Chapter 6. Evolution of the Brain and Behavior

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By Carl Zimmer Sign up for Science Times Get stories that capture the wonders of nature, the cosmos and the human body. Get it sent to your inbox. For half a billion years or so, our ancestors sprouted tails. As fish, they used their tails to swim through the Cambrian seas. Much later, when they evolved into primates, their tails helped them stay balanced as they raced from branch to branch through Eocene jungles. But then, roughly 25 million years ago, the tails disappeared. Charles Darwin first recognized this change in our ancient anatomy. But how and why it happened has remained a mystery. Now a team of scientists in New York say they have pinpointed the genetic mutation that may have erased our tails. When the scientists made this genetic tweak in mice, the animals didn’t grow tails, according to a new study that was posted online last week. This dramatic anatomical change had a profound impact on our evolution. Our ancestors’ tail muscles evolved into a hammock-like mesh across the pelvis. When the ancestors of humans stood up and walked on two legs a few million years ago, that muscular hammock was ready to support the weight of upright organs. Although it’s impossible to definitively prove that this mutation lopped off our ancestors’ tails, “it’s as close to a smoking gun as one could hope for,” said Cedric Feschotte, a geneticist at Cornell who was not involved in the study. Darwin shocked his Victorian audiences by claiming that we descended from primates with tails. He noted that while humans and apes lack a visible tail, they share a tiny set of vertebrae that extend beyond the pelvis — a structure known as the coccyx. “I cannot doubt that it is a rudimentary tail,” he wrote. © 2021 The New York Times Company

Keyword: Evolution; Genes & Behavior
Link ID: 28001 - Posted: 09.22.2021

Christie Wilcox If it walks like a duck and talks like a person, it’s probably a musk duck (Biziura lobata)—the only waterfowl species known that can learn sounds from other species. The Australian species’ facility for vocal learning had been mentioned anecdotally in the ornithological literature; now, a paper published September 6 in Philosophical Transactions of the Royal Society B reviews and discusses the evidence, which includes 34-year-old recordings made of a human-reared musk duck named Ripper engaging in an aggressive display while quacking “you bloody fool.” Ripper quacking "you bloody fool" while being provoked by a person separated from him by a fence The Scientist spoke with the lead author on the paper, Leiden University animal behavior researcher Carel ten Cate, to learn more about these unique ducks and what their unexpected ability reveals about the evolution of vocal learning. The Scientist: What is vocal learning? Carel ten Cate: Vocal learning, as it is used in this case, is that animals and humans, they learn their sounds from experience. So they learn from what they hear around them, which will usually be the parents, but it can also be other individuals. And if they don’t get that sort of exposure, then they will be unable to produce species-specific vocalizations, or in the human case, speech sounds and proper spoken language. © 1986–2021 The Scientist.

Keyword: Language; Evolution
Link ID: 27987 - Posted: 09.13.2021

Abby Olena Most people enjoy umami flavor, which is perceived when a taste receptor called T1R1/T1R3 senses the amino acid glutamate. In some other mammals, such as mice, however, this same receptor is much less sensitive to glutamate. In a new study published August 26 in Current Biology, researchers uncover the molecular basis for this difference. They show that the receptor evolved in humans and some other primates away from mostly binding free nucleotides, which are common in insects, to preferentially binding glutamate, which is abundant in leaves. The authors argue that the change facilitated a major evolutionary shift in these primates toward a plant-heavy diet. “The question always comes up about the evolution of umami taste: In humans, our receptor is narrowly tuned to glutamate, and we never had a good answer for why,” says Maude Baldwin, a sensory biologist at the Max Planck Institute for Ornithology in Germany. She was not involved in the new work, but coauthored a 2014 study with Yasuka Toda, who is also a coauthor on the new paper, showing that the T1R1/T1R3 receptor is responsible for sweet taste in hummingbirds. In the new study, the authors find “that this narrow tuning has evolved convergently multiple times [and] that it’s related to folivory,” she says, calling the paper “a hallmark, fantastic study, and one that will become a textbook example of how taste evolution can relate to diet and how to address these types of questions in a rigorous, comprehensive manner.” In 2011, Toda, who was then at the University of Tokyo and now leads a group at Meiji University in Japan, and Takumi Misaka of the University of Tokyo developed a strategy to use cultured cells to analyze the function of taste receptors. They used the technique to tease out the parts of the human T1R1/T1R3 that differed from that of mice and thus underlie the high glutamate sensitivity in the human receptor, work that they published in 2013. © 1986–2021 The Scientist.

