Chapter 6. Evolution of the Brain and Behavior

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By Natalie Angier Julia, her friends and family agreed, had style. When, out of the blue, the 18-year-old chimpanzee began inserting long, stiff blades of grass into one or both ears and then went about her day with her new statement accessories clearly visible to the world, the other chimpanzees at the Chimfunshi wildlife sanctuary in Zambia were dazzled. Pretty soon, they were trying it, too: first her son, then her two closest female friends, then a male friend, out to eight of the 10 chimps in the group, all of them struggling, in front of Julia the Influencer — and hidden video cameras — to get the grass-in-the-ear routine just right. “It was quite funny to see,” said Edwin van Leeuwen of the University of Antwerp, who studies animal culture. “They tried again and again without success. They shivered through their whole bodies.” Dr. van Leeuwen tried it himself and understood why. “It’s not a pleasant feeling, poking a piece of grass far enough into the ear to stay there,” he said. But once the chimpanzees had mastered the technique, they repeated it often, proudly, almost ritualistically, fiddling with the inserted blades to make sure others were suitably impressed. Julia died more than two years ago, yet her grassy-ear routine — a tradition that arose spontaneously, spread through social networks and skirts uncomfortably close to a human meme or fad — lives on among her followers in the sanctuary. The behavior is just one of many surprising examples of animal culture that researchers have lately divulged, as a vivid summary makes clear in a recent issue of Science. Culture was once considered the patented property of human beings: We have the art, science, music and online shopping; animals have the instinct, imprinting and hard-wired responses. But that dismissive attitude toward nonhuman minds turns out to be more deeply misguided with every new finding of animal wit or whimsy: Culture, as many biologists now understand it, is much bigger than we are. © 2021 The New York Times Company

Keyword: Evolution
Link ID: 27809 - Posted: 05.08.2021

By Virginia Morell Like members of a street gang, male dolphins summon their buddies when it comes time to raid and pillage—or, in their case, to capture and defend females in heat. A new study reveals they do this by learning the “names,” or signature whistles, of their closest allies—sometimes more than a dozen animals—and remembering who consistently cooperated with them in the past. The findings indicate dolphins have a concept of team membership—previously seen only in humans—and may help reveal how they maintain such intricate and tight-knit societies. “It is a ground-breaking study,” says Luke Rendell, a behavioral ecologist at the University of St. Andrews who was not involved with the research. The work adds evidence to the idea that dolphins evolved large brains to navigate their complex social environments. Male dolphins typically cooperate as a pair or trio, in what researchers call a “first-order alliance.” These small groups work together to find and corral a fertile female. Males also cooperate in second-order alliances comprised of as many as 14 dolphins; these defend against rival groups attempting to steal the female. Some second-order alliances join together in even larger third-order alliances, providing males in these groups with even better chances of having allies nearby should rivals attack. © 2021 American Association for the Advancement of Science

Keyword: Animal Communication; Language
Link ID: 27785 - Posted: 04.24.2021

By Emily Anthes Male tanagers are meant to be noticed. Many species of the small, tropical bird sport deep black feathers and splashes of eye-catching color — electric yellows, traffic-cone oranges and nearly neon scarlets. To achieve this flashiness, the birds must spend time and energy foraging for, and metabolizing, plants that contain special color pigments, which make their way into the feathers. A vibrantly colored male is thus sending an “honest signal,” many scientists have long theorized: He is alerting nearby females that he has a good diet, is in good health and would make a worthy mate. But some birds may be guilty of false advertising, a new study suggests. Male tanagers have microstructures in their feathers that enhance their colors, researchers reported Wednesday in the journal Scientific Reports. These microstructures, like evolution’s own Instagram filters, may make the males seem as if they are more attractive than they truly are. “Many male birds are colorful not just because they’re honestly signaling their quality, but because they’re trying to get chosen,” said Dakota McCoy, a doctoral student at Harvard University who conducted the research as part of her dissertation. “This is basically experimental evidence that whenever there’s a high-stakes test in life, it’s worth your while to cheat a little bit.” The new study is an important contribution to the longstanding debate over how, and why, brightly colored feathers evolved in birds, said Geoffrey Hill, an ornithologist and evolutionary ecologist at Auburn University. “Scientists have spent the last 150 years since Darwin and Wallace trying to understand ornaments in animals and especially colors in birds,” he said. “And this is the kind of original approach that helps us.” © 2021 The New York Times Company

