By Kathryn Hulick Dolphins whistle, humpback whales sing and sperm whales click. Now, a new analysis of sperm whale codas — a unique series of clicks — suggests a previously unrecognized acoustic pattern. The finding, reported November 12 in Open Mind, implies that the whales’ clicking communications might be more complex — and meaningful — than previously realized. But the study faces sharp criticism from marine biologists who argue that these patterns are more likely to be recording artifacts or by-products of alertness rather than language-like signals. For decades, biologists have known that both the number and timing of clicks in a coda matter and can even identify the clan of a sperm whale (Physeter macrocephalus). Sperm whales in the eastern Caribbean Sea off the coast of Dominica, for example, often use a series of two slow and three quick sounds: “click…click… click-click-click.” Relying on artificial intelligence and linguistics analysis, the new study finds that sometimes this series sounds more like “clack…clack… clack-clack-clack,” says Shane Gero, a marine biologist at Project CETI, a Dominica-based nonprofit studying sperm whale communication. Project CETI linguist Gašper Beguš wonders about the meanings a coda might convey. “It sounds really alien,” almost like Morse code, says Beguš, of the University of California, Berkeley. Based on his team’s result, he now speculates that sperm whales might use clicks or clacks “in a similar way as we use our vowels to transmit meaning.” Not everyone agrees with that assessment. The comparison to vowels is “completely nonsense,” says Luke Rendell, a marine biologist at the University of St. Andrews in Scotland who has studied sperm whales for more than 30 years. “There’s no evidence that the animals are responding in any way to this [new pattern].” © Society for Science & the Public 2000–2025

Keyword: Language; Animal Communication
Link ID: 30013 - Posted: 11.15.2025

By Katarina Zimmer The 10 snakes faced a tough predicament. Collected from the Colombian Amazon, they had been without food for several days in captivity and then were presented with extremely unappetizing prey: three-striped poison dart frogs, Ameerega trivittata. The skin of those frogs contains deadly toxins — such as histrionicotoxins, pumiliotoxins and decahydroquinolines — that interfere with essential cell proteins. Six of the royal ground snakes (Erythrolamprus reginae) preferred to go hungry. The other four intrepidly slithered in for the kill. But before swallowing their meals, they dragged the frogs across the ground — akin to the way some birds rub toxins off their prey, noted biologist Valeria Ramírez Castañeda of the University of California, Berkeley, and her colleagues, who conducted the experiment. In a recent study, some royal ground snakes dragged poison frogs along the ground before eating them, probably in an effort to rub off some of the frogs’ deadly toxins. Three of the four snakes survived the meal — suggesting that their bodies were capable of handling the toxins that remained. Living beings have been wielding deadly molecules to kill each other for hundreds of millions of years. First came microbes that used the chemicals to weed out competitors or attack host cells they were invading; then animals, to kill prey or ward off predators, and plants, to defend against herbivores. In response, many animals have evolved ways to survive these toxins. They sometimes even store them to use against opponents.

Keyword: Neurotoxins; Evolution
Link ID: 29989 - Posted: 10.29.2025

By Roberta McLain Two small genetic changes reshaped the human pelvis, setting our early ancestors on the path to upright walking, scientists say. One genetic change flipped the ilium — the bone your hands rest on when you put them on your hips — 90 degrees. The rotation reoriented the muscles that attach to the pelvis, turning a system for climbing and running on all four legs into one for standing and walking on two legs. The other change delayed how long it takes for the ilium to harden from soft cartilage into bone, evolutionary biologist Gayani Senevirathne of Harvard University and colleagues report in the Sept. 25 Nature. The result: a distinctive bowl-shaped pelvis that supports an upright body. While nonhuman primates can walk upright to some extent, they typically move on all fours. The newly identified changes to human pelvic development were “essential for creating and shifting muscles that are usually on the back of the animal, pushing the animal forward, to now being on the sides, helping us stay upright as we walk,” says coauthor Terence Capellini, a Harvard evolutionary biologist. The researchers examined tiny slices of developing pelvic tissue from humans, chimpanzees and mice under a microscope, and paired those findings with CT imaging. Human ilium cartilage grows sideways, not vertically as it does in other primates, the team found. What’s more, the cartilage transitions to bone more slowly than in nonhuman primates and in other human body parts. Together, these shifts allow the pelvis to expand sideways and maintain its wide, bowl-like shape as it grows. © Society for Science & the Public 2000–2025.

