Chapter 6. Evolution of the Brain and Behavior

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by Adam Kirsch Giraffes will eat courgettes if they have to, but they really prefer carrots. A team of researchers from Spain and Germany recently took advantage of this preference to investigate whether the animals are capable of statistical reasoning. In the experiment, a giraffe was shown two transparent containers holding a mixture of carrot and courgette slices. One container held mostly carrots, the other mostly courgettes. A researcher then took one slice from each container and offered them to the giraffe with closed hands, so it couldn’t see which vegetable had been selected. In repeated trials, the four test giraffes reliably chose the hand that had reached into the container with more carrots, showing they understood that the more carrots were in the container, the more likely it was that a carrot had been picked. Monkeys have passed similar tests, and human babies can do it at 12 months old. But giraffes’ brains are much smaller than primates’ relative to body size, so it was notable to see how well they grasped the concept. Such discoveries are becoming less surprising every year, however, as a flood of new research overturns longstanding assumptions about what animal minds are and aren’t capable of. A recent wave of popular books on animal cognition argue that skills long assumed to be humanity’s prerogative, from planning for the future to a sense of fairness, actually exist throughout the animal kingdom – and not just in primates or other mammals, but in birds, octopuses and beyond. In 2018, for instance, a team at the University of Buenos Aires found evidence that zebra finches, whose brains weigh half a gram, have dreams. Monitors attached to the birds’ throats found that when they were asleep, their muscles sometimes moved in exactly the same pattern as when they were singing out loud; in other words, they seemed to be dreaming about singing. © 2023 Guardian News & Media Limited

Keyword: Evolution; Learning & Memory
Link ID: 28808 - Posted: 05.31.2023

By Carolyn Wilke Costello the octopus was napping while stuck to the glass of his tank at the Rockefeller University in New York. He snoozed quietly for half an hour, and then entered a more active sleep stage, his skin cycling through colors and textures used for camouflage — typical behavior for a cephalopod. But soon things became strange. A minute later, Costello scuttled along the glass toward his tank’s sandy bottom, curling his arms over his body. Then he spun like a writhing cyclone. Finally, Costello swooped down and clouded half of his tank with ink. As the tank’s filtration system cleared the ink, Eric Angel Ramos, a marine scientist, noticed that Costello was grasping a pipe with unusual intensity, “looking like he was trying to kill it,” he said. “This was not a normal octopus behavior,” said Dr. Ramos, who is now at the University of Vermont. It’s not clear when or if Costello woke up during the episode, Dr. Ramos said. But afterward, Costello returned to normal, eating and later playing with his toys. “We were completely dumbfounded,” said Marcelo O. Magnasco, a biophysicist at Rockefeller. Perhaps Costello was having a nightmare, he and a team of researchers speculated. They shared this idea and other possible explanations in a study uploaded this month to the bioRxiv website. It has yet to be formally reviewed by other scientists. After the incident, Dr. Ramos reviewed the footage of Costello’s activity, which was recorded as part of a behavior and cognition study (the lab was also observing another octopus, Abbott; both were named after the heptapod aliens in the movie “Arrival”). In total, the team found three more shorter instances that appeared similar. To Dr. Magnasco, the behaviors exhibited in Costello’s longest spell evoked the acting out of a dream. The curling of arms over his body looked like a defensive posture, he said. In the footage, the animal is seen perhaps trying to make himself look larger, and then he tries an evasive maneuver — inking. When he fails to escape, it seems like Costello seeks to subdue a threat by strangling the pipe, Dr. Magnasco said, adding, “This is the sequence of a fight.” © 2023 The New York Times Company