Keyword: Chemical Senses (Smell & Taste); Evolution
Link ID: 27986 - Posted: 09.13.2021

By Nicholas Bakalar Many animals are known to use tools, but a bird named Bruce may be one of the most ingenious nonhuman tool inventors of all: He is a disabled parrot who has designed and uses his own prosthetic beak. Bruce is a kea, a species of parrot found only in New Zealand. He is about 9 years old, and when wildlife researchers found him as a baby, he was missing his upper beak, probably because it had been caught in a trap made for rats and other invasive mammals the country was trying to eliminate. This is a severe disability, as kea use their dramatically long and curved upper beaks for preening their feathers to get rid of parasites and to remove dirt and grime. But Bruce found a solution: He has taught himself to pick up pebbles of just the right size, hold them between his tongue and his lower beak, and comb through his plumage with the tip of the stone. Other animals use tools, but Bruce’s invention of his own prosthetic is unique. Researchers published their findings Friday in the journal Scientific Reports. Studies of animal behavior are tricky — the researchers have to make careful, objective observations and always be wary of bias caused by anthropomorphizing, or erroneously attributing human characteristics to animals. “The main criticism we received before publication was, ‘Well, this activity with the pebbles may have been just accidental — you saw him when coincidentally he had a pebble in his mouth,’” said Amalia P.M. Bastos, an animal cognition researcher at the University of Auckland and the study’s lead author. “But no. This was repeated many times. He drops the pebble, he goes and picks it up. He wants that pebble. If he’s not preening, he doesn’t pick up a pebble for anything else.” Dorothy M. Fragaszy, an emerita professor of psychology at the University of Georgia who has published widely on animal behavior but was unacquainted with Bruce’s exploits, praised the study as a model of how to study tool use in animals. © 2021 The New York Times Company

Keyword: Intelligence; Evolution
Link ID: 27984 - Posted: 09.11.2021

Virginia Morell Goffin’s cockatoos (Cacatua goffiniana) are so smart they’ve been compared to 3-year-old humans. But what 3-year-old has made their own cutlery set? Scientists have observed wild cockatoos, members of the parrot family, crafting the equivalent of a crowbar, an ice pick, and a spoon to pry open one of their favorite fruits. This is the first time any bird species has been seen creating and using a set of tools in a specific order—a cognitively challenging behavior previously known only in humans, chimpanzees, and capuchin monkeys. The work “supports the idea that parrots have a general [type of] intelligence that allows them to innovate creative solutions to the problems they run into in nature,” says Alex Taylor, a biologist who studies New Caledonian crows at the University of Auckland. “[It] establishes this species as one of the avian family’s most proficient wild tool users.” The discovery happened serendipitously when behavioral ecologist Mark O’Hara was working with wild but captive birds in a research aviary on Yamdena Island in Indonesia. “I’d just turned away, and when I looked back, one of the birds was making and using tools,” says O’Hara, of the Messerli Research Institute. “I couldn’t believe my eyes!” The Goffin’s cockatoo is known for being a clever and innovative social learner. In captivity, the birds have solved complex puzzle boxes and invented rakelike tools to retrieve objects. Several other birds, including hyacinth macaws and New Caledonian crows, make and use tools in the wild, often to extract food, but none seems to make a set of tools. For the new study, O’Hara and his colleagues traveled to this cockatoo’s home on Indonesia’s Tanimbar Islands. The birds live high in the tropical forest canopy, making them difficult to observe. The scientists spent almost 900 hours looking up to watch wild cockatoos feed, but didn’t witness tool use.