Keyword: Evolution
Link ID: 29986 - Posted: 10.29.2025

By Rachel Nuwer No one knows why magic mushrooms evolved to produce psilocybin, a powerful psychedelic molecule. But this trait was apparently so beneficial for fungi that it independently evolved in two distantly related types of mushrooms. An even greater surprise to biologists was that rather than arriving at the same solution for producing psilocybin, the two groups pursued completely different biochemical pathways, according to a study published last month in the journal Angewandte Chemie International Edition. “This finding reminds us that nature finds more than one way to make important molecules,” said Dirk Hoffmeister, a pharmaceutical microbiologist at Friedrich Schiller University Jena in Germany and an author of the study. He added that it was also evidence that mushrooms were “brilliant chemists.” Practically speaking, Dr. Hoffmeister said, the research also suggested a possible new path for synthesizing psilocybin for use in scientific research and therapies. “We can expand our toolbox,” he said. Psilocybe and Inocybe mushrooms occur in some of the same habitats, but they follow different lifestyles. Psilocybe, the group that includes what are traditionally called magic mushrooms, thrives on decaying material such as decomposing organic matter or cow dung. Inocybe, commonly known as fiber caps, are symbiotic organisms that form intimate, mutually beneficial relationships with trees. In 1958, Albert Hofmann, the Swiss chemist who discovered LSD, became the first researcher to isolate psilocybin from Psilocybe mushrooms. Some scientists later suspected that a few Inocybe mushrooms also produced the compound. Since then, psilocybin has been identified in around half a dozen Inocybe species. (The other species tend to produce a potent neurotoxin.) © 2025 The New York Times Company

Keyword: Drug Abuse; Evolution
Link ID: 29985 - Posted: 10.25.2025

By Keith Schneider Jane Goodall, one of the world’s most revered conservationists, who earned scientific stature and global celebrity by chronicling the distinctive behavior of wild chimpanzees in East Africa — primates that made and used tools, ate meat, held rain dances and engaged in organized warfare — died on Wednesday in Los Angeles. She was 91. Her death, while on a speaking tour, was confirmed by the Jane Goodall Institute, whose U.S. headquarters are in Washington, D.C. When not traveling widely, she lived in Bournemouth, on the south coast of England, in her childhood home. Dr. Goodall was 29 in the summer of 1963 when National Geographic magazine published her 7,500-word, 37-page account of the lives of primates she had observed in the Gombe Stream Chimpanzee Reserve in what is now Tanzania. The National Geographic Society had been financially supporting her field studies there. The article, with photographs by Hugo van Lawick, a Dutch wildlife photographer whom she later married, also described Dr. Goodall’s struggles to overcome disease, predators and frustration as she tried to get close to the chimps, working from a primitive research station along the eastern shore of Lake Tanganyika. On the scientific merits alone, her discoveries about how wild chimpanzees raised their young, established leadership, socialized and communicated broke new ground and attracted immense attention and respect among researchers. Stephen Jay Gould, the evolutionary biologist and science historian, said her work with chimpanzees “represents one of the Western world’s great scientific achievements.” On learning of Dr. Goodall’s documented evidence that humans were not the only creatures capable of making and using tools, Louis Leakey, the paleoanthropologist and Dr. Goodall’s mentor, famously remarked, “Now we must redefine ‘tool,’ redefine ‘man,’ or accept chimpanzees as humans.” © 2025 The New York Times Company

