Chapter 6. Evolution of the Brain and Behavior

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By Tess Joosse “Bird brain” insults be damned. The noggins of our flying friends are packed with neurons, and recent studies have shown birds can develop complex tools and even discriminate between paintings by Claude Monet and Pablo Picasso. But is this avian acumen a recent development, evolutionarily speaking, or does it trace back tens of millions of years? A remarkably preserved fossil unearthed in Brazil may hold some answers. The 80-million-year-old bird skull contains impressions of advanced brain structures, suggesting early birds were bright like modern ones. The preserved braincase, from a now-extinct bird lineage, is “exceptional … a big step forward,” says Matteo Fabbri, an evolutionary biologist at the Field Museum of Natural History who was not involved with the work. “This is the first time we have really good information regarding the brain of [this] group.” Birds began to evolve about 165 million to 150 million years ago from dinosaurs. Some of the earliest—whose ancestors were carnivorous icons such as Velociraptor—were the famous feathered Archaeopteryx. Over time, avians branched into a group called the enantiornithines and close cousins who became modern birds. Ranging from the size of hummingbirds to turkeys, enantiornithines took to the skies in the Mesozoic era beginning 130 million years ago. The creatures eventually spanned the globe before going extinct 66 million years ago from the same asteroid impact that killed off the dinosaurs. Their position between Archaeopteryx and living birds gives them a “magical place on the dino-bird family tree,” says Daniel Field, a paleontologist at the University of Cambridge and co-author of the new study. To reconstruct the brains of ancient birds, researchers need fossils that preserve the hollow space where a brain would sit: the braincase. But no enantiornithine skeletons have preserved that space—until the new find. © 2022 American Association for the Advancement of Science.

Keyword: Evolution
Link ID: 28492 - Posted: 09.28.2022

By Darren Incorvaia Songbirds get a lot of love for their dulcet tones, but drummers may start to steal some of that spotlight. Woodpeckers, which don’t sing but do drum on trees, have brain regions that are similar to those of songbirds, researchers report September 20 in PLOS Biology. The finding is surprising because songbirds use these regions to learn their songs at an early age, yet it’s not clear if woodpeckers learn their drum beats (SN: 9/16/21). Whether woodpeckers do or not, the result suggests a shared evolutionary origin for both singing and drumming. The ability to learn vocalizations by listening to them, just like humans do when learning to speak, is a rare trait in the animal kingdom. Vocal learners, such as songbirds, hummingbirds and parrots, have independently evolved certain clusters of nerve cells called nuclei in their forebrains that control the ability. Animals that don’t learn vocally are thought to lack these brain features. While it’s commonly assumed that other birds don’t have these nuclei, “there’s thousands of birds in the world,” says Matthew Fuxjager, a biologist at Brown University in Providence, R.I. “While we say these brain regions only exist in these small groups of species, nobody’s really looked in a lot of these other taxa.” Fuxjager and his colleagues examined the noggins of several birds that don’t learn vocally to check if they really did lack these brain nuclei. Using molecular probes, the team checked the bird brains for activity of a gene called parvalbumin, a known marker of the vocal learning nuclei. Many of the birds, including penguins and flamingos, came up short, but there was one exception — male and female woodpeckers, which had three spots in their brains with high parvalbumin activity. © Society for Science & the Public 2000–2022.

Keyword: Animal Communication; Language
Link ID: 28486 - Posted: 09.21.2022

Michael Nolan Jellyfish, anemones and coral polyps, known collectively as cnidarians, have captured the imaginations of scientists across biological disciplines for centuries. Their radial symmetries and graceful, fluid movements lend them an undeniable appeal, but it’s their peculiar nervous systems that have drawn recent attention from neuroscientists. Unlike in most animals, whose neurons are gathered into bundles of nerves and larger structures like brains and ganglia, cnidarian neurons are distributed through their tissues in structures called nerve nets. This diffuse organization makes it possible to observe neural activity from many neurons simultaneously: Because neurons are spread in a thin layer, no neuron blocks an observer’s view of another. That means researchers can use techniques like calcium imaging to potentially capture the activity of a cnidarian’s entire nervous system, rather than a subset of neurons in the dense tangle of a mouse brain, for example. Neuroscientists are leveraging the accessibility of nerve nets to more deeply explore the properties of neural ensembles, groups of neurons that fire in a correlated fashion. Ensembles are a fundamental feature of the brain; they offer a simple example of functional structure in an animal’s nervous system and have become a popular target for systems neuroscientists because they combine population coding (how neural activity encodes information in populations of cells) and connectivity (how connections among neurons relate to population activity). Understanding how these groups form, how they coordinate patterns of neural activity, and how they drive behavior may reveal organizational principles also present in larger and more complicated nervous systems. © Simons Foundation Terms and Conditions Privacy Policy Image Credits