Keyword: Sexual Behavior; Evolution
Link ID: 27781 - Posted: 04.21.2021

By Charles Choi Even after ancient humans took their first steps out of Africa, they still unexpectedly may have possessed brains more like those of great apes than modern humans, a new study suggests. For decades, scientists had thought modern humanlike organization of brain structures evolved soon after the human lineage Homo arose roughly 2.8 million years ago (SN: 3/4/15). But an analysis of fossilized human skulls that retain imprints of the brains they once held now suggests such brain development occurred much later. Modernlike brains may have emerged in an evolutionary sprint starting about 1.7 million years ago, researchers report in the April 9 Science. What sets modern humans apart most from our closest living relatives, the great apes, is most likely our brain. To learn more about how the modern human brain evolved, the researchers analyzed replicas of the brain’s convoluted outer surface, re-created from the oldest known fossils to preserve the inner surfaces of early human skulls. The 1.77-million to 1.85-million-year-old fossils are from the Dmanisi archaeological site in the modern-day nation of Georgia and were compared with bones from Africa and Southeast Asia ranging from roughly 2 million to 70,000 years old. The scientists focused on the brain’s frontal lobes, which are linked with complex mental tasks such as toolmaking and language. Early Homo from Dmanisi and Africa still apparently retained a great ape–like organization of the frontal lobe 1.8 million years ago, “a million or so years later than previously thought,” says paleoanthropologist Philipp Gunz at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, who did not take part in this study. © Society for Science & the Public 2000–2021.

Keyword: Evolution
Link ID: 27768 - Posted: 04.10.2021

By Nikk Ogasa Honey bees can’t speak, of course, but scientists have found that the insects combine teamwork and odor chemicals to relay the queen’s location to the rest of the colony, revealing an extraordinary means of long distance, mass communication. The research is “really nice, and really careful,” says Gordon Berman, a biologist at Emory University who was not involved in the study. It shows once again, he says, that insects are capable of “exquisite and complex behaviors.” Honey bees communicate with chemicals called pheromones, which they sense through their antennae. Like a monarch pressing a button, the queen emits pheromones to summon worker bees to fulfill her needs. But her pheromones only travel so far. Busy worker bees, however, roam around, and they, too, can call to each other by releasing a pheromone called Nasanov, through a gesticulation known as “scenting; they raise their abdomens to expose their pheromone glands and fan their wings to direct the smelly chemicals backward (seen in the video above, and close-up in the video below). Scientists have long known individual bees scented, but just how these individual signals work together to gather tens of thousands of bees around a queen, such as when the colony leaves the hive to swarm, has remained a mystery. © 2021 American Association for the Advancement of Science.

Keyword: Animal Communication; Evolution
Link ID: 27767 - Posted: 04.10.2021

Nicola Davis It is a trope used in films from King Kong to Tarzan – a male primate standing upright and beating its chest, sometimes with a yell and often with more than a dash of hubris. But it seems the pounding action is less about misplaced bravado than Hollywood would suggest: researchers studying adult male mountain gorillas say that while chest-beating might be done to show off, it also provides honest information. “We found it is definitely a real, reliable signal – males are conveying their true size,” said Edward Wright, co-author of the research from the Max Planck Institute for Evolutionary Anthropology in Germany. Advertisement Writing in the journal Scientific Reports, Wright and colleagues report how they studied chest-beating in six adult male mountain gorillas in the Volcanoes national park in Rwanda. The team used a camera setup involving two parallel green lasers a known distance apart to determine the breadth of each gorilla’s back from a photograph. They then recorded 36 chest-beating episodes among these six males between November 2015 and July 2016, and analysed the recordings. The results revealed that the duration of the chest-beating, number of beats and the rate of the beats during an episode were not associated with the size of the gorilla. However, the average peak frequency of the sound produced was – the larger the gorilla, the lower the frequency of the sound produced. © 2021 Guardian News & Media Limited

Keyword: Sexual Behavior; Evolution
Link ID: 27765 - Posted: 04.10.2021

By Meagan Cantwell In order to see the world as clearly as we do, we process vision from each eyeball on both sides of our brain—a capability known as bilateral visual projection. For a long time, researchers thought this feature developed after fish transitioned to land, more than 375 million years ago. But does this theory hold water today? In a new study, scientists injected fluorescent tracers into the eyes of 11 fish species to illuminate their visual systems. After examining their brains under a specialized 3D fluorescence microscope, they found ancient fish with genomes more similar to mammals can project vision on both the same and opposite side of their brain (see video, above). This suggests bilateral vision did not coincide with the transition from water to land, researchers report this week in Science. In the future, scientists plan to uncover the genes that drive same-sided visual projection to better understand how vision evolved. © 2021 American Association for the Advancement of Science.

