the videos recorded were mostly of captive apes. 

“What we wanted to try to understand through this study is whether spinning can be studied as a primordial behavior that human ancestors would have been able to autonomously engage in and tap into other states of consciousness,” Lamiera said. “If all great apes seek dizziness, then our ancestors are also highly likely to have done so.”

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Tiny, annoying, flying pests might seem as old as time. Gnats are the general name for a bunch of species in the diptera suborder Nematocera, which the Smithsonian describes as “non-biting flies, no bigger than a few grains of salt, [that] are attracted to fluids secreted by your eyes.” 

While their average lifespan is only about a week long, their survival through evolutionary history stretches way further. According to new research, the insects may have been around 247 million years, older than the earliest dinosaurs. 

In a new study published March 10 in the journal Papers in Paleontology, geologists and biologists from Spain and England delved into a recently discovered fossil that can teach us more about the beginnings, and incredible survival abilities, of the gnat. The fossil was found in a small harbor in Estellencs, located in Spain’s Balearic Islands, known for its bluish rock layers that hide remains of plants, insects, fish, and more from the Middle Triassic. 

[Related: When insects got wings, evolution really took off.]

Mallorcan scientist Josep Juárez spotted the find—a complete larva sample that left an imprint on the sides of a split rock. Upon further examination, the well-preserved fossil was identified as part of the insect order that now claims mosquitoes, midges, flies, and of course, gnats. It may be the oldest diptera specimen discovered to date, and could be a common ancestor to the more than million species in the group today.

“While I was inspecting it under the microscope, I put a drop of alcohol on it to increase the contrast of the structures,” says study author Enrique Peñalver, a scientist from the Spanish National Research Council at the Spanish Geological Survey, said in a press release. “I was able to witness in awe how the fossil had preserved both the external and internal structures of the head, some parts of the digestive system, and, most importantly, the external openings to its respiratory system, or spiracles.”

But beyond just revealing what a baby gnat looked like at the time, the existence of this fossil shows the insect’s remarkable ability to adapt to what Oxford University Museum of Natural History’s Ricardo Pérez-de la Fuente called a “post apocalyptic environment.” 

[Related: Eyeless army ants chomped their way through Europe millions of years ago.]

The Permian-Triassic extinction occurred around the last 15 million years of the Permian period, and is famous for the extinction of around 95 percent of marine species and 70 percent of terrestrial species in such a, evolutionarily speaking, short period of time. (Some scientists even propose that the bulk of these species disappeared over a 20,000-year span right at the end of the period.) It’s known as the most severe of any major extinction episodes in Earth’s recorded history, wiping out more than half of the taxonomic groups that roamed the land and seas. Potential causes include a change in the planet’s atmosphere that led to radiation poisoning or a change in oxygen levels.

The authors of the new study also noted how this newly discovered specimen has a similar breathing system to that in some modern insects. Perhaps it’s time to add gnats to the short list of animals that could survive an apocalypse alongside tardigrades and cockroaches.

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Social learning and knowledge sharing from generation to generation is a hallmark of a culture among living things. While it’s been documented in many animals including tiny naked mole rats, songbirds, sperm whales, and humans, early social learning has only just been demonstrated in insects. 

A study published March 9 in the journal Science is offering evidence that generational knowledge is fundamental for honeybees.

[Related: The first honeybee vaccine could protect the entire hive, starting with the queen.]

“We are beginning to understand that, like us, animals can pass down information important for their survival through communities and families. Our new research shows that we can now extend such social learning to include insects,” said study co-author and University of California San Diego biologist James Nieh, in a statement. 

Nieh and a team of researchers took a deeper look at a bee’s “waggle dance.”  Bees have a highly organized community structure and use the waggle dance to tell hivemates where critical food resources are located with an intricate series of movements. In the waggle dance, bees circle around in figure-eight patterns, while wagging their bodies during the central part of the dance. It’s kind of like a breakdance performed at a breakneck speed, with each bee moving a body length in less than one second. 

The very precise motions in the dance translate visual information from the environment around the hive, Sending accurate information is especially remarkable since bees must move rapidly across an often uneven honeycomb hive surface. The team discovered that this dance is improved by learning and can be culturally transmitted. 

Nieh and fellow researchers Shihao Dong, Tao Lin, and Ken Tan of the Chinese Academy of Sciences created colonies with bees that were all the same age as an experiment to watch how experienced forager bees pass this process down to younger, less-experienced nestmates. 

Bees typically begin to dance when they reach the right age and always follow the lead of experienced dancers first, but in these experimental colonies, they weren’t able to learn the waggle dance from older bees.

[Related: Bees choose violence when attempting honey heists.]

By comparison, the bees that shadowed other dancers in the control colonies that had a mix of different aged bees didn’t have problems learning to waggle. The acquired social cues stayed with them for the roughly 38 day lifespan of the bees in the study. 

Those that didn’t learn the correct waggle dance in that critical early stage of learning could improve by watching other dancers and by practicing, but they couldn’t correctly encode the distance which created distinct “dialects.” The dialect was then maintained by the bees for the rest of their lives. 

“Scientists believe that bee dialects are shaped by their local environments. If so, it makes sense for a colony to pass on a dialect that is well adapted to this environment,” said Nieh. The results therefore provided evidence that social learning shapes honey bee signaling as it does with early communication in many vertebrate species that also benefit from learning.

The next steps for this research is better understanding the role that the environment plays in shaping bee language. Additionally, the team would like to know more about external threats like pesticides to bees that could disrupt early language learning. 

“We know that bees are quite intelligent and have the capacity to do remarkable things,” said Nieh. “Multiple papers and studies have shown that pesticides can harm honey bee cognition and learning, and therefore pesticides might harm their ability to learn how to communicate and potentially even reshape how this communication is transmitted to the next generation of bees in a colony.”

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Fossils can help us peer deep into the planet’s past. But that doesn’t mean that the interpretations of them are set in stone—in fact, experts often change their minds on what a fossil really is depending on new analysis and discoveries. In 2021, for instance, scientists decided that a 515-million-year-old fossil showed the earliest evidence of an animal group called the bryozoans, named Protomelission gatehousei. This discovery put the origin of the simple, filter-feeding colonies of aquatic invertebrates over 35 million years earlier than previously thought, putting their evolution around the same time as the Cambrian explosion. This period, taking place some 541-530 million years ago, marks the origins of most modern animal life. 

But, a second look at these fossils might indicate that’s not such a great fit after all. A new study published in Nature suggests that the Protomelission gatehousei fossil isn’t a bryozoan, or even an early animal after all. Experts from Durham University in the UK, as well as Yunnan University and Guizhou University in China determined, instead, that the fossil is just that of a dasyclad green algae. 

[Related: Scientists find 319-million-year-old fossilized fish brain.]

For their research, the international team of scientists looked at a new specimen discovered in China’s Xiaoshiba Biota, known for well-preserved Cambrian fossils. The new, larger specimens make it appear that Protomelission probably isn’t a bryozoan, considering the fossils don’t have bryozoan type tentacles—instead they had little cactus-like projections. That’s not ideal for animals, Martin Smith, author of the new study and associate professor in paleontology at Durham, tells New Scientist, but it could be helpful for photosynthesis.

Even as dasyclad algae, the fossils are still pretty exciting. According to the authors, seaweeds were previously believed to be rare in the early Cambrian, but these fossils (and similar fossils called cambroclaves, which are abundant across the world but have uncertain origins) may actually point to a bit of an earlier seaweed renaissance.

“It could even be speculated that the diversification of seaweed could have contributed to the diversification of animals we see during the Cambrian,” Smith said in a release.  

[Related: This fossil-sorting robot can identify millions-year-old critters for climate researchers.]

Of course, there’s still plenty of debate—Paul Taylor, a scientific associate at the Natural History Museum in London and author of the 2021 paper, argues that these new findings aren’t enough to nix their bryozoan theory. After all, tentacles are often made of soft tissue, he told The Guardian, which doesn’t fossilize well. 

Either way, the fossils have quite a story to tell. On one hand, they could hold the key to bryozoan early roots. On the other hand, if the fossil is simple algae, it still  shows how evolution still kept its “creative touch” even after the incredibly unique Cambrian period. Until more fossils are found, the algae versus animal debate isn’t history yet.

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As far as birds go, the tiny, swift hummingbird is pretty in touch with color— they can see hues that we can’t imagine. Their feathers come in many shades as well, which is believed to help males find mates during courtship. Some females even use flashy feathers as a way to appear male to keep other birds from bothering them. 

They can be purple like the Lucifer hummingbird (Calothorax lucifer), a bright turquoise like Rivoli’s hummingbird (Eugenes fulgens), and the appropriately named pink-throated brilliant hummingbird (Heliodoxa gularis) is pink. Biologists are still figuring out the role of these colors and how they appear in hummingbird feathers. 

[Related: Hummingbirds get their wild coloring from ‘air-filled pancakes’ in their feathers.]

“I look out across the bird world for interesting colors and try to understand the physics of how those colors are being produced. With that knowledge, I could understand why some of these colors might be evolving more rapidly or why there might be more colorful species in certain areas of the world,” evolutionary biologist Chad Eliason from Chicago’s Field Museum tells PopSci. 

However, when a team of scientists found a normally pink throated Heliodoxa hummingbird that had a gold throat instead, they thought it was a completely new species. DNA revealed something else– the gold-throated bird was a never-before-documented hybrid of two pink-throated species.

The team describes this unique bird that they first encountered during field work in the isolated Cordillera Azul National Park of central Peru in a study published February 28 in the journal Royal Society Open Science.

“I looked at the bird and said to myself, ‘This thing doesn’t look like anything else.’ My first thought was, it was a new species,” said John Bates, a curator of birds at Chicago’s Field Museum and study co-author, in a statement. 

The team gathered more data using the museum’s DNA lab to confirm the surprise, and found that  it matched one of the pink-throated hummingbirds local to the area, Heliodoxa branickii (H. branickii) in some markers. Still, most hummingbirds don’t vary this greatly within their own species, 

[Related: Hummingbirds routinely hit 9Gs like it’s no big deal.]

The DNA sequencing looked at mitochondrial DNA–genetic material that is only passed down through the mother. The mitochondrial DNA provided a clear result that matched H. branickii.

When the team analyzed the bird’s nuclear DNA, which has contributions from both parents, it showed similarities to both H. branickii and a genetic cousin, Heliodoxa gularis (H. gularis). 

However, the bird wasn’t half branickii and half gularis. One of its ancestors must have been half-and-half, and subsequent generations then mated with more branickii birds.

In order to answer the question of how two pink-throated bird species ended up producing a non-pink-throated hybrid, the team had to look at the complex ways in which iridescent feather colors are determined. Pigments like carotenoids (red and yellow) and melanin (black) give the feathers their base colors, but the structure of the feather’s cells and the way that the light bounces off of them produces structural color. The result is color-shifting iridescence in the feathers. 

“We knew coming into this that [hummingbirds] had the most complex melanin structures or the iridescent structures of all birds,” says Eliason, who is also a co-author on the study. 

An electron microscope examined the subcellular level of the throat feather structure and spectroscopy to measure how light bounces off the feathers to produce different colors. Subtle differences were found in the origin of the hummingbird parent’s colors, which may explain why hybrid offspring produced such a vastly different color. 

“There’s more than one way to make magenta with iridescence,” Eliason said in a statement. “The parent species each have their own way of making magenta, which is, I think, why you can have this nonlinear or surprising outcome when you mix together those two recipes for producing a feather color.”

Sometimes hybrids are one-off occurrences or cannot reproduce like mules, but in other cases, they form new species. While it is not clear how common these kinds of hummingbird hybrids are, the team believes that they might contribute to the diversity of structural colors found across the hummingbird family tree.

They calculated that it would take six to 10 million years for this pink to gold color shift to evolve in a single species of bird, based on the speed of color evolution seen in hummingbirds. 

On an evolutionary time scale, six to 10 million years is pretty fast, according to Eliason. Further study will help them understand how many generations it takes for these strange changes to occur and apply some newer genetics and genome sequencing tools to older studies on hummingbirds.

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The waters of the 360-million-year-old subcontinent Gondwana were a dangerous place for a swim. A killer, bony fish the length of an adult California sea lion stalked freshwater rivers as a top predator. It was massive—as a new discovery reveals, this was the largest prehistoric bony fish ever discovered in southern Africa. 

Its ferocity is reflected in its name, Hyneria udlezinye (H. udlezinye), which means the “one who consumes others,” in IsiXhosa, an Indigenous language spoken widely in southeastern South Africa where its bones were found.

[Related: One wormy Triassic fossil could fill a hole in the evolutionary story of amphibians.]

“Picture a fish looking a bit like a gigantic alligator. About 8 feet long, but with a more rounded head like the front end of a torpedo,” Per Ahlberg, a paleontologist and zoologist at Uppsala University in Sweden, tells PopSci. Ahlberg is the co-author of a study published February 22 in the journal PLOS One describing the carnivore. “The small eyes are located near the front of the head. In the mouth there were rows of small pointed teeth together with pairs of large fangs, up to a couple of inches tall.”

The specimen was found on the edge of Makhanda, South Africa, at the Waterloo Farm lagerstatte, a fossil site rich in specimens from the Late Devonian world, about 419.2 million and 358.9 million years ago. Co-author Rob Gess, a paleontologist from the Albany Museum and Rhodes University, South Africa has been collecting specimens from the site since 1985, where he has uncovered bones, teeth, and small invertebrates, as well as weeds and plants. 

“This fossil site is globally significant for understanding biogeography of the Late Devonian world as it provides us with the only known window into a polar ecosystem during this pivotal time interval,” Gess tells PopSci.

But the remains of bigger things lurk there, too. H. udlezinye belongs to an extinct group of lobe-finned fish called the Tristichopterids. Late in the Devonian period, one branch of the Tristichopterid family developed into a cluster of giants. These huge Tristichopterids possibly arose in Gondwana, the ancient supercontinent, before migrating to Euramerica. The study authors determined that H. udlezinye is closely related to its North American cousins by comparing it with specimens of Hyneria lindae found in Pennsylvania’s Catskill Formation. The authors say that this supports the idea that all of these giants originated in Gondwana and adds a piece to their evolutionary puzzle.

[Related: Tiktaalik’s ancient cousin decided life was better in the water.]

All other fish in the Tristichopterid group were largely believed to live in the more tropical, or central, regions of the subcontinent, but these specimens were found south of where the paleoantarctic circle (our southern polar circle) was at this time. This suggests a more global distribution of the fish, from the equator down closer to the poles. 

H. udlezinye was a ferocious predator that would have eaten most of the larger kinds of fish—including the relatives of modern coelacanths—and four-legged animals found near the site. Their body shape also suggests that they were likely “lie-in-wait predators,” who quietly hid and then quickly lunged to grab passing prey with fanged jaws. 

As fearsome as it must have been, this apex predator was not completely invulnerable. The Tristichopterids, along with many other species of lobe-finned and armor-plated fish, “went extinct in the End Devonian Mass Extinction event 358.9 million years ago—the second of the big five global extinction events that radically altered the make-up of life on Earth,” explains Gess.

Learning more about the Denovian world can help scientists better understand not only the flora and fauna that went extinct during this mass extinction event, but also more about evolution and even ourselves as humans.

“This was a particularly interesting time in the history of the planet, when life had recently become established on land and was diversifying rapidly,” Ahlberg says. “Our own distant ancestors”—the earliest animals with four limbs, or tetrapods—“emerged out of the water during the Devonian.” 

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When it comes to what freaks American adults out, snakes rank right up there with heights, public speaking, and bugs. They can carry lethal venom in their bites and be strong enough to strangle and eat alligators. Still, snakes are an important part of the ecosystem as a whole because they help control pest populations and help maintain the planet’s biodiversity.

They can also probably hear all of the bad things humans are saying about them. In a study published February 14 in the journal PLOS One found that snakes can hear and react to sounds in the air in addition to feeling vibrations in the ground. 

[Related: Scientists just found out female snakes have two clitorises.]

A team at the University of Queensland (UQ) in Australia played three different sound frequencies–two that were airborne and one that was a ground vibration– to captive-bred snakes one at a time in a soundproof room and observed their reactions. They used 19 snakes that represented five genetic families of reptiles.

“Because snakes don’t have external ears, people typically think they’re deaf and can only feel vibrations through the ground and into their bodies,” said study co-author Christina Zdenek, a biologist from UQ’s School of Biological Sciences, in a statement. “But our research – the first of its kind using non-anesthetized, freely moving snakes – found they do react to sound waves traveling through the air, and possibly human voices.”

By testing both vibrations and airborne sounds, they were able to test two types of hearing in snakes. The tactile hearing that occurs in the snake’s belly scales and the airborne hearing that occurs in the snakes’ internal ear. 

According to the study, the reaction strongly related to the genus of the snakes.

“Only the woma python tended to move toward sound, while taipans, brown snakes, and especially death adders were all more likely to move away from it,” Zdenek said.  “The types of behavioral reactions also differed, with taipans in particular more likely to exhibit defensive and cautious responses to sound.

These different reactions are likely due to evolutionary pressures over millions of years that were designed to help snakes survive and reproduce.

[Related: After the dinosaurs, Earth became an all-you-can-eat buffet for snakes.]

“For example, woma pythons are large nocturnal snakes with fewer predators than smaller species and probably don’t need to be as cautious, so they tended to approach sound,” Zdenek said. “But taipans may have to worry about raptor predators and they also actively pursue their prey, so their senses seem to be much more sensitive.”

The findings challenge the assumption that snakes can’t hear sounds like yelling or humans talking and may reshape beliefs and ideas on how they react to sounds. Since snakes are generally timid and hide much of the time, it has been harder to study them.

“We know very little about how most snake species navigate situations and landscapes around the world,” Zdenek said. “But our study shows that sound may be an important part of their sensory repertoire.

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Roughly 125 million years ago, when the world was warmer, more humid, with higher sea levels, Spinosaurs were a genus of theropod (or “beast-footed”) dinosaurs. These unusual 13 to 22 ton dinos were known for their long, crocodile-like jaws and cone shaped teeth. They stalked riverbanks preying on large fish and lived a different lifestyle than more familiar theropods, such as Allosaurus and Tyrannosaurus. Some spinosaur species include Spinosaurus aegyptiacus and Spinosaurus marocannus and many specimens have been found in northern Africa.

But, paleontologists still don’t know quite as much about these “enormous river monsters.”

An international team of scientists has reconstructed the brains and inner ears of two spinosaur specimens found in England.  Not only does reconstructing a dino brain sound awesome, it’s also a step in understanding how these theropod dinosaurs interacted with their environment. The study was published February 13 in the Journal of Anatomy.

[Related: Cushy feet supported sauropods’ gigantic bodies.]

In order to get a better understanding of how their brains and senses evolved, the team scanned fossils of two different theropod species—Baryonyx found in Surrey, in southern England and Ceratosuchops, which was found on the Isle of Wight. Baryonyx was about 32 feet long and bore the same crocodile-like mouth. Ceratosuchops has been nicknamed the “hell heron,” and was about 27 feet long.

These specimens are special because they are two of the oldest spinosaur fossils that contain the dinosaur’s braincase material. The team was able to digitally reconstruct the internal soft brain tissues that rotted away over time.

They found that the olfactory bulbs—responsible for processing smells—weren’t particularly developed. However, their ears were likely attuned to picking up low frequency sounds. They also found that the parts of the brain that keep the head stable and eyes fixed on prey were possibly less developed than they were in more specialized spinosaurs that evolved later on.

“Despite their unusual ecology, it seems the brains and senses of these early spinosaurs retained many aspects in common with other large-bodied theropods – there is no evidence that their semi-aquatic lifestyles are reflected in the way their brains are organized,” said Chris Barker, a PhD student at the University of Southampton and co-author, in a statement.

One of the team’s interpretations of this evidence is that the ancestors of spinosaurs already had sensory adaptations and brains that were suited to catching fish. To become more adept at living in a specialized semi-aquatic lifestyle, they needed to evolve an unusual snout and teeth.  

[Related: Spinosaurus bones hint that the spiny dinosaurs enjoyed water sports.]

“Because the skulls of all spinosaurs are so specialized for fish-catching, it’s surprising to see such ‘non-specialised’ brains,” said University of Southampton paleontologist and co-author Darren Naish, in a statement. “But the results are still significant. It’s exciting to get so much information on sensory abilities – on hearing, sense of smell, balance and so on – from British dinosaurs. Using cutting-edge technology, we basically obtained all the brain-related information we possibly could from these fossils.”

One of the most powerful CT scanners in Great Britain scanned the braincase of the Cretaceous era-Ceratosuchops, and a model of its brain will be on display alongside of its bones at Dinosaur Isle Museum on the Isle of Wight.

“This new research is just the latest in what amounts to a revolution in paleontology due to advances in CT-based imaging of fossils,” said co-author Lawrence M. Witmer, professor of anatomy at the Ohio University Heritage College of Osteopathic Medicine, in a statement. “We’re now in a position to be able to assess the cognitive and sensory capabilities of extinct animals and explore how the brain evolved in behaviorally extreme dinosaurs like spinosaurs.”

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Orca whales are among the world’s most recognizable whales, with their round Oreo-cookie colored bodies, acrobatics, and apex ocean predator status. Many populations of orcas–aka killer whales–are also in trouble, and not just due to decades of captivity.

The unique and endangered Southern Resident killer whales (SRKW) that live off of the northwest coast of North America specialize in eating Chinook salmon, a particularly large, fatty, and nutritious Pacific salmon. The whales have become endangered for multiple reasons including reduced salmon availability, chemical pollution, and noise pollution. 

[Related: A baby orca sparks a glimmer of hope for an endangered group of whales.]

“They’re starving all the time because there’s just not enough fish out there,” Deborah Giles, the Science and Research Director for the Washington-based group Wild Orca, told PopSci last year.

Only 73 of these orca whales are left, a critically low number since they do not interbreed with other orca populations.  

While their tight knit familiar bonds are remarkable–they’re even known to instinctually push around deceased calves–their parenting tactics may also be hurting them, particularly when it comes to raising male offspring. A study published February 8 in the journal Current Biology found that raising sons is so exhausting that it leaves whale mothers less likely to produce more offspring. 

The study found that each living son cut an orca mother’s annual likelihood of producing a calf that survives to one year old in half. This effect continued as the sons grew older, which suggests that the sons are a lifelong burden on their mothers. 

“Our previous research has shown that sons have a higher chance of survival if their mother is around,” said Michael Weiss, a co-author from the Centre for Research in Animal Behaviour at the University of Exeter, in a statement. “In this study, we wanted to find out if this help comes at a price.”

Orca mothers are known from previous research to provide their female offspring with less support than their male offspring, especially after daughters reach adulthood. 

The team looked at data from 1982 to 2021 on 40 SRKW females. Male and female SRKWs stay in the group they were born into, with each led by an experienced female matriarch. They come from one of three pods–J Pod, K Pod, and L Pod. One headline grabbing matriarch was Granny (officially named J2), a possibly 103 year-old orca who died in 2016.

While feeding, mothers commonly bite salmon in two pieces, eating one half themselves and giving the other half to their sons. While they also feed young daughters, this tends to stop when they reach reproductive age in their early teens, but continues for adult males.  

[Related: Granny, the world’s oldest known orca, is likely dead.]

According to the team, this strategy of sacrificing their future reproduction to keep their sons alive found in this study is highly unusual in nature and may even be unique to this population and species.

It’s possible that mother’s gain an “indirect fitness” benefit where helping their sons survive and reproduce improves the changes of genes passing along to future generations. 

This strategy has been effective in the past, as mothers pouring effort into their sons’ survival would be beneficial since male offspring can mate with multiple females and create many grand offspring. But this strategy may cause problems for the future viability of endangered whales. 

“For this population that’s living on a knife’s edge, the potential for population recovery is going to be limited by the number of females and those females’ reproductive output,” said co-author Darren Croft, an animal behavior specialist from the University of Exeter, in a statement. “A strategy of females reducing reproduction to increase the survival of male offspring may therefore have negative impacts on this population’s recovery.”

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What types of food would be served at a Paleolithic Period buffet for Neanderthals? Fruits, plants, and nuts for sure, but the former inhabitants of Gruta de Figueira Brava in Portugal would have also expected lots of seafood, especially brown crab (Cancer pagurus).

“Neanderthals in Gruta da Figueira Brava were eating a lot of other marine resources, like limpets, mussels, clams, fish, as well as other terrestrial animals, such as deer, goats, aurochs and tortoises,” archaeologist Mariana Nabais from the Catalan Institute of Human Paleoecology and Social Evolution tells PopSci.  

[Related: Skull research sheds light on human-Neanderthal interbreeding.]

Nabais specializes in zooarchaeology, or the study of animal remains that are found at archaeological sites. She is the lead author on a study published February 7 in the journal Frontiers in Environmental Archaeology that presents evidence that Nednderthals were cooking and eating crabs 90,000 years ago. 

She and her team studied the deposits of stone tools, shells, and bones uncovered at Figueira Brava, south of the capital city of Lisbon. While they found a wide variety of shellfish in the deposits, remnants of brown crab were the most common in the deposits. Neanderthals possibly used low tide pools during the summer to harvest the crustaceans, according to the team. 

Most of the crabs were adults which would yield roughly seven ounces of meat. “I was very surprised about the unexpected large amount of crab remains, and their large size, similar to those we eat today,” says Nabais.

The team looked at the patterns of damage on the crab’s shells and claws and did not find any marks from rodents or evidence that birds had broken into the shells. When looking for signs of butchery and percussion marks from tools, they found fracture patterns in the shells that indicate that the shells were intentionally broken up to access the meat.

[Related: Why everything eventually becomes a crab.]

Burns were found on about eight percent of the crab shells, indicating that Neanderthals were roasting the crabs in addition to harvesting them. Comparing the black burns on the shells with studies of other mollusks showed that the crabs were heated to 572 to 932 degrees Fahrenheit, a typical temperature for cooking. 

“Our results add an extra nail to the coffin of the obsolete notion that Neanderthals were primitive cave dwellers who could barely scrape a living off scavenged big-game carcasses,” Nabais said in a statement. 

According to Nabais, it is impossible to know why Neanderthals chose to harvest brown crabs or if they attached any significance to eating them, but consuming them would have given added nutritional benefits. This study was limited to observational and not experimental data, but another study Nabais’ co-authored has been submitted for publication and validated the inferences made in this paper. 

“The origin and destiny of the Neanderthal lineage remains one of the key research questions addressed by paleoanthropology and paleolithic archaeology,” Nabais says. “Our research advances our knowledge of the Neanderthals, especially with regards to those who lived in southern Europe.”

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While wolves and domesticated dogs are distantly related, selective breeding has obviously led to some major differences between the wild predator and their cousins. One similarity that has remained over the years is in their vocalizations. 

Howling is a form of communication in wolves that is also found in numerous canine species, like Alaskan malamutes and Kleiner Münsterländer. However, domesticated dogs and their wild counterparts use howling a bit differently.

[Related: Ancient wolf DNA is being used to sniff out where our love story with dogs began.]

In wolves, howling is primarily used for long-distance communication with other wolves, as a way to mark territory boundaries, and to figure out where other wolves are based on their replies to howls.