Keyword: Evolution
Link ID: 28485 - Posted: 09.21.2022

Sara Reardon More than 500,000 years ago, the ancestors of Neanderthals and modern humans were migrating around the world when a pivotal genetic mutation caused some of their brains to improve suddenly. This mutation, researchers report in Science1, drastically increased the number of brain cells in the hominins that preceded modern humans, probably giving them a cognitive advantage over their Neanderthal cousins. “This is a surprisingly important gene,” says Arnold Kriegstein, a neurologist at the University of California, San Francisco. However, he expects that it will turn out to be one of many genetic tweaks that gave humans an evolutionary advantage over other hominins. “I think it sheds a whole new light on human evolution.” When researchers first reported the sequence of a complete Neanderthal genome in 20142, they identified 96 amino acids — the building blocks that make up proteins — that differ between Neanderthals and modern humans, as well as some other genetic tweaks. Scientists have been studying this list to learn which of these changes helped modern humans to outcompete Neanderthals and other hominins. Cognitive advantage To neuroscientists Anneline Pinson and Wieland Huttner at the Max Planck Institute of Molecular Cell Biology and Genetics in Dresden, Germany, one gene stood out. TKTL1 encodes a protein that is made when a fetus’s brain is first developing. A mutation in the human version changed one amino acid, resulting in a protein that is different from those found in hominin ancestors, Neanderthals and non-human primates. The researchers suspected that this protein could increase the proliferation of neural progenitor cells, which become neurons, as the brain develops, specifically in an area called the neocortex — a region involved in cognitive function. This, they reasoned, could contribute to modern humans’ cognitive advantage. © 2022 Springer Nature Limited

Keyword: Evolution; Genes & Behavior
Link ID: 28477 - Posted: 09.14.2022

By Erin Garcia de Jesús Human trash can be a cockatoo’s treasure. In Sydney, the birds have learned how to open garbage bins and toss trash around in the streets as they hunt for food scraps. People are now fighting back. Bricks, pool noodles, spikes, shoes and sticks are just some of the tools Sydney residents use to keep sulphur-crested cockatoos (Cacatua galerita) from opening trash bins, researchers report September 12 in Current Biology. The goal is to stop the birds from lifting the lid while the container is upright but still allowing the lid to flop open when a trash bin is tilted to empty its contents. This interspecies battle could be a case of what’s called an innovation arms race, says Barbara Klump, a behavioral ecologist at the Max Planck Institute of Animal Behavior in Radolfzell, Germany. When cockatoos learn how to flip trash can lids, people change their behavior, using things like bricks to weigh down lids, to protect their trash from being flung about (SN Explores: 10/26/21). “That’s usually a low-level protection and then the cockatoos figure out how to defeat that,” Klump says. That’s when people beef up their efforts, and the cycle continues. Researchers are closely watching this escalation to see what the birds — and humans — do next. With the right method, the cockatoos might fly by and keep hunting for a different target. Or they might learn how to get around it. In the study, Klump and colleagues inspected more than 3,000 bins across four Sydney suburbs where cockatoos invade trash to note whether and how people were protecting their garbage. Observations coupled with an online survey showed that people living on the same street are more likely to use similar deterrents, and those efforts escalate over time. © Society for Science & the Public 2000–2022.