Keyword: Vision; Evolution
Link ID: 27764 - Posted: 04.10.2021

By Jake Buehler Fairy wrasses are swimming jewels, flitting and flouncing about coral reefs. The finger-length fishes’ brash, vibrant courtship displays are meant for mates and rivals, and a new study suggests that the slow waxing and waning of ice sheets and glaciers may be partly responsible for such a variety of performances. A new genetic analysis of more than three dozen fairy wrasse species details the roughly 12 million years of evolution that produced their vast assortment of shapes, colors and behaviors. And the timing of these transformations implies that the more than 60 species of fairy wrasses may owe their great diversity to cyclic sea level changes over the last few millions of years, scientists report February 23 in Systematic Biology. Within the dizzying assembly of colorful reef fishes, fairy wrasses (Cirrhilabrus) can’t help but stand out. They are the most species-rich genus in the second most species-rich fish family in the ocean, says Yi-Kai Tea, an ichthyologist at the University of Sydney. “That is quite a bit of biodiversity,” says Tea, who notes that new fairy wrasse species are identified every year. Despite this taxonomic footprint, Tea says, scientists knew “next to nothing” about the fairy wrasses’ evolutionary history or why there were so many species. © Society for Science & the Public 2000–2021.

Keyword: Sexual Behavior; Evolution
Link ID: 27755 - Posted: 04.03.2021

By Laura Sanders Octopuses cycle through two stages of slumber, a new study reports. First comes quiet sleep, and then a shift to a twitchy, active sleep in which vibrant colors flash across the animals’ skin. These details, gleaned from four snoozing cephalopods in a lab in a Brazil, may provide clues to a big scientific mystery: Why do animals sleep? Sleep is so important that every animal seems to have a version of it, says Philippe Mourrain, a neurobiologist at Stanford University who recently described the sleep stages of fish (SN: 7/10/19). Scientists have also catalogued sleep in reptiles, birds, amphibians, bees, mammals and jellyfish, to name a few. “So far, we have not found a single species that does not sleep,” says Mourrain, who was not involved in the new study. Cephalopod neuroscientist and diver Sylvia Medeiros caught four wild octopuses, Octopus insularis, and brought them temporarily into a lab at the Brain Institute of the Federal University of Rio Grande do Norte in Natal, Brazil. After tucking the animals away in a quiet area, she began to carefully record their behavior during the day, when octopuses are more likely to rest. Two distinct states emerged, she and her colleagues report March 25 in iScience. In the first, called quiet sleep, the octopuses are pale and motionless with the pupils of their eyes narrowed to slits. Active sleep comes next. Eyes dart around, suckers contract, muscles twitch, skin textures change and, most dramatically, bright colors race across octopuses’ bodies. This wild sleep is rhythmic, happening every half an hour or so, and brief; it’s over after about 40 seconds. Active sleep is also rare; the octopuses spent less than 1 percent of their days in active sleep, the researchers found. © Society for Science & the Public 2000–2021.