For our domestic best friends, it’s a little more complex. Some breeds (such as sled dogs) are considered “hard howlers,” which means that they howl frequently and in “reply” to a non-howl sound like a bell or music. Other dog breeds never howl, despite being able to produce them. 

But how much of this distant language is shared? Researchers at Eötvös Loránd University (ELTE) in Budapest, Hungary are investigating how domesticated dogs react to wolf howls and the role that genetics, sex, and age have on howling behavior. 

Their study published February 6 in the journal Communications Biology found that the dogs more closely related to wolves genetically, such as the Siberian husky, respond to wolf howls more than dog breeds like labrador retrievers which are more split from wolves genetically. 

They played recordings of wolf howls for 68 purebred family dogs and observed their behaviors. 

A root distance, or a breed’s genetic similarity to wolves, was used as a measure to test the effect of the howls on the breed. The breeds that are more closely related wolves, like huskies, are considered the “ancient breeds” while  domesticated dogs like beagles are the “modern breeds.”

“According to our results, breeds which are genetically more similar to wolves, are more prone to reply with their own howls to wolf howl playbacks,” said ELTE ethologist and study co-author Fanni Lehoczki, in a statement. “On the other hand, breeds more distantly related to wolves typically reacted with barking instead of howls. It seems that although howling is present in most breeds’ repertoire, it lost its functionality due to the changed social environment, thus, modern breeds do not use it in adequate situations.”

The team believes that those more closely related to wolves are able to process the information in the wolf howls better, and the ancient breeds may have gotten stressed about intruding on another pack’s territory and used howling as a way to avoid conflict—just like wolves in the wild.

[Related: Puppies beat out young wolves in one important skill.]

“Interestingly, this genetic effect on howling occurs only among older dogs [over 5 years old], for which an experience- or some age-related personality effect can be a plausible explanation,” said Tamás Faragó, a postdoctoral researcher at ELTE and study co-author, in a statement. “It is possible that, in line with our hypothesis, howling appearing with a higher level of stress is a fear reaction—older dogs are more fearful, which was already suggested by previous studies, but these speculations require further investigation.”

The team also tested the effects of sex and reproductive status of the dogs on howling behavior. They found that there was no difference between intact and spayed females, but intact and neutered males behaved differently. 

“Neutered males, which are in lack of testosterone, howl more in response to the playbacks. As neutered males are suggested to be more fearful, this result can be in line with our findings about responsiveness and more stressed behavior. Thus, the dog howl may mean ‘I am scared, don’t come closer’,” said Lehoczki.

This research is helping scientists understand how domestication and selective breeding by humans have changed canine vocal repertoire and the impact it has had on human relationships with the domestic dog.

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Fossils have been recovered in a number of strange and surprising places including museum drawers and deep in present day deserts. More than a century ago, a 319-million-year-old fossilized fish was found at the Mountain Fourfoot coal mine in Lancashire, England. It was safely stored at the Manchester Museum and scientists are still learning from it 125 years later.

A CT scan of the fossil has revealed it contains the oldest example of a well-preserved vertebrate brain. The findings are documented in a study published February 1 in the journal Nature. The brain and cranial nerves are about an inch long and belong to the extinct Coccocephalus wildi (C. wildi). This was an early ray-finned fish that likely ate small crustaceans, cephalopods, and aquatic insects while swimming around estuaries. Backbones and fins supported by bony rods called rays are a feature of all ray-finned fishes. 

[Related: One wormy Triassic fossil could fill a hole in the evolutionary story of amphibians.]

Surprisingly, Friedman wasn’t looking for a brain when examining the C. wildi skull fossil.

“I scanned it, then I loaded the data into the software we use to visualize these scans and noticed that there was an unusual, distinct object inside the skull,” said co-author and University of Michigan (U-M) paleontologist Matt Friedman, in a statement.  

The unusual unidentified blob was brighter on the CT image, which means it was likely denser than skull bones or rock surrounding the fossil. It also displayed multiple features common in vertebrate brains, including bilateral symmetry, hollow spaces that look similar to ventricles, and multiple filaments.

These softer parts of vertebrate fossils are preserved, via a unique fossilization process where the soft tissues that made up the fish’s brain and cranial nerves were replaced with a dense mineral that preserved three-dimensional structure in remarkable detail.

The skull fossil is the only known C. wildi specimen of its species, so the team could only use nondestructive techniques to study it. The team used CT scanning to look inside these early ray-finned fish skulls to learn more about their anatomy and make inferences on evolutionary relationships.

 “With the widespread availability of modern imaging techniques, I would not be surprised if we find that fossil brains and other soft parts are much more common than we previously thought. From now on, our research group and others will look at fossil fish heads with a new and different perspective,” said co-author and U-M doctoral student Rodrigo Figueroa, in a statement.

[Related: Spinosaurus bones hint that the spiny dinosaurs enjoyed water sports.]

Specimens from early ray-finned fishes like Coccocephalus can fill in the gaps about initial evolutionary phases of the roughly 30,000 ray-finned fish species living today. According to the authors, the brain structure of Coccocephalus shows that there is a more complicated pattern of fish-brain evolution than is suggested by what’s found in living species alone. 

“Not only does this superficially unimpressive and small fossil show us the oldest example of a fossilized vertebrate brain, but it also shows that much of what we thought about brain evolution from living species alone will need reworking,” said Figueroa.

The findings also highlight why it’s important to preserve specimens and maybe clean out junk drawers every now and then. 

“Here we’ve found remarkable preservation in a fossil examined several times before by multiple people over the past century,” Friedman said. “That’s why holding onto the physical specimens is so important. Because who knows, in 100 years, what people might be able to do with the fossils in our collections now.”

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The Arctic Circle hasn’t always been so, well, arctic. About 52 million years ago, during the early Eocene Epoch, it was still mostly dark for half the year like it is today, but it was quite a bit warmer, more humid. The Arctic of years past had a boreal forest ecosystem similar to what is seen in Canada and parts of Russia today. It was even home to many early Cenozoic era vertebrates, including ancient crocodiles and camels. 

It was also home to at least two near-primate sister species, Ignacius mckennai and I. dawsonae. Scientists have found new specimens that are the oldest near-primate remains that have been found north of the Arctic Circle to date. The specimens and what we could learn from them are described in a study published January 25 in the journal PLOS ONE.

[Related: Adolescent chimpanzees might be less impulsive than human teens.]

“No primate relative has ever been found at such extreme latitudes,” study co-author Kristen Miller, a doctoral student with the University of Kansas’ Biodiversity Institute and Natural History Museum, said in a statement. “They’re more usually found around the equator in tropical regions.”

A process called phylogenetic analysis, which uses branching diagrams to show the evolutionary history and relationships of a species, helped the team to figure out how the fossils from these newly found species were related to those found in modern-day mid-latitude locations in North America. 

The specimens were found on Ellesmere Island in Nunavut, Canada, near the northwest coast of Greenland. They were found in sediment that dates back to the warmer Eocene, and studying this time period could foretell how Earth’s ecosystems will fare in coming years due to climate change.

According to Miller, both species are descended from a common northbound ancestor who possessed a spirit “to boldly go where no primate has gone before.”

The intense periods of darkness of the Arctic Circle may have triggered both of these species to evolve a surprising trait compared to their other primate relatives: more robust teeth and jaws. The team believes that it was much more difficult to find food during dim winter months. The Arctic primate relatives likely had to eat tougher harder material like nuts and seeds, as opposed to softer snacks like fruit, which could have impacted their unique dentistry.

“A lot of what we do in paleontology is look at teeth—they preserve the best,” said Miller. “Their teeth are just super weird compared to their closest relatives. So, what I’ve been doing the past couple of years is trying to understand what they were eating, and if they were eating different materials than their middle-latitude counterparts.”

[Related: There Used To Be Freaking Camels In The Arctic.]

The closest relatives of these species were likely a group of primates called plesiadapiforms, which were found further to the south during this time period. The northern primates were bigger than the southern ones, but all of them appear to be around rodent size.

“Some plesiadapiforms from the midlatitudes of North America are really, really tiny,” said Miller. “Of course, none of these species are related to squirrels, but I think that’s the closest critter that we have that helps us visualize what they might have been like. They were most likely very arboreal—so, living in the trees most of the time.”

The team believes that some of the adaptations that Arctic near-primate species took during another period of global warming demonstrates how some animals could evolve new traits–lessons that animals could be undergoing due to climate change today. 

 “I think probably what it says is [that] primates’ range could expand with climate change or move at least towards the poles rather than the equator,” said Miller. “Life starts to get too hot there, perhaps we’ll have a lot of taxa moving north and south, rather than the intense biodiversity we see at the equator today.”

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When you think of an amphibian, the first thing to jump to mind is probably a springy frog or a salamander or maybe a giant cane toad. But some newly found fossils of a lesser known amphibian order called caecilians—limbless, worm-like critters that live and burrow underground—could fill in some big evolutionary gaps in how present day amphibians came to be.

Caecilians look kind of like large earthworms and there are over 124 known species of them. Like all amphibians, they find themselves at home in both water and land. Modern caecilians are now exclusively home to southern Asia, South and Central America, and parts of Africa. Their enigmatic underground lives make them difficult for scientists to study, and while they can live up to 13 years long in captivity, it’s unknown exactly how long they live in the wild.

[Related: These pleasantly plump salamanders dominated the Cretaceous period.]

Previously, only 10 fossil caecilian occurrences have been found by scientists, and they date back roughly 183 million years ago to the Early Jurassic Period.

Now, a team of paleontologists have unearthed a new and older caecilian fossil, extending the record of this small animal by roughly 35 million years, all the way back to the Triassic Period (roughly 250 million to 200 million years ago). This fossil has a reddish hue and offers some clues into what the weird family of creatures may have looked like. The fossil find is described in a study published January 25 in the journal Nature.

“Seeing the first jaw under the microscope, with its distinctive double row of teeth, sent chills down my back,” Virginia Tech doctoral student Ben Klingman and co-author of the new study said in a statement. “We immediately knew it was a caecilian, the oldest caecilian fossil ever found, and a once-in-a-lifetime discovery.”

Klingman named the new fossil “Funcusvermis gilmorei.” The genus name ‘Funcusvermis’ was inspired by a song by the Ohio Players called “Funky Worm,” a favorite excavation tune for the authors. 

Funcusvermis shares some skeletal features with early frog and salamander fossils and an ancient group of amphibians called dissorophoid temnospondyls. “Unlike living caecilians, Funcusvermis lacks many adaptations associated with burrowing underground, indicating a slower acquisition of features associated with an underground lifestyle in the early stages of caecilian evolution,” Klingman said.

The discovery was found in Arizona’s Petrified Forest National Park during a dig in 2019. The fossils were found in a part of the park nicknamed Thunderstorm Ridge that is well known for fossil discoveries. They were deposited in a layer of the Chinle Formation dated to approximately 220 million years ago. At the time, the state of Arizona was near the equator at the central part of the ancient supercontinent Pangaea. Like today, the region was hot, but unlike today, it was much more humid.  

[Related: This fossil-sorting robot can identify millions-year-old critters for climate researchers.]

At least 70 individuals of Funcusvermis have been recovered as of summer 2022 at Petrified Forest National Park. Only a handful of Funcusvermis bones have been found, but until the team can find a complete skeleton, they cannot exactly determine the body length of Funcusvermis. Early inferences estimate that it was pretty tiny since remains of its lower jaws are less than a quarter inch long.  

“The discovery of the oldest caecilian fossils highlights the crucial nature of new fossil evidence. Many of the biggest outstanding questions in paleontology and evolution cannot be resolved without fossils like this,”said Kligman. “Fossil caecilians are extraordinarily rare, and they are found accidentally when paleontologists are searching for the fossils of other more common animals.”

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Human teenagers aren’t exactly known for their restraint. An incompletely developed region of the brain called the ventromedial prefrontal cortex (vmPFC), which acts a bit like a parking break, can make adolescents more likely to engage in risky behaviors including reckless driving, substance abuse, and risky sexual behavior. It turns out, the same can be said for adolescent chimpanzees, except reckless behaviors for them may look more like increased aggression.

A study published January 23 by the Journal of Experimental Psychology: General from the American Psychological Association finds that while chimps and teens share these risk-taking behaviors, the chimpanzees may be may be less impulsive.

[Related: Squirrels gamble too—but with their genes.]

“Adolescent chimpanzees are in some sense facing the same psychological tempest that human teens are,” said co-author Alexandra Rosati, an associate professor of psychology and anthropology at the University of Michigan, in a statement. “Our findings show that several key features of human adolescent psychology are also seen in our closest primate relatives.”

Chimpanzees can live up to age 50 and their adolescence occurs from around age eight up to 15. Chimpanzees show rapid changes in hormone levels during adolescence, form new bonds with their peers, demonstrate some increases in aggression, and compete for social status just like their human counterparts.

In the study, the team of researchers performed two tests using food rewards on 40 wild-born chimpanzees at Tchimpounga Chimpanzee Sanctuary in the Republic of Congo in central Africa. It included 21 males and 19 females from six to 25 years-old and an average age of 15.

During test number one, adults and adolescent chimpanzees performed a gambling task and could choose between two containers. One of the containers always had peanuts, which chimpanzees somewhat like. The other had either a disliked snack (a cucumber slice) or their favorite, a banana slice. They had a choice between playing it safe and getting some the sort of delicious peanuts, or take a chance at getting the coveted banana with the risk of getting a yucky cucumber.

The team recorded the chimpanzees’ vocalizations and emotional reactions, including moans, screams, whimpers, banging on the table, or scratching themselves. To track hormone levels, they also collected saliva samples.

Adolescent chimpanzees took the risky option more often than the adults, but both expressed negative reactions if they got the cucumber.

Test number two was modeled after the famous Stanford marshmallow experiment performed on human children to examine delayed gratification. The chimpanzees could either get one banana slice immediately or wait for 60 seconds to receive three tasty banana slices.

[Related: Eurasian jays show masterful intelligence in human psychology test.]

Adult and adolescent chimpanzees both chose to delay gratification at a similar rate. In this situation, human teens tend to be more impulsive than adults and would more likely chose the instant gratification.

“Prior research indicates that chimpanzees are quite patient compared with other animals, and our study shows that their ability to delay gratification is already mature at a fairly young age, unlike in humans,” said Rosati.

What did separate the adolescent chimpanzees from the adults is that they threw more tantrums during the delay than the adults did.

According to Rosati, risk-taking behavior in both adolescent humans and chimpanzees appears to be biologically ingrained, but also certain increases in impulsive behavior may be more of a human thing. Additionally, future studies could look into differences in impulsive behaviors in male and female chimpanzees.

“We are currently looking at the development of several other cognitive abilities in chimpanzees, including capacities for self-regulation and the emergence of social skills that help chimpanzees form and maintain relationships,” Rosati told PopSci in an email.

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Let’s talk about sex. Partnerless sex that is. While this form of sex isn’t typically associated with reproduction, generating offspring without a partner is common in small, spineless animals like sea stars and stick insects, but it is more rare in vertebrates. Through a process called parthenogenesis, some female animals in the order elasmobranch that includes sharks, rays, and skates can fertilize an egg using their own genetic material. 

This process is usually reserved as a last resort for sharks if there aren’t any mates to go around, but a recent study revealed that female zebra sharks at Shedd Aquarium in Chicago, Illinois, reproduced by themselves, even though there were healthy males in the same enclosure.

[Related: Shark Week may be hurting, not helping, its namesake creature]

“This changes what we think we know about parthenogenesis and why it occurs,” says Lise Watson, assistant director of animal operations and habitats at Shedd Aquarium and a co-author of the study, in reference to the biological phenomenon behind these partner-less births. “From observing our population for 20 years, we have a long history with them. One thing that we’ve noticed is sometimes the females are not very receptive to males at certain times, or at all.”

While previous studies have detailed parthenogenesis in zebra sharks at other aquariums, the report published in December 2022 in the Journal of Fish Biology is another step in understanding why these births happen. This research focuses on a female zebra shark—a dark fish with yellowish stripes found in the Pacific and Indian Oceans—that lived in Shedd’s Wild Reef exhibition.

In 2008, Watson and her colleagues moved a clutch of eggs to a baby shark nursery behind the scenes, where they could safely hatch beyond the limelight of an aquarium tank.

An analysis of the newly hatched shark pups’ DNA revealed seemingly impossible results. The pups didn’t have any genetic markers with any of the potential fathers. They had identical copies of some alleles, or alternative versions of a gene. This showed that they were getting DNA strands from their mother rather than two different parents. 

“These pups didn’t match any of the mature males that were in the enclosure. But they did match the female that laid the eggs,” says Kevin Feldheim, a biologist and researcher at the neighboring Field Museum and co-author of the study, in a statement. 

Offspring born from parthenogenesis often die young, and the shark pups in this study only survived for a few months.

“We don’t exactly know why they have shorter lifespans,” Feldheim tells Popular Science. “In genetics, in general, inbreeding is bad and what can happen is the expression of a lethal recessive [gene], or the expression of two alleles that essentially cause you to die.” 

But it’s still unclear exactly what causes animals born in this manner to die before sexual maturity, while others will survive. “In one species called the white spotted bamboo shark, an aquarium found that one of their females gave birth by parthenogenesis, and then one of those offspring actually went on to reproduce parthenogenetically herself,” says Feldheim.

The findings in zebra sharks have implications for not only the continued care of zebra sharks in zoos and aquariums, but also for conservation efforts focused on their wild counterparts.

“Sharks studied in the field always face some barriers,” says Sara Asadi Gharabaghi, a PhD candidate at Shahid Beheshti University in Tehran and member of Minorities in Shark Sciences, who was not involved in the study. One of those barriers is not being able to access the DNA of all of all adults and offspring to find biological parents.

“Sharks are the same as all animals trying to survive, so it would not be surprising to have pups from virgin birth either in the wild, even if we can’t prove it,” Asadi explains. It’s possible that sharks living in deep sea zones might use the same tactic, she adds

[Related: Baby sharks are eating the birds that live in your backyard]

For scientists studying endangered sharks in the wild and in aquariums, understanding reproduction will help conservation strategies. 

Zebra sharks are listed as threatened on the IUCN Red List, and aquariums like Shedd are working to preserve the species. Their genetic tests are part of a Species Survival Plan, or SSP, which brings together expert advisors to maximize genetic diversity and protect endangered species long-term. 

One aspect of an SSP is to determine “the genetics of the population and the sustainability of that population,” Watson says. Through genetic analysis she and her colleagues can make assumptions about how related an individual shark is to the whole group. From there, they can measure what the population size might look like for the next 100 years. 

“Studying these animals in our care is the foundation of us being able to help this species in the wild,” says Watson. “The care that we do for these animals here is of utmost importance for us.”

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About 250 million years ago, some very important arthropods went extinct. Trilobites were marine animals similar to today’s spiders and crustaceans known for a wide variety of body designs. One particular trilobite called the Walliserops also could have given Aquaman a worthy fight thanks to a flat, trident-shaped appendage jutting out from its head.

A study published January 16 in the journal Proceedings of the National Academy of Sciences (PNAS) finds that these tridents may have been used by males to compete in fights for sexual dominance. These ancient invertebrates may have “jousted” millions of years before the medieval sport.

[Related: These ancient trilobites are forever frozen in a conga line.]

These appendages may have been used to try to prod at each other before attempting to get underneath their rival and turn them over, and this could be some of the oldest evidence of sexual competition and sexual selection. Sexual selection is an evolutionary process that affects the characteristics associated with reproduction. It affects both primary sexual characteristics, such as the genitals, and secondary features that influence reproduction, such as the antlers of deer or the tail of male peacocks.

“The extraordinary Devonian trilobite Walliserops carried a unique, giant trident on its head, the purpose of which has long been a mystery,” said Richard Fortey, study co-author and scientific associate at the Natural History Museum, London, in a statement. “We now believe that it was used for jousting between males striving for dominance. The evolution of sexually motivated competition in animals is hundreds of millions of years older than we thought.”

The study also speculates that they may have been sexually dimorphic, where females and males have differences in appearance, but more evidence is needed.

[Related: Newly discovered fossils give a whole new meaning to jumbo shrimp.]

Scientists are still studying how far back sexual selection goes in the evolutionary tree. There is some thought the that the frills of Protoceratops is evidence of this process in dinosaurs, but there still isn’t enough evidence to rule out other potential roles for these features.

One way to decode what was happening in extinct animals is by making comparisons with living species. However, when structures are found in fossils, comparisons can be problematic since its not always clear what feature on a living species can be used to compare.

Ever since the description of Walliserops in 2001, the role of trilobite tridents has been tough to understand. In addition to their possible role in sexual selection, other defense possibilities and burrowing or sensing food are possible uses for the tridents.

To determine that the tridents were likely to be used in sexual selection, the team used evidence from a specimen at the Houston Museum of Natural History. Instead of having three points, or tines, this unique Walliserops specimen had four. The tines are about the same size and do not show evidence of an injury, and may have been born as a result of a genetic mutation.

“Even more important than the four-tined trident itself is the fact that the specimen is fully grown. By making it to adulthood, it shows that the feature that makes it different from other trilobites didn’t have a significant impact on its chances of survival,” the team wrote.

Changes in the fourth tine changes the overall shape of the trident, which suggests that the appendage likely wasn’t used for digging for feeing.

The team compared the specimen with the the striking weapons found on rhinoceros beetles. These present-day bugs have large horns that can grow to half of their body length and are used in fights between males during the mating season. They found the trident shape was most similar to the beetles that try to tip over their opponents with shovel-like weapons.

The amount of time it could have taken for the bugs to right themselves (like a knight in heavy armor trying to get up after being knocked off of his horse by a lance in a jousting match) would have allowed victorious males more time and opportunity to mate with females.

“It’s possible that these females may have been trident-less if the trident is a sexually selected characteristic. In this case, females may have been inadvertently placed into a different group of species altogether, but this would be difficult to prove,” the team wrote. If these tridents are examples of sexually selected characters, they body parts add to a growing body of evidence, showing that at least some at least some trilobite species could be sexually dimorphic.

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Urbanization has dramatically transformed landscapes all over the world, with many animals currently running out of space to live. Habitat encroachment affects everything from animal diets to social behaviors, and some organisms can even survive and thrive in urban spaces.

These species, like cougars and geese, take advantage of habitats created by humans. Researchers who study evolutionary change in urban species have even seen changes in animal metabolic rates or increase in heat tolerance.

[Related: Some of Asia’s iconic wildlife doesn’t seem to mind human encroachment.]

Cities can also alter their genes. In a study published on January 9 in the Proceedings of the National Academy of Sciences (PNAS), scientists found that Anolis cristatellus lizards, a small species of lizard also called the Puerto Rican crested anole that are commonly found in Puerto Rico’s forests and urban spaces, have parallel genomic markers across different urban ecosystems on the island. This explains previous research that found physical differences between city-dwellers and neighboring forest lizards.

The variations urban Anolis cristatellus lizards have evolved include larger toe pads with more specialized scales that help them cling to smooth surfaces (walls, glass windows, etc.) and their longer limbs help them sprint across open areas.

“Urbanization impacts roughly two-thirds of the Earth and is expected to continue to intensify, so it’s important to understand how organisms might be adapting to changing environments,” said Kristin Winchell, assistant professor of biology at New York University and the study’s first author, in a statement. “In many ways, cities provide us with natural laboratories for studying adaptive change, as we can compare urban populations with their non-urban counterparts to see how they respond to similar stressors and pressures over short periods of time.”

In this new study, the team examined 96 Anolis cristatellus lizards from three separate regions (San Juan, Arecibo, and Mayagüez) and compared the urban lizards with those in the forests surrounding each city.

First, the team confirmed that the lizard populations in the three regions had genetic distinctions from one another, so that any similarities they found among lizards could be attributed to urbanization. Then, they measured their toe pads and legs. These measurements show that the urban lizards had significantly longer limbs and larger toe pads with more specialized scales on their toes, supporting their earlier study.

Genomic analysis on exomic DNA (regions of the genome that code for proteins) was then conducted, so that they could understand the genetic basis of these physical trait differences. The analysis identified a set of 33 genes in three regions of the lizard genome that were repeatedly associated with urban populations, including genes related to metabolism and immune function.

[Related: Animals notice—and adapt—when humans are in national parks.]

“While we need further analysis of these genes to really know what this finding means, we do have evidence that urban lizards get injured more and have more parasites, so changes to immune function and wound healing would make sense,” said Winchell. “Similarly, urban anoles eat human food, so it is possible that they could be experiencing changes to their metabolism.”

Another analysis found 93 genes important for skin and limb development in the urban lizards. This showed a gene-level explanation for why city lizards have longer legs and toe pads. 

“The physical differences we see in the urban lizards appear to be mirrored at the genomic level,” said Winchell. “If urban populations are evolving with parallel physical and genomic changes, we may even be able to predict how populations will respond to urbanization just by looking at genetic markers.”

Understanding adaptations to urban environments can help scientists focus conservation efforts and build urban environments to better maintain species.

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This article was originally featured on Hakai Magazine, an online publication about science and society in coastal ecosystems. Read more stories like this at hakaimagazine.com.

Planet Earth used to be something like a cross between a deep freeze and a car crusher. During vast stretches of the planet’s history, everything from pole to pole was squashed beneath a blanket of ice a kilometer or more thick. Scientists call this snowball Earth.

Some early animals managed to endure this frigid era from roughly 720 to 580 million years ago, but they had their work cut out for them. Despite their valiant successes, the repeated expansion and contraction of giant ice sheets pulverized the hardy extremophiles’ remains leaving almost no trace of them in the fossil record and scientists with little to no idea of how they managed to survive.

“It’s basically like having a giant bulldozer,” says Huw Griffiths of the British Antarctic Survey. “The next glacial expansion would have just erased all that and turned it into mush, basically.”

Despite the lack of direct evidence thanks to all that glacial churning, Griffiths argues it is reasonable to propose that a diverse range of animal life inhabited snowball Earth. He suggests that this flourishing would have pre-dated the so-called Cambrian explosion, a period around 540 million years ago when a great and unprecedented diversity of animal life emerged on Earth. “It’s not a huge leap of imagination that there were much smaller, simpler things that existed before that,” Griffiths says.

The full picture of animal life during this time is lost, but Griffiths and his colleagues take a stab in a recent paper at trying to figure out what it might have looked like.

The team considered three different frozen periods. The first was the Sturtian snowball Earth, which began about 720 million years ago. It lasted for up to 60 million years. This is a mind-blowingly long time—it’s nearly as long as the period between the end of the dinosaur era and today. Then came the Marinoan snowball Earth, which started 650 million years ago and lasted a mere 15 million years. It was eventually followed by the Gaskiers glaciation around 580 million years ago. This third glaciation was shorter still and is often called a slushball rather than a snowball Earth because the ice coverage was likely not as extensive.

Though the ice smushed most of the fossils from these periods, scientists have found a handful of remnants. These rare fossils portray the weird animals that existed around the time of the Gaskiers glaciation. Among these ancient slushball-Earth dwellers were the frondomorphs—organisms that looked a bit like fern leaves. Frondomorphs lived fixed to the seafloor beneath the ice and possibly absorbed nutrients from the water as it flowed around them.