Keyword: Sleep; Evolution
Link ID: 28798 - Posted: 05.27.2023

By Carl Zimmer One of the greatest transformations in the history of life occurred more than 600 million years ago, when a single-celled organism gave rise to the first animals. With their multicellular bodies, animals evolved into a staggering range of forms, like whales that weigh 200 tons, birds that soar six miles into the sky and sidewinders that slither across desert dunes. Scientists have long wondered what the first animals were like, including questions about their anatomy and how they found food. In a study published on Wednesday, scientists found tantalizing answers in a little-known group of gelatinous creatures called comb jellies. While the first animals remain a mystery, scientists found that comb jellies belong to the deepest branch on the animal family tree. The debate over the origin of animals has endured for decades. At first, researchers relied largely on the fossil record for clues. The oldest definitive animal fossils date back about 580 million years, although some researchers have claimed to find even older ones. In 2021, for example, Elizabeth Turner, a Canadian paleontologist, reported finding 890-million-year-old fossils of possible sponges. Sponges would make sense as the oldest animal. They are simple creatures, with no muscles or nervous system. They anchor themselves to the ocean floor, where they filter water through a maze of pores, trapping bits of food. Sponges are so simple, in fact, that it can come as a surprise that they are animals at all, but their molecular makeup reveals their kinship. They make certain proteins, such as collagen, that are produced only by animals. What’s more, their DNA shows they are more closely related to animals than to other forms of life. Starting in the 1990s, as scientists gathered DNA from more animal species, they tried to draw the animal family tree. In some studies, the sponges ended up on the deepest branch of the tree. In this scenario, animals evolved a nervous system only after the sponges branched off. © 2023 The New York Times Company

Keyword: Evolution
Link ID: 28793 - Posted: 05.23.2023

By Ula Chrobak A couple of weeks after I adopted my dog, Halle, I realized she had a problem. When left alone, she would pace, bark incessantly, and ignore any treats I left her in favor of chewing my belongings. When I returned, I’d find my border collie mix panting heavily with wide, fearful eyes. As frustrated as I was, though, I restrained the urge to scold her, realizing her destruction was born out of panic. Halle’s behavior was a textbook illustration of separation anxiety. Distressed over being left alone, an otherwise perfectly mannered pup might chomp the couch, scratch doors, or relieve themselves on the floor. Problem behaviors like these tend to be interpreted as acts of willful defiance, but they often stem from intense emotions. Dogs, like humans, can act out of character when they are distressed. And, as with people, some dogs may be neurologically more prone to anxiety. So concluded a recent brain imaging study, published in PLOS One, in which researchers performed resting-state functional magnetic resonance imaging on 25 canines that were deemed behaviorally “normal,” and 13 that had been diagnosed with anxiety, based on a behavioral evaluation. The scans revealed that anxious dogs had stronger connections between several of five brain regions that the researchers called the anxiety circuit: the amygdala, frontal lobe, hippocampus, mesencephalon, and thalamus. The team also saw weaker connections between the hippocampus and midbrain in anxious dogs, which can signal difficulties in learning and might explain why the owners reported decreased trainability in these dogs. That the neurological architecture of anxious dogs seems to parallel the signatures of human anxiety comes as little surprise to many animal behavior experts.

Keyword: Emotions; Evolution
Link ID: 28782 - Posted: 05.13.2023

By Annie Roth It long seemed as though African elephants were the champions of the all-nighter. They can get by on about two hours of sleep. Other mammals need much more, like koalas (20 hours) or you (at least seven plus at least one strong cup of coffee). But the largest living mammals on land have some competition at sea. Northern elephant seals are also able to sustain themselves on about two hours’ sleep, according to a study published Thursday in the journal Science. The study found that Northern elephant seals sleep far less at sea than they do on land, and the z’s they do catch at sea are caught hundreds of feet below the ocean’s surface. The study’s authors believe that sleeping in the deep allows the seals to power-nap without being eaten by prowling predators. Northern elephant seals, which are found along the West Coast, are champion divers that can descend to depths of 2,500 feet and stay under for about two hours. They are not as big as elephants, but males can weigh as much as a car and stretch 13 feet long. To maintain their blubbery bulk, Northern elephant seals must spend around seven months at sea each year, gorging on fish and squid. During these epic voyages, the seals are vulnerable to predation by great white sharks and killer whales. Some marine mammals, such as dolphins and fur seals, can rest half of their brain at a time. This type of slumber, known as unihemispheric sleep, enables some mammals at sea to snooze with one eye open, literally, which prevents predators from catching them off guard. However, elephant seals sleep like us, shutting down their brains completely. Jessica Kendall-Bar, now a postdoctoral fellow at the Scripps Institution of Oceanography in San Diego, wondered how Northern ​​elephant seals managed to sleep, given how much time they need to spend eating and avoiding being eaten while at sea. © 2023 The New York Times Company