Keyword: Learning & Memory; Evolution
Link ID: 28476 - Posted: 09.14.2022

ByRodrigo Pérez Ortega We humans are proud of our big brains, which are responsible for our ability to plan ahead, communicate, and create. Inside our skulls, we pack, on average, 86 billion neurons—up to three times more than those of our primate cousins. For years, researchers have tried to figure out how we manage to develop so many brain cells. Now, they’ve come a step closer: A new study shows a single amino acid change in a metabolic gene helps our brains develop more neurons than other mammals—and more than our extinct cousins, the Neanderthals. The finding “is really a breakthrough,” says Brigitte Malgrange, a developmental neurobiologist at the University of Liège who was not involved in the study. “A single amino acid change is really, really important and gives rise to incredible consequences regarding the brain.” What makes our brain human has been the interest of neurobiologist Wieland Huttner at the Max Planck Institute of Molecular Cell Biology and Genetics for years. In 2016, his team found that a mutation in the ARHGAP11B gene, found in humans, Neanderthals, and Denisovans but not other primates, caused more production of cells that develop into neurons. Although our brains are roughly the same size as those of Neanderthals, our brain shapes differ and we created complex technologies they never developed. So, Huttner and his team set out to find genetic differences between Neanderthals and modern humans, especially in cells that give rise to neurons of the neocortex. This region behind the forehead is the largest and most recently evolved part of our brain, where major cognitive processes happen. The team focused on TKTL1, a gene that in modern humans has a single amino acid change—from lysine to arginine—from the version in Neanderthals and other mammals. By analyzing previously published data, researchers found that TKTL1 was mainly expressed in progenitor cells called basal radial glia, which give rise to most of the cortical neurons during development. © 2022 American Association for the Advancement of Science.

Keyword: Development of the Brain; Evolution
Link ID: 28472 - Posted: 09.10.2022

Michael Heithaus Could you explain how fish sleep? Do they drift away on currents, or do they anchor themselves to a particular location when they sleep? – Laure and Neeraj, New York From the goldfish in your aquarium to a bass in a lake to the sharks in the sea – 35,000 species of fish are alive today, more than 3 trillion of them. All over the world, they swim in hot springs, rivers, ponds and puddles. They glide through freshwater and saltwater. They survive in the shallows and in the darkest depths of the ocean, more than five miles down. If those trillions of fish, three major types exist: bony fish, like trout and sardines; jawless fish, like the slimy hagfish; and sharks and rays, which are boneless – instead, they have skeletons made of firm yet flexible tissue called cartilage. And all of them, every last one, needs to rest. Whether you’re a human or a haddock, sleep is essential. It gives a body time to repair itself, and a brain a chance to reset and declutter. As a marine biologist, I’ve always wondered how fish can rest. After all, in any body of water, predators are all over the place, lurking around, ready to eat them. But somehow they manage, like virtually all creatures on Earth. See the mysterious spot off the coast of Mexico where sharks take a nap. How they do it Scientists are still learning about how fish sleep. What we do know: Their sleep is not like ours. © 2010–2022, The Conversation US, Inc.

Keyword: Sleep; Evolution
Link ID: 28465 - Posted: 09.07.2022

By Emily Anthes My cat is a bona fide chatterbox. Momo will meow when she is hungry and when she is full, when she wants to be picked up and when she wants to be put down, when I leave the room or when I enter it, or sometimes for what appears to be no real reason at all. But because she is a cat, she is also uncooperative. So the moment I downloaded MeowTalk Cat Translator, a mobile app that promised to convert Momo’s meows into plain English, she clammed right up. For two days I tried, and failed, to solicit a sound. On Day 3, out of desperation, I decided to pick her up while she was wolfing down her dinner, an interruption guaranteed to elicit a howl of protest. Right on cue, Momo wailed. The app processed the sound, then played an advertisement for Sara Lee, then rendered a translation: “I’m happy!” I was dubious. But MeowTalk provided a more plausible translation about a week later, when I returned from a four-day trip. Upon seeing me, Momo meowed and then purred. “Nice to see you,” the app translated. Then: “Let me rest.” (The ads disappeared after I upgraded to a premium account.) The urge to converse with animals is age-old, long predating the time when smartphones became our best friends. Scientists have taught sign language to great apes, chatted with grey parrots and even tried to teach English to bottlenose dolphins. Pets — with which we share our homes but not a common language — are particularly tempting targets. My TikTok feed brims with videos of Bunny, a sheepadoodle who has learned to press sound buttons that play prerecorded phrases like “outside,” “scritches” and “love you.” MeowTalk is the product of a growing interest in enlisting additional intelligences — machine-learning algorithms — to decode animal communication. The idea is not as far-fetched as it may seem. For example, machine-learning systems, which are able to extract patterns from large data sets, can distinguish between the squeaks that rodents make when they are happy and those that they emit when they are in distress. Applying the same advances to our creature companions has obvious appeal. “We’re trying to understand what cats are saying and give them a voice” Javier Sanchez, a founder of MeowTalk, said. “We want to use this to help people build better and stronger relationships with their cats,” he added. © 2022 The New York Times Company