Short on direct evidence, Griffiths and his colleagues instead argue that the survival strategies of animals during the great freezes of the past are likely echoed by the life that dwells in the most similar environment on Earth today—Antarctica.

Some modern Antarctic inhabitants such as anemones live upside down affixed to the underside of the sea ice. One of the favorite feeding strategies of krill is grazing microorganisms on this upturned plane. Perhaps early animals foraged and found shelter in such locations, too, Griffiths and his colleagues suggest.

It’s also possible that the waxing and waning of sea ice introduced algae or other microorganisms living on the ice into seawater allowing them to bloom, which might have provided food for other early animals.

One of the challenges that inhabitants of a snowball Earth faced was the possible lack of oxygen, both because the oxygen levels in the air were low and because there was limited mixing from the atmosphere into the water. But oxygenated meltwater high in the water column might have supported animals that depended on it. Some denizens that live on the Antarctic seafloor today, such as certain species of feather star, solve this problem by relying on water currents to bring a steady flow of oxygen and nutrients from the small areas of open water at the surface to deep below the ice shelves. There’s no reason to think this didn’t happen during the Gaskiers slushball Earth period, too.

“We are really talking about very basic forms of life … but at the time that’s all you’d have needed to be king of the animals,” says Griffiths.

Alongside frondomorphs, the seafloor might also have been inhabited by sponges. Some fossil evidence of sponges dates back to well before the Sturtian snowball Earth, though there is some debate over this, says Griffiths.

Ashleigh Hood, a sedimentologist at the University of Melbourne in Australia who was not involved in the research, jokes that “everyone, including us, has their oldest sponge that they’ve found in the record and no one else believes them.”

Some modern sponges live symbiotically with bacteria, which may help them access nutrients when other food is scarce. “That’s probably based off a survival strategy they had really early on in their history,” Hood suggests.

Andrew Stewart, assistant curator at the Museum of New Zealand Te Papa Tongarewa who also wasn’t involved in the paper, has studied countless species from harsh Antarctic environments. Many of these organisms cope in incredibly dark, cold, or chemically toxic places. For Stewart, Antarctic extremophiles are a reminder of how robust life on Earth really is—and perhaps always has been.

“It’s just the most amazing place,” he says. “You go, No, bollocks, nothing can survive there! Well, actually it can.”

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In 2003, a lost fictional clownfish named Nemo swim his way to box office success. If Nemo hadn’t ended up in a dentist’s fish tank, it’s possible an older region in the back of his brain could have kicked in to help him find his way back to his home to a reef, according to a new study.

A team of scientists at Howard Hughes Medical Institute’s (HHMI) Janelia Research Campus are now better understanding how animals know where they are in relation to their environment—and how to find their way back on the path they were taking. A study published December 22 in the journal Cell details how a region called the hindbrain helps animals determine location and use that information to plan where to go next.

[Related: Fish brains provide insight on how humans store memories.]

The hindbrain is an older region located in the back of the brain that has been evolutionarily conserved, or virtually unchanged throughout the process of evolution. The authors looked at tiny translucent zebrafish. They have historically been used in research, especially in genetics, for many reasons, including their quick growth rates, translucent bodies that can help scientists peer inside, and similar genetic structure to humans. The zebrafish genome was fully sequenced in 2013.

The fish were placed in an environment that simulates currents, and were then pushed off course when the currents shifted unexpectedly. However, they were able to course-correct and get back where they started. While the zebrafish were swimming, the researchers used a whole-brain imaging technique to measure what was going on inside the fish’s brain. The scientists could search the entire brain to note which circuits were activated when the zebrafish course corrected and separate the individual activities.

The team expected to see the forebrain, where the hippocampus that houses an internal map of an animal’s environment is stored. Instead, they saw several regions of the medulla activate. This is where information about the animal’s location was being transmitted through a newly identified circuit. A part of the hindbrain called the inferior olive used motor circuits to move the information to the cerebellum that made the fish move. The fish were unable to move back to its original spot when these pathways were blocked.

[Related: These jellyfish don’t have brains, but still somehow seem to sleep.]

“We found that the fish is trying to calculate the difference between its current location and its preferred location and uses this difference to generate an error signal,” says En Yang, the first author of the new study, and a post doctoral researcher at Janelia’s Ahrens Lab, in a statement. “The brain sends that error signal to its motor control centers so the fish can correct after being moved by flow unintentionally, even many seconds later.”  

Previous studies have shown that the inferior olive and the cerebellum performed actions related to reaching and locomotion, but not this type of navigation. According to the team, this hindbrain network could also lay the basis for other navigational skills, including when a fish swims to a specific spot to take shelter.

“This is a very unknown circuit for this form of navigation that we think might underlie higher order hippocampal circuits for exploration and landmark-based navigation,” said Misha Ahrens, Janelia Senior Group Leader, in a statement.

Further study is needed to determine whether these same networks are involved in similar behavior in other animals.

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Across the planet, there are roughly 7,000 languages spoken by humans. But, how humans got to be such robust conversationalists is a bit of a mystery.

A new study published Tuesday in the journal Trends in Cognitive Sciences could show a bit more of the link between human speech and sounds that our animal cousins make. The new research finds that orangutans produce consonant-like calls more often and of a greater variety than their African ground-dwelling cousins (gorillas, bonobos, and chimpanzees).

While orangutans and humans share about 97 percent of their DNA, chimpanzees and bonobos are more closely related to our species. Since orangutans still exhibit this robust vocal repertoire, the location where our non-human primate ancestors lived might be another crucial piece of the puzzle in understanding the origins of human speech.

Orangutans are the most arboreal-or tree dwelling-of the great apes. Whether an ape lives among trees or on the ground may have driven the development of different vocal repertoires.

[Related: Artificial intelligence is helping scientists decode animal languages.]

This study suggests that human’s evolutionary ancestors may have lived a more tree-dwelling lifestyle than previously believed since a larger and more varied body of consonant-like calls arose in arboreal apes like orangutans.

“Existing theories of speech evolution have thus far, focused exclusively on the connection between primate laryngeal anatomy and human use of vowels,” Adriano Lameira, associate professor of psychology at the University of Warwick, said in a statement. “This doesn’t explain though, how voice-less, consonant-like sounds became a fundamental component of every language spoken around the globe.” 

All spoken languages are composed of both vowels and consonants. Vowels are almost always voiced produced by the larynx. Consonants are typically more voiceless and produced by moving the supra-laryngeal articulators, such as, the lips, tongue, and mandible.

Lameira investigated the origins of human spoken language, which is universally made up of vowels that take the form of voiced sounds, and voiceless sounds in the form of consonants. However, the calls of non-human primates are primarily composed or exclusively made up of voiced vowel-like sounds.

“This raises questions about where all the consonants, that compose all the world’s languages, originally come from,” said Lameira. 

The study compares the patterns of consonant-like vocal production in three major great ape linages– orangutans, gorillas, bonobos, and chimpanzees. Their call repertoire features sounds that are similar to both vowels and consonants, but there are inconsistencies within how great apes use consonant sounds in nature.  

“Wild gorillas, chimpanzees and bonobos don’t use a huge variety of consonant-like calls,” Lameira explained. “Gorillas for example, have been found to use a particular consonant-like call, but this is only prevalent in some gorilla populations and not others. Some chimpanzee populations produce one or two consonant-like calls associated with a single behaviour, for example while they are grooming, but these same grooming calls are uncommon in other chimpanzee populations.”

Wild orangutans use consonant-like calls for multiple behaviors consistently and universally, similar to what humans do with speech.

According to Lameira, orangutans have a diverse array of smacking, clicks, kiss-sounds, splutters, and raspberries within their vocal repertoire. Some of the aspects of an arboreal lifestyle and feeding habits could help explain the sophistication and complexity of their consonant-like calls.

“All apes are accomplished extractive foragers. They have developed complex mechanisms to access protected or hidden foods like nuts or plant piths, which often requires either meticulous use of hands or tools,” said Lameira.

[Related: Foraging in trees might have pushed human ancestors to walk on two feet.]

Terrestrial dwelling apes such as chimpanzees and gorillas use the stability of the ground to handle food and use tools, but orangutans need at least one of their limbs to be stable when accessing and handling food.

“It is because of this limitation, that orangutans have developed greater control over their lips, tongue and jaw and can use their mouths as a fifth hand to hold food and [maneuver] tools,” said Lameira.  “Orangutans are known for peeling an orange with just their lips so their fine oral neuro-motoric control is far superior to that of African apes, and it has evolved to be an integral part of their biology.”

This speech research mirrors a recent study that argues human ancestors transitioned to two-footed movement as a way to better forage for food among tree branches. These new findings could revise a long-standing theory of how human bipedalism evolved.

The more we learn about our relatives and ancestors’ relationship with tree-filled environments, the more scientists can put together a picture of how humans came to be.

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Deep in the stone at the Berlin-Ichthyosaur State Park (BISP) in Nevada’s Humboldt-Toiyabe National Forest, many 50-foot-long ichthyosaur (Shonisaurus popularis) specimens lay petrified and frozen in time. This order of extinct marine reptiles (and Nevada’s state fossil) looked like a chunky dolphin and lived during the late Triassic age, roughly 237-227 million years ago.

New research also suggests that the predator may have performed similar migrations to modern whales. Today’s blue and humpback whales make annual migrations thousands of miles across oceans to breed and give birth in regions where predators are scarce. Many of these whales gather together year after year along the same stretches of coastline.

[Related: These ancient, swimming reptiles may have been the biggest animals of all time.]

Shonisaurus may have done something very similar. An international team of researchers published their findings Monday in the journal Current Biology, explaining how at least 37 of these marine reptiles died in the same location—a question that has stumped paleontologists for more than 50 years.

“We present evidence that these ichthyosaurs died here in large numbers because they were migrating to this area to give birth for many generations across hundreds of thousands of years,” said co-author and Smithsonian National Museum of Natural History curator Nicholas Pyenson, in a statement. “That means this type of behavior we observe today in whales has been around for more than 200 million years.”

Some paleontologists have proposed that BISP’s ichthyosaurs died in a mass stranding event similar to the ones seen in whales today, or that a harmful algal bloom may have poisoned the animals. But these hypotheses do not have strong scientific evidence supporting them.

To try to solve this prehistoric puzzle, the team combined 3D scanning and geochemistry and combed through archival materials, photographs, maps, and field notes, for shreds of evidence.

Within BISP is a barn-like building that researchers call Quarry 2, which houses partial skeletons from an estimated seven individual ichthyosaurs that all appear to have died around the same time. 

“When I first visited the site in 2014, my first thought was that the best way to study it would be to create a full-color, high-resolution 3D model,” lead author Neil Kelley, an assistant professor of geology at Vanderbilt University, said in a statement. “A 3D model would allow us to study the way these large fossils were arranged in relation to one another without losing the ability to go bone by bone.”

The team then collaborated with Jon Blundell, a Smithsonian Digitization Program Office’s 3D Program team member, and Holly Little, informatics manager in the museum’s Department of Paleobiology. Little and Blundell used digital cameras and a spherical laser scanner to take hundreds of photographs and millions of point measurements. These were then stitched together using specialized software to create a 3D model of the fossil bed while the paleontologists on the team physically measured the bones.

“Our study combines both the geological and biological facets of paleontology to solve this mystery,” co-author Randall Irmis, a paleontology professor at the University of Utah and the chief curator of the Natural History Museum of Utah’s Department of Geology & Geophysics, said in a statement. “For example, we examined the chemical make-up of the rocks surrounding the fossils to determine whether environmental conditions resulted in so many Shonisaurus in one setting. Once we determined it did not, we were able to focus on the possible biological reasons.”

Geochemical tests in the rock didn’t reveal any signs that these ichthyosaurs died due to a major environmental event like a harmful algal bloom that would have also disturbed the ecosystem. They expanded their search beyond Quarry 2 to the surrounding geology and fossils that scientists had previously excavated from the area. 

[Related: This whale fossil could reveal evidence of a 15-million-year-old megalodon attack.]

The geologic evidence showed that when the ichthyosaurs died, their bones sank to the bottom of the sea over time instead of collecting along the shoreline, which would have suggested stranding. The area’s mudstone and limestone were also full of large adult Shonisaurus specimens but not as many specimens of other marine vertebrates.

“There are so many large, adult skeletons from this one species at this site and almost nothing else,” said Pyenson. “There are virtually no remains of things like fish or other marine reptiles for these ichthyosaurs to feed on, and there are also no juvenile Shonisaurus skeletons.”

After ruling out the algae and stranding hypotheses, the team found a key clue in tiny ichthyosaur remains among some of the new fossils collected at the park and hiding within older museum collections. Micro-CT x-ray scans and a comparison of the bones and teeth showed that the small bones were embryonic and newborn Shonisaurus.

“Once it became clear that there was nothing for them to eat here, and there were large adult Shonisaurus along with embryos and newborns but no juveniles, we started to seriously consider whether this might have been a birthing ground,” said Kelley.

Additional analysis revealed that the ages of the many fossil beds of BISP were actually separated by at least hundreds of thousands of years, if not millions of years.

“Finding these different spots with the same species spread across geologic time with the same demographic pattern tells us that this was a preferred habitat that these large oceangoing predators returned to for generations,” said Pyenson. “This is a clear ecological signal, we argue, that this was a place that Shonisaurus used to give birth, very similar to today’s whales. Now we have evidence that this sort of behavior is 230 million years old.”

The next step for this research is to look into other ichthyosaur and Shonisaurus sites in North America with these new findings in mind. It will help scientists recreate this ancient world by looking for other breeding sites or places with greater diversity of other species that could have provided rich feeding grounds for this extinct apex predator. 

“One of the exciting things about this new work is that we discovered new specimens of Shonisaurus popularis that have really well-preserved skull material,” Irmis said. “Combined with some of the skeletons that were collected back in the 1950s and 1960s that are at the Nevada State Museum in Las Vegas, it’s likely we’ll eventually have enough fossil material to finally accurately reconstruct what a Shonisaurus skeleton looked like.”

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CONSIDER THE CAT: aloof, independent, bestowing and withdrawing affection according to rules only they understand. Capable of friendship with their human, but not requiring it, and rarely as much as a dog. These tropes are ubiquitous, though many people know from experience just how warm and affectionate cats can be. That’s not news to us. So what can science tell us that we don’t already know? Quite a lot, actually. We matter to cats even more than we think, and our assumptions about their character can easily become self-fulfilling prophecies. 

Several years ago, animal behavior specialist Monique Udell of the University of Oregon and her then doctoral student Kristyn Vitale decided to look at cat-human relationships through the lens of attachment theory. The theory, originally developed in the 1970s by psychiatrist John Bowlby, describes the types of relationships that young humans form with their guardians.

Bowlby and the researchers who built on his work observed that infants whose caregivers were consistent, responsive, and affectionate developed what he called secure attachments. Confronted with stress, securely attached children looked to their caregivers for security. Children whose caregivers were distant and unresponsive, or inconsistent with their care, formed insecure attachments, their experience characterized by fear and uncertainty.

Monkeys too demonstrated these types of attachments—an insight in part produced by some of the most infamous research in the grim history of animal experimentation. One key example is Harry Harlow’s maternal deprivation studies on infant rhesus macaques who were separated from their mothers. 

Dogs have attachment styles as well, which Udell observed using what is called the Secure Base Test. In 2019 Udell and Vitale published a similar experiment with cats, enrolling 79 people and their kittens; each pair would spend two minutes together in an unfamiliar room, after which the person would step out for just two minutes, leaving the kitten alone. Then the person would return and the researchers would observe the kitten’s reaction.

The young cats responded much as dogs—or human infants—would. Alone in that strange place, they became distressed. When their person returned, most of the kittens sought them out for a rub and perhaps a kind word, then proceeded to explore. The animals were said to be securely attached: They depended on their caregiver for security and, with that as their foundation, engaged with the world. About one-third of the them, however, either avoided the human or snuggled up and stayed there, unwilling to wander on their own. These kittens were insecurely attached, either taking no comfort in their person or clinging to them.

Udell and Vitale explain that feline relationships are more similar to those seen with canines than one might think. Confronted with something strange and upsetting, cats turned to their person for reassurance, says Vitale, who is now a professor of animal behavior at Unity College. Some retreated to a corner of the room; others crawled up into a lap and stayed put.

And when they don’t? A cat may indeed be distant by nature, but this is often not preordained. Instead, an inability to find comfort and security in their person “may be an outcome of life experiences,” says Vitale, as well as that particular cat’s predisposition. Both nature and nurture matter—and even well-meaning people may not appreciate just how sensitive cats can be.

“Common misconceptions that cats need less social interaction, or are more independent, can impact both the amount and quality of social interactions we offer cats,” Udell says. In other words, people who think felines don’t need much attention might be less hands-on with their own companion, which in turn results in a more aloof kitty. (Udell also recently published a study in the journal Animal Cognition on how different pet parenting styles affect dog attachments.) 

Sometimes, however, it’s out of a cat lover’s hands. Udell adds that temperament or past history might make it more difficult for a feline to form a secure attachment, even with a warm and responsive person; she hopes to eventually study this. But her and Vitale’s research made me consider my own relationships to the cats in my life: I think of myself as nurturing, and yet there have been times when I disappeared for a day, or entered a room without saying hello and left without saying goodbye. Had they been dogs, I might have been more considerate.

It didn’t occur to me that interaction mattered as much to them as it did to me. I had internalized, albeit subtly, that trope of cats as being content without contact. Heck, as bioethicist Jessica Pierce writes, people who don’t have time for dogs are encouraged to get cats instead; leaving a dog alone for a day or two is understood as distressing to them, even cruel, yet little attention is given to what that is like for a cat.

And as testament to how much their human connections can matter, consider another study from Udell and Vitale, published in 2017. They presented adult cats—pets as well as potential adoptees at a shelter—with a choice of how to spend their time. The animals could investigate an interesting scent, like catnip, play with a toy, interact with a person, or eat.  “Social interaction was the most-preferred stimulus category overall for the majority of cats,” the researchers concluded. A human connection was food for their hearts.

We hope you enjoyed Pet Psychic, Brandon Keim’s new column. Check back on PopSci+ in February for the next article.

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Walking on the moon is hailed as one of the greatest human achievements, but if you talk to any biological anthropologist, they’d probably say it’s the ability to walk upright on two legs in the first place. But the exact driving force that shifted locomotor behavior in our early human ancestors has largely remained a mystery. A new study published today in Science Advances makes the case that our ancestors transitioned to two-footed movement to better forage for food on tree branches. The research findings could potentially revise a long-standing theory of human bipedalism.

“Bipedalism is a defining feature of the human lineage and is the first thing to separate our fossil ancestors from other apes. Understanding why it evolved is thus key to understanding what made us human,” says Rhianna Drummond-Clarke, the study’s lead author and a biological anthropology Ph.D. student at the University of Kent in the United Kingdom.

If something jeopardized a basic need—food, water, air, and shelter—the evolutionary pressure to survive would have forced our early ancestors to adapt, the authors explain. The prevailing explanation supported by anthropologists is the “savanna hypothesis,” in which our ancestors began walking on two feet in response to changing environments. About 10 to 2.5 million years ago, tropical forests began shifting into dry and open savannas. Losing trees restricted the number of food options available, pushing human ancestors to move from foraging in trees to gathering down on the ground. This habitat transition is theorized to have been the driving force behind bipedalism.

However, some anthropologists have been skeptical of this explanation. A dwindling forest likely influenced but did not necessarily drive us toward two-legged walking, explains Alexander Piel, a biological anthropologist at the University College London and senior study author. 

One reason there hasn’t been a clear-cut answer is that there are limited fossil records of our ancestors during the timeframe that human bipedalism is thought to have emerged. What’s more, the evidence that does exist, doesn’t seem to align with the savanna hypothesis. For instance, past research reconstructing ancient habitats during that time period has suggested that fossils are not in open grasslands but found in wooded areas. What’s more, the hominin fossils that are available show signs of ape-like forelimbs that would have helped swing and climb trees. That’s why Piel leans towards an “arboreal hypothesis,” where humans evolved to walk upright as a way of better foraging for food in the trees.

[Related: Shifting ancient climates shaped human evolution]

For the current study, the authors spent 15 months studying the behavior of 13 chimpanzees in the savannas of Issa, Tanzania. The team chose the Issa community because it’s a closely related ape that lives in a habitat resembling the one from a million years ago, Piel says. “What better place to investigate some of the key features—and the pressures on their evolution—that define our own species?”

The Issa chimpanzees are a primate species that spend about half of their life in trees, with the rest of the time on the ground. The study authors wanted to test whether living in a savanna increased their time on land compared to living in a forested habitat. Results showed that Issa chimpanzees spent the same time in trees regardless of whether they were in a forest or savanna setting. Additionally, locomotion data of other chimpanzee groups from past research revealed that the Issa chimpanzees spent more time in the trees than those that primarily live in forested habitats. In fact, their behavior most closely resembled Kibale chimpanzees which reside in forests.

When it comes to walking upright, the researchers noticed something interesting in the chimps. Issa chimpanzees were seen walking with two feet when up on the trees more frequently than on the ground. Bipedal movement often happened when searching for food in the forest. The results suggest that bipedalism may have emerged as a way to spend more time thoroughly searching for food in trees that were still available in the savanna. 

Scott Williams, an evolutionary morphologist and paleoanthropologist at New York University who was not affiliated with the study, says this research is a “fantastic” contribution of locomotion data. However, he maintains that bipedalism primarily evolved because of savannas. He says the data showing savanna Issa chimps engaging in bipedal locomotion 4 to 25 times more than those in forests could actually be interpreted differently. “To me, this suggests almost the opposite of what the authors interpret—that savanna habitats selected for bipedal locomotion in early hominins.” Alternatively, Williams says chimps may have spent more time up in the trees because searching for food in higher locations may have been safer and made them less exposed to predators than foraging on the ground in an open savanna environment.

Some anthropologists, on the other hand, are open to the idea that bipedalism arose from something more than changing landscapes. Alyssa Crittenden, an anthropology professor at the University of Nevada, Las Vegas, says the study provides strong evidence towards the arboreal hypothesis, especially because of where the research took place. “While savanna ecologies are often centered in conversations on bipedalism, rarely do we have the opportunity to learn from chimpanzees living in such habitats,” she wrote in an email to PopSci. “This important study provides support for the hypothesis that hominin bipedalism likely evolved within an arboreal context and persisted long after hominids began living in and utilizing more open landscapes with less vegetation.”

[Related: Our long childhoods could be linked to food-gathering skills]

Despite the unique location that closely resembles the prehistoric landscape, Williams points out that one flaw to the arboreal hypothesis is that it does not explain how non-tree dwellers—think of kangaroos, hopping mice, and even cockroaches—also evolved to have bipedal movements as well.

“The traits we identify in hominins like Ardipithecus, Australopithecus, and Homo are clearly related to terrestrial, not arboreal, bipedalism,” Williams says. “Although many species seem to have retained [other] adaptations to arboreality, which is a useful thing when food is in the trees and predators are on the ground.”

The next step the authors are taking in their research is studying the resources available to Issa chimpanzees. Doing so will help to answer how our ancestors spent so much time in trees, given the sparse supply in savannas.

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Australia and the Oceania region in general are known for beautiful beaches, rugged terrain, and incredible biodiversity. Australia itself is home to over one million species of plants and animals, and between 600,000 and 700,000 species that aren’t found anywhere else on planet Earth, according to the Australian Department of Climate Change, Energy, the Environment, and Water.

It also used to be an even bigger ecological playground. Roughly 80,000 years ago it was also home to extinct megafauna, or giant animals similar to ones found today that once lived in the country’s forests and plains. That includes giant wombat relatives. However, there has been a bit of a wombat relative identity crisis occurring in the study of these marsupials.

[Related: Giant beasts once roamed Madagascar. What happened to them?]

Remains of the extinct Diprotodon are commonly believed to be Australia’s “giant wombat,” but it isn’t the closest wombat relative since it belongs to the family Diprotodonidae and not Vombatidae. But new research published Monday in the journal Papers In Paleontology details the discovery of the remains a true giant wombat relative Ramsayia magna.

Extinct giant wombats of the family Vombatidae are a more rare find that than the fossilized Diprotodon specimens, which may be why the species has been overlooked as the true wombat relative. They share some similar traits to the present-day marsupial, but this new find suggests that Ramsayia magna is the closer ancestor to the wombat.

“The extinct megafauna of Australia never ceases to amaze and intrigue not just Australians, but people all over the world,” said co-author and associate professor Julien Louys from Griffith University’s Australian Research Centre for Human Evolution, in a statement. “Although one of the most charismatic of the giant mammals to go extinct, Diprotodon is commonly referred to as a ‘giant wombat’. But this is incorrect as Diprotodon belongs to an entirely different family- equivalent to saying a hippo is just a giant pig.”

The discovery of a mostly complete skull of the poorly understood species Ramsayia magna helped the team reconstruct what the animal looked like, when it lived, and where it roamed in Australia.

[Related: This is the most-complete woolly mammoth ever found in North America.]

The Ramsayia magna cranium and mandible (lower jaw) fossil were discovered in Lower Johansons Cave in Rockhampton, Queensland, Australia in the early 2000s. Subsequent excavations in the cave and analysis by the team on this study confirmed that it belonged to this elusive megafauna species. The specimen had extensive cranial sinuses, which had not been previously reported for a giant wombat. 

“This indicates that the wombat had a large, rounded skull for the attachment of specific and strong chewing muscles,” said Louys. “The giant wombat also possessed a ‘premaxillary spine’, an indication that it had a large, fleshy nose. In this paper, we show that all true giant wombats evolved large body sizes first, then individually became quite specialized to eat different types of grasses.”

The paper also dates this species for the first time. At 80,000 years-old, this earlier than when humans arrived in Australia (about 48,000 to 50,000 years ago), but it is still unknown when Ramsayia magna went extinct.

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Morocco is making headlines for more than just its incredible run at this year’s World Cup. A new fossil find at Taichoute in the country’s fossil-rich Fezouata Shale formation in southeastern Morocco’s Zagora region is filling in some gaps in evolutionary history.

Fezouata Biota is a the name of a unique assembly of fossilized animals from the Early Ordovician period found in this area which includes radiodonts, lobopodians, nektaspidids, and marrellomorphs. The greater Fezouata Shale formation is home to the remains of numerous large “free-swimming” arthropods that dominated the Earth’s seas about 470 million years ago. These are the relatives of present day shrimp, insects, and spiders.

A study published today in the journal Scientific Reports describes the early evidence found at the site. While more research is needed to analyze these fragments, the giant arthropods could be up to six and a half feet long, a new meaning to the term jumbo shrimp.

[Related: World’s Oldest Fossils Show Sulfur-Based Microbes Lived 3.4 Billion Years Ago, Presenting a New Target for Astrobiology.]

The team says the findings at Taichoute open up new avenues for studying paleontology and ecology.

“Everything is new about this locality—its sedimentology, paleontology, and even the preservation of fossils—further highlighting the importance of the Fezouata Biota in completing our understanding of past life on Earth,” lead author Farid Saleh, a paleontology PhD student at the University of Lausanne and and Yunnan University, said in a statement.