Keyword: Learning & Memory; Intelligence
Link ID: 27974 - Posted: 09.01.2021

By Carolyn Wilke Some female hummingbirds don flashy feathers to avoid being bothered by other hummingbirds, a new study suggests. Male white-necked jacobin hummingbirds (Florisuga mellivora) have bright blue heads and throats. Females tend to have more drab hues, but some sport the blue coloring too. Appearing fit and fine to impress potential mates can often explain animals’ vibrant colors. But mate choice doesn’t seem to drive these females’ pretty plumage since males don’t appear to prefer the blue females. Instead, bright colors may help lady birds blend in with the guys, and as a result, feed for longer without harassment from other hummingbirds, researchers report August 26 in Current Biology. Beyond vying for mates, animals often also compete for territory, parental attention, social ranks and food (SN: 4/7/16). Mating choices don’t capture all those other interactions and can’t always explain animals’ looks, says Jay Falk, an evolutionary biologist at the University of Washington in Seattle. To begin investigating why some female jacobins have colorful blue plumage, Falk and colleagues captured and released over 400 of the birds in Gamboa, Panama, using genetics to determine their sex. Most females had drab colors — olive green heads and backs and mottled throats. But nearly 30 percent of females had the shimmery blue noggins that all juveniles have and that are characteristic of adult males. © Society for Science & the Public 2000–2021.

Keyword: Sexual Behavior; Evolution
Link ID: 27969 - Posted: 08.28.2021

By Carolyn Wilke Frog and toad pupils come in quite the array, from slits to circles. But overall, there are seven main shapes of these animals’ peepholes, researchers report in the Aug. 25 Proceedings of the Royal Society B. Eyes are “among the most charismatic features of frogs and toads,” says herpetologist Julián Faivovich of the Museo Argentino de Ciencias Naturales “Bernardino Rivadavia” in Buenos Aires. People have long marveled at the animals’ many iris colors and pupil shapes. Yet “there’s almost nothing known about the anatomical basis of that diversity.” Faivovich and colleagues catalogued pupil shapes from photos of 3,261 species, representing 44 percent of known frogs and toads. The team identified seven main shapes: vertical slits, horizontal slits, diamonds, circles, triangles, fans and inverted fans. The most common shape, horizontal slits, appeared in 78 percent of studied species. Mapping pupil shapes onto a tree of evolutionary relationships allowed the scientists to infer how these seven shapes emerged. Though uncommon in other vertebrates, horizontal pupils seem to have given rise to most of the other shapes in frogs and toads. All together, these seven shapes have evolved at least 116 times, the researchers say. Pupil shape affects the amount of light that reaches the retina and its light-receiving cells, says Nadia Cervino, a herpetologist also at the Argentine museum. But how the shape influences what animals actually see isn’t well-known. © Society for Science & the Public 2000–2021.

Keyword: Vision; Evolution
Link ID: 27958 - Posted: 08.25.2021

By Priyanka Runwal Brain tissue is innately squishy. Unlike bones, shells or teeth, it is rich in fat and rots quickly, seldom making an appearance in the fossil record. So when Russell Bicknell, an invertebrate paleontologist at the University of New England in Australia, noticed a pop of white near the front of a fossilized horseshoe crab body where the animal’s brain would have been, he was surprised. A closer look revealed an exceptional imprint of the brain along with other bits of the creature’s nervous system. Unearthed from the Mazon Creek deposit in northeastern Illinois, and dating back 310 million years, it’s the first fossilized horseshoe crab brain ever found. Dr. Bicknell and his colleagues reported the find last month in the journal Geology. “These kinds of fossils are so rare that if you happen to stumble upon one, you’d generally be in shock,” he said. “We’re talking a needle-in-a-haystack level of wow.” The find helps fill a gap in the evolution of arthropod brains and also shows how little they have changed over hundreds of millions of years. Soft-tissue preservation requires special conditions. Scientists have found brains encased in fossilized tree resin, better known as amber, that were less than 66 million years old. They have also found brains preserved as flattened carbon films, sometimes replaced or overlaid by minerals in shale deposits that are more than 500 million years old. Such deposits include corpses of ocean-dwelling arthropods that sank to the seafloor, were rapidly buried in mud and remained shielded from immediate decay in the low-oxygen environment. However, the fossilized brain of Euproops danae, which is kept in a collection at the Yale Peabody Museum of Natural History, required a different set of conditions to be preserved. © 2021 The New York Times Company