Keyword: Sleep; Evolution
Link ID: 28746 - Posted: 04.22.2023

By Jake Buehler Shimmering, gelatinous comb jellies wouldn’t appear to have much to hide. But their mostly see-through bodies cloak a nervous system unlike that of any other known animal, researchers report in the April 21 Science. In the nervous systems of everything from anemones to aardvarks, electrical impulses pass between nerve cells, allowing for signals to move from one cell to the next. But the ctenophores’ cobweb of neurons, called a nerve net, is missing these distinct connection spots, or synapses. Instead, the nerve net is fused together, with long, stringy neurons sharing a cell membrane, a new 3-D map of its structure shows. While the nerve net has been described before, no one had generated a high-resolution, detailed picture of it. It’s possible the bizarre tissue represents a second, independent evolutionary origin of a nervous system, say Pawel Burkhardt, a comparative neurobiologist at the University of Bergen in Norway, and colleagues. Superficially similar to jellyfish, ctenophores are often called comb jellies because they swim using rows of beating, hairlike combs. The enigmatic phylum is considered one of the earliest to branch off the animal tree of life. So ctenophores’ possession of a simple nervous system has been of particular interest to scientists interested in how such systems evolved. Previous genetics research had hinted at the strangeness of the ctenophore nervous system. For instance, a 2018 study couldn’t find a cell type in ctenophores with a genetic signature that corresponded to recognizable neurons, Burkhardt says. Burkhardt, along with neurobiologist Maike Kittelmann of Oxford Brookes University in England and colleagues, examined young sea walnuts (Mnemiopsis leidyi) using electron microscopes, compiling many images to reconstruct the entire net structure. Their 3-D map of a 1-day-old sea walnut revealed the funky synapse-free fusion between the five sprawling neurons that made up the tiny ctenophore’s net. © Society for Science & the Public 2000–2023.

Keyword: Evolution
Link ID: 28745 - Posted: 04.22.2023

By Elizabeth Preston Several years ago, Christian Rutz started to wonder whether he was giving his crows enough credit. Rutz, a biologist at the University of St. Andrews in Scotland, and his team were capturing wild New Caledonian crows and challenging them with puzzles made from natural materials before releasing them again. In one test, birds faced a log drilled with holes that contained hidden food, and could get the food out by bending a plant stem into a hook. If a bird didn’t try within 90 minutes, the researchers removed it from the dataset. But, Rutz says, he soon began to realize he was not, in fact, studying the skills of New Caledonian crows. He was studying the skills of only a subset of New Caledonian crows that quickly approached a weird log they’d never seen before—maybe because they were especially brave, or reckless. The team changed their protocol. They began giving the more hesitant birds an extra day or two to get used to their surroundings, then trying the puzzle again. “It turns out that many of these retested birds suddenly start engaging,” Rutz says. “They just needed a little bit of extra time.” Scientists are increasingly realizing that animals, like people, are individuals. They have distinct tendencies, habits, and life experiences that may affect how they perform in an experiment. That means, some researchers argue, that much published research on animal behavior may be biased. Studies claiming to show something about a species as a whole—that green sea turtles migrate a certain distance, say, or how chaffinches respond to the song of a rival—may say more about individual animals that were captured or housed in a certain way, or that share certain genetic features. That’s a problem for researchers who seek to understand how animals sense their environments, gain new knowledge, and live their lives. © 2023 NautilusNext Inc.,