This site and its fossil record are very different from other previously described and studied Fezouata Shale sites, according to the team that represents multiple countries. At the other sites, located about 50 miles away from Taichoute, researchers have found fossils from after the Cambrian Explosion.

“While the giant arthropods we discovered have not yet been fully identified, some may belong to previously described species of the Fezouata Biota, and some will certainly be new species,” Xiaoya Ma, a co-author and palentologist from the University of Exeter and Yunnan University, said in a statement. “Nevertheless, their large size and free-swimming lifestyle suggest they played a unique role in these ecosystems.”

The fossils discovered in this rocks include harder shells and some well-preserved soft body parts such as internal organs. These discoveries help scientists investigate the anatomy of early animal life on Earth and how it has changed over time. The animals here lived in a shallow, stormy, and wavy sea that buried their remains and preserved them in place. However, the free-swimming (or nektonic) animals are actually a relatively minor component overall in the Fezouata Biota. 

[Related: A Scottish fossil is helping scientists fill the gaps in the lizard family tree.]

This new study finds that the Taichoute fossils are preserved in sediments that are a few million years younger than other discoveries from the Zagora area and are dominated by fragments of the giant arthropods. Underwater landslides further delivered the carcasses of these animals to the deeper marine environment.

“Animals such as brachiopods are found attached to some arthropod fragments, indicating that these large carapaces acted as nutrient stores for the seafloor dwelling community once they were dead and lying on the seafloor,” said Allison Daley, a co-author paleontologist the University of Lausanne, in a statement.

Even for seasoned paelentologists, these new species are a surprising find, according to the team.

“The Fezouata Biota keeps surprising us with new unexpected discoveries,” Bertrand Lefebvre, the paper’s the senior author and a palentologist at the University of Lyon, concluded in a statement.

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Recently, scientists have uncovered a lizard fossil that hadn’t been seen since the 1950s and army ant fossils that were hidden at Harvard University for almost 100 years. It turns out that there is yet another big fossil find traced back to a museum cupboard, this time at the Tasmanian Museum and Art Gallery (TMAG) in Hobart, Tasmania. Researchers there found the long-lost remains of the last known Tasmanian tiger, or thylacine (Thylacinus cynocephalus). The remains have been missing for over 85 years.

[Related: A genetics startup wants to bring the Tasmanian tiger back from extinction.]

“For years, many museum curators and researchers searched for its remains without success, as no thylacine material dating from 1936 had been recorded,” said researcher and comparative psychologist from the Australian Catholic University Robert Paddle, in a statement. “It was assumed its body had been discarded,” he added.

The Tasmanian tiger was a dog-sized carnivorous marsupial with sharp claws, that was native to New Guinea, the Australian mainland, and Tasmania for four million years. Sporting yellowish to gray fur and distinctive tiger stripes covering its body, it first disappeared from the mainland about 2,000 years ago. The National Australia Museum speculates multiple factors, including over hunting and the introduction of the dingo, led to this first wave of extinction.

By the late 19th and early 20th centuries, Europeans began to colonize the island of Tasmania—an island about 150 miles south of Australia. They incorrectly blamed the marsupials for killing their chickens and sheep and thylacines were slaughtered by the thousands, with the government even offering bounties for thylacine pelts. Throw in the same fight for dominance with dingoes and the Tasmanian tiger was doomed. The last known thylacine died in the Beaumaris Zoo in Hobart on September 7, 1936.

However, the thylacine that was often dubbed the last thylacine in photos, was actually the second-to-last thylacine. According to Paddle, the actual last thylacine, also called the “endling” of the species, was an older female animal and is the specimen that had been lost in a cupboard for all these years. The thylacine had been captured by a trapper from the Florentine Valley named Elias Churchill and sold to Beaumaris Zoo in May 1936, before it died. The skeleton and skin of the specimen were then stashed away in the cupboard at the musuem, due to its “somewhat shady” acquisition and the experts lost track of it.

“The sale was not recorded or publicised by the zoo because, at the time, ground-based snaring was illegal and Churchill could have been fined,” Paddle said. “The thylacine only lived for a few months and, when it died, its body was transferred to TMAG.”

Curators used the discovery of a previously unpublished museum taxidermist’s report dated back to 1936-1937 to verify when the last thylacine specimen arrived at TMAG. The report mentioned a thylacine among the list of specimens that the institution worked on during that year, according to Honorary Curator of Vertebrate Zoology at TMAG, Kathryn Medlock.

[Related: The search for the extinct Tasmanian tiger.]

“The thylacine body had been skinned, and the disarticulated skeleton was positioned on a series of five cards to be included in the newly formed education collection overseen by museum science teacher Mr. A W G Powell,” Medlock said, in a statement. “The arrangement of the skeleton on the cards allowed museum teachers to explain thylacine anatomy to students.”

Both Paddle and Medlock said that the species will take its place alongside the passenger pigeon and Carolina parakeet in the museum. A paper detailing the findings will be published at a later date in Australian Zoologist.

The thylacine has been in headlines recently for efforts to resurrect the extinct marsupial. Gene-editing startup Colossal Biosciences & Laboratories announced its plans to use CRISPR gene-editing technology to bring back the thylacine. While the Jurassic Park-esque science isn’t quite here yet, the company founded by tech entrepreneur Ben Lamm and geneticist George Church laid out a 10 step plan to re-introduce a Tasmanian tiger like animal back into the wild. They are partnering with and investing in the University of Melbourne’s Thylacine Integrated Genetic Restoration Research Lab (TIGRR). TIGRR is currently led by marsupial evolutionary biologist and Tasmanian tiger expert Andrew Pask and has already performed the crucial first step of sequencing most of the animal’s genome.

However, not everyone is onboard with this plan. In an interview with the Sydney Morning Herald in August, Jeremy Austin from the Australian Centre for Ancient DNA described this de-extinction effort as “fairytale science,” and claimed that efforts to bring back the thylacine or the mammoth are more about media attention than the actual science. In the same interview, marsupial DNA expert Mike Westerman from La Trobe University added that he is “not convinced that it can be done with our current knowledge. Where on earth would a self-sustaining population be maintained?”

Editor’s Disclosure: Matt Sechrest, the managing partner of Popular Science‘s parent company, North Equity, is an investor in Colossal. He was not involved in the assigning, writing, or editing of this story.

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Over the weekend, a three-day long birthday celebration for the ages began for a very special reptile. Jonathan the tortoise turned 190 yesterday, with a tortoise-friendly birthday cake and an animated video about his life.

Jonathan has lived through multiple human milestones, including the first photograph of a person (1838), the invention of the first incandescent lightbulb (1878), the Wright Brother’s first flight (1903), and more, according to Guinness World Records.

[Related: Did a high sex drive really save the giant tortoise from extinction?]

No stranger to the spotlight, Jonathan has been featured on the back of St. Helena’s five-pence coin and is also on a postage stamp. He was officially named the oldest known living land animal and oldest chelonian ever recorded by Guinness World Records in February. Chelonians, also called Testudines, are the order of animals that includes turtles, terrapins, and tortoises.

He lives at the governor’s house alongside three other giant tortoises-David, Emma, and Fred.

In 1882, the Seychelles giant tortoise (Aldabrachelys gigantea hololissa) was brought from the Seychelles Islands off the eastern coast of Africa and gifted to St. Helena, a British territory in the southern Atlantic Ocean. Jonathan was a gift to Sir William Grey-Wilson, who was the island’s first colonial secretary and later became governor of the island.

While the exact date of his birth is unknown, it’s estimated that he hatched around 1832. In November of this year, St. Helena governor Nigel Phillips granted Jonathan the official birthday of December 4, 1832. However, it’s possible that he is as old as 200, according to St. Helena head of tourism, Matt Joshua.

[Related: An unknown Galapagos tortoise species may be lurking in museum bones.]

While the tortoise has long been covered with distinguished wrinkles, he is blind, has cataracts, and can’t smell. Despite his senses failing, Jonathan’s vet Joe Hollins reports that he still has plenty of energy—though this varies with the weather.

“On mild days, he will sunbathe—his long neck and legs stretched fully out of his shell to absorb heat and transfer it to his core,” Hollins told Guinness World Records. During colder weather, Jonathan prefers to, “dig himself into leaf mold or grass clippings and remain there all day.”

Hollins added, “In spite of his age, Jonathan still has a good libido and is seen frequently to mate with Emma and sometimes Fred—animals are often not particularly gender-sensitive!”

Jonathan’s romantic life and libido has also interested the public. In 1991, Jonathan was presented with a mate after his handlers found that he was pretty irritable and cranky. He happily developed an intimate relationship with the other tortoise, but didn’t produce any offspring over 26 years. It turns out, Jonathan’s partner Frederica, is actually male, which explains the lack of baby tortoises.

The three-day party began at the governor’s residence house in Saint Helena on Friday December 2.

According to Guinness World Records, the previous oldest chelonian was Tu’i Malila. This radiated tortoise was presented to the royal family of Tonga by British explorer Captain James Cook around 1777. Tu’i Malila died in 1965 at the estimated age of 188.

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It might be time for the megalodon to move over and make room for a new ancient aquatic animal. There’s a newly discovered dinosaur species that may also be pretty good swimmer with duck-like diving abilities.

Natovenator polydontus was a theropod (a hollow-bodied dinosaur) that had three toes and claws on each limb. It lived about 145 to 66 million years ago in Mongolia, during the Upper Cretaceous period. Its recent discovery was outlined in a study published last week in the journal Communications Biology. The name Natovenator polydontus means “many-toothed swimming hunter.”

[Related: Were dinosaurs warm-blooded or cold-blooded? Maybe both.]

One of the similarities that Natovenator has with modern, diving birds is it’s streamlined ribs.

“Whereas diving birds are well known to have streamlined bodies, such body shapes have not been documented in non-avian dinosaurs,” wrote the authors in the study. “Its body shape suggests that Natovenator was a potentially capable swimming predator, and the streamlined body evolved independently in separate lineages of theropod dinosaurs.”

The specimen that the team from Seoul National University, the University of Alberta, and the Mongolian Academy of Sciences examined in this study is similar to Halszkaraptor, another dinosaur that was discovered in Mongolia. Scientists believe Halszkaraptor was likely semiaquatic, but the Natovenator specimen in the study is more complete than one of the Halszkaraptor. This makes it easier for scientists to see Natovenator’s streamlined body shape.

Natovenator is a cousin of the famous Velociraptor, but has a much more streamlined look, with its long jaws and tiny teeth. The specimen was discovered at a spot in the Gobi Desert called Hermiin Tsav or (Khermen Tsav), which is a hot spot for preserving multiple dinosaur species.

David Hone, a paleontologist and professor at Queen Mary University of London, told CNN that it is difficult to say exactly where the new species falls on the spectrum of totally land-dwelling animals to totally aquatic animals. However, the specimen’s arms, “look like they’d be quite good for moving water,” he said. Hone participated in the peer review for this study.

[Related: Spinosaurus bones hint that the spiny dinosaurs enjoyed water sports.]

According to Hone, the next steps to understand Natovenator’s motion should be modeling of the dinosaur’s body shape to help scientists understand exactly how it might have moved. “Is it paddling with its feet, a bit of a doggy-paddle? How fast could it go?”

Additional research should also look back at the environment in which Natovenator lived. “There is a real question of, OK, you’ve got a swimming dinosaur in the desert, what’s it swimming in?” Hone said. “Finding the fossil record of those lakes is gonna be tough, but sooner or later, we might well find one. And when we do, we might well find a lot more of these things.”

In addition to biomechanical studies that will test how Natovenator and related water-dwelling species moved around, studies of geochemical clues in the dinosaur’s teeth and bones, will either confirm or challenge the idea that Natovenator was as strong a swimmer as the study suggests.

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A new fossil find in the United Kingdom is a victory for de-cluttering and organization enthusiasts everywhere.

The fossil specimen of an ancestor of present day lizards first unearthed in the 1950s was recently found stored in a cupboard at the Natural History Museum in London. The discovery potentially shows that today’s lizards likely originated in the Late Triassic period (about 200 million years ago) and not during the Middle Jurassic as previously believed.

[Related: A Scottish fossil is helping scientists fill the gaps in the lizard family tree.]

The findings are described in a paper published today in the journal Science Advances. The team named their discovery Cryptovaranoides microlanius, which means meaning “small butcher,” as a tribute to the animal’s jaws filled with sharp-edged slicing teeth.

“I first spotted the specimen in a cupboard full of Clevosaurus fossils in the storerooms of the Natural History Museum in London where I am a Scientific Associate,” said David Whiteside, from the University of Bristol’s School of Earth Sciences and a co-author of the paper, in a statement. “This was a common enough fossil reptile, a close relative of the New Zealand Tuatara that is the only survivor of the group, the Rhynchocephalia, that split from the squamates over 240 million years ago.

The specimens were originally unearthed from a quarry in southwest England.

“Our specimen was simply labelled ‘Clevosaurus and one other reptile.’ As we continued to investigate the specimen, we became more and more convinced that it was actually more closely related to modern day lizards than the Tuatara group,” Whiteside added. “We made X-ray scans of the fossils at the University, and this enabled us to reconstruct the fossil in three dimensions, and to see all the tiny bones that were hidden inside the rock.”

The age of the new fossil impacts the general estimates of when Squamata, the order of reptiles that includes lizards and snakes, evolved, how quickly they evolved, and even what triggered the general origin of the order.

The study shows that Cryptovaranoides is clearly a squamate due to multiple features including its braincase (which encloses the brain), neck vertebrate, upper median tooth in front of the mouth, and the way that the teeth are set on a shelf in the jaws. It also has features seen in more primitive squamates, including an opening on one side of the end of the upper arm bone (the humerus) where a nerve and an artery pass through and few rows of teeth on the bones making up the roof of the lizard’s mouth.

[Related: These tiny ‘dragons’ flew through the trees of Madagascar 200 million years ago.]

“In terms of significance, our fossil shifts the origin and diversification of squamates back from the Middle Jurassic to the Late Triassic,” says co-author Mike Benton a palentologist also from the University of Bristol, in a statement. “This was a time of major restructuring of ecosystems on land, with origins of new plant groups, especially modern-type conifers, as well as new kinds of insects, and some of the first of modern groups such as turtles, crocodilians, dinosaurs, and mammals.

Adding in older modern squamates help complete this evolutionary picture as the Earth rebuilt after the end-Permian mass extinction, which killed about 95 percent of the Earth’s marine species and 70 percent of land species about 252 million years ago.

“The name of the new animal, Cryptovaranoides microlanius, reflects the hidden nature of the beast in a drawer but also in its likely lifestyle, living in cracks in the limestone on small islands that existed around Bristol at the time,” Sofia Chambi-Trowell, co-author and PhD research student at the University of Bristol said in a statement.

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It looks like Tyrannosaurus rex has another relative to add to its ever-growing family tree. In 2017, Badlands Dinosaur Museum crew member Jack Wilson spotted the remains of what turned out to be a new species of tyrannosaur, named Daspletosaurus wilsoni, or D. wilsoni. Wilson first saw a small, flat piece of bone projecting out of the bottom of a cliff at the Judith River Formation in northeastern Montana. The fossil Wilson spotted turned out to be part of the dinosaur’s nostril.

Additional fossils were uncovered between 2017 and 2021, including skeletal fragments of a rib and toe bone and parts of a fossilized skull. Those bits were enough to determine this was a new species, as detailed in a paper published on November 25 in the journal Paleontology and Evolutionary Science. The remains date back to 76.5 million years ago, during the Cretaceous period, millions of years before T. rex stomped through the Late Cretaceous.

[Related: Is T. rex really three royal species? Paleontologists cast doubt over new claims.]

One of D. wilsoni‘s unique features is an arrangement of spiked hornlets around its eyes. It also has a mix of attributes that were found in more primitive types of tyrannosaurs, such as prominent set of horns around the eye. It also boasts physical features more common in later members of this group, including the famed T. rex. One of these more advanced tyrannosaur features is a tall eye socket and expanded air-pockets inside of the skull.

“In this way, D. wilsoni is a ‘halfway point’ or  ‘missing link’ between older and younger tyrannosaur species,” wrote study authors Elías Warshaw, a paleontology student at Montana State University and Denver Fowler, a paleontologist and curator of Badlands Dinosaur Museum, in a statement.

The Tyrannosaur family is large: It has nine genera, which falls above species and below family in the system that classifies animal and plants. The family includes a genus of predators called daspletosaurs, which lived about 79.5 million and 74 million years ago, during the Late Cretaceous Period. The team believes that D. wilsoni is an intermediate daspletosaur, the descendant of Daspletosaurus torosus, and the predecessor of Daspletosaurus horneri. Daspletosaurus is Greek for “frightful lizard,” and the specimen was nicknamed Sisyphus, in reference to the myth of the man cursed to push a boulder up a hill for eternity. It took an enormous amount of effort to extract the bones from the surrounding rock, including removing about 25 feet of stone from the top of the skeleton.

In North America during the Late Cretaceous, multiple closely related species made up the evolutionary families of dinosaurs. It was previously thought that these species lived at the same time, which would be evidence of what biologists call branching evolution.  However, newly discovered specimens such as this one and a better understanding of when the animals lived has changed how paleontologists understand dinosaur evolution.

[Related: The T. rex ‘dynasty’ reigned for more than 125,000 generations.]

“We can now see that many of these species are actually very finely separated in time from each other, forming consecutive ladder-like steps in a single evolutionary lineage where one ancestral species evolves directly into a descendant species,” wrote Warshaw and Fowler.

This process is called anagenesis, or linear evolution. It is different from cladogenesis evolution, where successive branching events create many closely related species that that look similar but are evolutionary “cousins,” not descendants and ancestors.

“The new study supports the addition of tyrannosaurs to a growing list of dinosaurs (including horned and duckbilled dinosaurs) for which anagenesis (linear evolution) has been proposed,” said Warshaw and Fowler. This suggests that linear evolution may be more widespread in dinosaurs and that branching evolution occurs less frequently than previously thought.

Warshaw is currently conducting more detailed research into the link between T. rex and Daspletosaurus.

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Update (March 23, 2022): The journal Biology Letters retracted “An Eocene army ant” on March 22, 2023. According to the New Jersey Institite of Technology, “once published, other scientists in the field questioned the age of the specimen based on similar samples and upon further analysis, the researchers concluded that their findings were unfounded, and worked with Biology Letters to issue a retraction.”

The army ant (Dorylinae) is generally good at two things: traveling all around the world and having a ravenous appetite. Through their highly coordinated foraging, the ants can eat up to 500,000 prey animals in a single a day. Its nomadic lifestyle has taken the insects to most continents on Earth and there are currently about 270 army ant species living in the planet’s Eastern Hemisphere and roughly 150 species across North and South America.

Thanks to a rare fossil discovery, scientists are now exploring the first evidence that the predators once swarmed where they are not eating and scrurrying around today—Europe.

In a new paper published yesterday in the journal Biology Letters, researchers from New Jersey Institute of Technology (NJIT) and Colorado State University detail the discovery of the oldest army ant on record. The specimen was preserved in Baltic amber dates back to the Eocene Epoch, about 35 million years ago.

[Related: How many ants are there on Earth? Thousands of billions.]

The specimen is about three millimeters long (less than an inch), shows an animal without eyes, and is named Dissimulodorylus perseus (D. perseus), after the mythical Greek hero Perseus. The legend goes that Perseus defeated Medusa with limited use of sight.

The fossil is just the second fossilized evidence of an army ant species ever described and is the first army ant fossil recovered from the Eastern Hemisphere, according to the study.

The team says that this ant fossil is evidence of previously unknown army ant lineages that would have existed across Continental Europe before going extinct throughout the past 50 million years AGO.

Incidently, this huge find was hidden for nearly 100 years at Harvard University’s Museum of Comparative Zoology.

“The museum houses hundreds of drawers full of insect fossils, but I happened to come across a tiny specimen labeled as a common type of ant while gathering data for another project,” the paper’s lead author and NJIT PhD candidate Christine Sosiak said in a statement. “Once I put the ant under the microscope, I immediately realized the label was inaccurate. I thought, this is something really different.”

It’s likely that the amber encasing the fossil was excavated sometime near or before the 1930s.

“From everything we know about army ants living today, there’s no hint of such extinct diversity,” said Phillip Barden, assistant professor of biology at NJIT and senior author of the paper. “With this fossil now out of obscurity, we’ve gained a rare paleontological porthole into the history of these unique predators.”

The team used X-rays and CT-scans to analyze the fossil and determined that D. perseus as a close relative to eyeless species of army ants currently found in Africa and Southern Asia, named Dorylus.

[Related: Ants have teeth. Here’s how they keep them sharp.]

When this fossil was formed, Europe had a much hotter and wetter climate than it has today, which might have provided an ideal living environment for ancient army ants. Since the Eocene (over tens of millions of years), Europe has undergone several cooling cycles, which may have made the continent been inhospitable for the ancient ants.

They also found an enlarged antibiotic gland on the specimen that is typically found in other army ants, that helps them live underground. This gland suggests that this European army ant lineage was well suited for subterranean living.

According to Sosiak, it’s one factor that sets this fossil a rarity.

“This was an incredibly lucky find. Because this ant was probably subterranean like most army ants today, it was much less likely to come into contact with tree resin that forms such fossils,” said Sosiak. “We have a very small window into the history of life on our planet, and unusual fossils such as this provide fresh insight.”

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Millions of years before Americans started celebrating Thanksgiving, Ediacara biota were munching on the bacteria and algae along the ocean floor.

The world’s oldest large organisms, Ediacara biota are a family of animals that date back 575 million years ago. They even existed before the Cambrian explosion, a major expansion of animal life that happened approximately 541 million to 530 million years ago and changed the course of evolution for all life on Earth. They are extinct, and the fossil specimens recovered have been shaped like discs or plant fronds and some rare specimens are close to eight inches in diameter. From the fossils, it’s possible that they were similar to soft-bodied marine organisms like jellyfish.

Researchers from Australia recovered fossils of two Ediacara—Kimberella and Dickinsonia—in 2018 from steep cliffs in a remote area of Russia near the White Sea. Now, scientists are figuring out what these ancient creatures snacked on.

[Related: This 120-million-year-old bird may have been one of the first to shake its tail feathers.]

A new study published today in the journal Current Biology is revealing more about these strange and incredibly old bottom dwellers, including how they were able to consume and digest food. The team analyzed ancient fossils of the Kimberella that had a natural chemical product found in plants called phytosterol molecules preserved inside of them, which could have come from this animals’ last meal. Further examination of the molecular left overs confirmed that the slug-like Kimberella actually had a mouth, a gut, and even digested food the same way that present-day animals do.

“Our findings suggest that the animals of the Ediacara biota, which lived on Earth prior to the ‘Cambrian Explosion’ of modern animal life, were a mixed bag of outright weirdos, such as Dickinsonia, and more advanced animals like Kimberella that already had some physiological properties similar to humans and other present-day animals,” said lead author Ilya Bobrovskiy, who is now at GFZ-Potsdam in Germany, in a statement. 

Kimberella was likely one of the most advanced of all Ediacarans, but both creatures are part of the Ediacara biota family and have a structure and symmetry unlike anything living on Earth today. “Ediacara biota really are the oldest fossils large enough to be visible with your naked eyes, and they are the origin of us and all animals that exist today. These creatures are our deepest visible roots,” said Bobrovskiy. 

[Related: Who Were The First Organisms To Live On Land?]

The algae that they ate are rich in energy and nutrients and may have been key to Kimberella’s growth, according to the study. Nearly all fossils of organisms that pre-date Ediacara biota were single-celled and microscopic in size.

Using chemical analysis, the team was able to extract and analyze the sterol molecules contained in the fossil tissue. Cholesterol is important because it is one of the hallmarks that differentiates animals from plants and it’s how scientists found out that Ediacara biota are among the earliest known ancestors of all present-day animals. 

Scientists already knew that Kimberella left feeding marks by scraping the algae up off of the sea floor, which was a possible sign that it had a gut. When the team on this study analyzed the gut molecules, they were able to determine that Kimberella could determine exactly what it was eating and how to digest it. Additionally, Kimberella was so advanced that it even knew exactly which sterols were good for it and had fine-tuned gut to filter out all the rest. 

“This was a Eureka moment for us; by using preserved chemical in the fossils, we can now make gut contents of animals visible even if the gut has since long decayed,” said co-author Jochen Brocks, from the Australian National University Research School of Earth Sciences.

But, Dickinsonia, which Brooks deems even weirder than Kimberella, did not have a gut, which really shows how advanced Kimerella is.

So, as you gather around the table to give thanks on Thursday, say a quick thank you to Kimberella and all the other Ediacara, because without them, you might not be able to stuff your face with turkey, stuffing, and cranberry sauce.

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Throughout ancient history, giant animal versions of some of your modern favorite creatures were running wild— Madagascar’s extinct giant lemur, the ocean’s mighty megalodon, and the ground sloth are just some of many. But a salamander the size of a pygmy hippo probably wasn’t something we could’ve expected, yet the giant slippery critters ruled parts of the United States and Australia for a a solid 200 million year run on Earth.

Temnospondyls were a group of bulbous, four legged, amphibians that went extinct around 120 million years ago. They ranged from Eryops megacephalu to the aquatic Paracyclotosaurus davidi and have some similar shared features with modern salamanders, but not directly related to any living ones. In a new paper published this week in the journal Palaeontology, a team from the University of New South Wales in Sydney, Australia detail various methods of estimating the weight of these animals—not an easy feat.

[Related: Hellbender salamanders may look scary, but the real fright is extinction.]

“Estimating mass in extinct animals presents a challenge, because we can’t just weigh them like we could with a living thing,” Lachlan Hart, a paleontologist and PhD candidate in the School of Biological, Earth & Environmental Sciences said in a statement. “We only have the fossils to tell us what an animal looked like, so we often need to look at living animals to get an idea about soft tissues, such as fat and skin.”

They estimate that many of the species in this group weighed close to 600 pounds, or about about as much as the pygmy hippo.

Since temnospondyls do not have any direct living relatives, the team of used five modern animals as a stand-in, including the Chinese giant salamander and the saltwater crocodile, as a way to test 19 different body mass estimation techniques. Some of the methods that provided consistently accurate body mass estimates, included using mathematical equations and digital 3D models of the animals.

“We hypothesised that as these methods are accurate for animals which lived and looked like temnospondyls, they would also be appropriate for use with temnospondyls,” said Nicolas Campione from the University of New England, Armidale, an authority on body mass estimation who was also involved in the study.

[Related: Skydiving salamanders have mastered falling with style.]

According to Hart, temnospondyls were “very strange animals,” that also grew to roughly 19 to 22 feet long. Like amphibians, they went through a tadpole stage and some of them had broad and round heads, for example Australia’s Koolasuchus, while others had heads that looked more like a crocodile. The animals in this study had the more pointy, reptilian noggins.

Some notable temnospondyls are Eryops megacephalus, which clocked in at almost six feet long and 252 pounds, and lived in the present day US and the slightly longer Paracyclotosaurus davidi from Triassic Era Australia. Paracyclotosaurus was an aquatic amphibian that tipped the scales at about The more aquatically inclined Paracyclotosaurus was the heftier of the two, tipping the scales at roughly 573 pounds.

