Chapter 6. Evolution of the Brain and Behavior

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By Juan Siliezar Harvard Staff Writer When Erin Hecht was earning her Ph.D. in neuroscience more than a decade ago, she watched a nature special on the Russian farm-fox experiment, one of the best-known studies on animal domestication. The focus of that ongoing research, which began in 1958, is to try to understand the process by which wild wolves became domesticated dogs. Scientists have been selectively breeding two strains of silver fox — an animal closely related to dogs — to exhibit certain behaviors. One is bred to be tame and display dog-like behaviors with people, such as licking and tail-wagging, and the other to react with defensive aggression when faced with human contact. A third strain acts as the control and isn’t bred for any specific behaviors. Hecht, who’s now an assistant professor in the Harvard Department of Human Evolutionary Biology, was fascinated by the experiment, which has helped scientists closely analyze the effects of domestication on genetics and behavior. But she also thought something fundamental was missing. What she didn’t know was that filling that knowledge gap could potentially force reconsideration of what was known about the connection between evolutionary changes in behavior and those in the brain. “In that TV show, there was nothing about the brain,” Hecht said. “I thought it was kind of crazy that there’s this perfect opportunity to be studying how changes in brain anatomy are related to changes in the genome and changes in behavior, but nobody was really doing it yet.”

Keyword: Aggression; Evolution
Link ID: 27872 - Posted: 06.23.2021

By Christa Lesté-Lasserre In the animal kingdom, killer whales are social stars: They travel in extended, varied family groups, care for grandchildren after menopause, and even imitate human speech. Now, marine biologists are adding one more behavior to the list: forming fast friendships. A new study suggests the whales rival chimpanzees, macaques, and even humans when it comes to the kinds of “social touching” that indicates strong bonds. The study marks “a very important contribution to the field” of social behavior in dolphins and whales, says José Zamorano-Abramson, a comparative psychologist at the Complutense University of Madrid who wasn’t involved in the work. “These new images show lots of touching of many different types, probably related to different kinds of emotions, much like the complex social dynamics we see in great apes.” Audio and video recordings have shown how some marine mammals maintain social structures—including male dolphins that learn the “names” of close allies. But there is little footage of wild killer whales—which hunt and play in open water. Although the whales only swim at about 6 kilometers per hour, it’s hard to fully observe them from boats, and they might not act naturally near humans, Zamorano-Abramson says. That’s where drone technology came swooping in. Michael Weiss, a behavioral ecologist at the Center for Whale Research in Friday Harbor, Washington, teamed up with colleagues to launch unmanned drones from their 6.5-meter motorboat and from the shores of the northern Pacific Ocean, flying them 30 to 120 meters above a pod of 22 southern resident killer whales. That was high enough to respect federal aviation requirements—and not bother the whales. They logged 10 hours of footage over a 10-day period, marking the first time drones have been used to study friendly physical contacts in any cetacean. © 2021 American Association for the Advancement of Science.

Keyword: Evolution; Stress
Link ID: 27864 - Posted: 06.19.2021

By Veronique Greenwood The coin is in the illusionist’s left hand, now it’s in the right — or is it? Sleight of hand tricks are old standbys for magicians, street performers and people who’ve had a little too much to drink at parties. Sign up for Science Times: Get stories that capture the wonders of nature, the cosmos and the human body. On humans, the deceptions work pretty well. But it turns out that birds don’t always fall for the same illusions. Researchers in a small study published on Monday in the Proceedings of the National Academy of Sciences reported on Eurasian jays, birds whose intelligence has long been studied by comparative psychologists. The jays were not fooled, at least by tricks that rely on the viewer having certain expectations about how human hands work. However, they were fooled by another kind of trick, perhaps because of how their visual system is built. Magic tricks often play on viewers’ expectations, said Elias Garcia-Pelegrin, a graduate student at the University of Cambridge who is an author of the study. That magic can reveal the viewers’ assumptions suggests that tricks can be a way into understanding how other creatures see the world, he and his colleagues reasoned. Eurasian jays are not newcomers to subterfuge: To thwart thieves while they’re storing food, jays will perform something very like sleight of hand — sleight of beak, if you will — if another jay is watching. They’ll pretend to drop the food in a number of places, so its real location is concealed. © 2021 The New York Times Company

Keyword: Attention; Learning & Memory
Link ID: 27843 - Posted: 06.02.2021

Vincent Acovino A young, red-handed tamarin monkey. Some of these monkeys are changing their vocal call to better communicate with another species of tamarin. Schellhorn/ullstein bild/Getty Images In the Brazilian Amazon, a species of monkey called the pied tamarin is fighting for survival, threatened by habitat loss and urban development. But the critically endangered primate faces another foe: the red-handed tamarin, a more resilient monkey that lives in the same region. They compete for the same resources, and the red-handed tamarin's habitat range is expanding into that of the pied tamarins'. Their clashes sometimes end in violent altercations. But in a recent study, scientists have discovered that the red-handed tamarin is altering its vocal calls to better communicate with the pied tamarin. Tainara Sobroza, an ecology Ph.D. student who worked on the study, says these "territorial calls" are used to warn other species that they are encroaching on their territory, or coming too close to a crucial survival resource. "When this happens, [the two species] usually engage in vocal battles," she says, which sometimes prevent the violent physical battles between the two species. Researchers likened the change in calls to speaking with an accent. "They might need to say 'tomahto' instead of 'tomayto' — that's the kind of nuance in the accent, so that they can really understand each other," Jacob Dunn, a professor of evolutionary biology who worked on the study, told The Guardian. Article continues after sponsor message When analyzing the vocal call of both species, the scientists discovered that the red-handed tamarins new call has a narrower bandwidth and an increased amplitude, making the sound clearer and the duration of the call longer. The result is a call that travels better through the dense forest. © 2021 npr