Keyword: Sleep; Evolution
Link ID: 27749 - Posted: 03.27.2021

By Jake Buehler A light crackling sound floats above a field in northern Switzerland in late summer. Its source is invisible, tucked inside a dead, dried plant stem: a dozen larval mason bees striking the inner walls of their herbaceous nest. While adult bees and wasps make plenty of buzzy noises, their young have generally been considered silent. But the babies of at least one bee species make themselves heard, playing percussion instruments growing out of their faces and rear ends, researchers report February 25 in the Journal of Hymenoptera Research. The larvae’s chorus of tapping and rasping may be a clever strategy to befuddle predatory wasps. Unlike honeybees, the mason bee (Hoplitis tridentata) lives a solitary life. Females chew into dead plant stems and lay their eggs inside, often in a single row of chambers lined up along its length. After hatching, the larvae feed on a provision of pollen left by the mom, spin a cocoon and overwinter as a pupa inside the stem. Andreas Müller, an entomologist at the nature conservation research agency Natur Umwelt Wissen GmbH in Zurich, has been studying bees in the Osmiini tribe, which includes mason bees and their close relatives, for about 20 years. Noticing that H. tridentata populations have been declining in northern Switzerland, he and colleague Martin Obrist tried to help the bees. “We offered the bees bundles of dry plant stems as nesting sites, and when we checked the bundles we heard the larval sounds for the first time,” says Müller. “This is a new phenomenon not only in the osmiine bees, but in bees in general.” He and Obrist, a biologist at the Swiss Federal Institute for Forest, Snow and Landscape Research in Birmensdorf, gathered stem nests from the field and subjected them to various types of physical disturbance, trying to determine what kinds of pestering triggers the bee larvae to drum. In some nests, the duo cut windows into the stems to observe larvae through the translucent cocoon walls, unveiling the secret of how the insects were creating the noises. © Society for Science & the Public 2000–2021.

Keyword: Animal Communication; Language
Link ID: 27737 - Posted: 03.17.2021

By Christa Lesté-Lasserre If you’ve ever counted to three before jumping into the pool with a friend, you’ve got something in common with dolphins. The sleek marine mammals use coordinated clicks and whistles to tell each other the precise moment to perform a backflip or push a button, according to new research. That makes them the only animals besides humans known to cooperate with vocal cues. The new work is “fascinating,” says Richard Connor, a cetacean biologist at the University of Massachusetts, Dartmouth, who was not involved with the research. “We just see so much cooperation and synchrony [among dolphins] in the wild. This helps us understand how they accomplish that.” Free-roaming dolphins are often in sync. They hunt in large groups and drive away rivals with coordinated displays. They can even match others’ movements down to their breathing patterns. But how do they achieve such synchronicity? Scientists have long suspected the cetaceans coordinate their actions through vocal cues. Underwater microphones, called hydrophones, have been picking up their whistles and clicks for decades. But dolphins don’t open their mouths when they “talk,” and tracking underwater sound has long been a technical challenge. So scientists have been developing ways to capture those sounds. In France, researchers recently combined five hydrophones to set up a star-shaped pattern that can pinpoint which dolphin in a group is “speaking,” says ethologist Juliana Lopez-Marulanda of Paris-Saclay University who co-developed the approach. © 2021 American Association for the Advancement of Science.

Keyword: Animal Communication; Language
Link ID: 27736 - Posted: 03.17.2021

By Annie Roth A few years ago, Sayaka Mitoh, a Ph.D. candidate at Nara Women’s University in Japan, was perusing her lab’s vast collection of sea slugs when she stumbled upon a gruesome sight. One of the lab’s captive-raised sea slugs, an Elysia marginata, had somehow been decapitated. When Ms. Mitoh peered into its tank to get a better look, she noticed something even more shocking: The severed head of the creature was moving around the tank, munching algae as if there was nothing unusual about being a bodiless slug. Ms. Mitoh also saw signs that the sea slug’s wound was self-inflicted: It was as if the sea slug had dissolved the tissue around its neck and ripped its own head off. Self-amputation, known as autotomy, isn’t uncommon in the animal kingdom. Having the ability to jettison a body part, such as a tail, helps many animals avoid predation. However, no animal had ever been observed ditching its entire body. “I was really surprised and shocked to see the head moving,” said Ms. Mitoh, who studies the life history traits of sea slugs. She added that she expected the slug “would die quickly without a heart and other important organs.” But it not only continued to live, it also regenerated the entirety of its lost body within three weeks. This prompted Ms. Mitoh and her colleagues to conduct a series of experiments aimed at figuring out how and why some sea slugs guillotine themselves. The results of their experiments, published Monday in Current Biology, provide evidence that Elysia marginata, and a closely related species, Elysia atroviridis, purposefully decapitate themselves in order to facilitate the growth of a new body. Although more research is needed, the researchers suspect these sea slugs ditch their bodies when they become infected with internal parasites. © 2021 The New York Times Company