“The size of an animal is important for many aspects of their life,” said Hart. “It impacts what they feed on, how they move and even how they handle cold temperatures. So naturally, palaeontologists are interested in calculating the body mass of extinct creatures so we can learn more about how they lived.”

According to the authors, this is the first time mass weights of temnospondyls have been studied exclusively. The team hopes that this type of knowledge can help scientists understand adaptation strategies.

“They survived two of Earth’s Big Five mass extinction events which makes them a very interesting case study on how animals adapted following these global catastrophes,” Hart said.

Correction (November 29, 2022): Temnospondyls were likely 19 to 22 feet, not meters, long.

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If the Teenage Mutant Ninja Turtles were looking for heavyweight back-up while fighting their arch-nemesis Shredder, it would be hard to do better than a newly discovered species of ancient sea turtle. Leviathanochelys aenigmatica is the newest member of an extinct genus named Archelon, which boasts multiple kinds species of turtles that could grow to 15 feet long and weighed in about 7,000 pounds, more than a hippopotamus.

The new species, described in a paper published today in the journal Scientific Reports, swam the seas surrounding the present-day North American continent during the end of the Cretaceous period, about 145 million to 66 million years ago.

“The discovery of the new species itself was a surprise,” Albert G. Sellés, a co-author of the paper and postdoctoral researcher at Universitat Autònoma de Barcelona in Spain, tells PopSci. “We are used to finding dinosaur bones in northeastern Spain, and some of them are really big, but until now we have never found the fossil remains of a marine animal, and even less one of such colossal size.”

According to Sellés, a hiker found the bone fragments near the small village of Coll de Nargó in Catalonia in August 2016. The the remains were excavated between 2016 and 2021. The fossils include a fragmented but almost complete pelvis and parts of the upper shell called the carapace. The study authors date the specimens back to the Cretaceous period’s Campanian Age, roughly 83.6 million to 72.1 million years ago.

From the size of the pelvis, the team was able to estimate the turtle’s size: It was gigantic and aligns with other massive Archelons. “The size of Leviathanochelys aenigmatica is perhaps the most surprising characteristic. With up to 3.7 meters [about 12 feet] in total body length, it is within the top three largest marine turtles ever live on Earth,” Sellés says. The researchers are still working to determine what evolutionary processes could have made such a huge animal possible.

Previously, no known European marine turtle, extinct or living, had shells that measured 4.9 feet long.

Further study will be needed to learn more about what Leviathanochelys aenigmatica ate—and who ate it. But there may be one tiny clue to its predators. “It is still too early to say for sure, but it is likely that the turtle was preyed on by sharks,” said Sellés. “This conjecture is based on the fact that the shell presents some peculiar marks that could be from bites, and that a shark tooth was found near the skeleton.”

The paper says that this discovery shows that gigantism in marine turtles evolved independently in different groups in Europe and North America, where fossils of Ctenochelys acris and Peritresius ornatus and other ancient sea turtles have been found. It has been difficult for scientists to develop a consensus for the role these animals played in the evolutionary history of sea turtles, and this discovery will help fill in those gaps. Today’s largest sea turtles are the mighty leatherbacks (Dermochelys coriacea). The largest leatherbacks can grow up to 6 feet, half the size of Leviathanochelys aenigmatica, and can weigh up to 2,000 pounds.

“One of the most beautiful things about doing paleontology is that each new discovery represents a new challenge. And with each discovery, as if it were a giant puzzle, we rediscover the past history of our planet,” Sellés says.

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The species Homo sapiens (or “wise man”) began to evolve about 300,000 years ago, and eventually won out the evolutionary battle and became the only Homo species to reign on Earth about 40,000 years ago. During the early days of human life, another species named Homo neanderthalensis, or more commonly called Neanderthals, co-existed with Homo sapiens. In 2010, a ground-breaking analysis of a Neanderthal genome revealed that the two species could successfully interbreed.

It was once thought that war and violence caused the demise of the Neanderthals. However, a new study out this week in the journal PalaeoAnthropology adds to a growing body of research that proposes that Homo sapiens may have been responsible for the extinction of Neanderthals in a different manner—sex.

The researchers compared the genomes of Neanderthals and present day humans, and discovered that breeding in between the two species could have led to the eventual extinction of Neanderthals. When looking closer at the genomes of a Neanderthal with five modern humans, researchers discovered that Asians and Europeans share roughly one to four percent of their DNA with Neanderthals, while Africans don’t share any. This suggests that modern humans bred with Neanderthals after they left the African continent, but before they spread East to Asia and north towards Europe roughly 250,000 years ago.

[Related: Nobel Prize in medicine awarded to scientist who sequenced Neanderthal genome.]

However, there currently isn’t any evidence of Homo sapiens genetics in late Neanderthal genomes dating to between 40,000 to 60,000 years ago. Only 32 Neanderthal genomes have been sequenced, which makes it possible that a lack of Homo sapiens DNA within the Neanderthal genome is simply due to a low sampling. 

It is also possible this is due to hybridization—where one species starts mating with another, creating offspring of a new variety. There are plenty of examples of hybrids in nature, such as the liger, which is the offspring of a male lion and a female tiger, or a mule, which is the offspring of a horse and donkey. For some species combinations, it makes a difference which parent is from which species, and often the offspring are infertile.

The lack of mitochondrial DNA (inherited from mother to child) from Neanderthals present in living humans might be evidence that only male Neanderthals and female Homo sapiens could successfully mate. If the researchers’ theory is correct, fewer Neanderthals may have been breeding with one another, opting for interspecies mating. This would decimate populations of the already existing small and scattered groups of Neanderthal families, eventually pushing them towards decline.

“We don’t know if the apparent one-way gene flow is because it simply wasn’t happening, that the breeding was taking place but was unsuccessful, or if the Neanderthal genomes we have are unrepresentative,” said Chris Stringer, the Research Leader in Human Evolution at London’s Natural History Museum and study author,  in a statement. “As more Neanderthal genomes are sequenced, we should be able to see whether any nuclear DNA from Homo sapiens was passed on to Neanderthals and demonstrate whether or not this idea is accurate.”

[Related: Researchers found proof of Neanderthals reproducing with other species.]

“Our knowledge of the interaction between Homo sapiens and Neanderthals has got more complex in the last few years, but it’s still rare to see scientific discussion of how the interbreeding between the groups actually happened,”  added Stringer. “We propose that this behavior could have led to the Neanderthals’ extinction if they were regularly breeding with Homo sapiens, which could have eroded their population until they disappeared.”

Around 600,000 years ago, Homo sapiens and Neanderthals diverged from each other and evolved in very different parts of the world. Neanderthal fossils have been found in Asia and Europe, with some as far from Africa and southern Siberia. 
Meanwhile, Homo sapiens evolved in Africa, but scientists are uncertain whether our ancestors are the direct descendants of one specific group of ancient African hominins or came about as the result of mixing between different groups spread across the continent.

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While lizards and dinosaurs trotted the Earth together, lizards were the one of the newer animals on the block during the Middle Jurassic period. Scientists are still unraveling their unique history. Now, roughly 166 million years later, a nearly-complete fossil of a lizard skeleton is helping scientists fill in some of those evolutionary gaps.

The specimen was discovered on Scotland’s Isle of Skye and is called Bellairsia gracilis. Bellairsia was a tiny lizard ancestor and was only about two inches long. The “exceptional” new fossil is described in a study published this week in Nature. The fossil is only missing its snout and tail and is likely the most complete fossil lizard of this age anywhere in the world.

[Related: This 6-inch-long Jurassic creature does a great lizard impersonation.]

Within Bellairsia‘s skeleton are a mixture of older ancestral features and modern features, which provides evidence of what the ancient ancestor of present-day lizards might have looked like. “This little fossil lets us see evolution in action,” said first author Mateusz Tałanda from the University of Warsaw and University College London, in a statement. “In paleontology you rarely have the opportunity to work with such complete, well-preserved fossils coming from a time about which we know so little.”

A team led by Oxford University and the National Museums Scotland first found the fossil in 2016. In addition to its beautiful scenery, the Isle of Skye is a hot spot for fossils (including ones from extinct amphibians and mammals) that is giving scientists a window into how present-day animal groups evolved through time.

“Bellairsia has some modern lizard features, like traits related to cranial kinesis–that’s the movement of the skull bones in relation to one another. This is an important functional feature of many living squamates,” Tałanda said.

Squamates are a huge present-day animal group that includes lizards, snakes, chameleons, and geckos. With more than 10,000 species of squamates living today, they are one of the most species-rich living vertebrate animal groups. The smallest living squamate is the Virgin Islands Dwarf Sphaerodactylus, coming in at only about an inch long and less than one-tenth of an ounce. The Komodo Dragon is the largest living squamate, which has been known to reach about 10 feet long and weigh over 350 pounds.

[Related: This pterosaur ancestor was a tiny, flightless dog-like dinosaur.]

Elsa Panciroli from the Oxford University Museum of Natural History and National Museums Scotland is one of the study’s co-authors and also was the lucky scientist to first discover the fossil. “It was one of the first fossils I found when I began working on Skye,” Panciroli said in a statement. “The little black skull was poking out from the pale limestone, but it was so small I was lucky to spot it. Looking closer I saw the tiny teeth, and realized I’d found something important, but we had no idea until later that almost the whole skeleton was in there.”

While scientists know that the earliest origins of squamates lie about 240 million years ago during the Triassic period, a lack of fossils from both the the Triassic and Jurassic period has made their early evolution and anatomy difficult to trace. Analyzing the new fossil alongside some living and extinct squamates shows that Bellairsia belongs to the “stem” of the squamate family tree. It likely split from other lizards just before modern groups of lizards arose. It also supports the idea that geckos branched out early and that Oculudentavis is actually a stem on the squamate family tree and not a dinosaur.

“Fossils like this Bellairsia specimen have huge value in filling gaps in our understanding of evolution and the history of life on Earth,” said co-author Roger Benson from the University of Oxford, in a statement. “It used to be almost impossible to study such tiny fossils like this, but this study shows the power of new techniques including CT scanning to image these non-destructively and in great detail.”

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Eight-armed, pink-spotted argonauts live what appears to be a mysterious life. Unlike other octopuses, they spend their days floating near the surface of tropical waters, detaching their arms to have sex, and curling up in a milky white case. And that’s only what we’ve observed in the wild so far. But through studying argonaut genomes, scientists are hoping to reveal a whole lot more about these puzzling cephalopods.

For researchers in Japan, the latest of the argonaut mysteries concerns its “shell,” which is actually a self-built, paper-thin egg case that surrounds the females. This case—which is the reason argonauts are commonly referred to as the paper nautilus (despite their status as octopuses)—has been of particular interest to scientists and philosophers for thousands of years, even piquing Aristotle’s curiosity. 

Argonauts are distantly related to a hard-shelled cephalopod called nautiluses, leading scientists to question whether shared genetic information may lead to similar shell formation. Researchers have already known that some proteins used to build nautilus shells weren’t present in argonaut cases, meaning the “shell” of argonauts is not compositionally the same as those of the nautilus. What they didn’t know was whether argonauts still harbor the genetic information used to build these nautilus shells in their genomes.

In a study published today in Genome Biology and Evolution, a team of biologists sequenced genomes from the species Argonauta argo, the greater argonaut, to figure out the origin of argonaut shells. According to Davin Setiamarga, a molecular biologist at the National Institute of Technology, Wakayama College, and a lead researcher on the genome project, although argonauts have the genes needed to build shells like their nautilus relatives, they use completely different genes to make their egg cases.

That came as a surprise, says Setiamarga. “We were thinking that there is a possibility that argonauts just reactivated some of these old genes to form the mollusk shell,” he says. “But we found out that actually, that’s not the case. They use a different set of genes.”

[Related: Slap another cephalopod on the vampire squid’s family tree]

The scientists looked at genetic information in argonaut cells to determine whether the genes required for shell-building in other species of cephalopods, such as nautiluses, are repurposed to form an egg case in these animals. 

Argonauts are notoriously difficult to keep in captivity, so to secure genetic information, Setiamarga and his team gathered samples from greater argonauts with the help of local fishermen in the Sea of Japan near the Oki Islands. The researchers then sequenced the extracted argonaut DNA to understand its functions. By comparing this information to that of related mollusks, scientists were able to determine that the proteins needed to form egg cases were not used to build shells in their relatives, suggesting the egg cases had independently evolved. Still, the authors note that further research is needed to better understand why argonauts have retained the genetic information that their relatives use for their own shells and if those genes might serve another purpose for the argonauts.

“While you can find the genes being used to form the mollusk shell inside the argonaut genome, they don’t use them to form their [egg cases]. So we don’t know what they’re still doing in the genome. That will be another question,” Setiamarga says. 

Although this research suggests that the egg case evolved separately from the nautilus shell, these structures still share a key function: buoyancy. Unlike many octopuses that live in the benthic zone along the ocean floor, argonauts are pelagic: They bob about in the open sea. Without the anchor of the sea floor, buoyancy control is vital. “Inside the shell, the female makes a point to have a pocket of air,” says Janet Voight, associate curator of invertebrates at Chicago’s Field Museum, who wasn’t part of the research team. “And then she goes down in the water column, that pocket of air gets compressed, and it gives her some buoyancy. So it offsets the weight of her and her developing eggs.” Nautiluses similarly use their shells to regulate their buoyancy, relying on osmosis to control water and gas movement inside.

However, both male and female nautiluses are born with shells and add more chambers as they age, whereas male argonauts, which are about the size of the tip of a human thumb, never build egg cases. Female argonauts, on the other hand—or eight—make their own “shells” after mating, literally with their own hands, by secreting a mineral called calcite from two specialized arms.

This study is a small step in better understanding these elusive creatures, Setiamarga says. “If you want to know the details of how certain characteristics evolve, at the end of the day, you still have to look back at the genome,” he says. About ninety-eight percent of animals on the planet are, like argonauts, invertebrates, he notes. ”And we don’t have enough genomic information on them. If you’re interested in conservation, we don’t have enough information to devise scientifically accurate policies.”

Sequencing the genome of argonauts doesn’t only fill out our comprehension of animals without backbones–it enhances what we know about marine life, too. “This is a group of species that occur in almost every ocean, and we don’t know the fundamental things about it. So doesn’t it seem like we should?” Voight says. “The oceans are just so important to us, and as climate change gets worse, we’ll find that out. If we don’t learn about them now, we may not be able to.”

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A lion’s mane is a striking feature—the bigger and darker those luscious locks, the more appealing to lionesses. This classic example of sexual dimophism is primarily flaunted by the males of the species. But caretakers at Topeka Zoo and Conservation Center in Kansas have reported that in late fall 2020, one of their lionesses, Zuri, has grown a mini-mane of her own. 

“It’s extremely rare,” says Shanna Simpson, animal curator at the Topeka Zoo. “We never even heard about this happening until we saw Zuri.”

Zuri currently looks a bit like a teenage male lion just beginning to grow out a mane despite being an 18-year-old female. The caretakers began to notice the tresses after Avus, the only male of the zoo’s three lions, died in October 2020, Simpson suggesting that the new do may be linked to a change in hormones and that she may be taking on more of a protector role of the pride. Zuri and her same-aged sister Asante arrived at Topeka Zoo in 2006 and are currently the only members of their species there. 

Lions are the only known big cats to form unique social structures. The females do most of the hunting and care for the cubs, while the males’ primary job is to keep rivals away and protect the pride, says Simpson. The days after Avus passed away, zoo caretakers were surprised to observe unusual behavior in Asante and Zuri. They were more skittish, jumpy, and were not eating as much, Simpson recalls. 

“Usually, lions are very confident animals. They don’t care who or what’s around them because very few things threaten them,” she says. 

Around one to two months later, Zuri also started to grow longer patches of fur around her nape. Simpson had asked her colleagues at other zoos about the odd new mane, and found that—while very rare—other lionesses have been spotted with them, both in captivity and in the wild. 

[Related: Androgynous lionesses strut and roar in manly manes]

In 2011, the National Zoological Gardens of South Africa’s lioness had a mane; and in 2018, the Oklahoma City Zoo’s 18-year-old lioness sported a shaggy beard. Tests on the lioness at the National Zoological Gardens detected high levels of testosterone, which researchers associated with a problem in the ovaries. After her death, the Oklahoma City Zoo found that their lioness had a benign tumor that likely caused elevated hormone levels. 

Meanwhile, a 2016 study in the African Journal of Ecology reported five wild lionesses with manes in the Moremi Game Reserve in Botswana. While blood samples and health exams could not be conducted, the team studying the wild lionesses in Botswana observed that the maned lionesses were seen mating but none of them became pregnant, leading them to surmise that the females could be infertile possibly due to high levels of testosterone. (While exact ages couldn’t be determined, the researchers estimated maned lionesses aged three to 11 years old.) 

“We know that manes are testosterone-dependent,” Bruce Patterson, curator emeritus of mammals at the Field Museum of Natural History in Chicago, wrote to PopSci in an email. “Males only grow their manes with the onset of sexual maturity, and this continues into adulthood.”

In African lions, male cubs typically begin to develop manes around 18 months when they become sexually mature. Researchers have documented malnourished and sick male lions with unhealthy hair and sparser manes. “The better the mane on a male lion, the more testosterone they have, which just makes sense,” Simpson says. “You have to be able to breed. You have to be able to protect your pride. So you have to have that level of aggression that often comes with more testosterone. The wild’s no joke. It’s brutal out there.”

While Topeka Zoo does conduct full health checkups and safely takes blood samples from their lions, testosterone levels haven’t been included in regular tests. “That is something that I would love to look into,” says Simpson. Patterson, who has worked with Topeka Zoo’s lions to study manes in the past, believes it’s possible that Zuri is experiencing hormone shifts like other maned lionesses. “I’m guessing that either [Zuri’s] social position among the remaining lions has elicited heightened androgen production, or perhaps her ovarian production of female hormones is impaired,” he explains.

Zuri had always been a lioness in charge, says Simpson. Avus maintained the dominant male leader position, however “Zuri kind of ruled the day-to-day stuff,” says Simpson. While Avus did bear a cub with Asante, he never attempted to mate with Zuri, Simpson says. In his absence, Simpson suggests that Zuri might be taking on a “protector role” for her and her sister.

However, Kris Everatt, conservation scientist for Panthera, a global wild cat conservation organization, isn’t quite convinced that Avus’ death triggered the role change or Zuri’s mane. “I don’t think that the loss of a male would bring that result at all,” says Everatt, who has studied poaching and stewardship of wild African lions. “Maybe this lioness is more dominant than the others, and maybe that’s related to her hormones, but there isn’t a hierarchy [or competition] among lionesses within a pride in the wild.” 

[Related: African lions are now considered an endangered species]

The exact cause for the mane—and change in hormones—is unclear, especially seeing that the feature wouldn’t benefit a lioness in the same way as a lion. Physically, a big fluffy mane can be a disadvantage in the wild, Everatt explains—it isn’t ideal in hot habitats and makes it harder for lions to hide when they hunt. It’s why males in certain populations, like Kenya’s Tsavo lions, skip the flourish entirely, he says. “There isn’t any advantage other than the fact that it’s selected for sexually by females.” So, in the case of lionesses with manes, he adds, it’s most likely “just a fluke.” 

Another possible explanation is that maned lionesses might have a slight difference in their genes, where the one for male sex hormones are expressed more than in other females. These differences in sex hormone levels might also happen in females of other animals, but the sexual dimorphism in lions makes it more noticable, Everatt says. “If the same thing happened, for instance, in a cheetah, or a leopard, or a wolf, we probably wouldn’t even notice,” he says. “When that happens with lions, it’s easy to notice [the mane], and so it grabs our attention like this. But it’s nothing special to lions.” 

Everatt does note the significance of Zuri’s age—lions in the wild typically only live around 10 to 11 years old, while the median age for captive ones is about 14.5. The Topeka Zoo staff found it surprising to see a shift in hormones so late in age. “That’s interesting too that as late in life as she is, she has a hormonal change,” says Brendan Wiley, director of Topeka Zoo. “I think that is the thing that’s the most shocking.”

Zuri and Asante have since returned to their normal diets and habits, and have been “thriving” for their ripe ages, says Simpson. Aside from “being good-looking,” she adds, Zuri’s new mane doesn’t seem to be a sign of any health issues. In fact, many of the visitors at Topeka Zoo have mistaken the lioness for a new well-groomed lion, Simpson notes. “It’s really fun to engage with our guests and say, ‘That’s Zuri, the same lioness that’s been here your whole life.’”

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Many eons ago, the Earth was a vastly different place from our home. A great supercontinent called Rodinia was fragmenting into shards with faintly familiar names like Laurentia, Baltica, and Gondwanaland. For a time, Earth was covered, in its entirety, by sheets of ice. Life was barely clinging onto this drastically changing world.

All this came from the chapter of our planet’s history that scientists today have titled the Neoproterozoic Era, which lasted from roughly 1 billion to 540 million years ago. The long stretches of time within its stony pages were a very distant prelude to our world today: a time when the first animals stirred to life, evolving from protists in ancient seas.

Just as humans and their fellow animals do today, these ancient precursors would have needed oxygen to live. But where did it come from, and when? We still don’t have firm answers. But experts have developed a blurry snapshot of how oxygen built up in the Neoproterozoic, published today in the journal Science Advances. And that picture is a bumpy ride, filled with periods of oxygen entering the atmosphere before disappearing again, on repeat, in cycles that lasted tens of millions of years.

To look that far back, you have to throw much of what we take for granted about the modern world right out the window. “As you go further back in time, the more alien of a world Earth becomes,” says Alexander Krause, a geologist at University College London in the United Kingdom, and one of the paper’s authors.

[Related: Here’s how life on Earth might have formed out of thin air and water]

Indeed, after the Earth formed, its early atmosphere was a medley of gases burped out by volcanic eruptions. Over several billion years, they coated our planet with a stew of noxious methane, hydrogen sulfide, carbon dioxide, and water vapor.

That would change in time. We know that some 2.3 billion years ago, microorganisms called cyanobacteria created a windfall of oxygen through photosynthesis. Scientists call these first drops of the gas, creatively, the Great Oxygenation Event. But despite its grandiose name, the juncture only brought our atmosphere’s oxygen to at most a small fraction of today’s levels. 

What happened between then and now is still a murky question. Many experts think that there was another oxygenation event about 400 million years ago in the Paleozoic Era, just as animals were starting to crawl out of the ocean and onto land. Another camp, including the authors of this new research, think there was a third event, sometime around 700 million years ago in the Neoproterozoic. But no one knows for sure if oxygen gradually increased over time, or if it fluctuated wildly. 

That’s important for geologists to know, because atmospheric oxygen is involved in virtually every process on Earth’s surface. Even if early life mostly lived in the sea, the upper levels of the ocean and the atmosphere constantly exchange gases.

To learn more, Krause and his collaborators simulated the atmosphere from 1.5 billion years ago until today—and how oxygen levels in the air fluctuated over that span. Though they didn’t have the technology to take a whiff of billion-year-old air, there are a few fingerprints geologists can use to reconstruct what the ancient atmosphere might have looked like. By probing sedimentary rocks from that era, they’re able to measure the carbon and sulfur isotopes within, which rely on oxygen in the atmosphere to form.

Additionally, as the planet’s tectonic plates move, oxygen buried deep within the mantle can emerge and bubble up into the air through a process known as tectonic degassing. Using information on tectonic activity from the relevant eras, Krause and his colleagues previously estimated the history of degassing over time.

By putting those scraps of evidence together, the team came up with a projection of how oxygen levels wavered in the air until the present day. It’s not the first time scientists have tried to make such a model, but according to Krause, it’s the first time anyone has tried it over a billion-year timescale. “Others have only reconstructed it for a few tens of millions of years,” Krause says.

He and his colleagues found that atmospheric oxygen levels didn’t follow a straight line over the Earth’s history. Instead, imagine it like an oxygen roller coaster. Across 100-million-year stretches or so, oxygen levels rose to around 50 percent of modern levels, and then plummeted again. The Neoproterozoic alone saw five such peaks.

Only after 540 million years ago, in the Paleozoic Era, did the atmosphere really start to fill up. Finally, close to 350 million years ago, oxygen reached something close to current-day levels. That increase coincided with the great burst of life’s diversity known as the Cambrian Explosion. Since then, while oxygen levels have continued to fluctuate, they’ve never dropped below around 60 percent of the present.

“It’s an interesting paper,” says Maxwell Lechte, a geologist at McGill University in Montréal, who wasn’t involved in the research. “It’s probably one of the big contentious discussion points of the last 10 years or so” in the study of Earth’s distant past.

[Related: Enjoy breathing oxygen? Thank the moon.]

It’s important to note, however, that the data set used for the simulation was incomplete. “There’s still a lot of rock out there that hasn’t been looked at,” says Lechte. “As more studies come out, they can probably update the model, and it would potentially change the outputs significantly.”

The obvious question then is how oxygen trends left ripple effects on the evolution of life.After all, it’s during that third possible oxygenation event that protists began to diversify and fan out into the very first animals—multicellular creatures that required oxygen to live. Paleontologists have found an abundance of fossils that date to the very end of the era, including a contested 890-million-year-old sponge.

Those animals might have developed and thrived in periods when oxygen levels were sufficiently high, like the flourishing Cambrian Explosion. Meanwhile, drops in oxygen levels might have coincided with great die-offs. 

Astronomers might take note of this work, too. Any oxygenation answers have serious implications for what we might find on distant Earth-like exoplanets. If these geologists are correct, then it’s evidence that Earth’s history is not linear, but rather bumpy, twisted, and sometimes violent. “These questions that this paper deals with represent a fundamental gap in our understanding of how our planet actually operates,” says Lechte.

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Some animals are able to stand, walk, or even run moments after birth. Baby humans can pretty much only cry, spit up, and poop, and don’t really start doing anything very physical until several months into their lives.

But there may be a reason why that, as a species, humans are late bloomers. A new study published today in the journal Science Advances finds that the ability to forage for difficult-to-extract resources increases slowly over the course of a human childhood. Because foraging as a human is a tricky task, we need plenty of time to learn how to do it.

“Early human life history is quite unique, in the sense that childhood, as a period loosely delimited by weaning and the onset of the physiological and social changes that lead to maturation, is a period of life unique to humans,” Ilaria Pretelli, lead author of the study, tells Popular Science. Pretelli is currently a PhD student at the Max Planck Institute for Evolutionary Anthropology in Germany and is studying life history theory, a field that analyzes the general features of the life cycle.

[Related: Evolution doesn’t work the way you think it does.]

Other animals have a tendency to transition from infancy to adulthood much more smoothly, meaning that they go from being dependent to fully self-sufficient adults without a long transitional phase. “Our children, on the contrary, spend many years apparently idling around, biologically speaking. Our somatic growth slows down. We play, simulate adult life, help our caretakers, experiment, and learn,” explains Pretelli.

For the study, Pretelli and her team built a dataset of already published research on foraging returns, or how many items a child or adolescent is able to find while out gathering. It included data from 714 children and adolescents representing 28 societies around the world, including the Cree and Inuit in North America, Hadza in Tanzania, and Martu in Australia.