Keyword: Evolution; Intelligence
Link ID: 28724 - Posted: 04.01.2023

By Bethany Brookshire Cockroaches are changing up their sex lives, and it’s all our fault. Faced with sweet poisoned bait, roaches first ended up with a mutation that made them hate sweets, hindering their mating strategies. Now, more roach mutations are emerging, showing you can’t keep a good pest down. Like many animals, cockroaches have a sweet tooth, and that preference for sugar plays a central role in their reproductive activities. When a male roach targets a female roach, he will back up to her, secreting a solution called a nuptial gift from the tergal gland under his wings. The solution is full of proteins, fats and sugars, what some researchers call the chocolate of roach food. The female cockroach will crawl up on his back to take a sample, and while she is occupied, the male will whip out a hooked penis to latch onto her reproductive tract. They will then turn back to back and do the deed for about 90 minutes. Humans have aimed to exploit this love of sweet stuff to push cockroaches — particularly the German cockroaches that turn up in American homes — out of our spaces. For decades, people used poisoned roach baits baited with solutions containing glucose. Cockroaches took the bait. But some time in the late 20th century, a new mutation arose — glucose aversion. No one knows how many roaches now hate the sweet stuff, but Coby Schal, an evolutionary biologist at North Carolina State University, suspects the mutation is very common. “There are more and more papers being published on the fact that a whole suite of baits don’t work so well,” he said. This lack of a sweet tooth saved cockroaches from death, but it hurt their sex lives. The gift that normal males secrete contains maltose, a sugar that cockroach saliva transforms into glucose. But if females had the glucose averse mutation, they did not find the male secretions sexy and turned away before the male could hook on. © 2023 The New York Times Company

Keyword: Chemical Senses (Smell & Taste); Evolution
Link ID: 28722 - Posted: 03.29.2023

By Jack Tamisiea Even a fisher’s yarn would sell a whale shark short. These fish—the biggest on the planet—stretch up to 18 meters long and weigh as much as two elephants. The superlatives don’t end there: Whale sharks also have one of the longest vertical ranges of any sea creature, filter feeding from the surface of the ocean to nearly 2000 meters down into the inky abyss. Swimming between bright surface waters and the pitch black deep sea should strain the shark’s eyes, making their lifestyle impossible. But researchers have now uncovered the genetic wiring that prevents this from happening. The study, published this week in the Proceedings of the National Academy of Sciences, pinpoints a genetic mutation that makes a visual pigment in the whale shark’s retina more sensitive to temperature changes. As a result, the pigments—which sense blue light in dark environments—are activated in the chilly deep sea and deactivated when the sharks return to the balmy surface to feed, allowing them to prioritize different parts of their vision at different depths. Ironically, the genetic alteration is surprisingly similar to one that degrades pigments in human retinas, causing night blindness. It remains unclear why whale sharks dive so deep. Because prey is scarce at these depths, the behavior may be linked to mating. But whatever they do, the sharks rely on a light-sensing pigment in their retinas called rhodopsin to navigate the dark waters. Although the pigments are less useful in sunny habitats, they help many vertebrates, including humans, detect light in dim environments. In the deep sea, the rhodopsin pigments in whale shark eyes are specifically calibrated to see blue light—the only color that reaches these depths. Previous research has revealed bottom-dwelling cloudy catsharks (Scyliorhinus torazame) have similarly calibrated pigments in their eyes to spot blue light. But these small sharks are content in the deep, making whale sharks the only known sharks to sport these pigments in the shallows. In lighter waters, these blue light–sensing pigments could act as a hindrance to seeing other kinds of light, but whale sharks are still able to maneuver with ease as they vacuum up seafood.

Keyword: Vision; Genes & Behavior
Link ID: 28719 - Posted: 03.25.2023

By Elizabeth Preston Several years ago, Christian Rutz started to wonder whether he was giving his crows enough credit. Rutz, a biologist at the University of St. Andrews in Scotland, and his team were capturing wild New Caledonian crows and challenging them with puzzles made from natural materials before releasing them again. In one test, birds faced a log drilled with holes that contained hidden food, and could get the food out by bending a plant stem into a hook. If a bird didn’t try within 90 minutes, the researchers removed it from the dataset. But, Rutz says, he soon began to realize he was not, in fact, studying the skills of New Caledonian crows. He was studying the skills of only a subset of New Caledonian crows that quickly approached a weird log they’d never seen before — maybe because they were especially brave, or reckless. The team changed their protocol. They began giving the more hesitant birds an extra day or two to get used to their surroundings, then trying the puzzle again. “It turns out that many of these retested birds suddenly start engaging,” Rutz says. “They just needed a little bit of extra time.” Scientists are increasingly realizing that animals, like people, are individuals. They have distinct tendencies, habits and life experiences that may affect how they perform in an experiment. That means, some researchers argue, that much published research on animal behavior may be biased. Studies claiming to show something about a species as a whole — that green sea turtles migrate a certain distance, say, or how chaffinches respond to the song of a rival — may say more about individual animals that were captured or housed in a certain way, or that share certain genetic features. That’s a problem for researchers who seek to understand how animals sense their environments, gain new knowledge and live their lives. “The samples we draw are quite often severely biased,” Rutz says. “This is something that has been in the air in the community for quite a long time.” In 2020, Rutz and his colleague Michael Webster, also at the University of St. Andrews, proposed a way to address this problem. They called it STRANGE. © 2023 Annual Reviews