Keyword: Evolution; Animal Communication
Link ID: 29953 - Posted: 10.04.2025

By Lauren Schneider Bad news for mouse poker players: Their facial movements offer “tells” about decision-making variables that the animals track without always acting on them, according to a study published today in Nature Neuroscience. The findings indicate that “cognition is embodied in some surprising ways,” says study investigator Zachary Mainen, a researcher at the Champalimaud Center for the Unknown. And this motor activity holds promise as a noninvasive bellwether of cognitive patterns. The study builds on mounting evidence that mouse facial expressions are not solely the result of a task’s motor demands and provides a “very clear” illustration of how this movement reflects cognitive processes, says Marieke Schölvinck, a researcher at the Ernst Strüngmann Institute for Neuroscience, who was not involved with the work. For years, mouse facial movements have mostly served as a way for researchers to gauge an animal’s pain levels. Now, however, machine-learning technology has made it possible to analyze this fine motor behavior in greater detail, says Schölvinck, who has investigated how facial expressions reflect inner states in mice and macaques. Evidence that mouse facial expressions correspond to emotional states inspired the new analysis, according to Fanny Cazettes, who conducted the experiments as a postdoctoral researcher in Mainen’s lab. She says she wondered what other ways the “internal, private thoughts of animals” might manifest on their faces. Two variables shape most mouse decisions over different foraging sites, the team found: the number of failures at a site (unrewarded licks from a source of sugar water) and the site’s perceived value (the difference between reward and failure). © 2025 Simons Foundation

Keyword: Emotions; Evolution
Link ID: 29950 - Posted: 10.01.2025

By Katarina Zimmer Few mammals sleep as deeply as the ampurta. When the blonde, rat-like marsupial returns to its burrow after a night of hunting in the Australian desert, it drifts into a slumber known as torpor. While many other mammals quickly burn through their energy reserves in order to maintain stable body temperatures as they fall asleep, ampurtas allow their bodies to cool down to as low as 50 degrees Fahrenheit, saving energy critical to survival in this harsh desert environment. “I’ve held some when they’re in torpor, and they feel like they’ve been in a freezer,” says wildlife ecologist Dympna Cullen of the University of New South Wales in Sydney. Instead of using their own energy to warm up again, upon waking, the animals drag themselves to the mouths of their burrows to soak up the morning sun. Some scientists say this energy-saving trick helped the ampurta—once thought doomed to extinction—to make a comeback during a severe drought. In what they call a “rare and hopeful conservation signal,” the authors document in a new study in Biological Conservation how, during a two-year drought that lasted from 2017 to 2019—one of the region’s harshest droughts on record—the vulnerable marsupials actually significantly extended their range, reclaiming a large chunk of lost habitat. “Everything crashes during a drought,” Cullen says, “so it was quite unexpected that not only were [ampurtas] increasing in abundance but also increasing their area of occupancy by quite a significant amount during a drought.” Like many other Australian mammals, the ampurta—the Aboriginal name for Dasycercus hillieri or the crest-tailed mulgara—once seemed like it might vanish from the Earth. Rabbits brought to Australia by European colonists in the 19th century wreaked ecological havoc on the continent. They ravaged Australia’s vegetation, robbing small native herbivores of cover and food, including some of the ampurta’s prey, such as smaller mammals. The rabbit boom also fed the spread of non-native foxes and cats, which picked off ampurtas and other native wildlife. But in 1996, the Australian government released a rabbit-killing virus to quash rabbit populations, which allowed some native species populations to recover. Ampurtas were downgraded from endangered in the mid-1990s to “vulnerable” in 2013, and eventually to a species of “least concern.” © 2025 NautilusNext Inc.,

Keyword: Sleep; Evolution
Link ID: 29949 - Posted: 10.01.2025

By Brandon Keim Should you meet a turtle basking on a log in the sun, you might reasonably conclude that the turtle is in a good mood. Granted, there has been little scientific evidence that reptiles experience such emotional richness — until now, at least. Researchers in England identified what they describe as “mood states” — emotional experiences that are more than momentary — in red-footed tortoises by administering cleverly designed tests that use responses to ambiguity as windows into the psyche. The results of the study, published in the journal Animal Cognition in June, could apply to many more reptiles and have profound implications for how people treat them. “There was an acceptance that reptiles could do these short-term emotions,” said Oliver Burman, who studies animal behavior at the University of Lincoln in England and is an author of the paper. “They could respond to positive things and unpleasant things. But the long-term mood states are really important.” As for why it took so long to show this in reptiles, Dr. Burman said, “maybe we just haven’t asked them correctly.” Reptiles have a longstanding reputation as being unintelligent. Writing in 1892, Charles Henry Turner, the pioneering comparative psychologist, described reptiles as “intellectual dwarfs.” Eight decades later, in 1973, prominent scientists were referring to them as “reflex machines” and (in a paper titled “The Evolutionary Advantages of Being Stupid”) as possessing “a very small brain which does not function vigorously. Dr. Burman is among the scientists responsible for what some have called a “reptilian renaissance.” An array of findings — tortoises learning from one another, snakes with social networks, crocodiles displaying complex communication — indicate that reptiles are no less brainy than mammals and birds. © 2025 The New York Times Company