The study examines four resources that differ in complexity. The least difficult are fruit and marine resources, because they typically require less physical strength and individual knowledge to obtain. Game and tubers (a special kind of stem) are the more complex items, because they require specialized tools (like a bow and arrow), knowledge, and strength to gather.

According to the study, foraging returns increase steadily throughout childhood and adolescence. The average child has achieved 20 percent of the productivity they will have reached by the age of 20 and 50 percent by age 10.

[Related: These photos are proof that evolution is wild and wondrous.]

The returns for these easier-to-extract resources (items like fruit, fish, and shellfish) increased rapidly during childhood into adolescence and then tapered off, while gains of game items and tubers continued steadily throughout adolescence. This suggests that getting better at foraging requires longer periods of skill development, supporting the theory that long human childhoods may partially result from the need to learn how to extract complex resources.

“A very interesting take on these findings is the variability that emerges. We looked across cultures and across resources, and even though there are key differences at the resource level, in practice there is a lot of variability in the schedules of learning to forage,” says Pretelli. “Unfortunately, this means that looking at a single resource in a single population to infer things about the evolution of human life history won’t work, because the neighbors might behave in a completely different way, thus invalidating the findings.” Pretelli stresses the need for longitudinal, cross-cultural data, and attention to ethnographic details to better understand this process.

The results supports one of the key principles of an anthropological idea called Embodied Capital Theory which theorizes that humans’ long childhood developmental period may have evolved due to the need to learn complex foraging skills.

“We are still engaged in trying to disentangle the processes underlying human life history evolution,” Pretelli says. “We aim to try and tease apart the importance of cognitive, and I would also like to move forward in investigating the social aspects of foraging and the role that children play in supporting their families.”

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The Red Planet is home to some pretty nasty conditions: extreme cold temperatures of about –80 degrees Fahrenheit, an atmosphere that doesn’t provide much protection from the cold, and a very different definition of water. It likely won’t be harboring life anytime soon, but questions still remain about whether it once had lifeforms.

A new study published in the journal Nature Astronomy finds that roughly four billion years ago, Mars could have been home to an underground world of microscopic organisms. However, if simple life like microbes existed, they “might actually commonly cause its own demise,” the study’s lead author, Boris Sauterey, now a post-doctoral researcher at Sorbonne University, told the Associated Press. He added that the results, “are a bit gloomy, but I think they are also very stimulating. They challenge us to rethink the way a biosphere and its planet interact.”

[Related: 5 new insights about Mars from Perseverance’s rocky roving.]

Early on in its life, Mars likely had an atmosphere that was much denser than the one it has today, and the planet itself was possibly even filled with water. According to Regis Ferrière, a lead author on the study and an evolutionary biologist at the University of Arizona, the carbon dioxide and hydrogen in this ancient atmosphere could have created a temperate climate that allowed water to flow and, possibly, microbial life to thrive.

For a hypothetical simulation of what Mars may have looked like billions of years ago, the team created a model of Mars’ crust, atmosphere, and climate and paired it with an ecological model of a group of microbes that we would find on Earth that metabolize hydrogen and carbon dioxide. “Our goal was to make a model of the Martian crust with its mix of rock and salty water, let gases from the atmosphere diffuse into the ground, and see whether methanogens could live with that,” Ferrière said in a press release. “And the answer is, generally speaking, yes, these microbes could have made a living in the planet’s crust.”

Methanogenic microbes live by converting chemical energy from their environment and releasing methane as a waste product, the same way that humans convert the oxygen they breathe into carbon dioxide. They thrive in the most extreme habitats on Earths like hydrothermal vents along fissures in the ocean floor and can support entire ecosystems that are adapted to living with crushing water pressures, near-freezing temperatures, and total darkness.

The team theorized that Mars’s methane-releasing microbes might been living just beneath the surface of the planet, with a few inches of dirt protecting them against radiation. According to Sauterey, any spot on Mars that was free of ice could have been swimming with these microbes, just like on Earth.

However, so much hydrogen being sucked out of the thin and carbon dioxide-rich atmosphere would have put the planet’s protective layer in jeopardy. As the amount of hydrogen in the atmosphere depleted, the temperature on the planet plummeted and any of the microbes at or near the Martian surface probably would have gone deeper in an attempt to survive.

[Related: NASA’s Perseverance rover is on a hunt for microbes on Mars.]

“We think Mars may have been a little cooler than Earth at the time, but not nearly as cold as it is now, with average temperatures hovering most likely above the freezing point of water,” Ferrière said. “While current Mars has been described as an ice cube covered in dust, we imagine early Mars as a rocky planet with a porous crust, soaked in liquid water that likely formed lakes and rivers, perhaps even seas or oceans.”

The team also applied models that predict the temperatures at the surface and crust to simulate the weather conditions faced by early Martian lifeforms. They combined that with a separate ecosystem model to predict whether or not life of this kind would have been able to survive in this environment over time.

“The problem these microbes would have then faced is that Mars’ atmosphere basically disappeared, completely thinned, so their energy source would have vanished and they would have had to find an alternate source of energy,” Sauterey said in a press release. “In addition to that, the temperature would have dropped significantly, and they would have had to go much deeper into the crust. For the moment, it is very difficult to say how long Mars would have remained habitable.”

The researchers suggest that the best places to look for evidence of this past life is Hellas Planitia (a still unexplored area) and the Jezero Crater. NASA’s Perseverance Rover is collecting rocks in the crater on the northwestern side of Isidis Planitia that will be returned to Earth within the next decade.

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Pterosaurs are some of the stars of the latest chapters of Jurassic Park franchise and the cinematic television streaming series Prehistoric Planet. These giant winged dinosaurs scoured the skies from the late Triassic Period all the way up to the demise of the dinosaurs in the late Cretaceous Period, but they weren’t always so large. Some new clues are revealing just how tiny the ancestors of these winged reptiles once were.

In a study out today in the journal Nature, an international group of scientists discuss their new examination of a Triassic-era fossil that was first discovered 100 years ago in Scotland. Computed Tomography (CT scanning) helped create the first accurate and whole skeleton reconstruction of the non-avian Scleromochlus taylori, revealing physical features that show that it’s a close pterosaur relative. The specimen is within a group known as Pterosauromorpha, an extinct group of reptiles called lagerpetids (which means “rabbit-reptiles”) that are grouped together with the pterosaurs.

[Related: The biggest animal ever to fly was a reptile with a giraffe-like neck.]

“Pterosaurs were the first vertebrates to evolve powered flight and for nearly two centuries, we did not know their closest relatives,” Sterling Nesbitt, a paleontologist and professor from Virgina Tech University, said in a press release. “Now we can start filling in their evolutionary history with the discovery of tiny close relatives that enhance our knowledge about how they lived and where they came from.”

Lagerpetids lived about 240 to 210 million years ago and they were relatively small, even by modern mammal standards. They were generally about the size of a cat or small dog. Schleromochlus was even smaller, at under 7 inches (20 centimeters) in length, a little more than half the size of a standard school ruler. The results of this study support the general hypothesis that the first flying reptiles evolved from small, bipedal ancestors like Schleromochlus.

These findings also settle a 100 year-long debate: Scientists have long disagreed as to whether Scleromochlus were an evolutionary step in the direction of pterosaurs, dinosaurs, or else some other reptile entirely.

[Related: Zimbabwe’s newest dinosaur may be Africa’s oldest.]

“It’s exciting to be able to resolve a debate that’s been going on for over a century, but it is far more amazing to be able to see and understand an animal which lived 230 million years ago and its relationship with the first animals ever to have flown,” said Davide Foffa, a research associate at National Museums Scotland, and a research fellow at the University of Birmingham, in a press release. “This is another discovery which highlights Scotland’s important place in the global fossil record, and also the importance of museum collections that preserve such specimens, allowing us to use new techniques and technologies to continue to learn from them long after their discovery.”

The fossil of Scleromochlus has been difficult to study in depth due to its size and because it is poorly preserved in a block of sandstone. The specimen is part of the Elgin reptiles, a group of Triassic and Permian fossils that were found in the Lossiemouth Sandstone Formation near the town of Elgin in the Morayshire region of northeast Scotland.

“The Elgin reptiles aren’t preserved as the pristine, complete skeletons that we often see in museum displays,” said Paul Barrett, a professor and paleobiologist at the Natural History Museum, in a press release. “They’re mainly represented by natural moulds of their bone in sandstone and—until fairly recently—the only way to study them was to use wax or latex to fill these moulds and make casts of the bones that once occupied them. However, the use of CT scanning has revolutionized the study of these difficult specimens and has enabled us to produce far more detailed, accurate and useful reconstructions of these animals from our deep past.”

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The origins of how life on Earth arose remains a deep existential and scientific mystery. It’s long been theorized that our planet’s plentiful oceans could hold key to the secret. A new study from scientists at Purdue University could advance that idea one step further.

The paper published, on October 3 in the Proceedings of the National Academy of Sciences (PNAS), look at peptides: strings of amino acids that are important and tiny building blocks of protein and life itself. The authors found that amino peptides can spontaneously generate in droplets of water during the quick reactions that happen when water meets the atmosphere, such as when a waterfall crashes down to a rock and the spray is lifted into the air. It’s possible that this action happened when the Earth was a life-less, volcanic, watery, molten rock-filled planet about four billion years ago when life first began.

“This is essentially the chemistry behind the origin of life,” Graham Cooks, an author of the study and professor of analytical chemistry at Purdue, said in a press release. “This is the first demonstration that primordial molecules, simple amino acids, spontaneously form peptides, the building blocks of life, in droplets of pure water. This is a dramatic discovery.”

[Related: A primer on the primal origins of humans on Earth.]

In the study, the authors write that this discovery provides “a plausible route for the formation of the first biopolymers,” or the complex structures produced by living things. Scientists have been chipping away at the goal of understanding how this works for decades, since decoding the secret of how (and even why) life arose on Earth can help scientists better search for life on other planets, or even moons in our galaxy and beyond.

Understanding this water-based chemistry circles back to the proteins that created life on Earth itself. Billions of years ago, the raw amino acids that built life are believed to have been delivered to Earth by meteorites. These amino acids reacted and clung together to form peptides, the building blocks of proteins and eventually life itself. However, a water molecule must be lost when the amino acids cling together for peptides to form. That’s not easy to do in a planet that is mostly covered in water. Basically, for life to form, it needs water, but also the loss of some water.

Cooks explained this “water paradox,” to VICE. “The water paradox is the contradiction between (i) the very considerable evidence that the chemical reactions leading to life occurred in the prebiotic ocean and (ii) the thermodynamic constraint against exactly these (water loss) reactions occurring in water. Proteins are formed from amino acids by loss of water” and “loss of water in water will not occur because the process will be reversed by the water (thermodynamically forbidden).”

The new study has taken a rare glimpse into the Earth’s early years, when nonliving compounds suddenly combined to form living things. This process of nonliving things giving rise to life called abiogenesis and it is a still not completely clear how it works. Since peptides form the basis of proteins (and other biomolecules that can self-replicate), the creation of peptides is a crucial step in abiogenesis.

[Related: Comets Could Have Kickstarted Life On Earth And Other Worlds.]

Cooks and his team demonstrated that peptides can readily form in the kinds of chemical environments that were present on Earth billions of years ago. A key aspect, however, is the size of the tiny droplets flying through the air or sliding down rocks, interacting with the air and forming quick chemical reactions. “The rates of reactions in droplets are anywhere from a hundred to a million times faster than the same chemicals reacting in bulk solution,” said Cooks.

This speedy chemical reactions do not require a catalyst to begin the reaction, which made the evolution of life on Earth possible. The team used “droplet fusion” experiments to reconstruct the possible formation of peptides, that simulate how water droplets collide in the air. Understanding the chemical synthesis process at play when amino acids built themselves into protein could help synthetic chemists speed up the chemical reactions critical to creating new drugs and therapeutic treatments for diseases.

“If you walk through an academic campus at night, the buildings with the lights on are where synthetic chemists are working,” Cooks said. “Their experiments are so slow that they run for days or weeks at a time. This isn’t necessary, and using droplet chemistry, we have built an apparatus, which is being used at Purdue now, to speed up the synthesis of novel chemicals and potential new drugs.” 

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“WE DESCEND SLOWLY, the noise and busyness of the outside, and the light of day, dims behind us,” says Zachary Klukkert, making the scene at the mouth of the foreboding Vintany cave sound calm, almost meditative. At about 83°F, the waters are indeed soothing—nearly bathtub warm. But while the Central Michigan University anthropologist’s initial descent may drown out the chaos of the topside world, it leads him ever deeper, inch by inch, into a dark and stony maw.

His venture will take him nearly 100 feet beneath the surface of Madagascar, to the last resting place of giant lemurs, crocodiles with devilish horny protuberances, and some of the largest birds to ever walk the Earth. They’re remnants of a world that thrived here thousands of years ago, then vanished for reasons we’re still trying to understand. Back then, the spot’s winding limestone passages funneled the remains of such ancient creatures into mass graves. Now the very fissures and tunnels that gathered and trapped those relics are the only routes in and out for curious scientists.

Klukkert has been part of three expeditions to this spot near the western coast of Madagascar since 2016, but its layers and layers of fossils will likely take more than a decade to fully uncover. The stories in those bones may well be worth the trouble. Together, the skeletal pieces—and even the rocks of the cave itself—document life before and after humans arrived on the East African island. These specimens, perhaps more than any others yet found, are helping paleontologists understand why so many of this place’s immense and magnificent animals disappeared and how humans figured into that story.

Many of the bones left behind by the island’s exceptional primates, birds, and reptiles are less than 10,000 years old—falling into the category of “subfossils,” or ancient specimens that hail from after the end of the Ice Age. In fact, researchers eventually realized, many of these animals became extinct only after humans arrived. People traipsing around so close to a mass die-off seemed too perfect to be a coincidence. Then again, the disappearance of massive lemurs and towering birds also seemed to line up with harsh droughts.

For years, consensus on what had driven the extinctions seemed impossible to reach. But a diver’s chance discovery of bones beneath Vintany nearly a decade ago has given paleontologists a unique window through the murk of the past.

Scientists, in fact, have been collaborating with cavers to plumb the depths since at least the 1930s. “Caves can be excellent places to find fossils, because the bones of deceased animals often preserve very well within them, and they may be undisturbed,” says Laurie Godfrey, an anthropologist at the University of Massachusetts. Back in 1930, divers working with the Florida Geological Society found mastodon bones in caverns below the surface of the Aucilla River. More recently, in 2016, another group turned up the remains of a prehistoric human in Mexico’s Chan Hol cave. Two years later, another explorer discovered a trove of Pleistocene mammal bones in South Australia’s Mount Gambier system.

Vintany, though, is something special. Godfrey got recruited to study the site in 2014 by Alfred Rosenberger, an expert on the living and prehistoric monkeys of Central and South America. He’d just been on the receiving end of a thrilling dispatch from cave diver Phillip Lehman, who had previously helped him study fossilized primates in the Dominican Republic. Those first impressions were too good to sit on: Godfrey recalls that Lehman phoned Rosenberger in the middle of the night. “He had never seen so many fossils in an underwater cave,” she says.

“Every subfossil site tells its own story,” she says, and so “every site may yield secrets that others cannot.” She and her colleagues had already studied the dry caves in the region—a process that didn’t require air tanks, wetsuits, or much mortal peril—but the sheer number of specimens in the submerged site promised a view of the past the surface could never provide.

Lehman and Rosenberger set about assembling a team familiar with Madagascar, its fossils, and the caves below, including Godfrey, as an expert on the subfossil creatures, and Klukkert, then a new cave diver ready to take the plunge.

To call his quest “dangerous” would be a gross understatement. All diving is risky, but submersion in cramped, pitch-black spaces severely compounds those risks. A flooded flashlight, a broken face mask, a ruptured air hose connection, or blinding clouds of kicked-up sediment can have grave consequences. Even highly trained explorers can run out of air if a spray of debris takes too long to settle. One 2015 study concluded that an average of three people perish while cave diving each year, but the actual number of fatalities could be even higher.

For some, the ever-present threat of disaster is likely the point. But Klukkert didn’t come to Vintany in search of subterranean thrills. There’s simply no other way to access the treasure trove. Crucially, the boneyard holds more than the secrets of the strange fauna of millennia past. The remains within Vintany, and even the stone of the cave itself, also speak to a much more urgent story—a tale of humans teaming up with ecological disasters to push life on Earth to the brink.

PREPPING TO DESCEND is a delicate balance between being ready for trouble and becoming so bogged down that it’s difficult to move—and easy to get hopelessly stuck. Klukkert learned this as a graduate student working on fossil primates found in the Dominican Republic’s underwater troves, where his diver colleagues rekindled a spark of fascination with underwater worlds he’d first felt as a kid in landlocked New Mexico. “Cave divers have a complicated relationship with equipment,” Klukkert says. The cave is too deep for a quick return to the surface, meaning a busted or misplaced piece of gear can derail a whole day of work—if it doesn’t kill you. So they need duplicates of all the essentials, like flashlights and face masks.

Then there’s the survey equipment to mark the locations of fossils, a camera to document the site, and plastic bins to hold specimens. “We place the bones into these small bins and carefully carry each full bin back to the surface individually to be sure that there isn’t any excess movement and avoid impacts with rocks on the way out,” Klukkert says. It’d be a shame for a lemur skull that’s survived for more than a thousand years to bite the dust moments after discovery.

The script has played out more or less the same since the team’s first expedition to uncover the bones at Vintany in 2014—and for subsequent visits in 2016, 2018, and 2019. Once the crew reaches Madagascar, they travel three days by car and boat to get to their base of operations. Each day they load up trucks and spend a couple of hours driving in a caravan across dried-out lake beds and sand dunes to reach Tsimanampetsotsa National Park. The researchers and locally hired assistants then hike all their equipment half a mile to the dive site. It’s usually midday by the time they’re ready to take the plunge, which they’ll do once or twice a day for up to two weeks at a stretch.

At least sliding into the water is a relief from the heat, Klukkert says, which can break 90 degrees in the shade. He usually pauses briefly once his body is horizontal, waiting to ensure all his gear settles into place. In those moments, he says, the tension and worry give way to focus on the work ahead.

It may sound absurd to those who don’t spend time trapped in flooded dens, but Vintany is a relatively simple place to swim. The cave lacks the scary pinch points of some others, like a nearby cavern called Mitoho the divers have also explored. That spot, Klukkert says, “requires some vertical corkscrew maneuvers and some minor squeezes,” which can feel much tighter when your only air is strapped to your torso.

Even with a relatively roomy route, divers face a long list of potential disasters—and a tight schedule. Not only do they have to bring their own air, which is limited by space constraints to around four hours of breathing time, but the caves are deep enough to necessitate decompression stops to avoid the notorious “bends”—the effects of gas bubbles that form inside the body and can cause everything from joint pain to death.

The moment fins touch water, the clock starts ticking. Most of that time, Klukkert says, is spent mapping where the subfossils lie, providing essential context for experts trying to understand how such a graveyard came to be. The divers also stop to recover bits that seem especially interesting. Luckily, they don’t have to dig: Just waving a hand stirs the sediment on the cave floor to reveal the treasures beneath.

But that creates its own problem.

“The rising silt in the water reduces visibility and dims our powerful dive lights,” Klukkert says, which can obscure fossils. More importantly, it can make it difficult or impossible for them to see where they’re going. Knowing these delays are inevitable, the crew factors in time spent waiting for sediment to settle as part of the work.

By the time they finish, it’s near sunset—time to haul out any last finds, dry them, pack them up, and amble past the ring-tailed lemurs that sometimes come to watch their primate cousins bustle around the cave. The team starts the long drive back, then goes through a process Klukkert summarizes as “unload, eat, sleep, repeat.”

The sheer bounty is difficult to overstate: Vintany is so rich with bones that it’s impossible to get them all. During one trip down, divers were able to collect about 500 subfossils in just two hours. “There are times when I have to step back and make a decision about where to collect, recognizing that I can’t get it all, but I can’t cherry-pick either,” Klukkert says. It might save time to snag only specimens that look new and surprising, but even a common find can have major implications.

For example, Vintany is replete with Pachylemur insignis, an ancient lemur some four times heftier than modern species, and Voay robustus, a large horned crocodile. Researchers assumed that the reptile must have munched on primates, but it wasn’t until Klukkert found a particular Pachylemur skull that they found the evidence. “I fanned the teeth and palate to cleanse it of the extra bits still hanging on,” Klukkert says, “and that’s when I noticed that the teeth were brown, not white.” Later, after analysis, Godfrey and colleagues realized that the dark stain reflected the lemur’s violent end: Its modern relatives take on the same kind of dental hue when they’re eaten (and partially digested) by crocodiles. “This was the first sign of any direct interaction between the animals at our site,” Klukkert says, part of an ancient drama that likely played out over and over again.

PLUMBING THE DEPTHS of Vintany’s dark tomb tells us part of a broader story that may help us understand why Pachylemur and so many of Madagascar’s other unusual creatures disappeared. Paired with evidence from other sites around the island, such as butchered lemur bones and signs of human-introduced livestock, findings from the site and other caves have allowed Godfrey and colleagues to reconstruct what transpired on the island with a precision not seen before.

Take, for example, Vintany’s speleothems (the rock formations created by the drip, drip, drip of mineral-laden water). Researchers can use them to estimate past shifts in the local climate, knowing that they grow only when rain is plentiful. Analyzing the age of various speleothem lengths produces a reliable record of wet and dry stretches long past. By lining up these dates with the ages of fossils from Vintany—as well as specimens from other archaeological sites—Godfrey and colleagues have been able to track how closely weather shifts match up with the disappearances of elephant birds, pygmy hippos, and other fantastic beasts that once lived on the island.

Even though ideas about what triggered extinctions on Madagascar have often viewed ancient climate change and human activity as mutually exclusive options, the researchers found that what happened was not so clear-cut. Based on their findings, Godfrey and colleagues have come to suspect that the large animals around what’s now Tsimanampetsotsa began to die or migrate away during a drought about two thousand years ago. That didn’t totally topple the populations into oblivion, but it did thin their numbers. Another arid period would follow just a few hundred years later.

People arrived on the island shortly before the first deadly drought—about 2,500 years ago. They did butcher and eat the vulnerable animals, but didn’t immediately hunt them into nothingness. The real danger came from human land use. Just after the second major dry spell, the people began to grow crops from nonnative plants, raise cattle and pigs, and keep cats and dogs. These introduced species competed for space, food, and water with Madagascar’s native fauna, sometimes even preying on them. Already weakened by environmental change, many of the island’s most distinctive animals vanished.

Perhaps those amazing tortoises, crocodiles, hippos, birds, and primates would have survived our meddling if they had not been pummeled by inescapable droughts. Vintany confirms that both factors are part of the story—and both should serve as a warning for modern humans. Even species that seem to be faring well under our ecological influence may still be reduced, weakened, and stressed to the point where just one more bad year could push them over the edge. This lesson couldn’t be gleaned from the surface alone.

Vintany is far from the only cave to hold warnings about lost worlds. As-yet-unpublished findings on fossils from the Yucatán Peninsula’s Hoyo Negro may help paleontologists understand how Ice Age beasts and humans, like the teenager dubbed “Naia” found there in 2007, coexisted. Bones of a similar age in Australia’s Tank Cave could reveal how the continent’s car-size wombats and carnivorous koala cousins went extinct.

In these caverns—and in ones not yet discovered—history unfurls in a way rarely seen topside. “Being at a site is nothing like visiting a museum collection,” Klukkert says. Instead of cleaned bones in a box, a diver is greeted by remains of once-living things in their home habitat—precisely where death left them. It gives a sense of connection to a place and its history that can be hard to conceive of otherwise. The stories in Vintany and other watery graves are cautionary tales of our species’s interaction with nature—what Klukkert calls “a critical and unique resource for understanding the world that we live in as a product of how we live in it.”

This story originally ran in the Fall 2022 Daredevil Issue of PopSci. Read more PopSci+ stories.

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Earlier today, Swedish scientist Svante Pääbo won the 2022 Nobel Prize in physiology or medicine today for his discoveries on human evolution. According to the award panel, his work provided key insights into the human immune system and what makes present day humans unique compared with our extinct cousins.

Pääbo sequenced the genome of a Neanderthal, a feat that was once believed to be impossible, according to the panel.

About 300,000 years ago, Homo sapiens first appeared in Africa. But, they weren’t alone on the planet. Neanderthals, an extinct relative of modern day humans, developed outside Africa and lived in Europe and Western Asia from around 400,000 years until 30,000 years ago.

Roughly 70,000 years ago, groups of Homo sapiens migrated from Africa to the Middle East, eventually spreading around the rest of the world. This overlapping timeline shows that Homo sapiens and Neanderthals coexisted in large parts of Eurasia for tens of thousands of years. Genetic information is one of the only ways for scientists to understand what our relationship with these extinct cousins was like. Following the sequencing of the human genome in the 1990s, scientists were able to conduct more studies of the genetic relationship between humans. Neanderthal genome sequencing is offering another crucial step in understanding the relationship between humans of the past with those in the present.

[Related: From the archives: The discovery of DNA’s structure explained how life ‘knows’ what to do.]

After Pääbo and his team first extracted 40,000 year old DNA from a tiny finger bone found in a cave in Siberia in 2008, he discovered a previously unknown hominin species called Denisova in 2018. This discovery showed that the first generation of humans with parents from two different groups (Neanderthal and Denisovian) could produce successful offspring.

“Importantly, Pääbo also found that gene transfer had occurred from these now extinct hominins to Homo sapiens following the migration out of Africa around 70,000 years ago. This ancient flow of genes to present-day humans has physiological relevance today, for example affecting how our immune system reacts to infections,” the panel wrote in a press release.

This research has helped paleogenomics take off—a discipline of science devoted to genetic differences between living humans from extinct ones. It’s helped determine that human and Neanderthal evolution diverged about 800,000 years ago. “Pääbo and his team also surprisingly found that gene flow had occurred from Neanderthals to Homo sapiens, demonstrating that they had children together during periods of co-existence,” Nobel Committee chair Anna Wedell told the Associated Press. And this has had lasting impacts—people with ancestry outside of the African continent typically have 1 to 2 percent Neanderthal genes in their DNA, which can affect immune system responses and appearance.

The genome sequencing by Pääbo and his team also showed that Neanderthals and the newly discovered Denisovans were sister groups that split from each other about 600,000 years ago. Denisovan genes have been found in up to six percent of the population of modern humans in Asia and Southeast Asia, indicating that interbreeding between species occurred there too.

[Related: Why are there no black Nobel laureates in science?]

“By mixing with them after migrating out of Africa, homo sapiens picked up sequences that improved their chances to survive in their new environments,” said Wedell. One example is a gene that helps the body adapt to life at a high altitude that Tibetans share with Denisovans.

Pääbo conducted the prizewinning studies at the University of Munich and at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. He is the son of 1982 Nobel prize winner Sune Bergstrom who won the medicine prize for his work in understanding a hormone group called prostaglandins. According to the Nobel Foundation, this is the eighth time that the son or daughter of a Nobel laureate also won a Nobel Prize.

Winners of the annual awards recieve a cash prize of about $900,000 (10 million Swedish kronor) and will be celebrated at a ceremony on December 10.