Keyword: Emotions; Evolution
Link ID: 28700 - Posted: 03.11.2023

By Bruce Bower Monkeys in southern Thailand use rocks to pound open oil palm nuts, inadvertently shattering stone pieces off their makeshift nutcrackers. These flakes resemble some sharp-edged stone tools presumed to have been created on purpose by ancient hominids, researchers say. Thailand’s long-tailed macaques (Macaca fascicularis) produce shards that could easily be mistaken for stone flakes previously found at 17 East African hominid sites dating from about 3.3 million to 1.56 million years ago, say archaeologist Tomos Proffitt and colleagues. The finding suggests that ancient hominids may sometimes have created the stone flakes by accident while using rocks to smash nuts, bones or other objects, the scientists report March 10 in Science Advances. Previous research has already shown that rock-wielding capuchin monkeys in Brazil unwittingly produce hominid-like stone flakes (SN: 10/19/16). Observations of rock bashing by these two monkey species undermine a long-standing assumption that hominids must have intentionally made certain ancient stone flakes, including some of the earliest known examples of tools, Proffitt says (SN: 6/3/19). It’s time to reevaluate how such determinations are made, he contends. Proffitt’s group identified 219 complete and fragmented stone flakes at 40 macaque nut-cracking sites on the island where the monkeys live. The team also found rocks showing damage consistent with having been used either as pounding implements or pounding platforms. Some differences do exist between macaque and hominid stone flakes, says Proffitt, of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. For instance, many macaque flakes display battering damage on only one side, versus frequent two-sided damage on hominid artifacts. © Society for Science & the Public 2000–2023.

Keyword: Evolution; Intelligence
Link ID: 28699 - Posted: 03.11.2023

By Susan Milius In a castaway test setup, groups of young honeybees figuring out how to forage on their own start waggle dancing spontaneously — but badly. Waggling matters. A honeybee’s rump-shimmy runs and turning loops encode clues that help her colony mates fly to food she has found, sometimes kilometers away. However, five colonies in the new test had no older sisters or half-sisters around as role models for getting the dance moves right. Still, dances improved in some ways as the youngsters wiggled and looped day after day, reports behavioral ecologist James Nieh of the University of California, San Diego. But when waggling the clues for distance information, Apis mellifera without role models never did match the timing and coding in normal colonies where young bees practiced with older foragers before doing the main waggle themselves. The youngsters-only colonies thus show that social learning, or the lack of it, matters for communicating by dance among honeybees, Nieh and an international team of colleagues say in the March 10 Science. Bee waggle dancing, a sort of language, turns out to be both innate and learned, like songbird or human communication. The dance may appear simple in a diagram, but executing it on expanses of honeycomb cells gets challenging. Bees are “running forward at over one body length per second in the pitch black trying to keep the correct angle, surrounded by hundreds of bees that are crowding them,” Nieh says. Beekeepers and biologists know that some kinds of bees can learn from others of their kind — some bumblebees even tried soccer (SN: 2/23/17). But when it comes to waggle dancing, “I think people have assumed it’s genetic,” Nieh says. That would make this fancy footwork more like the chatty but innate communications of cuttlefish color change, for instance. The lab bee-castaway experiments instead show a nonhuman example of “social learning for sophisticated communication,” Nieh says. © Society for Science & the Public 2000–2023.