Keyword: Emotions; Evolution
Link ID: 29938 - Posted: 09.20.2025

By Sara Kiley Watson Humans started brewing alcohol for consumption thousands of years ago, and researchers have suggested that our ability to break down booze in our bodies has evolutionary roots dating back millions of years. Alcohol, known to scientists as ethanol, occurs naturally throughout nature, when microbes like bacteria and yeast break down sugars. This process of fermentation, harnessed by humans since ancient times, has given us the gifts of cheese, pickles, and wine, among other delights.* Nautilus Members enjoy an ad-free experience. Log in or Join now . But humans are far from the only creatures that imbibe—aye ayes, a species of lemur, will seek out nectar with a higher alcohol content, and spider monkey urine has been found to contain secondary metabolites of alcohol. Wild chimps, with whom humans share over 95 percent of our DNA, were caught on film snacking on fermenting fruit with their buddies earlier this year. Now, for the first time, researchers have discovered just how much alcohol some chimps are getting out of their fermented fruit snacks. In a new paper published in Science Advances, a team of scientists from the United States and the Ivory Coast reported that, in the course of a day, the wild chimps in their study consumed about 14 grams of pure ethanol. That’s about the equivalent, adjusting for body mass, of a human imbibing more than one standard drink a day, says University of California, Berkeley graduate student and study author Aleksey Maro. “We can say, pretty officially, that animals are chronically ingesting ethanol, especially our chimpanzee relatives,” Maro says. Maro and his colleagues made their discovery by following around wild chimps at two national parks in Africa—Kibale in Uganda and Taï in Ivory Coast—and scooping up test samples of 20 species of ripe fruits that the chimps typically like to eat. What they found is that these fruits have an average alcohol content of around 0.26 percent by weight. That might not sound like much, but primatologists at these locations estimate that chimps eat a whopping 10 pounds—or some 7 to 14 percent of their body weight—of fruit a day. The apes tended to prefer a fig called the Ficus mucuso at Kibale and the plum-esque fruit from Parinari excelsa trees at Taï. These treats were among the fruits with the highest alcohol content. © 2025 NautilusNext Inc.,

Keyword: Drug Abuse; Evolution
Link ID: 29937 - Posted: 09.20.2025

By Viviane Callier All animals, from jellyfish to humans, need sleep. But how these wide-ranging organisms control that need has remained a mystery. It turns out that—in fruit flies, at least—sleep might be an “inescapable consequence” of aerobic metabolism, according to a new study. Mitochondria in Drosophila’s sleep-regulating neurons sense metabolic damage that accumulates during waking hours and trigger the pressure to sleep. “It’s a really beautiful contribution,” says Keith Hengen, associate professor of biology at Washington University in St. Louis, who was not involved in the work. The study explains how the brain integrates information from a metabolic thermostat to regulate sleep pressure, Hengen says. “That’s a really hard problem, and I think they’ve nailed it.” The regulators of sleep are distinct from the function of sleep, Hengen and other sleep researchers note. Just as fullness regulates food intake, but food intake doesn’t so much serve to fill the stomach as to get calories and nutrients, “we need to make this distinction between sensing of sleep pressure and the function of sleep,” says Giorgio Gilestro, associate professor of systems neurobiology at Imperial College London, who was not involved in the new study. And with respect to sleep pressure, he adds, there are two processes at play: a well-studied circadian clock mechanism that links sleep to daylight cycles, and a less-understood homeostatic process that fine-tunes the need for sleep based on other factors. © 2025 Simons Foundation