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Excerpted from A Voice in the Wilderness: A Pioneering Biologist Explains How Evolution Can Help Us Solve Our Biggest Problems, by Joseph L. Graves Jr. Copyright © 2022. Available from Basic Books, an imprint of Hachette Book Group, Inc.

Given the weak differentiation between human populations, those who continue to champion the notion that genomic foundations to racial differences in intelligence must exist are left with a huge elephant in the living room. Why and how should such differences exist? The key adaptation of our species is its greater intelligence compared to other animals. Our evolutionary lineage was characterized by increased brain size and complexity along with facial reduction. Many authors also suggest that the primary driving force of all primate intelligence (including our own) is social interactivity. Primates are highly social. Over the period from 2.5 million to 500,000 years ago the brain size of our hominid ancestors doubled. Over this same period the technical sophistication of these hominids was somewhat stagnant. Yet something was driving the brain growth (and possibly the intelligence growth). The seeming disparity between brain growth and lack of technical innovation has led some to propose that sexual selection rather than natural selection might have been at play. Sexual selection for a trait differs from natural selection in that it need not lead to greater survivorship of the individual so long as individuals with the trait in question come to have greater numbers of offspring. Evolutionary psychologist Geoffrey Miller went so far as to propose that the main driving force of this early physical change in brain size was the competition for mates. In this model, the benefit of greater cognitive capacity for technical innovation was a by-product of runaway sexual selection, not something directly selected for.

Whether Miller’s model is true or not, it is important to recognize that the majority of behavioral traits and intelligence of our species evolved long before anyone left Africa. We spent about two-thirds of our 300,000-year existence there. This time depth also explains why the majority of the genetic variation found in our species is found in Africans. There is also a direct linear relationship between a population’s migratory distance from Africa and its genetic variation. Given the amount of genetic variation in Africa, it is notable that psychometricians never argue (as the melanist Afrocentrics do) that Africans are more genetically endowed for cognitive function than the rest of humanity. If genes were all there was to cognitive performance, we might expect that the most intelligent and the least intelligent populations would be found there. Maybe the Wakandans are still successfully hiding away from the world?

So we are still left with the question of whether and how there could have been direct selection for greater intelligence as humans migrated into Eurasia. One convenient answer to this mystery is winter. In 1864 Alfred Russel Wallace (codiscoverer of evolution by means of natural selection) proposed that winter selection would have favored greater intelligence. In 1925 Ellsworth Huntington argued that adaptation to the temperate zones caused strong selection for intelligence in Eurasians that was not experienced by sub-Saharan Africans. It is notable that Carleton Coon, known for both his racialism and his racism, did not reiterate Huntington’s idea in his work on the origin of the human races. This is especially significant in that he spent some time in that work discussing the importance of adaptation to climate as a factor in human evolution. Seventy years later, the winter selection idea was resurrected by J. Philippe Rushton and Arthur Jensen in the context of r- and K-selection theory applied to human races.

Despite its obvious problems, the idea that climate drove evolution still seems to have some traction. A recent paper argued for the importance of cold winters in spurring the evolution of intelligence in Eurasians. The paper suggested that during the last glacial maximum (about ten thousand years ago), eastern European populations displayed remarkable technical innovations that allowed them to survive the harsh winter conditions of their latitudes. These innovations included both new technology and changes in social organization. The technical innovations were focused on keeping the cold out and warmth in (to create clothing, shelter, and fuel), on managing time (to conserve limited winter food resources), and on changing the sexual division of labor (to open new roles to women in garment making, shelter building, fire making, pottery design and manufacture, and ornamentation). The relationship between evolved greater intelligence and these new technical innovations is supported by the greater cranial size (and hence brain size) associated with populations that migrated to these northern latitudes.

The paper relied on a study of the relationship between head size and latitude showing a clear trend toward larger heads in populations further away from the equator. The study examined 122 human groups and showed a strong correlation between brain size and the variables of solar radiation intensity, vapor pressure, and latitude in both the Eastern and the Western hemi- spheres. The authors of the study concluded that populations under severe cold stress had larger cranial volumes more from a change in head shape (rounder) than from differentiation due to total body size. The authors also made it very clear that there was no established relationship between IQ and cranial case volume in human populations. Finally, they also pointed out that head size differentiation is always a function of total body size. They mentioned that particularly large brain-size-to-body-mass ratios are seen in San hunter-gatherers (Africa), the Andamanese indigenous peoples (islands in the Indian Ocean, India), and the Bengalis (India), and that particularly low brain-size-to-body-mass ratios are seen in the French (Europe), the Mapuche (indigenous Chile), the Choctaw (indigenous North America), and the Maori (Pacific islanders). The groups in the high and low categories don’t correspond to the groups psychometricians typically claim for the genetically high IQ (East Asians) and low IQ (sub-Saharan Africans) categories.

Finally, there is no reason to believe that modern humans did not already possess all the cognitive ability needed to technologically innovate to meet new conditions before they arrived in Eurasia. The reasoning used by the winter selection theorists is circular. They claim that new innovations were required because of the movement of human populations into temperature zones. They argue that the appearance of innovations is evidence of genetically based greater intelligence in temperate populations and their absence is evidence of a lack of that intelligence in African tropical populations. However, if the innovations required to survive in winter are unnecessary in tropical zones, why would anyone build them? The minds of tropical populations would have been engaged in other aspects of their
survival and reproduction. Their challenges were different (the rainy season, the barren soils of the tropics, the greater abundance of toxic plants and animals), but they were no less sophisticated than those associated with living in temperate zones.

If all human populations were engaged in struggles to survive and reproduce in the environments where they found themselves, then to defend an argument for genetically based differences in cognitive function, one has to come up with some reason why natural selection would have operated differently on specific groups with regard to the underlying architecture of cognitive function. It is precisely here that psychometricians have failed. Indeed, the origin of the field itself is connected to the fear of dysgenesis. Francis Galton wanted England to enact eugenical policies because he believed that people of lower IQ were reproducing at a higher rate than those of high IQ—hardly an argument for the importance of the trait from an evolutionary perspective.

Evolution can produce a change in a complex trait as a result of selection for another trait. This phenomenon is called a correlated response to selection and is well-known from quantitative genetics. Correlation can occur if the genes determining the traits in question reside close to each other on the
same chromosome (linkage) or if the traits result from the action of the same genes (pleiotropy). My understanding of these mechanisms and their impacts on complex traits was behind my lecture at the Peabody. Given that at all times, human populations are undergoing various forms of selection, the
chance of sustained selection of any single kind resulting in an “accidental” evolution of superior intelligence in one group compared to others is so low it simply isn’t worth calculating. In my paper responding to Reich’s accusation that I was a defender of orthodoxy, I gave a detailed explanation of this problem for the accidental evolution of racialized intelligence.

There is no doubt that individuals differ in their cognitive abilities. There is also no doubt that some of those differences result from genetic sources and some from environmental sources. Determining the balance between the two has been at the center of some of history’s most contentious debates, beginning in the Western world with Greek philosophers (Aristotle). Support for the ideas that genes played the most significant role in determining cognitive abilities and that such abilities were racially differentiated reached gale force in the 19th and 20th centuries with the ideas of people like Arthur de Gobineau, Francis Galton, Madison Grant, Ellsworth Huntington, Charles Davenport, Audrey Shuey, William Shockley, Arthur Jensen, Richard Herrnstein, Charles Murray, J. Philippe Rushton, Richard Lynn, Stephen Hsu, and many others. The vast majority of these individuals were males of European descent. Originally the genetic determinists based their conclusions on the design of a white supernatural entity (Agassiz’s zones of creation: Agassiz felt that the separate Adams and Eves had been created to occupy specific zones of the Earth—tropical, temper- ate, arctic—along with their associated fauna and flora). When special creation was debunked, they shifted their arguments to evolutionary foundations of differential adaptation favoring greater intelligence among Eurasians. They utilized their scientific expertise to seize the scientific high ground against their opponents. They proposed plausible evolutionary scenarios to explain Eurasian superiority based on winter adaptation and r- and K-selection life history theory.

The problem with all of this, of course, is that their science was and is wrong. There is no a priori reason to believe that winter is any harder to deal with than tropical conditions. Simplistic statements like “planning was necessary to address the lack of food in winter” ignore the fact that the tropics have seasonal variation as well, such as the rainy season, whose problems also need to be solved. To support their claims, proponents of racially based differences in cognitive abilities adopted the tools of modern genetics as soon as they were available. In the late twentieth and early twenty-first centuries, they rapidly deployed NGS tools to search for the enigmatic foundations of greater human intelligence, and they failed utterly. When that failure became apparent, they shifted their search for the genes
supporting educational attainment. Those studies, with larger cohorts, performed slightly better, but even the proponents of the approach had to admit that social, cultural, and environment influences play a substantial role in determining who gets educational opportunities and who does not.

I am not the first scholar (anthropologist or biologist) to take a stand against this pseudoscience. Franz Boas and his students (e.g., Ruth Benedict) took on this struggle in the early twentieth century; Ashley Montagu in the 1940s, Montague Cobb (an African American anthropologist) and his students in the 1950s, and Stephen Jay Gould and Richard Lewontin (and a host of others) in the 1970s all battled against this nonsense. I am the first African American evolutionary biologist to do so, and my training as an evolutionary biologist provided me with important skills that allow me to powerfully critique the logical fallacies so deeply interwoven in this program of disinformation.

Buy A Voice in the Wilderness by Joseph L. Graves Jr. here.

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This article was originally featured on The Conversation.

Omer Gokcumen is an associate professor of Biological Sciences, University at Buffalo.

Slime is everywhere. It shapes the consistency of your bodily fluids, from the saliva in your mouth to the goo that covers your organs. It protects you against pathogens, including the coronavirus, while creating a home in your mouth for billions of friendly bacteria. It helps slugs have Spiderman sex hanging from walls, hagfish turn water into rapidly expanding goo, lampreys filter their food, and swiftlets build nests.

But while slime is essential for all forms of complex life, its evolutionary origins have remained murky.

I am an evolutionary geneticist who studies how humans and their genomes evolve. Along with my colleagues, including my long-time collaborator Stefan Ruhl and my student Petar Pajic, we tackled this evolutionary puzzle in our recently published paper. We began by looking into how salivary slime is made in different species. What we found was that slime opens a window into the role that repetitive DNA plays in the mysteries of evolution.

What are mucins?

Slime is made up of proteins called mucins, which are vessels for sugar molecules. These sugars are the key taskmasters in making things slimy.

Unlike other proteins, which typically have intricate 3D shapes, mucins often take the shape of long, rigid rods. Sugar molecules are attached along the length of the rods, creating complex, brush-like structures.

This partnership between protein building blocks and the sugars bound to them, repeated over and over again, is essential to the properties of mucins. These structures can stick to other mucins and microbes, changing the physical properties of the fluids surrounding them into a sticky and slimy substance.

The evolution of slime

Despite the remarkable properties mucins have and their essential role in biology, how they evolved has eluded scientists.

To begin to figure out the evolutionary origins of mucins, my colleagues and I began by looking for common genetic ancestors for mucins across 49 mammal species. After all, evolution often tinkers but rarely invents. The easiest way for a new gene to evolve is by copying and pasting an existing one and making small changes to the new copy to fit the environmental circumstances. The chances of one species independently inventing a complex mucin from scratch are astronomically small. Our research team was sure that copying and pasting existing mucin genes that then adapt to a particular species’ needs was the main driver of mucin evolution.

But our initial assumptions proved incomplete. Copying and pasting mucin genes in a genome should lead to daughter genes that have similarities to each other. Even though some mucins did fit our criteria, a previous study reviewed all known genes coding for mucins in people and found a number of “orphan” mucins that do not belong to any gene family. They exist alone in the vast landscape of the human genome.

We then focused on searching for such orphan genes in the genomes of dozens of species in genetic databases. We found 15 instances of new mucin genes that evolved in different mammals, lacking any connection to known mucin genes.

Further investigation, however, revealed that these mucin genes do have relatives after all. They share ancestry with other rod-like proteins rich in the amino acid proline, which are commonly found in saliva. These proteins rich in proline, however, do not have the key repetitive protein structures that help mucins bind to sugar molecules.

We hypothesized that these proteins rich in proline could undergo “mucinization” by repeatedly adding proteins that bind to sugar molecules, called glycoproteins. To test this, we compared the sequences of genes coding for mucins and genes coding for proteins rich in proline in different mammals, including people. We found that the sequences were highly similar. The only difference was the presence of repeated segments of glycoproteins in mucins. What this meant is that certain proteins could be transformed into mucins just by adding on copies of these repeated segments.

Repetitive DNA and evolution

Our findings reveal the diversity of mucins in a whole manner of creatures, opening a view into evolution’s slimy playground of adaptation.

Researchers often ignore repetitive genetic sequences because they rarely occur within genes that code for the proteins that perform many biological functions in cells. But in the case of mucins, creating repeat sequences from scratch turns out to be a major engine for their evolution. Our earlier work in primates suggests that the number of repeated sugar-binding segments there are in a given mucin may be the factor that determines its differences from others.

It’s possible that the addition of repetitive genetic sequences may also discreetly shape other functions across the genome as well. Indeed, such tandem repeats are a common type of mutation in the human genome, and recent studies hint to their undiscovered role in biological variation between people.

Mucins and human health

Understanding how mucins work will also help researchers better understand a number of diseases.

When mucins do not work properly, it can lead to illness. People with a malfunctioning CFTR gene develop cystic fibrosis, where their bodies are unable to clear mucus from their lungs and make it difficult to breathe. Malfunctioning mucin regulation is also linked to cancer development.

Though it may not be obvious, you likely have a personal connection to mucins. Two years ago, I visited my mother after her cancer diagnosis. The rain had just ended, and the streets of Istanbul become a bustling village of unnervingly large snails. During a short walk with my mother, I picked up one of those snails with fascination, much to her horror.

I did not have the heart to tell her that the biological mechanism that allows these awesome creatures to move was the same one helping the tumor in her lungs grow. It reminded me of the scientist Michael Faraday’s words: “No matter what you look at, if you look at it closely enough, you are involved in the entire universe.”

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Deep within the genome of modern day humans lie trace amounts of the DNA of a long-lost relative: the Neanderthal (Homo neanderthalensis). They lived about 400,000 to 40,000 years ago, and are the closest extinct human relative to today’s human beings (Homo sapien). A body of research has shown that Neanderthals interbred with humans around 100,000 years ago and a new study published yesterday in the journal Biology is building upon our knowledge of where this interbreeding took place.

“Ancient DNA caused a revolution in how we think about human evolution,” said Steven Churchill, co-author of the study and a professor of evolutionary anthropology at Duke University in a press release. “We often think of evolution as branches on a tree, and researchers have spent a lot of time trying to trace back the path that led to us, Homo sapiens. But we’re now beginning to understand that it isn’t a tree–it’s more like a series of streams that converge and diverge at multiple points.”

The team of researchers from North Carolina State University, Duke University, and the University of the Witwatersrand in South Africa gathered already published data on Neanderthal craniofacial morphology, or facial structure. Neanderthals had larger faces than modern humans, but the size of the face isn’t enough to determine a genetic link between them and human populations.

A data set comprising of 13 Neanderthals, 233 prehistoric Homo sapiens, and 83 modern humans was built by the team from the available literature. They focused on standard skull measurements as a control to study the size and shape of key facial structures. Having the control allowed the team to best determine whether a human population was likely to have interbred with Neanderthal populations and the extent of interbreeding.

[Related: Ancient milk-drinkers were just fine with their lactose intolerance–until famine struck.]

The researchers also used environmental variables (like climate) that are associated with changes in human facial characteristics, to determine the possible likelihood that the connections made between Neanderthal and human populations were a result of interbreeding instead of another factor.

“We found that the facial characteristics we focused on were not strongly influenced by climate, which made it easier to identify likely genetic influences,” said Ann Ross, a corresponding author of the study and professor of biological sciences at North Carolina State University. “We also found that facial shape was a more useful variable for tracking the influence of Neanderthal interbreeding in human populations over time. Neanderthals were just bigger than humans. Over time, the size of human faces became smaller, generations after they had bred with Neanderthals. But the actual shape of some facial features retained evidence of interbreeding with Neanderthals.”

[Related: The debate over ‘Dragon Man’ shows that human origins are still kind of messy]

The next step for this type of study is to take measurements from more human populations, such as the Natufian culture that lived more than 11,000 years ago on the Mediterranean Sea in what is now the nations of Israel, Jordan, and Syria. Their findings from comparing these skulls supports the hypothesis that much of this interbreeding took place in a region ranging from North Africa to Iraq. “This was an exploratory study. And, honestly, I wasn’t sure this approach would actually work–we have a relatively small sample size, and we didn’t have as much data on facial structures as we would have liked. But, ultimately, the results we got are really compelling,” added Churchill.

“The picture is really complicated,” said Churchill. “We know there was interbreeding. Modern Asian populations seem to have more Neanderthal DNA than modern European populations, which is weird–because Neanderthals lived in what is now Europe. That has suggested that Neanderthals interbred with what are now modern humans as our prehistoric ancestors left Africa, but before spreading to Asia. Our goal with this study was to see what additional light we could shed on this by assessing the facial structure of prehistoric humans and Neanderthals.”

Neanderthals are known for making and using a wide range of sophisticated tools, controlling fire, living in shelter, making and wearing clothing, hunting large animals, and also eating plants. There is also evidence that they buried their dead, a marker of sophistication for the species. The first full genome of a Neanderthal was sequenced in 2010.

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Some of the most significant scientific inventions—penicillin, gunpowder, the microwave—were discovered by accident. Now a group of researchers investigating how some animals live in the freezing Arctic have another to tack on the list: natural antifreeze. A new study published today in the journal Evolutionary Bioinformatics found that a tiny snailfish species living in Greenland contained sky-high levels of antifreeze proteins that made it possible to survive subzero temperatures.

In 2019, study coauthor David Gruber, a research associate at the American Museum of Natural History in New York and a distinguished biology professor at CUNY’s Baruch College, was out with his team on an expedition to eastern Greenland to look for animals that glowed in the dark under the ice. Located in the Arctic Circle, this region of Greenland gets near-full days of summer sun, but is plunged in darkness during the winter months. The team’s goal was to understand the role light plays in marine species living in these environments with such drastic seasonal periods of never-ending and very limited sunlight. Their search led them to a juvenile biofluorescent snailfish, a small fish with a tadpole-like body typically found in frigid waters dipping well below freezing , at 28.4 degrees Fahrenheit. Biofluorescence is when an animal absorbs blue light and emits either green, red, or yellow light—a rarity among Arctic fishes that live in darkness for most of their lives.

To better understand how snailfish create light, the biology team examined its entire transcriptome—every gene it is making—where they were surprised to find that one of the most actively made proteins in the body was antifreeze proteins. “Similar to how antifreeze in your car keeps the water in your radiator from freezing in cold temperatures, some animals have evolved amazing machinery that prevent them from freezing, such as antifreeze proteins, which prevent ice crystals from forming,” Gruber said in a press release.

Marine biologists had already uncovered the existence of antifreeze proteins 50 years ago. Several species from fish, reptiles, insects, to bacteria are known to have evolved antifreeze proteins to survive in icy habitats. For snailfish, antifreeze protein is developed in the liver where it prevents large ice grains from forming inside cells and body fluids. Without antifreeze protein, the blood of snailfish would turn frozen solid. 

[Related: Fish blood could hold the answer to safer de-icing solutions during snowstorms]

Since the initial discovery, biologists have since found that antifreeze proteins are created through five different gene families. But marine biologists did not know how much energy snailfish spent in creating antifreeze proteins. “In retrospect it makes sense—of course a juvenile fish living on an iceberg is making lots of proteins that prevent it from freezing,” explained Gruber. In their genetic analysis, the team found two gene families in charge of encoding two types of antifreeze proteins, called Type I and LS-12-like proteins. These genes were highly expressed, making up the top 1 percent of expressed genes in snailfish.

The study authors suggest that the high expression levels for these antifreeze proteins are essential for living in extremely cold waters. Some marine biologists, however, have casted some doubts on how big of a conclusion to draw from these results. C.-H. Christina Cheng, an evolutionary biologist at the University of Illinois Urbana-Champaign who was not affiliated with the study, said that LS-12-like proteins also present in the Northwest Atlantic longhorn sculpin did not provide much help in preventing fish from freezing to death. Instead, she says it’s possible the snailfish could be expressing this protein for another developmental reason. What’s more, the expression Type I antifreeze protein found in the snailfish is different from other Type I proteins from the same species. 

Cheng said these discrepancies could be resolved by further looking at antifreeze protein activity directly in the blood plasma. “If all these detected transcripts are actually made into functional antifreeze proteins, the plasma antifreeze activity would be high,” she explains. “But if the plasma antifreeze activity is low, then it’s questionable that these transcripts are made into active antifreeze proteins.”

[Related: How polar animals cope with frigid darkness for months at a time]

Still, the new study does highlight the importance of antifreeze proteins in the survival of snailfish living in the Arctic—an environment that is particularly vulnerable to rising global temperatures. Since the past century, the Arctic has been warming four times as fast as the rest of the planet, with predictions projecting an ice-free Arctic ocean in 30 years.

As the region undergoes dramatic changes, ice-dwelling fish will be forced to adapt to warmer climates or face extinction. “For these juvenile snailfish, their superpower of making lots of antifreeze proteins will no longer be a superpower in an Arctic without icebergs,” Gruber said. To make matters worse, warmer waters may introduce more fish species that tend to reside in temperate climates, increasing competition for food and shelter.

In the future, Gruber and his team plan on further investigating the nuances of antifreeze in snailfish and other species living in these frozen environments. “Snailfishes are an interesting family as they have representatives that live at surface to beyond 8,000 meters deep [in the ocean],” he said. “We are curious to investigate if there are any connections between snailfishes ability to survive extreme cold and extreme pressure environments.”

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After a long day of hunting down prey or showing off to potential mates, jumping spiders typically slip into their snug silk hammocks for the night. This is how most of these tiny arachnids spend their evenings, but behavioral and evolutionary ecologist Daniela Rößler stumbled across one species with a striking nighttime pose: a jumping spider dangling dormant from a thin strand of silk, with its legs tucked and body slightly curled.

“It never occured to me that they would do anything but sit in their silk retreat at night,” Rößler, who studies jumping spiders at the University of Konstanz in Germany, wrote to PopSci in an email. “Finding them hanging that exposed was really fascinating.”

The vulnerable position gave Rößler a rare, unobstructed glimpse of the creatures during their inactive phase. This week in the journal Proceedings of the National Academy of Sciences, her team released recordings of the species Evarcha arcuata that suggest jumping spiders have an REM sleep-like state. 

In their upside-down slumber, the spiders’ bodies would occasionally wiggle or shimmy, with the limbs sometimes curling or unfurling in a good stretch. The sporadic movements are not too dissimilar from your napping pet dog or cat, says Paul Shamble, study coauthor and a former John Harvard Distinguished Science Fellow who studies jumping spider cognition. 

“Some of the twitches were really small, some of them were big, which is sort of the same way it is when people sleep,” Shamble says. These particular sleeping behaviors are a trademark of rapid eye movement (REM) sleep, he says, which is associated with brain development and emotional processing in humans—and is most well-known as the stage of sleep for dreaming.

[Related: Jumping spiders have a mysterious nighttime habit]

Jumping spiders are highly visual creatures with a set of eight eyes that can even pick up color. And unlike most other land-dwelling arthropods, they have muscles that can control and move their retinae. The team hatched and recorded spiderlings, which have clear exoskeletons right after they hatch, explains Shamble. “You could just see them moving their eyes.” 

The researchers then used infrared cameras to record nighttime observations, capturing that “real magical moment” on video, says Shamble. While there have been some rudimentary observations of sleep-like states in scorpions, says Rößler, her group’s findings give a new window into the cognition of arachnids and arthropods. 

“I’m thrilled to get to some of the fundamental hypotheses about REM sleep and test those in the jumping spider,” Rößler wrote in her email. “What happens when you deprive them of sleep? Do we see costs in fitness and cognitive ability?” 

University of Florida jumping spider expert Lisa Taylor, who was not involved in the research, says she would also be interested in how a bad night’s sleep could affect the spiders’ ability to form memories during the day. “Not to anthropomorphize, but we all know that having a crappy night’s sleep affects your cognitive abilities the next day,” she notes. “For these spiders, learning and memory is really important because they’re predators, and having a bad experience with toxic or dangerous prey is something that they should remember.” 

Jumping spiders are able to capture and sift through an incredible amount of sensory information for the size of their brains, which are no larger than a poppy seed. “I think a lot about how they process all that information and how they form memories,” says Taylor. “So in that context, the idea that maybe when they’re in their nests at night, that they’re sleeping and having REM states is just really interesting.” 

It’s only natural to wonder if spiders dream, too, says Shamble. “It wouldn’t surprise me if they are dreaming, and I suspect that they are,” he says. “I think it’s a very, very cool and really exciting thing, because it makes you not just think about the animals differently, but it makes you think about dreams in the brain differently.”

That said, Shamble admits that the team is far from scientifically determining if the spiders do dream—let alone sleep, in the way humans do. “Sleep as we tend to think of it, or something more like resting, is determined mostly on a neurobiological and molecular level,” he says. “We don’t have any of that for the jumping spider.” 

In the meantime, the researchers have other observational tests they can try to help determine if the jumping spiders are sleeping. For instance, to see how quickly the arachnids react to disturbances, Shamble and Rößler could “wake” them from their sleep-like states with flashing lights and clock their responses. Still, the previously recorded body posture and movements does suggest that the study subjects were in some kind of sleep state. Over the past couple decades, more research has gone into identifying sleep or sleep-like states in species beyond humans and primates. The second has been well-documented in reptiles; and in 2021, biologists recorded octopuses that drifted off into a possible dream phase.  

“Applying [the definition of human REM sleep] directly to various non-vertebrate animals can be a rough fit,” David Scheel, a marine biologist from Alaska Pacific University who documented the “sleepy” cephalopods, wrote in an email. “But there are great parallels in sleep across the animal taxas, and this seems like an interesting hint about how sleep evolved and how it may function.”

[Related: Why do people need to sleep?]

While jumping spiders might seem nothing like humans, their behaviors can actually inform us a lot about how we sleep, giving biologists insight into the origins of a trait so seemingly essential to survival. Studying very distant species—from spider to cephalopod to human—can reveal new patterns and connections in evolution, says Rößler. 

“While researchers tend to be out there looking for things that have or do not have REM sleep, finding it in spiders hints at the possibility that this sleep phase is actually quite universal, and must have some universal functions as well.” Rößler says that by casting a wider net, “we may be bound to find something similar to REM sleep in tons of other animals, too.”

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What do elephants, camels, and sauropod dinosaurs all have in common? Soft tissue pads beneath their heels support their enormous sizes and weights. A new study published in Science Advances found that sauropod dinosaurs were likely capable of evolving to heights up to 76 feet—almost as high as the White House—because their feet had cushions which helped their massive bodies move without crushing their foot bones.