Keyword: Animal Communication; Evolution
Link ID: 28695 - Posted: 03.11.2023

By Sam Jones Dolphins, pilot whales and sperm whales use echolocation clicks to hunt and subdue their prey. But the animals, known as toothed whales, also produce other sounds for social communication, like grunts and high-pitched whistles. For decades, scientists speculated that something in the nasal cavity was responsible for this range of sounds, but the mechanics were unclear. Now, researchers have uncovered how structures in the nose, called phonic lips, allow toothed whales to produce sounds at different registers, similar to the way the human voice functions, all while conserving air deep beneath the ocean’s surface. And the animals use the vocal fry register for echolocation. Yes, that vocal fryyyy. The work was published in the journal Science on Thursday. Bottlenose Sounds A sequence of vocal registers from a bottlenose dolphin: Echolocation clicks made with vocal fry; the bursts of standard vocalization; and whistles. Studying the structures responsible for whale sound production has been no small task. Over the last few decades, “there was a lot of circumstantial evidence — people filming things with X-rays or triangulating sound with different hydrophones,” said Coen P.H. Elemans, a biologist at the University of Southern Denmark. Taking a new approach, Dr. Elemans and colleagues inserted endoscopes into the nasal cavities of trained Atlantic bottlenose dolphins and harbor porpoises to get high-speed footage during sound production. They found that sound was indeed being produced in the nose. But to confirm that the phonic lips were involved — and to see if their movement was driven by muscles or by airflow — they created an experimental setup with deceased (beached or bycatch) harbor porpoises, filming the phonic lips as air was pushed through the nasal complex. They saw that the phonic lips would briefly separate and then collide back together, causing a tissue vibration that would release sound into the surrounding water. But relying on air-driven sound production would not seem to be the best idea if your food is in the murky deep. “One thousand meters down, you have 1 percent of the air you had at the surface,” said Peter Madsen, a zoophysiologist at Aarhus University in Denmark, who has been tagging toothed whales for decades and is a co-author of the study. “To me, it’s always been super provocative to see a sperm whale or beaked whale or pilot whale dive deep, clicking happily, while having the knowledge in the back of my head that they’re supposed to use air for this.” © 2023 The New York Times Company

Keyword: Animal Communication; Evolution
Link ID: 28686 - Posted: 03.04.2023

By Tara C. Smith In The Last of Us, a video game series and recent television show, fungal pathogens are to blame for a zombie-like plague. Once infected, humans lose control over their bodies and become increasingly aggressive, seeking to infect others through violence. It’s a familiar trope: The same fungus, Ophiocordyceps, torments humanity in the movie The Girl With All the Gifts, while viruses do the work in the film 28 Days Later and the novel World War Z. But the concept of a pathogen that can manipulate its host’s behavior — against their will and often to their detriment — is not purely the work of fiction. In these zombie-like cases, the pathogen (whether it’s a virus, bacteria or fungus, or something else) acts specifically to change the behavior of its host. While we know a decent amount about these pathogens — including the very real Ophiocordyceps fungus, which does turn insects into unwitting agents of societal collapse — there’s still much to learn. So the Cordyceps fungus is real? “Cordyceps” has become a common catch-all name for a group of fungi that infect insects. This grouping includes the species Ophiocordyceps unilateralis, better known as the “zombie ant fungus.” It spreads by sprouting fungal structures that erupt through the ant’s head after its death. A regular column in which top researchers explore the process of discovery. This month’s columnist, Tara C. Smith, is a professor of epidemiology and infectious-disease researcher. The challenge for this reproductive strategy is that ants are social insects, and so they act to protect the colony from infections. As part of this behavior, ants typically remove dead ants from the nest. A lone dead ant outside the nest won’t spread the fungus. All Rights Reserved © 2023