Keyword: Evolution
Link ID: 27956 - Posted: 08.21.2021

Natalie Grover Cuttlefish have one of the largest brains among invertebrates and can remember what, where, and when specific things happened right up to their final days of life, according to new research. The cephalopods – which have three hearts, eight arms, blue-green blood, regenerating limbs, and the ability to camouflage and exert self-control – only live for roughly two years. As they get older, they show signs of declining muscle function and appetite, but it appears that no matter their age they can remember what they ate, where and when, and use this to guide their future feeding decisions, said the lead study author, Dr Alexandra Schnell from the University of Cambridge. This is in contrast to humans, who gradually lose the ability to remember experiences that occurred at a particular time and place with age – for instance, what you ate for lunch last Wednesday. This “episodic memory” and its deterioration is linked to the hippocampus, a seahorse-shaped organ in the part of the brain near our ears. Cuttlefish, meanwhile, do not have a hippocampus, but a “vertical lobe” associated with learning and memory. In the study, Schnell and her colleagues conducted memory tests in 24 cuttlefish. Half were 10-12 months old (not quite adults) while the rest were 22-24 months old (the equivalent of a human in their 90s), according to the paper, published in the journal Proceedings of the Royal Society B. In one experiment, both groups of cuttlefish were first trained to approach a specific location in their tank, marked with a flag, and learn that two different foods would be provided at different times. At one spot, the flag was waved and the less-preferred king prawn was provided every hour. Grass shrimp, which they like more, was provided at a different spot where another flag was waved – but only every three hours. This was done for about four weeks, until they learned that waiting for longer meant that they could get their preferred food. © 2021 Guardian News & Media Limited

Keyword: Learning & Memory; Evolution
Link ID: 27951 - Posted: 08.18.2021

By Cara Giaimo Giraffes seem above it all. They float over the savanna like two-story ascetics, peering down at the fray from behind those long lashes. For decades, many biologists thought giraffes extended this treatment to their peers as well, with one popular wildlife guide calling them “aloof” and capable of only “the most casual” associations. Sign up for Science Times Get stories that capture the wonders of nature, the cosmos and the human body. Get it sent to your inbox. But more recently, as experts have paid closer attention to these lanky icons, a different social picture has begun to emerge. Female giraffes are now known to enjoy yearslong bonds. They have lunch buddies, stand guard over dead calves and stay close with their mothers and grandmothers. Females even form shared day care-like arrangements, called crèches, in which they take turns babysitting and feeding each others young. Observations like these have reached a critical mass, said Zoe Muller, a wildlife biologist who completed her Ph.D. at the University of Bristol in England. She and Stephen Harris, also at Bristol, recently reviewed hundreds of giraffe studies to look for broader patterns. Their analysis, published on Tuesday in the journal Mammal Review, suggests that giraffes are not loners, but socially complex creatures, akin to elephants or chimpanzees. They’re just a little more subtle about it. Dr. Muller’s sense of giraffes as secret socialites began in 2005, when she was researching her master’s thesis in Laikipia, Kenya. There to collect data on antelopes, she found herself drawn to the ganglier ungulates. “They are so weird to look at,” she said. “If somebody described them to you, you wouldn’t believe they even really existed.” After noticing that the same giraffes tended to spend time together — they looked “like teenagers hanging out,” she said — Dr. Muller started to read up on their lifestyles. “I was really surprised to see that all the scientific books said that they were completely non-sociable,” she said. “I thought, ‘Well, hang on. That’s not what I see at all.’” © 2021 The New York Times Company