The evolution of gigantic dinosaurs and how they carried their enormous stature has been a topic of debate among paleontologists for more than a century–that, until now, had no concrete answer. “What is exciting is that our research finally resolves this 120-year-old hypothesis by providing, for the first time, biomechanical evidence to show how gigantic sauropods could support their weight on land,” says Andréas Jannel, a research associate at The University of Queensland and lead author of the study. 

These gigantic plant-eating dinosaurs, iconic for their long necks and tails, roamed Earth in the Jurassic epoch as early as 201 million years ago. But it was not until 145 million years ago that they started evolving into bigger sizes—10 times the height of the modern-day African elephant. When paleontologists found the first sauropod tracks a century ago, Jannel says, the footprints seemed to show the animals were walking on heels. This led some paleontologists to speculate that giant dinosaurs had a kind of heel pad when walking—although there was no evidence to definitively support the theory. Hundred-year-old technology was unable to study soft tissue in fossils, which are rarely preserved in rock to begin with. 

[Related: Even dinosaurs couldn’t escape the sniffles]

Jannel and his co-authors created a new approach to study dinosaur foot anatomy that included the bones and soft tissue. Using fossil data from the Upper Triassic to the Upper Jurassic epoch, the researchers created 3D virtual models from five different sauropod species, which weighed between 1,984 to 74,957 pounds. They also created a model based on the foot of an existing African elephant. Virtually reconstructing the foot postures allowed them to track how the sauropods would walk on dry land with and without a soft tissue foot pad. 

Soft tissue pads underneath the heel were necessary for sauropod dinosaurs to walk without causing tissue damage or breaking any bones. Similar to elephants, the pad cushion directed the loads away from the bones.

Study author Olga Panagiotopoulou, a senior lecturer of anatomy and developmental biology at Monash University, says the idea of fleshy foot pads came from looking at the fat pads found in elephants, rhinoceroses, and other living giants. These animals evolved bottom cushions to serve as shock absorbers to redistribute the pressure on their feet. Panagiotopoulou says a 2011 study, which found that ancestral elephants evolved to have large foot fat pads as they grew in size, partly inspired their hypothesis that sauropods had similar structures to reduce the stress on their bones and avoid fractures.

[Related: Dinosaurs who stuck together, survived together]

Smaller members in the sauropod family, the scientists found, also shared their version of a cushy foot pad. Using the fossilized tracks of sauropod precursors known as Plateosaurus, the researchers created a reconstruction of their foot that had toes slightly raised off the ground with no heel pad. The results indicate there was no way the foot skeleton alone could support their weight without some form of additional padding. “Our work suggests that the presence of an incipient heel pad in sauropod precursors laid the foundations for the evolution of a more substantial structure,” says Jannel. 

Kimberley Chapelle, a Kalbfleisch postdoctoral fellow in the American Museum of Natural History’s Division of Paleontology who was not affiliated with the study, says before this paper, no other studies tested the theory of whether sauropods had fatty pads in their feet. “This provides yet another puzzle piece to how sauropod dinosaurs got so big.” Although Chapelle says her only reservation would be that, while the study methods were tested on a modern-day elephant, “it would have been useful to see what predictions the models made for other living animals that have fat pads such as camels and rhinos, as well as those who don’t.”

With evidence for fatty foot pads in sauropod dinosaurs, Panagiotopoulou says she is planning to investigate how exactly they distribute the stress of walking by studying the foot mechanics of elephants, rhinoceroses, and horses. 

Jannel, on the other hand, is working to expand the 3D computational models to an entire sauropod limb—complete with soft tissue such as muscles, which are also rarely preserved in fossils. “This research and methodology are relatively new in the field of paleontology,” he explains. “So stay tuned, because this has a lot of potential for more research in the future, not only in sauropods but also other dinosaurs and prehistoric animals!”

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Pandas love bamboo, but they might not have acquired a taste for this bitter, nutty-flavored plant until recently. Paleontologists discovered the fact while studying a newly described relative to giant pandas, named Agriarctos nikolovi, which hung out in Europe a few million years ago and sported a smaller set of teeth than their modern family. The findings, published on July 31 in the Journal of Vertebrate Paleontology, suggest the panda species was likely the last to live in Europe.

The fossil teeth were first unearthed in the late 1970s in northwestern Bulgaria in coal deposits that blackened the chompers. Because the Bulgarian National Museum of National History did not clearly list the specimens in their catalog of fossilized treasures, they remained untouched in storage until an accidental discovery by staff 40 years later.

“They had only one label written vaguely by hand,” Nikolai Spassov, a paleontologist and museum professor at Sofia University in California, explained in a press release. “It took me many years to figure out what the locality was and what its age was. Then it also took me a long time to realize that this was an unknown fossil giant panda.”

The upper canine and upper molar of the dental sample trace back to a species closely related to today’s giant pandas, which only live in southwest China. The ursids roamed the forested and swampy areas of Europe nearly 6 million years ago in the Miocene epoch. A. nikolovi had smaller teeth than present-day pandas, but bigger ones than other panda species of that time period. The study authors hypothesize that through evolution, the mammals’ canines and molars likely grew to protect them from predators. Bigger teeth also require a bigger mouth, suggesting these pandas were similar in size or just slightly smaller to present-day pandas.

[Related: Pandas have cute markings because their food supply sucks]

While this isn’t the first prehistoric panda found in Europe, the majority of the other specimens date back to around 10 million years ago. Given that the fossilized teeth at the Bulgarian National Museum of National History are more recent, it’s probable they belonged to the last panda species on the European continent. Though they are closely related, A. nikolovi is more of a cousin than a direct descendent of giant pandas. Previous research suggests the oldest direct descendent of the giant panda is a species found in Spain called the Kretzoiarctos beatrix. It existed at least 11.6 million years ago. 

Of further note, A. nikolovi was vegetarian, though bamboo was probably not part of its diet. Today’s giant pandas have strong jaws and large, flat teeth to help grind up the leaves, stem, and stalks of the sturdy plant. Bamboo makes up 99 percent of a giant panda’s diet: Adults can eat 26 to 83 pounds of it every day. But A. nikolovi’s smaller teeth indicate it probably did not have the strength to chew and mash up the plant’s tough and inedible stalks, and opted for softer greens for nourishment instead. 

“The likely competition with other species, especially carnivores and presumably other bears, explains the closer food specialization of [modern] giant pandas to vegetable food in humid forest conditions,” Spassov said in the press release.

So how did A. nikolovi go extinct? Climate change, and specifically the drying up of the Mediterranean basin, might have affected the entire ecosystem of plants the mammals thrived on. While this idea is still under investigation, paleontologists speculate that similar environmental conditions could have propelled other closely related panda species like Kretzoiarctos beatrix to move out of Europe and into Asia 8 million years ago. From there, ancient pandas would evolve into the Ailuropoda, making up the playful bamboo lovers we know today.

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At the end of the last Ice Age, 11,700 years ago, only babies would have been able to digest lactose, one of the key sugars in milk. Being able to do so into adulthood is a new development in our evolution. It’s especially common in people of European, South Asian, Middle Eastern, and West African descent, and evolved so quickly that it’s the textbook example of human adaptations to agriculture.

But according to new research published this week in the journal Nature, ancient humans in Europe drank lactose, even without being able to digest it. Only when famine and disease turned lactose into a liability did adults hang onto lactase, the key enzyme that breaks down the sugar.

“What we’ve shown is the received wisdom is erroneous,” says study co-author Richard Evershed, an archaeological and paleo-chemist at the University of Bristol. The textbook story is that the lucky few milk-drinkers got some kind of advantage from the beverage—maybe it let them grow faster, or gave them extra vitamin D in dark Northern latitudes—that led to the proliferation of lactase-processing genes.

The speed with which Europeans picked up lactose tolerance means that people without it must have been at an extreme disadvantage. “You’ve got to kill somebody to have [that kind of] selection, to put it bluntly,” Evershed says. 

The new story of milk-drinking unfolds through three lines of evidence. The first is a map of nearly 13,000 ancient pottery fragments collected from Portugal to Turkey to Finland. Although the contents of the pots were long dried up, animal fats leave distinctive residues—which allows researchers, 9,000 years later, to tell if they held milk.

[Related: How to make oat milk—with science]

Those ancient films show that milk drinking is essentially as old as farming, and spread into Europe as early as 6,500 BCE, 3,000 years before the rise of lactase in adults, or lactase persistence.

So how did farmers who couldn’t process lactose end up drinking milk? It turns out that the health effects of lactose intolerance are often blown out of proportion, George Davey Smith, an epidemiologist at the University of Bristol, and another author, says. Bloating, gas, and other purported signs of lactose intolerance are less common than people think. And while undigested lactose can cause diarrhea, so can coffee, prunes, and plenty of other enjoyable foods.

Using the 500,000-person genetic database UK Biobank, the researchers found that well over 90 percent of people who can’t process lactose still drink cow’s milk. It turns out that lactose tolerance just isn’t a big factor in determining your ability to stomach cow juice. “One of my co-authors only did a lactose test when she was part of the project,” says Evershed. “She found she was lactose intolerant, and she’d been drinking milk. She had no hint of it.” Some who don’t naturally produce lactase can still digest it with the help of an adapted gut biome. Others produce the enzyme to digest the sugar, but are allergic to another part of milk.

“It became clear that people could happily drink milk,” enzyme or no, says Davey Smith.

But if milk goes down so easily, that leaves another mystery: Why would ancient Europeans so quickly have developed lactose tolerance, if they didn’t need it?

The key is in understanding what happens when times get bad. In a person who can’t process milk sugar, the excess sits in a little wad in the colon. “The undigested lactose sort of sucks water out,” Davey Smith says, sometimes causing diarrhea. That’s not always a problem—but when a person is malnourished, or sick with an intestinal disease, the lactose poops can make them sicker.

On a population level, during disease outbreaks or famines, milk could turn from a source of calories into a kind of poison. And, based on the genes of ancient European bones, it was the ability to resist that poisoning that drove lactose tolerance across the continent.

[Related: Heat stress might curdle the dairy industry]

By lining up the map of ancient milk-vessels, the presence of the enzyme in ancient genes, and the frequency of ancient skeletons, the researchers found that people who drank milk faced no evolutionary pressure to digest lactose. “This pulls the rug out from under the feet of just about every theory for why that natural selection was there,” says Mark Thomas, a study co-author and expert in human evolution at University College London. “Milk use doesn’t explain anything.”

Instead, bumps in lactase persistence were best explained by evolutionary pressure during population crashes. “Those drops in population almost certainly indicate famines,” says Thomas. And famines would have had a two-fold effect. When food was scarce, ancient farmers would have eaten up all their low-lactose yogurts and cheeses first. Once crops fail, “they’re going to be left only with fresh milk,” Thomas says. Couple high-lactose foods with severe malnourishment, and diarrhea is no longer inconvenient—it’s fatal. 

Dense populations, measured via the distribution of skeletal remains, also explained some of the pressure towards lactase persistence. This, the researchers believe, happened as children—still young, but too old to produce lactase—were increasingly exposed to the threat of lactose diarrhea and intestinal infectious diseases that thrived in close quarters. The combination of those forces largely explain how, by the beginning of the Iron Age, roughly 3,000 years ago, lactase persistence had become so common.

That timeline also contradicts a theory that the adoption of agriculture, roughly 10,000 years ago, left humans sicker and malnourished, Davey Smith says. “It doesn’t fit in with the chronology… which says agriculture is the worst mistake humans ever made—that’s what I thought we’d find. It turns out it was 5,000 years later.”

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The 1947 children’s novel Misty of Chincoteague opens with a dramatic account of a small herd of horses escaping from the wreck of a colonial-era Spanish galleon. According to local folk stories, these same hardy animals thrived on the islands of Chincoteague and Assateague, which lie off the coasts of Maryland and Virginia. 

Scholars have long debated the likelihood of this origin story about the population of feral ponies that have made the islands famous. A new genetic analysis of a 16th-century horse tooth from the Caribbean doesn’t settle this question, but does offer some indirect support for the shipwreck tale’s plausibility.

Researchers found that the tooth fragment, which was discovered in present-day Haiti, belonged to a horse of southern European origin. Additionally, the specimen is most closely related to the Chincoteague pony breed, the team reported today in the journal PLoS ONE. 

“This helps us to have a better idea of what the origins of these early colonial horses are,” says Nicolas Delsol, a zooarchaeologist at the Florida Museum of Natural History in Gainesville and coauthor of the findings. “There is some documentary evidence from the historical literature stating that horses were boarded in southern Spain, where most of the first expeditions came from, but it’s always interesting to see how accurate these early colonial chronicles are.”

Michelle Delco, an equine orthopedic surgeon and assistant research professor at the Cornell University College of Veterinary Medicine who wasn’t involved with the research, said the findings “fill in a major gap.” 

“There is a lot of historical evidence that the modern domestic horse was introduced to the Americas from the Iberian peninsula around 1500, but we have surprisingly limited archeological and scientific evidence about this,” she said in an email.

[Related: Ancient sea creatures pioneered the gallop]

The horse family (whose members are known as equids) evolved in North America roughly 50 million years ago and spread to Eurasia around 2.5 million years ago. Equids disappeared, along with many other large animals, from the Western Hemisphere around 10,000 years ago. In the late 15th century, however, domesticated horses were brought to the Americas during the European invasion.

“Because they were so central to the European lifestyle, they brought [the horses] with them,” Delsol says. “They first were introduced in the Caribbean islands, where the first European settlements were, and then diffused throughout the continent along with the developments of European colonization.”

The tooth he and his collaborators analyzed was excavated in 1980 from a 16th-century town known as Puerto Real on Hispaniola, the island shared by the Dominican Republic and Haiti. The specimen dates to a period when occupation was sparse after Spanish authorities ordered the island’s northern ports abandoned in the 1570s in response to persistent pirate raids and smuggling. 

The tooth fragment was initially misidentified as belonging to a cow. But when Delsol examined DNA from the specimen, he realized that the tooth actually came from the molar of an adult horse. “Since it was the earliest horse genome that we had, we decided it was worth working a bit more on it and seeing what it could tell us,” Delsol says.

He and his team investigated a kind of genetic material known as mitochondrial DNA, which is passed down only through the maternal line. Mitochondrial DNA isn’t confined to the nucleus of a cell, which means it’s more abundant and easier to collect from ancient samples than nuclear DNA, Delsol says.

“Domesticated horses originated from a relatively small number of male ancestors and a great diversity of female ancestors,” said Delco, who studies the role of mitochondria in health and disease. “So, by fully reconstructing the mitochondrial genome of this early Caribbean horse, the authors could very specifically ‘place’ this individual in space and time—meaning both in the context of its origins from the Eastern Hemisphere, as well as its closest relatives among modern horses in the Americas.” 

The researchers determined that their specimen represents the oldest complete mitochondrial genome of a domestic horse in the Western Hemisphere. When they compared the Puerto Real horse’s genetic material with that of other breeds from around the world, the team concluded that it belonged to a group whose members are found in Central Asia, Southern Europe, and the Middle East—but not northern Europe. This suggests that the Puerto Real horse hailed from the Iberian Peninsula, which is occupied by Spain and Portugal. 

Additionally, the Puerto Real horse’s closest relatives turned out to be the feral ponies of Chincoteague and Assateague. This doesn’t necessarily mean that the ponies’ ancestors fled from a Spanish shipwreck, Delsol emphasizes, but it “gives more historical accuracy to this story.” 

Delco, who grew up reading the tale of Misty of Chincoteague, was excited to see a study put actual data and genetic findings behind these fables. “At the age of about 10, I persuaded my parents to take me to the Assateague Island National Seashore and will never forget the rainy, sandy week we spent with the wild ponies,” she said. “This scientific manuscript suggests the legendary origin story of the Chincoteague pony is true. It’s not often that reading a science paper gives me goosebumps.”

Beyond folk stories, Delsol adds, the ties between this Caribbean horse and the Chincoteague ponies may reflect an early Spanish presence along the Atlantic coast of North America. 

[Related: Ancient wolf DNA is being used to sniff out where our love story with dogs began]

“What we consider the different colonial spheres of influence—the French, the British, the Spanish—at that time weren’t completely watertight,” Delsol says. “Everybody was pretty much everywhere.”

However, the team acknowledges that the findings focus on a single horse and only include its mitochondrial DNA, which means that the tooth  “only gives us the story of the maternal lineage,” Delsol says. “To be more thorough, we would include an analysis of the paternal lineage.” Although DNA degrades more quickly in tropical climates, he’s successfully extracted snippets of nuclear DNA from similarly-aged cattle specimens and suspects it will be possible to do the same with the Puerto Real horse. Delsol and his team also plan to expand their analysis to the remains of other horses from Puerto Real.

The findings demonstrate how fragments of genetic material from organisms that died a long time ago, known as ancient DNA, can shed light on historical events.

“Ancient DNA is quite often associated with very remote periods of time and really ancient specimens, but it can also be pretty useful to clarify more recent history,” Delsol says. “Part of this history is the colonization of the Americas and how animals were a central part of the establishment of Europeans on the continent.”

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Nearly 20 years ago, scientists discovered a fossil in the Canadian Arctic that represented a transitional stage between marine and land-dwelling animals. Tiktaalik roseae—nicknamed a “fishapod,” or a fish with limbs—used its muscular front fins to prop itself up in shallow waters or on mudflats. 

But the course to dry land doesn’t always run smoothly. At least one close relative of Tiktaalik decided to return to the life aquatic, researchers reported on July 20 in Nature. A smaller fossil excavated from the same area as Tiktaalik shares some features with its land-curious cousins, but it has a fin much better suited for swimming than crawling. The ancient lobe-finned fish, which the team named Qikiqtania wakei, sheds light on a mysterious chapter of vertebrate evolution.

“This is a really unexpected variation in the group right at the cusp of the water-land transition,” says Thomas A. Stewart, an evolutionary biologist at Pennsylvania State University and coauthor of the findings. “It shows that there was a diversity of animals doing all kinds of different things.” 

Alice Clement, an evolutionary biologist and paleontologist who studies early vertebrates at Flinders University in Adelaide, Australia, described the work as a “lovely study.” 

“New finds such as this help us to piece together the sequence of characters acquired in the lead up to the colonization of land by our terrestrial ancestors,” she said in an email. More samples of this enigmatic group, she added, would help “confirm the authors’ interpretation about a possible ‘return to the water.’” 

The Qikiqtania fossil was first collected in 2004 on southern Ellesmere Island in Nunavut. “It was found because of bad weather,” recalls Neil H. Shubin, an evolutionary biologist at the University of Chicago and another coauthor of the study. He and his collaborators couldn’t access the site where, several days later, they would discover Tiktaalik, so the team searched for fossils near their camp. Among the finds was a block of rock with scales and part of a jaw exposed. The specimen “kind of sat in the drawer for 15 years,” Shubin says, before his colleagues began to examine it in detail. 

[Related: This ancient bony fish was a sexual pioneer]

The team initially suspected that the fish was a young Tiktaalik, Stewart says. But when they used CT scanning to get a better look at the fossil embedded within the rock, they realized that the creature’s upper arm bone had some unique characteristics.

“The surprise for us really was in the shape of the humerus, which suggested that this is not an animal that could support its body with its fins like Tiktaalik and like tetrapods,” Shubin says, referring to four-limbed animals with backbones. “This is an animal probably more suited for open-water habitats.”

The fossil included the lower jaws, partial upper jaws, fragments of neck bone, scales from various parts of the body, and the left pectoral fin. Qikiqtania was named for the Inuktitut word Qikiqtaaluk/Qikiqtani, the region where the fossil was found. The researchers estimate that it lived roughly 375 million years ago, making it slightly older than Tiktaalik. Qikiqtania would have reached about 2.5 feet in length and had an elongated body with a broad and paddle-like fin, sharp teeth, and eyes perched on top of a flat head.

To determine where Qikiqtania belonged on the prehistoric family tree, the researchers used the CT scans to create 3D reconstructions of the fossil and compared it to 12 other species. The team calculated how closely the anatomy of Qikiqtania resembled that of other early vertebrates by comparing 125 traits between the fossils.

“This animal is related to the first limbed vertebrates—the first animals with hands and feet,” Stewart says. However, “its humerus is quite distinct from other creatures that are closely related to it.”

In Qikiqtania, this arm bone is relatively small and shaped like a boomerang, whereas Tiktaalik has a blocky, angular humerus. Additionally, Qikiqtania lacks the ridges and crests in the bone that its relatives have where pectoral muscles were attached. “It’s not a humerus that could do a pushup,” Shubin says. 

Some evolutionary biologists are skeptical these unusual features represent a truly new find. Per Ahlberg, who studies vertebrate evolution at Uppsala University in Sweden, isn’t convinced that Qikiqtania is a different species from its cousin Tiktaalik. One possibility is that the distinctive humerus is “lightly ossified and crushed, which could affect the interpretation,” Ahlberg said in an email, adding that he hopes to examine the bone in more detail.

Still, he said, the new report is “an interesting paper that puts forward some novel ideas.”

[Related: An archerfish family tree is the best shot yet at the evolution of sniper fish]

Other species ancestral to Qikiqtania had fins that could support their bodies, suggesting that Qikiqtania returned to the water after its relatives crawled onto land.

“It’s a specialization which is fascinating because it’s showing that the transition from life to water to life on land is a bit more complex,” Shubin says. “You have some creatures evolving to walk on land or the water bottom, and others are evolving to open-water habitats; it’s going both ways.”

It’s not clear why Qikiqtania took to the water, but the researchers have a few guesses. “There’s a lot of meat in the water,” Shubin says. Qikiqtania’s skull has a few features that it shares withTiktaalik, indicating the fish could both bite and suck—a powerful edge while hunting. “This animal was probably able to do that as well,” Shubin speculates. “It had certain advantages to return to water in that way.”

The researchers hope to find more complete Qikiqtania specimens on future expeditions. A well-preserved shoulder or pelvis could reveal how the creature moved through the water. “What was its gait, how did it use the hind fins, how did it paddle?” Shubin says. “We don’t have enough of the anatomy to know those details.”

The post Tiktaalik’s ancient cousin decided life was better in the water appeared first on Popular Science.

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WHEN I MET my cat Pearlita, she lived in an alley between my apartment building and a gas station. She drank from puddles polluted by engine leaks and ate whatever she could find. Ten years later, with Pearlita curled up on my lap, making it hard to type, I can still remember how she wolfed down the food I put in the alley and how easy it was to lure her inside with more.

But does she remember her life on the streets? And if so, which parts of it?

This question has probably occurred to almost anyone with an animal friend, but for simplicity’s sake, we’ll limit this discussion to our feline and canine companions. Certainly they behave as though they have memories—after all, your special furball doesn’t treat you like a stranger each time you walk through the door—and evolutionary theory suggests as much: It behooves any long-lived animal to have long-lasting recollections. There have been rigorous scientific experiments, too, not enough to fully understand our dogs’ and cats’ memories, but enough to confirm their existence and to raise some interesting questions about how they compare to our own.

“It is tricky, because we can’t directly ask them,” says Mikel Delgado, an animal psychology researcher from the University of California, Davis who now dispenses advice on cat behavior with the company Feline Minds. “The way I think about it is: What’s important for animals to remember?”

For a cat or dog—or human—to remember events from way back, they must first be able to recall what happened just a few moments ago. To study this in controlled settings, scientists devise experiments in which animals are rewarded for correctly identifying objects they previously saw, asked to avoid obstacles without looking at them, or monitored while searching for food they saw being hidden. These methods don’t capture everything that cats and dogs can recall, of course; they’re intended to tease out the basics of their cognition.

A few decades’ worth of data have shown that the species do indeed have short-term recall, and they convert certain events and interactions into long-term memories as they sleep and, crucially, dream. “Dreaming is often connected to the reorganization of memory,” says Ádám Miklósi, an ethologist and canine cognition specialist at Hungary’s Eötvös Loránd University. Both dogs and cats display the telltale neurological signatures of REM, short-wave sleep, and other patterns of snoozing that, in human and rat brains, are linked to the sorting of a day’s experiences.

One of the best-documented examples of long-term memories in dogs involves Chaser, a border collie famous for learning the names of more than 1,000 objects in three years. Impressive as that is, however, such semantic feats don’t necessarily mean that Chaser, who died in 2019 at the ripe old age of 15, could remember his puppyhood. That requires so-called episodic memories containing the details of an experience, the who-what-when-where.

Until recently, scientists thought the canine mind was limited to associative memories: recollections of the relationships between experiences or events, but not the intricacies of the experiences and events themselves. Were that the case, then every time my dearly departed dog Comet climbed into our car the moment my parents started packing it, she wouldn’t have remembered the canoe rides, swims, and roasted marshmallows of past trips. Comet would simply have learned to identify the preparations with fun.

But in recent years, research conducted by Miklósi and his colleague Claudia Fugazza has shaken the idea that canines are restricted to such Pavlovian recall. In 2016 they confirmed, by way of an experiment in which they asked dogs to imitate actions modeled by a human minutes earlier, that the pooches did remember specific elements of what they’d experienced. In follow-up experiments, dogs repeated their own actions long after they first performed them, a finding that added an autobiographical layer to their episodic memories. Their thoughts didn’t just contain a jumble of disparate details, but were woven together by a sense of self.

As for cats, tests of whether they returned to containers where they were previously fed lend scientific support to their version of episodic memory. “Cat memory is probably very much like dog memory,” says Miklósi.

Still, he and Delgado note that this kind of reminiscence might differ from our own. Humans can reflect on their memories in spontaneous, self-directed ways: I can think about the first concert I ever attended, a Pink Floyd show, without needing to see the ticket stub to remind me of it. How cats and dogs guide their own recall—if they need cues to trigger it or have a proclivity, like us, for wandering the halls of memory—is a mystery.

It’s also less clear how our furry companions relive their distant memories. Mine play like a movie in my mind’s eye, which fits, as contemporary humans are a visually oriented species. But cats and dogs are far more reliant on other senses, especially smell. Could their recall come together as scents rather than images? Two studies—of dogs in a dark room finding familiar objects with their noses, and of kittens recognizing their mothers by scent after years of separation—suggest as much. “Animals, I’m sure, are much more multisensory,” Delgado says. “Their memories might be scent or sound and not necessarily the images that we tend to picture when we’re replaying an episode in our minds.” I can still see my first encounter with Pearlita. Perhaps she can still smell it.

Delgado also raises the question of language. In addition to being visually driven, human memories are structured by words and complex grammar, which some experts think is crucial to the power of recall. And while dogs and cats don’t have full-blown human-style language, they are able to communicate and represent meaning through sounds, postures, facial expressions, and other signals. Maybe memories formed without language are simply different, not weaker. They could even be more intense: less complex but undiluted by linguistic abstraction or, as Delgado points out, the second-guessing, what-if scenarios that humans tend to indulge in.

This and certain other questions about how cats and dogs perceive the past might prove impossible to illuminate scientifically and ethically. To empirically determine, for example, how adopted animals recall their people, we’d need to separate them from family for months—even years. “I’m okay with mystery,” Delgado says. “I’ve learned to live with the fact that there’s still so much we don’t know.” The details may be blurry, but it’s enough to know that our cats and dogs remember.

We hope you enjoyed “Pet Psychic,” Brandon Keim‘s new monthly column. Check back on PopSci+ for the next article in August.

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