Keyword: Animal Communication; Learning & Memory
Link ID: 28458 - Posted: 08.31.2022

Sofia Quaglia Dolphins form decade-long social bonds, and cooperate among and between cliques, to help one another find mates and fight off competitors, new research has found – behaviour not previously confirmed among animals. “These dolphins have long-term stable alliances, and they have intergroup alliances. Alliances of alliances of alliances, really,” said Dr Richard Connor, a behavioural ecologist at the University of Massachusetts Dartmouth and one of the lead authors of the paper. “But before our study, it had been thought that cooperative alliances between groups were unique to humans.” The findings, published on Monday in the journal Proceedings of the National Academy of Sciences, appear to support the “social brain” hypothesis: that mammals’ brains evolved to be larger in size for animals that keep track of their social interactions and networks. Humans and dolphins are the two animals with the largest brains relative to body size. “It’s not a coincidence,” Connor said. Connor’s team of researchers collected data between 2001 and 2006 by conducting intensive boat-based surveys in Shark Bay, Western Australia. The researchers tracked the dolphins by watching and listening to them, using their unique identifying whistles to tell them apart. They observed 202 Indo-Pacific bottlenose dolphins (Tursiops aduncus), including during the peak mating season between September and November. Back in the lab, they pored over data focusing on 121 of these adult male dolphins to observe patterns in their social networks. And for the next decade they continued to analyse the animals’ alliances. Dolphins’ social structures are fluid and complex. The researchers found alliances among two or three male dolphins – like best friends. Then the groups expanded to up to 14 members. Together, they helped each other find females to herd and mate with, and they help steal females from other dolphins as well as defend against any “theft” attempts from rivals. © 2022 Guardian News & Media Limited

Keyword: Sexual Behavior; Evolution
Link ID: 28457 - Posted: 08.31.2022

By Carl Zimmer One of the most remarkable things about our species is how fast human culture can change. New words can spread from continent to continent, while technologies such as cellphones and drones change the way people live around the world. It turns out that humpback whales have their own long-range, high-speed cultural evolution, and they don’t need the internet or satellites to keep it running. In a study published on Tuesday, scientists found that humpback songs easily spread from one population to another across the Pacific Ocean. It can take just a couple of years for a song to move several thousand miles. Ellen Garland, a marine biologist at the University of St. Andrews in Scotland and an author of the study, said she was shocked to find whales in Australia passing their songs to others in French Polynesia, which in turn gave songs to whales in Ecuador. “Half the globe is now vocally connected for whales,” she said. “And that’s insane.” It’s even possible that the songs travel around the entire Southern Hemisphere. Preliminary studies by other scientists are revealing whales in the Atlantic Ocean picking up songs from whales the eastern Pacific. Each population of humpback whales spends the winter in the same breeding grounds. The males there sing loud underwater songs that can last up to half an hour. Males in the same breeding ground sing a nearly identical tune. And from one year to the next, the population’s song gradually evolves into a new melody. Dr. Garland and other researchers have uncovered a complex, language-like structure in these songs. The whales combine short sounds, which scientists call units, into phrases. They then combine the phrases into themes. And each song is made of several themes. © 2022 The New York Times Company