Keyword: Evolution; Development of the Brain
Link ID: 27727 - Posted: 03.11.2021

James Doubek By being able to wait for better food, cuttlefish — the squishy sea creatures similar to octopuses and squids — showed self-control that's linked to the higher intelligence of primates. It was part of an experiment by Alex Schnell from the University of Cambridge and colleagues. "What surprised me the most was that the level of self-control shown by our cuttlefish was quite advanced," she tells Lulu Garcia-Navarro on Weekend Edition. The experiment was essentially a take on the classic "marshmallow" experiment from the 1960s. In that experiment, young children were presented with one marshmallow and told that if they can resist eating it, unsupervised, for several minutes, they will get two marshmallows. But if they eat it that's all they get. The conventional wisdom has been that children who are able to delay gratification do better on tests and are more successful later in life. (There are of course many caveats when talking about the human experiments.) To adapt the experiment for cuttlefish, the researchers first figured out the cuttlefish's favorite food: live grass shrimp; and their second-favorite food: a piece of king prawn. Instead of choosing one or two marshmallows, the cuttlefish had to choose either their favorite food or second-favorite food. "Each of the food items were placed in clear chambers within their tank," Schnell says. "One chamber would open immediately, whereas the other chamber would only open after a delay." © 2021 npr

Keyword: Evolution; Learning & Memory
Link ID: 27724 - Posted: 03.11.2021

By Erin Garcia de Jesus A whiff of catnip can make mosquitoes buzz off, and now researchers know why. The active component of catnip (Nepeta cataria) repels insects by triggering a chemical receptor that spurs sensations such as pain or itch, researchers report March 4 in Current Biology. The sensor, dubbed TRPA1, is common in animals — from flatworms to people — and responds to environmental irritants such as cold, heat, wasabi and tear gas. When irritants come into contact with TRPA1, the reaction can make people cough or an insect flee. Catnip’s repellent effect on insects — and its euphoric effect on felines — has been documented for millennia. Studies have shown that catnip may be as effective as the widely used synthetic repellent diethyl-m-toluamide, or DEET (SN: 9/5/01). But it was unknown how the plant repelled insects. So researchers exposed mosquitoes and fruit flies to catnip and monitored the insects’ behavior. Fruit flies were less likely to lay eggs on the side of a petri dish that was treated with catnip or its active component, nepetalactone. Mosquitoes were also less likely to take blood from a human hand coated with catnip. Insects that had been genetically modified to lack TRPA1, however, had no aversion to the plant. That behavior — coupled with experiments in lab-grown cells that show catnip activates TRPA1 — suggests that insect TRPA1 senses catnip as an irritant. Puzzling out how the plant deters insects could help researchers design potent repellents that may be easier to obtain in developing countries hit hard by mosquito-borne diseases. “Oil extracted from the plant or the plant itself could be a great starting point,” says study coauthor Marco Gallio, a neuroscientist at Northwestern University in Evanston, Ill. © Society for Science & the Public 2000–2021

Keyword: Pain & Touch; Evolution
Link ID: 27719 - Posted: 03.06.2021

By Veronique Greenwood Sign up for Science Times: Get stories that capture the wonders of nature, the cosmos and the human body. In the warm, fetid environs of a compost heap, tiny roundworms feast on bacteria. But some of these microbes produce toxins, and the worms avoid them. In the lab, scientists curious about how the roundworms can tell what’s dinner and what’s dangerous often put them on top of mats of various bacteria to see if they wriggle away. One microbe species, Pseudomonas aeruginosa, reliably sends them scurrying. But how do the worms, common lab animals of the species Caenorhabditis elegans, know to do this? Dipon Ghosh, then a graduate student in cellular and molecular physiology at Yale University, wondered if it was because they could sense the toxins produced by the bacteria. Or might it have something to do with the fact that mats of P. aeruginosa are a brilliant shade of blue? Given that roundworms do not have eyes, cells that obviously detect light or even any of the known genes for light-sensitive proteins, this seemed a bit far-fetched. It wasn’t difficult to set up an experiment to test the hypothesis, though: Dr. Ghosh, who is now a postdoctoral researcher at the Massachusetts Institute of Technology, put some worms on patches of P. aeruginosa. Then he turned the lights off. To the surprise of his adviser, Michael Nitabach, the worms’ flight from the bacteria was significantly slower in the dark, as though not being able to see kept the roundworms from realizing they were in danger. “When he showed me the results of the first experiments, I was shocked,” said Dr. Nitabach, who studies the molecular basis of neural circuits that guide behavior at Yale School of Medicine. In a series of follow-up experiments detailed in a paper published Thursday in Science, Dr. Ghosh, Dr. Nitabach and their colleagues establish that some roundworms respond clearly to that distinctive pigment, perceiving it — and fleeing from it — without the benefit of any known visual system. © 2021 The New York Times Company