Keyword: Sleep; Evolution
Link ID: 29923 - Posted: 09.10.2025

By Carl Zimmer Charles Darwin unveiled his theory of evolution in 1859, in “On the Origin of Species.” But it took him another 12 years to work up the courage to declare that humans evolved, too. In “The Descent of Man,” published in 1871, Darwin argued that humans arose from apes. And one of the most profound changes they underwent was turning into upright walkers. “Man alone has become a biped,” Darwin wrote. Bipedalism, he declared, was one of humanity’s “most conspicuous characters.” Scientists have now discovered some of the crucial molecular steps that led to that conspicuous character millions of years ago. A study published in the journal Nature on Wednesday suggests that our early ancestors became bipeds, as old genes started doing new things. Some genes became active in novel places in the human embryo, while others turned on and off at different times. Scientists have long recognized that a key feature for walking upright is a bone called the ilium. It’s the biggest bone in the pelvis; when you put your hand on your hip, that’s the ilium you feel. The left and right ilium are both fused to the base of the spine. Each ilium sweeps around the waist to the front of the belly, creating a bowllike shape. Many of the leg muscles we use in walking are anchored to the ilium. The bone also supports the pelvic floor, a network of muscles that acts like a basket for our inner organs when we stand up. As vital as the ilium is to everyday life, the bone can also be a source of suffering. The ilium can flare up with arthritis, grow brittle in old age, especially in women, and fracture from a fall. Genetic disorders can deform it, making walking difficult. The ilium also forms much of the birth canal — where babies can sometimes get stuck, endangering the mother’s life. © 2025 The New York Times Company

Keyword: Evolution
Link ID: 29906 - Posted: 08.30.2025

Nicola Davis Science correspondent Big hands might mean big feet, but it seems long thumbs are linked to large brains – at least in primates. Researchers say the results suggest the brain co-evolved with manual dexterity in such mammals. “We imagine an evolutionary scenario in which a primate or human has become more intelligent, and with that comes the ability to think about action planning, think about what you are doing with your hands, and realise that actually you are more efficient at doing it one way or another,” said Dr Joanna Baker, lead author of the research from the University of Reading. “And those that have longer thumbs or more ability to manipulate the objects in the way that the mind can see were likely to be more successful.” Large brains and manual dexterity are both thought to have played an important role in human evolution, with opposable thumbs a key feature that enabled a greater ability to grip and manipulate items – including tools. However, with some other primates having partly opposable thumbs, questions have remained over whether other changes in the hand – such as thumb length – could also be important in the evolution of tool use. “In general terms, you can say that the longer the thumb you have, the more motion you have to pick up and control small objects,” said Baker. To explore the issue Baker and colleagues studied the estimated brain mass and thumb length of 94 primate species, from five of our ancient hominin relatives to lemurs. The results, published in the journal Communications Biology, reveal humans and most other hominins have thumbs that are significantly longer than would be predicted based on the hand proportions of primates as a while. However, further analysis revealed an intriguing pattern. “When you have longer thumbs relative to your overall hand, that tends to come in conjunction with overall increased brain size,” said Baker. © 2025 Guardian News & Media Limited

Keyword: Evolution
Link ID: 29902 - Posted: 08.27.2025

By Marta Hill Most people flinch when a rat scurries into their path, but not one New York City-based research team: These researchers actively seek out urban rats to study their day-to-day behaviors and interactions. The work is part of a growing trend of neuroscientists studying animals in their natural environments rather than in the lab. “It’s a classic neuroscience model organism, but we don’t really know that much about their natural ecology,” says team member Emily Mackevicius, senior research scientist at Basis Research Institute. The fact that urban rats are ubiquitous presents a convenient opportunity for naturalistic study, adds Ralph Peterson, a postdoctoral fellow at the institute, who is also part of the team. Last year, Peterson, Mackevicius and their colleagues held a series of rat behavior stakeouts around New York City—in the Union Square subway station, in a wooded area of Central Park and on a street corner in Harlem. The team used thermal cameras to track the animals as they foraged in the dark and ultrasonic audio recorders to eavesdrop on rat vocalizations. Rats in the wild vocalize differently than laboratory rats, the team found. For example, lab rats typically emit calls at 22 kilohertz in negative contexts, such as when they sense danger, according to a 2021 review article. By contrast, the city rats used that frequency across more varied scenarios, including while they were foraging. The team posted their results on bioRxiv last month. “This creature that we see out at night all the time, running around, is actually vocalizing all the while, and we can’t hear it,” Peterson says. © 2025 Simons Foundation