Keyword: Animal Communication; Language
Link ID: 28456 - Posted: 08.31.2022

Steven Strogatz Dreams are so personal, subjective and fleeting, they might seem impossible to study directly and with scientific objectivity. But in recent decades, laboratories around the world have developed sophisticated techniques for getting into the minds of people while they are dreaming. In the process, they are learning more about why we need these strange nightly experiences and how our brains generate them. In this episode, Steven Strogatz speaks with sleep researcher Antonio Zadra of the University of Montreal about how new experimental methods have changed our understanding of dreams. Steven Strogatz (00:03): I’m Steve Strogatz, and this is The Joy of Why, a podcast from Quanta Magazine that takes you into some of the biggest unanswered questions in math and science today. (00:13) In this episode, we’re going to be talking about dreams. What are dreams exactly? What purpose do they serve? And why are they often so bizarre? We’ve all had this experience: You’re dreaming about something fantastical, some kind of crazy story with a narrative arc that didn’t actually happen, with people we don’t necessarily know, in places we may have never even been. Is this just the brain trying to make sense of random neural firing? Or is there some evolutionary reason for dreaming? Dreams are inherently hard to study. Even with all the advances in science and technology, we still haven’t really found a way to record what someone else is dreaming about. Plus, as we all know, it’s easy to forget our dreams as soon as we wake up, unless we’re really careful to write them down. But even with all these difficulties, little by little, dream researchers are making progress in figuring out how we dream and why we dream. (01:11) Joining me now to discuss all this is Dr. Antonio Zadra, a professor at the University of Montreal and a researcher at the Center for Advanced Research in Sleep Medicine. His specialties include the study of nightmares, recurrent dreams and lucid dreaming. He’s also the coauthor of the recent book When Brains Dream, exploring the science and mystery of sleep. Tony, thank you so much for joining us today. Strogatz (01:39): I’m very excited to talk to you about this. So let’s start with thinking about the science of dreams as you and your colleagues see it today. Why are dreams so hard to study? All Rights Reserved © 2022

Keyword: Sleep; Evolution
Link ID: 28454 - Posted: 08.27.2022

Jason Bruck Bottlenose dolphins’ signature whistles just passed an important test in animal psychology. A new study by my colleagues and me has shown that these animals may use their whistles as namelike concepts. By presenting urine and the sounds of signature whistles to dolphins, my colleagues Vincent Janik, Sam Walmsey and I recently showed that these whistles act as representations of the individuals who own them, similar to human names. For behavioral biologists like us, this is an incredibly exciting result. It is the first time this type of representational naming has been found in any other animal aside from humans. When you hear your friend’s name, you probably picture their face. Likewise, when you smell a friend’s perfume, that can also elicit an image of the friend. This is because humans build mental pictures of each other using more than just one sense. All of the different information from your senses that is associated with a person converges to form a mental representation of that individual - a name with a face, a smell and many other sensory characteristics. Within the first few months of life, dolphins invent their own specific identity calls – called signature whistles. Dolphins often announce their location to or greet other individuals in a pod by sending out their own signature whistles. But researchers have not known if, when a dolphin hears the signature whistle of a dolphin they are familiar with, they actively picture the calling individual. My colleagues and I were interested in determining if dolphin calls are representational in the same way human names invoke many thoughts of an individual. Because dolphins cannot smell, they rely principally on signature whistles to identify each other in the ocean. Dolphins can also copy another dolphin’s whistles as a way to address each other. My previous research showed that dolphins have great memory for each other’s whistles, but scientists argued that a dolphin might hear a whistle, know it sounds familiar, but not remember who the whistle belongs to. My colleagues and I wanted to determine if dolphins could associate signature whistles with the specific owner of that whistle. This would address whether or not dolphins remember and hold representations of other dolphins in their minds. © 2010–2022, The Conversation US, Inc.

Keyword: Language; Evolution
Link ID: 28441 - Posted: 08.24.2022

By Kate Golembiewski Humans spend about 35 minutes every day chewing. That adds up to more than a full week out of every year. But that’s nothing compared to the time spent masticating by our cousins: Chimps chew for 4.5 hours a day, and orangutans clock 6.6 hours. The differences between our chewing habits and those of our closest relatives offer insights into human evolution. A study published Wednesday in the journal Science Advances explores how much energy people use while chewing, and how that may have guided — or been guided by — our gradual transformation into modern humans. Chewing, in addition to keeping us from choking, makes the energy and nutrients in food accessible to the digestive system. But the very act of chewing requires us to expend energy. Adaptations to teeth, jaws and muscles all play a part in how efficiently humans chew. Adam van Casteren, an author of the new study and a research associate at the University of Manchester in England, says that scientists haven’t delved too deeply into the energetic costs of chewing partly because compared with other things we do, such as walking or running, it’s a thin slice of the energy-use pie. But even comparatively small advantages can play a big role in evolution, and he wanted to find out if that might be the case with chewing. To measure the energy that goes into chewing, Dr. van Casteren and his colleagues outfitted study participants in the Netherlands with plastic hoods that look like “an astronaut’s helmet,” he said. The hoods were connected to tubes to measure oxygen and carbon dioxide from breathing. Because metabolic processes are fueled by oxygen and produce carbon dioxide, gas exchange can be a useful measure for how much energy something takes. The researchers then gave the subjects gum. The participants didn’t get the sugary kind, though; the gum bases they chewed were flavorless and odorless. Digestive systems respond to flavors and scents, so the researchers wanted to make sure they were only measuring the energy associated with chewing and not the energy of a stomach gearing up for a tasty meal. The test subjects chewed two pieces of gum, one hard and one soft, for 15 minutes each. The results surprised researchers. The softer gum raised the participants’ metabolic rates about 10 percent higher than when they were resting; the harder gum caused a 15 percent increase. © 2022 The New York Times Company