Keyword: Vision; Evolution
Link ID: 27718 - Posted: 03.06.2021

By Elizabeth Pennisi For a glimpse of the power of sexual selection, the dance of the golden-collared manakin is hard to beat. Each June in the rainforests of Panama, the sparrow-size male birds gather to fluff their brilliant yellow throats, lift their wings, and clap them together in rapid fire, up to 60 times a second. When a female favors a male with her attention, he follows up with acrobatic leaps, more wing snaps, and perhaps a split-second, twisting backflip. “If manakins were human, they would be among the greatest artists, athletes, and socialites in our society,” says Ignacio Moore, an integrative organismal biologist at Virginia Polytechnic Institute and State University. As biologists have understood since Charles Darwin, such exhibitionism evolves when females choose to mate with males that have the most extravagant appearances and displays—a proxy for fitness. And now, by studying the genomes of the golden-collared manakin (Manacus vitellinus) and its relatives, researchers are exploring the genes that drive these elaborate behaviors and traits. Last month at the virtual meeting of the Society for Integrative and Comparative Biology, Moore and other researchers introduced four manakin genomes, adding to two already published, and singled out genes at work in the birds’ muscles and brains that may make the displays possible. © 2021 American Association for the Advancement of Science.

Keyword: Sexual Behavior; Evolution
Link ID: 27716 - Posted: 03.06.2021

By Richard Sima Sign up for Science Times: Get stories that capture the wonders of nature, the cosmos and the human body. Though it is well-known for its many arms, the octopus does not seem to know where those eight appendages are most of the time. “In the octopus, you have no bones and no joints, and every point in its arm can go to every direction that you can think about,” said Nir Nesher, a senior lecturer in marine sciences at the Ruppin Academic Center in Israel. “So even one arm, it’s something like endless degrees of freedom.” So how does the octopus keep all those wiggly, sucker-covered limbs out of trouble? According to a study published this month in The Journal of Experimental Biology by Dr. Nesher and his colleagues, the octopus’s arms can sense and respond to light — even when the octopus cannot see it with the eyes on its head. This light-sensing ability may help the cephalopods keep their arms concealed from other animals that could mistake the tip of an arm for a marine worm or some other kind of meal. Itamar Katz, one of the study’s authors, first noticed the light-detecting powers while studying a different phenomenon: how light causes the octopus’s skin to change color. With Dr. Nesher and Tal Shomrat, another author, Mr. Katz saw that shining light on an arm caused the octopus to withdraw it, even when the creature was sleeping. Further experiments showed that the arms would avoid the light in situations when the octopus could not see it with its eyes. Even when the octopuses reached an arm out of a small opening on an opaque, covered aquarium for food, the arm would quickly retract when light was shined on it 84 percent of the time. This was a surprise, as though the octopus “can see the light through the arm, it can feel the light through the arm,” Dr. Nesher said. “They don’t need the eye for that.” ImageScientists suspect octopuses keep their arms concealed from other animals that could mistake the tip of an arm for a meal. Scientists suspect octopuses keep their arms concealed from other animals that could © 2021 The New York Times Company