Keyword: Evolution; Emotions
Link ID: 27945 - Posted: 08.11.2021

Jordana Cepelewicz An understanding of numbers is often viewed as a distinctly human faculty — a hallmark of our intelligence that, along with language, sets us apart from all other animals. But that couldn’t be further from the truth. Honeybees count landmarks when navigating toward sources of nectar. Lionesses tally the number of roars they hear from an intruding pride before deciding whether to attack or retreat. Some ants keep track of their steps; some spiders keep track of how many prey are caught in their web. One species of frog bases its entire mating ritual on number: If a male calls out — a whining pew followed by a brief pulsing note called a chuck — his rival responds by placing two chucks at the end of his own call. The first frog then responds with three, the other with four, and so on up to around six, when they run out of breath. Practically every animal that scientists have studied — insects and cephalopods, amphibians and reptiles, birds and mammals — can distinguish between different numbers of objects in a set or sounds in a sequence. They don’t just have a sense of “greater than” or “less than,” but an approximate sense of quantity: that two is distinct from three, that 15 is distinct from 20. This mental representation of set size, called numerosity, seems to be “a general ability,” and an ancient one, said Giorgio Vallortigara, a neuroscientist at the University of Trento in Italy. Now, researchers are uncovering increasingly more complex numerical abilities in their animal subjects. Many species have displayed a capacity for abstraction that extends to performing simple arithmetic, while a select few have even demonstrated a grasp of the quantitative concept of “zero” — an idea so paradoxical that very young children sometimes struggle with it. All Rights Reserved © 2021

Keyword: Intelligence; Evolution
Link ID: 27944 - Posted: 08.11.2021

Max G. Levy Agony is contagious. If you drop a thick textbook on your toes, circuits in your brain’s pain center come alive. If you pick it up and accidentally drop it on my toes, hurting me, an overlapping neural neighborhood will light up in your brain again. “There's a physiological mechanism for emotional contagion of negative responses like stress and pain and fear,” says Inbal Ben-Ami Bartal, a neuroscientist at Tel-Aviv University in Israel. That's empathy. Researchers debate to this day whether empathy is a uniquely human ability. But more scientists are finding evidence suggesting it exists widely, particularly in social mammals like rats. For the past decade, Bartal has studied whether—and why—lab rodents might act on that commiseration to help pals in need. Picture two rats in a cage. One roams freely, while the other is constrained in a vented plexiglass tunnel with a small door that only opens from the outside. Bartal, along with teams at UC Berkeley and the University of Chicago, has shown that the free rat may feel their trapped fellow’s distress and learn to open the door. This empathic pull is so strong that rats will rescue their roommates instead of feasting on piles of chocolate chips. (Disclosure: I have three pet rats. My sources confirm that chocolate chips are borderline irresistible.) But there's been a catch: Bartal’s experiments over the years have shown that rats only help others they perceive as members of their social group—specific pals or entire genetic strains they recognize. So does this mean they can't empathize with strangers? In new results appearing in the journal eLife in July, Bartal and her adviser from Berkeley, Daniela Kaufer, uncovered a surprise. Rats do show the neural signatures of empathy for trapped strangers, but that alone isn’t enough to make them help. While seeing a trapped stranger lights up parts of the brain associated with empathy, only seeing a familiar rat or breed elicits a rush of activity in the brain’s so-called reward center, the nucleus accumbens—so only those rats get rescued. © 2021 Condé Nast