Keyword: Evolution
Link ID: 28440 - Posted: 08.20.2022

By Erin Garcia de Jesús Some mosquitoes have a near-foolproof thirst for human blood. Previous attempts to prevent the insects from tracking people down by blocking part of mosquitoes’ ability to smell have failed. A new study hints it’s because the bloodsuckers have built-in workarounds to ensure they can always smell us. For most animals, individual nerve cells in the olfactory system can detect just one type of odor. But Aedes aegypti mosquitoes’ nerve cells can each detect many smells, researchers report August 18 in Cell. That means if a cell were to lose the ability to detect one human odor, it still can pick up on other scents. The study provides the most detailed map yet of a mosquito’s sense of smell and suggests that concealing human aromas from the insects could be more complicated than researchers thought. Repellents that block mosquitoes from detecting human-associated scents could be especially tricky to make. “Maybe instead of trying to mask them from finding us, it would be better to find odorants that mosquitoes don’t like to smell,” says Anandasankar Ray, a neuroscientist at the University of California, Riverside who was not involved in the work. Such repellents may confuse or irritate the bloodsuckers and send them flying away (SN: 9/21/11; SN: 3/4/21). Effective repellents are a key tool to prevent mosquitoes from transmitting disease-causing viruses such as dengue and Zika (SN: 7/11/22). “Mosquitoes are responsible for more human deaths than any other creature,” says Olivia Goldman, a neurobiologist at Rockefeller University in New York City. “The better we understand them, the better that we can have these interventions.” © Society for Science & the Public 2000–2022.

Keyword: Chemical Senses (Smell & Taste); Evolution
Link ID: 28439 - Posted: 08.20.2022

By Carolyn Wilke 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. By day, jumping spiders hunt their prey, stalking and pouncing like cats. When the lights go down, these pea-sized predators hang out — and maybe their minds spin dreams. As they twitch their legs and move their eyes, Evarcha arcuata, a species of jumping spiders, show something reminiscent of rapid eye movement, or R.E.M., sleep, researchers report Monday in the Proceedings of the National Academy of Sciences. R.E.M. is the phase of sleep during which most human dreaming occurs. The study suggests that R.E.M. sleep may be more common than realized across animals, which may help untangle the mysteries of its purpose and evolution. To “look at R.E.M. sleep in something as distantly related to us as spiders is just utterly fascinating,” said Lauren Sumner-Rooney, a sensory biologist at the Leibniz Institute for Biodiversity and Evolution Research who wasn’t part of the new study. Daniela Roessler, a behavioral ecologist at the University of Konstanz in Germany and one of the study’s authors, was surprised when she noticed that jumping spiders sometimes dangle upside down during the night. Dr. Roessler started filming the resting arachnids and noticed other odd behaviors. “All of a sudden, they would make these crazy movements with the legs and start twitching. And it just reminded me immediately of a sleeping — not to say dreaming — cat or dog,” said Dr. Roessler. Such jerky movements in limbs are a marker of R.E.M. sleep, a state in which most of the body’s muscles go slack and the brain’s electrical activity mimics being awake. And then there’s the darting eyes, from which R.E.M. gets its name. But that’s tricky to spot it in animals with eyes that do not move, including spiders. However, part of a jumping spider’s eye does move. The acrobatic arachnids have eight eyes in total, and behind the lenses of their two biggest eyes are light-catching retinas that move to scan the environment. The arthropods’ exterior typically obscures these banana-shaped tubes, except when the spiders are babies and have translucent exoskeletons. So Dr. Roessler’s team looked for flitting retinas during rest in spiderlings younger than 10 days old. “It’s really clever,” said Paul Shaw, a neuroscientist at the Washington University School of Medicine. The researchers chose the right animal for this question, he added. © 2022 The New York Times Company