Keyword: Animal Communication; Evolution
Link ID: 29893 - Posted: 08.20.2025

By Sofia Caetano Avritzer Vomiting up a droplet of sugar might not seem like the most romantic gesture from a potential suitor. But for one fly species, males that spill their guts are quite a catch. Drosophila subobscura flies’ peculiar “romantic” barfing might have evolved by repurposing brain cells that usually control digestion for more romantic pursuits, researchers report August 14 in Science. Most male fruit flies court by following the females around and vibrating their wings to serenade them with a species-specific love song, says Adriane Otopalik. But some fly species, like D. subobscura, spice things up a little. The males will vomit a bit of their last meal and offer it to females they are interested in, says Otopalik, a neuroscientist at Howard Hughes Medical Institute’s Janelia Research Campus in Ashburn, Va. Nuptial gifts like these are common in some animals, like male spiders attempting to win over their mates without getting their heads bitten off. Scientists think female flies, which can be “very choosy,” might use this romantic barf to pick suitable suitors, says Otopalik, who was not involved in the study. The thousands of neurons that control most of male fruit flies’ courtship produce a male-specific version of a protein called fruitless. Artificially activating these neurons can make D. subobscura males go through the motions of their seduction dance — even when there aren’t any females around, says Daisuke Yamamoto, an evolutionary biologist at National Institute of Information and Communications Technology in Kobe, Japan. Yamamoto and his collaborators wondered if somewhere in these courtship brain cells was the key to understanding how nuptial gift giving evolved. © Society for Science & the Public 2000–2025

Keyword: Sexual Behavior; Genes & Behavior
Link ID: 29890 - Posted: 08.16.2025

By Phie Jacobs When it comes to telling males and females apart, many bird species reject subtlety altogether. Roosters stand out thanks to their big, bright comb and ear-splitting “cock-a-doodle-doo.” Bachelor birds-of-paradise flaunt their vibrant plumage to attract more subdued females. And the male peacock’s feathered train is so ostentatious it famously threw even Charles Darwin for a loop. But that’s not the case for all bird species. When males and females look pretty much the same, scientists must try harder—often using DNA testing—to separate the sexes. According to a new study of wild Australian birds, these methods may be leading to misidentification in cases where an individual’s gonads and outward appearance don’t align with the genetic sex determined by its chromosomes. As scientists report today in Biology Letters, this phenomenon—known as sex reversal—may be more common than anyone expected. The discovery is likely to “raise some eyebrows” (or is it ruffle some feathers?), says Blanche Capel, a biologist at Duke University who wasn’t involved in the new work. Although sex determination is often viewed as a straightforward process, she explains, the reality is much more complicated. In humans, individuals with XX chromosomes typically develop as female, whereas those with XY chromosomes are usually male. But Judith Mank, a zoologist at the University of British Columbia, notes it’s the genes carried on those chromosomes—not the chromosomes—that are the main players. The SRY gene on the Y chromosome, for example, kick-starts male development in mammals. Anyone missing this key gene will end up developing as female, even if they have XY chromosomes. “We think of sex chromosomes as being sex determining,” says Mank, who also wasn’t involved in the new research. “That’s not true.” What’s more, it can matter how these genes are expressed on a cell-by-cell basis. In some species such as fruit flies, zebrafish, and chickens, individual cells have their own sexual identity based on the genes they happen to contain or express, rather than being influenced by the body’s overall hormone levels. When different cells contain different sets of chromosomes, this process can give rise to individuals called gynandromorphs, which exhibit both male and female characteristics. © 2025 American Association for the Advancement of Science.