Keyword: Neuroimmunology; Aggression
Link ID: 28684 - Posted: 02.25.2023

By Allison Whitten The neocortex stands out as a stunning achievement of biological evolution. All mammals have this swath of tissue covering their brain, and the six layers of densely packed neurons within it handle the sophisticated computations and associations that produce cognitive prowess. Since no animals other than mammals have a neocortex, scientists have wondered how such a complex brain region evolved. The brains of reptiles seemed to offer a clue. Not only are reptiles the closest living relatives of mammals, but their brains have a three-layered structure called a dorsal ventricular ridge, or DVR, with functional similarities to the neocortex. For more than 50 years, some evolutionary neuroscientists have argued that the neocortex and the DVR were both derived from a more primitive feature in an ancestor shared by mammals and reptiles. Now, however, by analyzing molecular details invisible to the human eye, scientists have refuted that view. By looking at patterns of gene expression in individual brain cells, researchers at Columbia University showed that despite the anatomical similarities, the neocortex in mammals and the DVR in reptiles are unrelated. Instead, mammals seem to have evolved the neocortex as an entirely new brain region, one built without a trace of what came before it. The neocortex is composed of new types of neurons that seem to have no precedent in ancestral animals. The paper describing this work, which was led by the evolutionary and developmental biologist Maria Antonietta Tosches, was published last September in Science. This process of evolutionary innovation in the brain isn’t limited to the creation of new parts. Other work by Tosches and her colleagues in the same issue of Science showed that even seemingly ancient brain regions are continuing to evolve by getting rewired with new types of cells. The discovery that gene expression can reveal these kinds of important distinctions between neurons is also prompting researchers to rethink how they define some brain regions and to reassess whether some animals might have more complex brains than they thought. All Rights Reserved © 2023

Keyword: Development of the Brain; Evolution
Link ID: 28668 - Posted: 02.15.2023

By Erin Garcia de Jesús Forget screwdrivers or drills. A stick and a straw make for a great cockatoo tool kit. Some Goffin’s cockatoos (Cacatua goffiniana) know whether they need to have more than one tool in claw to topple an out-of-reach cashew, researchers report February 10 in Current Biology. By recognizing that two items are necessary to access the snack, the birds join chimpanzees as the only nonhuman animals known to use tools as a set. The study is a fascinating example of what cockatoos are capable of, says Anne Clark, a behavioral ecologist at Binghamton University in New York, who was not involved in the study. A mental awareness that people often attribute to our close primate relatives can also pop up elsewhere in the animal kingdom. A variety of animals including crows and otters use tools but don’t deploy multiple objects together as a kit (SN: 9/14/16; SN: 3/21/17). Chimpanzees from the Republic of Congo’s Noubalé-Ndoki National Park, on the other hand, recognize the need for both a sharp stick to break into termite mounds and a fishing stick to scoop up an insect feast (SN: 10/19/04). Researchers knew wild cockatoos could use three different sticks to break open fruit in their native range of Indonesia. But it was unclear whether the birds might recognize the sticks as a set or instead as a chain of single tools that became necessary as new problems arose, says evolutionary biologist Antonio Osuna Mascaró of the University of Veterinary Medicine Vienna. © Society for Science & the Public 2000–2023.

Keyword: Learning & Memory; Evolution
Link ID: 28663 - Posted: 02.11.2023

By Elizabeth Preston A fully grown male orca is one of the planet’s fiercest hunters. He’s a wily, streamlined torpedo who can weigh as much as 11 tons. No other animal preys on him. Yet in at least one population, these apex predators struggle to survive without their moms, who catch their food and even cut it up for them. Scientists have previously seen that some killer whale mothers share food with their grown sons. In a study published Wednesday in Current Biology, researchers found that this prolonged feeding carries a huge reproductive cost for mothers. Killer whales, actually the largest members of the dolphin family, swim throughout the world’s oceans. Yet they live in discrete populations with their own territories, dialects and hunting customs. A group that spends much of the year off the coast of British Columbia, Washington and Oregon is known as the southern residents. They eat mainly Chinook salmon, which have been increasingly hard to find. “Killer whales worldwide are doing fine,” said Michael Weiss, research director at the Center for Whale Research in Friday Harbor, Wash. But the southern residents, with a population of just 73, are considered endangered. These whales stay with their birth family for their whole lives. The families are led by matriarchs who can live 80 to 90 years. Yet the females stop reproducing in midlife: Orcas and a few other whale species are the only mammals, besides humans, known to undergo menopause. To try to explain menopause, scientists have looked for ways that matriarchs encourage the survival of their children and grandchildren. A 2012 study of southern resident killer whales, along with their neighbors, the northern residents, showed that the presence of older moms helped adult offspring stay alive — especially sons. Males over age 30 were eight times more likely to die in the year following their own mothers’ deaths. © 2023 The New York Times Company