Keyword: Animal Communication; Language
Link ID: 27842 - Posted: 06.02.2021

By Richard Sima An elephant’s trunk is a marvel of biology. Devoid of any joints or bone, the trunk is an appendage made of pure muscle that is capable of both uprooting trees and gingerly plucking individual leaves and also boasts a sense of smell more powerful than a bomb-sniffing dog’s. Elephants use their trunks in a variety of ways. They use it to drink, store and spray water, and they also blow air through it to communicate — their 110-decibel bellows can be heard for miles. “It’s like a muscular multitool,” said Andrew Schulz, a mechanical engineering doctoral student at the Georgia Institute of Technology. In a study published Wednesday in The Journal of the Royal Society Interface, Mr. Schulz and his colleagues reported on how elephants can use their trunks for yet another function: applying suction to grab food, a behavior previously thought to be exclusive to fishes. Despite the ubiquity of elephants in children’s books and nature documentaries, there are numerous gaps in scientific knowledge about the biomechanics of their trunks that the new study helps fill. For example, the most recent detailed account of elephant trunk anatomy is a hand-drawn monograph that was published in 1908, Mr. Schulz said. Contrary to popular belief, the trunk does not act like a straw. “What they do is actually drink water into their trunk and they store it,” Mr. Schulz said. “So the elephant trunk is actually like a trunk.” Mr. Schulz completed his research in the lab of David Hu, which studies how animals move and function with an eye toward applying the discoveries toward human engineering problems. He said one reason elephants’ anatomy is poorly understood is because they are difficult to work with. © 2021 The New York Times Company

Keyword: Evolution; Learning & Memory
Link ID: 27840 - Posted: 06.02.2021

By Sofia Moutinho Neotropical river otters spend most of their time alone, but that doesn’t stop them from being big chatterboxes. These animals—which live in Central and South America—make a variety of squeaks and growls to convey everything from surprise to playfulness, a new study has found. The discovery could help reveal how communication evolved in all otters—and perhaps help protect these endangered animals. “The study is an in-depth and insightful investigation into the vocal repertoire of this understudied otter species,” says Alexander Saliveros, a biologist and otter expert at the University of Exeter who was not part of the research. All otters make sounds like growls and squeaks to communicate. Some social species, such as the Amazon’s giant otter (Pteronura brasiliensis), use up to 22 different call types. Others, like the lonesome North American river otter (Lontra canadensis), only have four known calls. But the neotropical river otter (L. longicaudis) has largely remained a mystery. Solitary inhabitants of rivers and lakes, they come together only once a year to mate. That makes their communication especially hard to study, says Sabrina Bettoni, a bioacoustician at the University of Vienna. So Bettoni observed three pairs of playful neotropical river otters—orphans living in a shelter on the island of Santa Catarina, off the southern coast of Brazil. The animals were kept in female-male couples year-round at the Institute Ekko Brazil, a nonprofit focused on wildlife protection. Bettoni recorded every vocalization the animals made. Then, she and colleagues analyzed the sound waves to make sure they were distinct calls with unique properties. Bettoni also spent 3 months observing the animals to understand what calls they used in which situations. © 2021 American Association for the Advancement of Science.

Keyword: Animal Communication; Language
Link ID: 27829 - Posted: 05.27.2021

Veronique Greenwood The hydra is a simple creature. Less than half an inch long, its tubular body has a foot at one end and a mouth at the other. The foot clings to a surface underwater — a plant or a rock, perhaps — and the mouth, ringed with tentacles, ensnares passing water fleas. It does not have a brain, or even much of a nervous system. And yet, new research shows, it sleeps. Studies by a team in South Korea and Japan showed that the hydra periodically drops into a rest state that meets the essential criteria for sleep. On the face of it, that might seem improbable. For more than a century, researchers who study sleep have looked for its purpose and structure in the brain. They have explored sleep’s connections to memory and learning. They have numbered the neural circuits that push us down into oblivious slumber and pull us back out of it. They have recorded the telltale changes in brain waves that mark our passage through different stages of sleep and tried to understand what drives them. Mountains of research and people’s daily experience attest to human sleep’s connection to the brain. But a counterpoint to this brain-centric view of sleep has emerged. Researchers have noticed that molecules produced by muscles and some other tissues outside the nervous system can regulate sleep. Sleep affects metabolism pervasively in the body, suggesting that its influence is not exclusively neurological. And a body of work that’s been growing quietly but consistently for decades has shown that simple organisms with less and less brain spend significant time doing something that looks a lot like sleep. Sometimes their behavior has been pigeonholed as only “sleeplike,” but as more details are uncovered, it has become less and less clear why that distinction is necessary. All Rights Reserved © 2021

Keyword: Sleep; Evolution
Link ID: 27825 - Posted: 05.19.2021

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