Keyword: Sexual Behavior; Evolution
Link ID: 29886 - Posted: 08.13.2025

By Tim Vernimmen Mexican tetras are a most peculiar fish species. They occur in many rivers and lakes across Mexico and southern Texas, where they look perfectly ordinary. But unlike most other fishes, tetras also live in caves. And there, in the absence of light, they look dramatically different: They’re very pale and, remarkably, they lack eyes. Time and again, whenever a population was swept into a cave and survived long enough for natural selection to have its way, the eyes disappeared. “But it’s not that everything has been lost in cavefish,” says geneticist Jaya Krishnan of the Oklahoma Medical Research Foundation. “Many enhancements have also happened.” Though the demise of their eyes continues to fascinate biologists, in recent years attention has shifted to other intriguing aspects of cavefish biology. It has become increasingly clear that they haven’t just lost sight, but also gained many adaptations that help them to thrive in their cave environment, including some that may hold clues to treatments for obesity and diabetes in people. It has long been debated why the eyes were lost. Some biologists used to argue that they just withered away over generations because cave-dwelling animals with faulty eyes experienced no disadvantage. But another explanation is now considered more likely, says evolutionary physiologist Nicolas Rohner of the University of Münster in Germany: “Eyes are very expensive in terms of resources and energy. Most people now agree that there must be some advantage to losing them, if you don’t need them.” Scientists have observed that mutations in different genes involved in eye formation have led to eye loss. In other words, says Krishnan, “different cavefish populations have lost their eyes in different ways.”

Keyword: Evolution; Vision
Link ID: 29885 - Posted: 08.13.2025

By Tina Hesman Saey A snail may hold the key to restoring vision for people with some eye diseases. Golden apple snails (Pomacea canaliculata) are freshwater snails from South America. Alice Accorsi became familiar with the species as a graduate student in Italy. “You could literally buy them in a pet store as snails that clean the bottom of the fish tanks,” she recalls. Turns out, the snails are among the most invasive species in the world. And that got Accorsi thinking: Why are they so resilient and able to thrive in new environments? She began studying the snails’ immune systems and has now found they are not the only parts of the animals able to bounce back from adversity. These snails can completely regrow a functional eye within months of having one amputated, Accorsi and colleagues report August 6 in Nature Communications. Side-by-side images of snail eyes. On the left is a normal, intact snail eye. On the right is an eye that has regrown two months after it was surgically removed. The eyes look similar. They are both round with a black spot in the middle. A snail’s eye was surgically removed, but it grew a new one. Two months after amputation the new eye (right) looks much like the uninjured one (left).Alice Accorsi Scientists have known for centuries that some snails can regrow their heads, and research has revealed other animals can regenerate bodies, tails or limbs. But this finding is exciting because apple snails have camera-like eyes similar to those of humans. Understanding how the snails re-create or repair their eyes might lead to therapies to heal people’s eye injuries or reverse diseases such as macular degeneration. Accorsi, now a developmental biologist at the University of California, Davis, used the molecular scissors called CRISPR/Cas9 to genetically disable certain key genes involved in eye development and established lineages of snails carrying those mutations. © Society for Science & the Public 2000–2025.

Keyword: Vision; Regeneration
Link ID: 29879 - Posted: 08.06.2025

By Andrew Iwaniuk, Georg Striedter Sleep is the most obvious behavior that, in most animals, follows a circadian rhythm. But have you ever seen a bird asleep? Maybe you have, though they usually wake up before you get close enough to see whether they have their eyes closed. Moreover, just because an animal is still and closed its eyes, does that really mean it is sleeping? Maybe it is just resting. Conversely, might some birds sleep with one or both eyes open? Indeed, it is difficult to tell whether an animal is sleeping just by observing it. To overcome this problem, researchers may prod the animal to see whether it is less responsive at certain times of day. A more definitive method for demonstrating sleep in vertebrates is to record an animal’s brain waves (its electroencephalogram, or EEG), because these waves change significantly as an individual falls asleep and then progresses through several stages of sleep. In birds, the use of EEG recordings is essential because they can sleep with one or both eyes open, presumably so they can stay alert to threats. Ostriches, for example, tend to sleep while sitting on the ground, holding their head up high, and keeping both eyes open. They certainly look alert during this time, but EEG waves reveal that they are actually asleep Types and patterns of sleep An EEG measures the activity of many neurons simultaneously. In mammals, it is usually recorded from multiple electrodes placed over the neocortex; in birds, the electrodes are typically placed on top of the hyperpallium (aka the Wulst; see Chapter 1). In addition to performing an EEG, sleep researchers typically record the animal’s eye movements and an electromyogram (EMG), which is a measure of muscle activity, often characterized as muscle “tone.” These kinds of studies have revealed that, in mammals, the transition from the waking state to sleep is marked by a shift from EEG waves that are low in amplitude (i.e., small) and high in frequency (>20 Hz) to waves that are much larger but lower in frequency (1–4 Hz). Because the latter state is characterized by powerful low-frequency EEG waves (aka slow-wave activity), it is commonly called slow-wave sleep (SWS). The mechanisms that cause SWS are complicated and involve a variety of sleep-promoting processes. However, the large amplitude of these slow waves reflects that, during SWS, numerous neurons fire in rhythm with one another so that their electrical potentials sum when they are recorded through the EEG electrodes. © 2025 Simons Foundation