Keyword: Sexual Behavior; Evolution
Link ID: 28662 - Posted: 02.11.2023

By Betsy Mason Some fish can recognize their own faces in photos and mirrors, an ability usually attributed to humans and other animals considered particularly brainy, such as chimpanzees, scientists report. Finding the ability in fish suggests that self-awareness may be far more widespread among animals than scientists once thought. “It is believed widely that the animals that have larger brains will be more intelligent than animals of the small brain,” such as fish, says animal sociologist Masanori Kohda of Osaka Metropolitan University in Japan. It may be time to rethink that assumption, Kohda says. Kohda’s previous research showed that bluestreak cleaner wrasses can pass the mirror test, a controversial cognitive assessment that purportedly reveals self-awareness, or the ability to be the object of one’s own thoughts. The test involves exposing an animal to a mirror and then surreptitiously putting a mark on the animal’s face or body to see if they will notice it on their reflection and try to touch it on their body. Previously only a handful of large-brained species, including chimpanzees and other great apes, dolphins, elephants and magpies, have passed the test. In a new study, cleaner fish that passed the mirror test were then able to distinguish their own faces from those of other cleaner fish in still photographs. This suggests that the fish identify themselves the same way humans are thought to — by forming a mental image of one’s face, Kohda and colleagues report February 6 in the Proceedings of the National Academy of Sciences. “I think it’s truly remarkable that they can do this,” says primatologist Frans de Waal of Emory University in Atlanta who was not involved in the research. “I think it’s an incredible study.” © Society for Science & the Public 2000–2023.

Keyword: Attention; Evolution
Link ID: 28659 - Posted: 02.08.2023

By Darren Incorvaia The great apes do not have spoken language, but they share many gestures. Can humans like you understand those gestures too? Watch this short video and test your ability to read chimpanzee body language. What is this chimpanzee (the one scratching its arm) asking the other one to do? © 2023 The New York Times Company

Keyword: Animal Communication; Evolution
Link ID: 28640 - Posted: 01.25.2023

By Rodrigo Pérez Ortega Was Tyrannosaurus rex as smart as a baboon? Scientists don’t like to compare intelligence between species (everyone has their own talents, after all), but a controversial new study suggests some dino brains were as densely packed with neurons as those of modern primates. If so, that would mean they were very smart—more than researchers previously thought—and could have achieved feats only humans and other very intelligent animals have, such as using tools. The findings, reported last week in the Journal of Comparative Neurology, are making waves among paleontologists on social media and beyond. Some are applauding the paper as a good first step toward better understanding dinosaur smarts, whereas others argue the neuron estimates are flawed, undercutting the study’s conclusions. Measuring dinosaur intelligence has never been easy. Historically, researchers have used something called the encephalization quotient (EQ), which measures an animal’s relative brain size, related to its body size. A T. rex, for example, had an EQ of about 2.4, compared with 3.1 for a German shepherd dog and 7.8 for a human—leading some to assume it was at least somewhat smart. EQ is hardly foolproof, however. In many animals, body size evolves independently from brain size, says Ashley Morhardt, a paleoneurologist at Washington University School of Medicine in St. Louis who wasn’t involved in the study. “EQ is a fraught metric, especially when studying extinct species.” Looking for a more trustworthy alternative, Suzana Herculano-Houzel, a neuroanatomist at Vanderbilt University, turned to a different measure: the density of neurons in the cortex, the wrinkly outer brain area critical to most intelligence-related tasks. She had previously estimated the number of neurons in many animal species, including humans, by making “brain soup”—dissolving brains in a detergent solution—and counting the neurons in different parts of the brain. © 2023 American Association for the Advancement of Science.

Keyword: Evolution
Link ID: 28627 - Posted: 01.12.2023