Keyword: Emotions; Evolution
Link ID: 27943 - Posted: 08.11.2021

By Annie Roth As anyone who has ever tried to eat french fries on a beach will attest, stealing is not an uncommon behavior among birds. In fact, many birds are quite skilled at bold and brazen theft. Scientists have documented several species of birds, including magpies, bowerbirds, and black kites, looting everything from discarded plastic to expensive jewelry to decorate their nests. And then there are birds who want hair, and will go to great lengths to get their beaks on it. Hair from dogs, raccoons and even humans has been found in the nests of birds, which scientists believe makes the nests better insulated. For a long time, scientists assumed that birds had to collect hair that had been shed or scavenge it from mammal carcasses. However, a new study, published last week in the journal Ecology, shows that several species of bird, including chickadees and titmice, don’t just scavenge hair, they steal it. The study, based largely on analysis of YouTube videos, shows numerous examples of birds pulling tufts of hair from living mammals, including humans. This phenomenon, which the study’s authors have dubbed “kleptotrichy,” has been well-documented by birders on the web, but this is the first time scientists have formally recognized it. “This is just another example of something that was overlooked in the scientific literature but was common knowledge in the bird watching and bird feeding community,” said Henry Pollock, a postdoctoral researcher in ornithology at the University of Illinois and co-author of the new study. Last spring, Dr. Pollock was participating in his university’s annual spring bird count when a tufted titmouse caught his eye. It was flitting near a raccoon sleeping soundly on a tree branch, inching closer and closer to it. Then, to Dr. Pollock’s amusement, the tiny bird began plucking tufts of the raccoon’s fur. The titmouse managed to steal over 20 beak-fulls of the raccoon’s fur without waking it. © 2021 The New York Times Company

Keyword: Learning & Memory; Evolution
Link ID: 27937 - Posted: 08.07.2021

Jake Buehler As the midday sun hangs over the Scandinavian spruce forest, a swarm of hopeful suitors takes to the air. They are dance flies, and it is time to attract a mate. Zigzagging and twirling, the flies show off their wide, darkened wings and feathery leg scales. They inflate their abdomens like balloons, making themselves look bigger and more appealing to a potential partner. Suddenly, the swarm electrifies with excitement at the arrival of a new fly, the one they have all been waiting for: a male. It’s time for the preening flock of females to shine. The flies are flipping the classic drama reenacted across the animal kingdom, in which eager males with dazzling plumage, snarls of antlers or other extraordinary traits compete for a chance to woo a reluctant female. Such competitions between males for the favor of choosy females are enshrined in evolutionary theory as “sexual selection,” with the females’ choices molding the evolution of the males’ instruments of seduction over generations. Yet it’s becoming clear that this traditional picture of sexual selection is woefully incomplete. Dramatic and obvious reversals of the selection scenario, like that of the dance flies, aren’t often observed in nature, but recent research suggests that throughout the tree of animal life, females jockey for the attention of males far more than was believed. A new study hosted on the preprint server biorxiv.org has found that in animals as diverse as sea urchins and salamanders, females are subject to sexual selection — not as harshly as males are, but enough to make biologists rethink the balance of evolutionary forces shaping species in their accounts of the history of life. All Rights Reserved © 2021

Keyword: Sexual Behavior; Evolution
Link ID: 27934 - Posted: 08.07.2021

By James Gorman You’ve heard of trash pandas: Raccoons raiding the garbage. How about trash parrots? Sulfur-crested cockatoos, which may sound exotic to Americans and Europeans, are everywhere in suburban areas of Sydney. They have adapted to the human environment, and since they are known to be clever at manipulating objects it’s not entirely surprising that they went after a rich food source. But you might say that the spread of their latest trick, to open trash cans, blows the lid off social learning and cultural evolution in animals. Not only do the birds acquire the skill by imitating others, which is social learning. But the details of technique evolve to differ in different groups as the innovation spreads, a mark of animal culture. Barbara C. Klump, a behavioral ecologist at the Max Planck Institute of Animal Behavior in Germany, and the first author of a report on the cockatoo research in the journal Science, said, “It’s actually quite a complex behavior because it has multiple steps.” Dr. Klump and her colleagues broke the behavior down into five moves. First a bird uses its bill to pry the lid from the container. Then, she said, “they open it and then they hold it and then they walk along one side and then they flip it over. And at each of these stages, there is variation.” Some birds walk left, some right, they step differently or hold their heads differently. The process is similar to the spread and evolution of human cultural innovations like language, or a classic example of animal culture, bird song, which can vary from region to region in the same species. Dr. Klump and her colleagues in Germany and Australia plotted the spread of the behavior in greater Sydney over the course of two years. The behavior became more common, but it didn’t pop up in random locations as it might if different birds were figuring out the trash bin technique on their own. It spread outward from its origin, indicating that the cockatoos were learning how to do it from each other. © 2021 The New York Times Company