Keyword: Sleep; Evolution
Link ID: 29878 - Posted: 08.06.2025

By Bridget Alex More than 10 million years ago, ancestral apes in Africa rummaged through leaf litter for tasty morsels: fallen, fermenting fruit. Tapping this resource may have given some apes a nutritional boost, an advantage that could have paved the way for the evolution of our own alcohol tolerance. A study out today in BioScience adds support to this so-called “drunken monkey” hypothesis by examining just how often living apes indulge in fallen—presumably boozy—fruits. The research also gives this behavior a much-needed name: “scrumping.” The work provides “a fresh and useful perspective on the importance of fallen fruit,” says Amanda Melin, a biological anthropologist at the University of Calgary who was not involved with the research. She adds that scrumping “is an efficient and evocative way to describe this behavior” that she will use in the future. The form of alcohol we imbibe, ethanol, occurs naturally when yeast grows in fruits, saps, or nectars. Many animals, from elephants to songbirds, can get buzzed off these wild taps. Meanwhile, most human societies have invented ways to ferment food and drink. Biomolecular traces on artifacts show that by at least 8000 years ago, people in the Caucasus region were brewing alcoholic beverages from grapes, while people in China were sipping on boozy drinks made from many ingredients, including millet, rice, ginger, and yam. These beverages’ arrival coincides roughly with the start of farming. In fact, some scholars think cereals may have been domesticated for beer rather than bread. The idea that our species’ ability to consume alcohol arose in our distant primate ancestors was formulated by evolutionary biologist Robert Dudley 25 years ago as he was studying monkeys—hence the name of the hypothesis—rather than the chimps and other apes analyzed in the new study. Rank, fermenting fruit is easy to sniff out, the idea goes, so being able to eat it would have given ancient apes an additional resource that other animals avoided.

Keyword: Drug Abuse; Evolution
Link ID: 29876 - Posted: 08.06.2025

By Sofia Caetano Avritzer The original paleo diet might have included fewer succulent steaks and more juicy maggots. Neandertals are often depicted at the top of the food chain for their time, consuming as much meat as lions or hyenas. But maggots growing on rotting meat might have been the real signature dish of the Neandertal diet, researchers report July 25 in Science Advances. The idea that Neandertals were extreme carnivores comes partly from the high levels of a specific type of nitrogen called N-15 in their bones. Nitrogen has two stable forms. N-14 is lighter and a lot more common in nature, while N-15 is heavier and much rarer. When an animal eats a plant with both types of nitrogen, it will keep more N-15 than N-14 in its body after digestion. If that animal gets eaten, its predator will have an even higher proportion of N-15. That makes this molecule more prominent in animals that eat a lot of meat, says Melanie Beasley, a biological anthropologist at Purdue University in West Lafayette, Ind. The proportion of N-15 to N-14 found in Neandertal bones is similar to that found in animals like hyenas, which eat almost exclusively meat, Beasley says. But humans can’t consume as much meat as specialized carnivores, says Karen Hardy, a prehistoric archeologist at the University of Glasgow in Scotland. Without a balanced diet, the human body transforms protein into energy instead of using it to develop muscle, hormones and more. This creates toxic waste products that can cause nausea, diarrhea and even death. So, if Neandertals probably couldn’t eat as much meat as lions or hyenas, where does all the N-15 come from? Rotting meat. © Society for Science & the Public 2000–2025.

Keyword: Evolution; Obesity
Link ID: 29866 - Posted: 07.26.2025