Keyword: Vision; Evolution
Link ID: 27704 - Posted: 02.23.2021

Ariana Remmel Researchers have created tiny, brain-like ‘organoids’ that contain a gene variant harboured by two extinct human relatives, Neanderthals and Denisovans. The tissues, made by engineering human stem cells, are far from being true representations of these species’ brains — but they show distinct differences from human organoids, including size, shape and texture. The findings, published1 in Science on 11 February, could help scientists to understand the genetic pathways that allowed human brains to evolve. Can lab-grown brains become conscious? “It’s an extraordinary paper with some extraordinary claims,” says Gray Camp, a developmental biologist at the University of Basel in Switzerland, whose lab last year reported2 growing brain organoids that contained a gene common to Neanderthals and humans. The latest work takes the research further by looking at gene variants that humans lost in evolution. But Camp remains sceptical about the implications of the results, and says the work opens more questions that will require investigation. Humans are more closely related to Neanderthals and Denisovans than to any living primate, and some 40% of the Neanderthal genome can still be found spread throughout living humans. But researchers have limited means to study these ancient species’ brains — soft tissue is not well preserved, and most studies rely on inspecting the size and shape of fossilized skulls. Knowing how the species’ genes differ from humans’ is important because it helps researchers to understand what makes humans unique — especially in our brains. © 2021 Springer Nature Limited

Keyword: Development of the Brain; Evolution
Link ID: 27687 - Posted: 02.13.2021

By Jonathan Lambert When one naked mole-rat encounters another, the accent of their chirps might reveal whether they’re friends or foes. These social rodents are famous for their wrinkly, hairless appearance. But hang around one of their colonies for a while, and you’ll notice something else — they’re a chatty bunch. Their underground burrows resound with near-constant chirps, grunts, squeaks and squeals. Now, computer algorithms have uncovered a hidden order within this cacophony, researchers report in the Jan. 29 Science. These distinctive chirps, which pups learn when they’re young, help the mostly blind, xenophobic rodents discern who belongs, strengthening the bonds that maintain cohesion in these highly cooperative groups. “Language is really important for extreme social behavior, in humans, dolphins, elephants or birds,” says Thomas Park, a biologist at the University of Illinois Chicago who wasn’t involved in the study. This work shows naked mole-rats (Heterocephalus glaber) belong in those ranks as well, Park says. Naked mole-rat groups seem more like ant or termite colonies than mammalian societies. Every colony has a single breeding queen who suppresses the reproduction of tens to hundreds of nonbreeding worker rats that dig elaborate subterranean tunnels in search of tubers in eastern Africa (SN: 10/18/04). Food is scarce, and the rodents vigorously attack intruders from other colonies. While researchers have long noted the rat’s raucous chatter, few actually studied it. “Naked mole-rats are incredibly cooperative and incredibly vocal, and no one has really looked into how these two features influence one another,” says Alison Barker, a neuroscientist at the Max Delbrück Center for Molecular Medicine in Berlin. © Society for Science & the Public 2000–2021.

Keyword: Language; Evolution
Link ID: 27673 - Posted: 01.30.2021

By Veronique Greenwood Last spring, robins living on an Illinois tree farm sat on some unusual eggs. Alongside the customary brilliant blue ovoids they had laid were some unusually shaped objects. Although they had the same color, some were long and thin, stretched into pills. Others were decidedly pointy — so angular, in fact, that they bore little resemblance to eggs at all. If robins played Dungeons and Dragons, they might have thought, “Why do I have an eight-sided die in my nest?” The answer: Evolutionary biologists were gauging how birds decide what belongs in their nests, and what is an invasive piece of detritus that they need to throw out. Thanks to the results of this study, published Wednesday in Royal Society Open Science, we now know what the robins thought of the eggs, which were made of plastic and had been 3-D printed by the lab of Mark Hauber, a professor of animal behavior at the University of Illinois, Urbana-Champaign and a fellow at Hanse-Wissenschaftskolleg in Delmenhorst, Germany. He and his colleagues reported that the thinner the fake eggs got, the more likely the birds were to remove them from the nest. But curiously, the robins were more cautious about throwing out the pointy objects like that eight-sided die, which were closer in width to their own eggs. Birds, the results suggest, are using rules of thumb that are not intuitive to humans when they decide what is detritus and what is precious cargo. It’s not as uncommon as you’d think for robins to find foreign objects in their nests. They play host to cowbirds, a parasitic species that lays eggs in other birds’ nests, where they hatch and compete with the robins’ own offspring for nourishment. Confronted with a cowbird egg, which is beige and squatter than its blue ovals, parent robins will often push the parasite’s eggs out. That makes the species a good candidate for testing exactly what matters when it comes to telling their own eggs apart from other objects, Dr. Hauber said. © 2021 The New York Times Company

Keyword: Attention; Evolution
Link ID: 27669 - Posted: 01.30.2021