Keyword: Learning & Memory; Evolution
Link ID: 27928 - Posted: 07.28.2021

By Melissa J. Coleman, Eric Fortune A fundamental feature of vocal communication is taking turns: when one person says something, the other person listens and then responds. Turn-taking requires precise coordination of the timing of signals between individuals. We have all found over the past year communicating over Zoom that disruptions of the timing of auditory cues—like those annoying delays caused by poor connections—make effective communication difficult and frustrating. How do the brains of two individuals synchronize their activity patterns for rapid turn-taking during vocal communication? We addressed this question in a recently published paper by studying turn-taking in a specialist, the plain-tailed wren (Pheugopedius euophrys), which sings precisely timed duets. Our findings demonstrate the ability to coordinate relies on sensory cues from one partner that temporarily inhibit vocalizations in the other. These birds sing duets in which females and males alternate their vocalizations, called syllables, so rapidly it sounds as if a single bird is singing. These wrens live in dense bamboo on the slopes of the Andes. To study the neural basis of duet singing, we flew to Ecuador where we loaded up a truck with equipment and drove to a remote field-site called the Yanayacu Biological Field Station and Center for Creative Studies. Much of our equipment required electricity, so we had to bring car batteries for backup and used a six-meter copper rod that we drove into the soft mountain earth for our electrical ground. Our “lab bench” was a door that we placed on two Pelican suitcases. First, we had to catch pairs of wrens, so we hacked through bamboo with machetes and set up mist nets. We then attracted pairs to the nets by playing the duets of wrens. To see how neurons responded during duets, we surgically implanted very small wires into a specific region of the brain, called HVC. Neurons in this region are responsible for producing the song—that is, they are premotor—and they also respond to auditory signals. To transmit the neural signals (i.e., action potentials) to a computer, a small wireless digital transmitter was then connected to the wires. We then had to wait for the birds to sing their remarkable duets. © 2021 Scientific American,

Keyword: Animal Communication; Language
Link ID: 27908 - Posted: 07.14.2021

By Jaime Chambers Wiggles and wobbles and a powerful pull toward people — that’s what 8-week-old puppies are made of. From an early age, dogs outpace wolves at engaging with and interpreting cues from humans, even if the dogs have had less exposure to people, researchers report online July 12 in Current Biology. The result suggests that domestication has reworked dogs’ brains to make the pooches innately drawn to people — and perhaps to intuit human gestures. Compared with human-raised wolf pups, dog puppies that had limited exposure to people were still 30 times as likely to approach a strange human, and five times as likely to approach a familiar person. “I think that is by far the clearest result in the paper, and is powerful and meaningful,” says Clive Wynne, a canine behavioral scientist at Arizona State University in Tempe who was not involved in the study. Wolf pups are naturally less entranced by people than dogs are. “When I walked into the [wolf] pen for the first time, they would all just run into the corner and hide,” says Hannah Salomons, an evolutionary anthropologist studying dog cognition at Duke University. Over time, Salomons says, most came to ignore her, “acting like I was a piece of furniture.” But dogs can’t seem to resist humans’ allure (SN: 7/19/17). They respond much more readily to people, following where a person points, for example. That ability may seem simple, but it’s a skill even chimpanzees — humans’ close relatives — don’t show. Human babies don’t learn how to do it until near their first birthday. © Society for Science & the Public 2000–2021

Keyword: Evolution; Learning & Memory
Link ID: 27906 - Posted: 07.14.2021

By Veronique Greenwood Captive cuttlefish require entertainment when they eat. Dinner and a show — if they can’t get live prey, then they need some dancing from a dead shrimp on a stick in their tank. When the food looks alive, the little cephalopods, which look like iridescent footballs with eight short arms and two tentacles, are more likely to eat it. Because a person standing before them has to jiggle it, the animals start to recognize that mealtime and a looming human-shaped outline go together. As soon as a person walks into the room, “they all swim to the front of the tank saying, give me food!” said Trevor Wardill, a biologist at the University of Minnesota who studies cuttlefish vision. You may get a squirt of water from a cuttlefish’s siphon if you don’t feed them, though. Alexandra Schnell, a comparative psychologist at the University of Cambridge, recalled some who sprayed her if she was even a little slow with the treats. It’s the kind of behavior that researchers who’ve worked with cuttlefish sometimes remark on: The critters have character. But they do not have the name recognition of their cousins — the octopus and the squid. Even Tessa Montague, a neuroscientist who today studies cuttlefish at Columbia University, hadn’t really heard of them until an aquarium visit during graduate school. “Octopus are obviously part of lots of children’s story books,” she notes. Cuttlefish were not present. During the last week of a course at the Marine Biological Laboratory in Woods Hole, Mass., though, she heard a talk by Bret Grasse, whom she called a “cephalopod guru.” “He said they have three hearts, green blood and one of the largest brains among invertebrates,” she said. “And they can regenerate their limbs, they can camouflage. Within about 30 seconds, I had basically planned out my entire life. That lunchtime I went to the facility where he was culturing all these animals. My entire scientific career flashed in front of me. I was like, this is it, this is what I’ve been looking for.” © 2021 The New York Times Company

Keyword: Evolution; Intelligence
Link ID: 27903 - Posted: 07.10.2021

By Lizzie Wade They were buried on a plantation just outside Havana. Likely few, if any, thought of the place as home. Most apparently grew up in West Africa, surrounded by family and friends. The exact paths that led to each of them being ripped from those communities and sold into bondage across the sea cannot be retraced. We don’t know their names and we don’t know their stories because in their new world of enslavement those truths didn’t matter to people with the power to write history. All we can tentatively say: They were 51 of nearly 5 million enslaved Africans brought to Caribbean ports and forced to labor in the islands’ sugar and coffee fields for the profit of Europeans. Nor do we know how or when the 51 died. Perhaps they succumbed to disease, or were killed through overwork or by a more explicit act of violence. What we do know about the 51 begins only with a gruesome postscript: In 1840, a Cuban doctor named José Rodriguez Cisneros dug up their bodies, removed their heads, and shipped their skulls to Philadelphia. He did so at the request of Samuel Morton, a doctor, anatomist, and the first physical anthropologist in the United States, who was building a collection of crania to study racial differences. And thus the skulls of the 51 were turned into objects to be measured and weighed, filled with lead shot, and measured again. Morton, who was white, used the skulls of the 51—as he did all of those in his collection—to define the racial categories and hierarchies still etched into our world today. After his death in 1851, his collection continued to be studied, added to, and displayed. In the 1980s, the skulls, now at the University of Pennsylvania Museum of Archaeology and Anthropology, began to be studied again, this time by anthropologists with ideas very different from Morton’s. They knew that society, not biology, defines race. © 2021 American Association for the Advancement of Science.

Keyword: Brain imaging; Evolution
Link ID: 27902 - Posted: 07.10.2021

Rebecca Hersher Big bodies are good for cold places. That's the gist of a foundational rule in ecology that has been around since the mid-1800s: Animals that live in colder places tend to have larger bodies, especially birds and mammals that need to regulate their body temperatures. For example, some of the largest whale and bear species have evolved in the coldest reaches of the planet. The rule applies broadly to modern humans too. Populations that evolved in colder places generally have bigger bodies. That's also true of human ancestors, a new study finds. The research offers conclusive evidence that human body size and climate are historically connected. In general, our ancient relatives got much larger as they evolved. "Over the last million years, you see that body size changes by about 50% and brain size actually triples, which is a lot," explains Andrea Manica, an evolutionary ecologist at the University of Cambridge. "And there have been all sorts of theories about what might have underpinned those two big changes in size." Article continues after sponsor message Manica and a team of paleontologists and climate scientists in Germany and the United Kingdom set out to test one of those theories: that the local climate was driving brain and body growth. They examined about 300 fossils of human ancestors collected in Europe, Asia and Africa, and they used the same basic climate data that scientists use to predict future climate change to estimate instead temperature and precipitation over the last million years. © 2021 npr

Keyword: Evolution
Link ID: 27901 - Posted: 07.10.2021