Keyword: Sleep; Evolution
Link ID: 28431 - Posted: 08.11.2022

By Oliver Whang Read this sentence aloud, if you’re able. As you do, a cascade of motion begins, forcing air from your lungs through two muscles, which vibrate, sculpting sound waves that pass through your mouth and into the world. These muscles are called vocal cords, or vocal folds, and their vibrations form the foundations of the human voice. They also speak to the emergence and evolution of human language. For several years, a team of scientists based mainly in Japan used imaging technology to study the physiology of the throats of 43 species of primates, from baboons and orangutans to macaques and chimpanzees, as well as humans. All the species but one had a similar anatomical structure: an extra set of protruding muscles, called vocal membranes or vocal lips, just above the vocal cords. The exception was Homo sapiens. The researchers also found that the presence of vocal lips destabilized the other primates’ voices, rendering their tone and timbre more chaotic and unpredictable. Animals with vocal lips have a more grating, less controlled baseline of communication, the study found; humans, lacking the extra membranes, can exchange softer, more stable sounds. The findings were published on Thursday in the journal Science. “It’s an interesting little nuance, this change to the human condition,” said Drew Rendall, a biologist at the University of New Brunswick who was not involved in the research. “The addition, if you want to think of it this way, is actually a subtraction.” That many primates have vocal lips has long been known, but their role in communication has not been entirely clear. In 1984, Sugio Hayama, a biologist at Kyoto University, videotaped the inside of a chimpanzee’s throat to study its reflexes under anesthesia. The video also happened to capture a moment when the chimp woke and began hollering, softly at first, then with more power. Decades later, Takeshi Nishimura, a former student of Dr. Hayama and now a biologist at Kyoto University and the principal investigator of the recent research, studied the footage with renewed interest. He found that the chimp’s vocal lips and vocal cords were vibrating together, which added a layer of mechanical complexity to the chimp’s voice that made it difficult to fine-tune. © 2022 The New York Times Company

Keyword: Language; Evolution
Link ID: 28426 - Posted: 08.11.2022

By Tim Vernimmen Just a few decades ago, even most biologists would have readily agreed that culture is a quintessentially human feature. Sure, they already knew there were dialects in birdsong, and good evidence that many birds largely learned these regional songs by copying other birds. They knew that some enterprising European songbirds called tits had learned how to open milk bottles by watching one another. Scientists had even reported that the practice of washing sweet potatoes in seawater had spread among the members of a Japanese colony of macaque monkeys. But these and similar behavioral differences between populations — ones that couldn’t easily be explained by differences in their genes or environment — seemed limited in scope. Compare that with human culture, which creates variation in nearly everything we do. In recent decades, however, scientists have learned that culture plays a much more pervasive role in the lives of nonhuman animals than anyone had imagined. “The whole field has absolutely exploded in discoveries in the present century,” says primatologist Andrew Whiten of the University of St. Andrews, Scotland, the author of a 2019 overview of cultural evolution in animals in the Annual Review of Ecology, Evolution, and Systematics. Whiten was one of the pioneers of the surge in animal culture research. In 1999, he oversaw an analysis in which primatologists published their findings from nearly four decades of studying wild chimpanzees, our closest living relatives. “We could show chimpanzees have multiple traditions affecting all different aspects of their lives,” he says — from foraging to tool use to courtship. Similar findings followed for several other apes and monkeys. © 2022 Annual Reviews

Keyword: Evolution; Learning & Memory
Link ID: 28417 - Posted: 08.03.2022

By Lesley Evans Ogden Hana aced her memory test. After viewing the contents of three identical boxes arrayed in an arc on the back deck of her home, the 3-year-old Cavalier King Charles spaniel had to remember which box held a treat — a task she quickly learned after just a few trials. Hana is part of a pack that has grown to nearly 40,000 pet dogs enrolled in a citizen science initiative known as the Dog Aging Project, founded in 2014. Understanding the biology of aging in companion dogs is one of two main goals of the project, says cofounder and codirector Matt Kaeberlein, a pathologist at the University of Washington in Seattle who focuses on aging. “The other is to do something about it.” Through veterinary records, DNA samples, health questionnaires and cognitive tests like Hana’s treat-finding challenge, the initiative of the University of Washington and Texas A&M University will track many aspects of dogs’ lives over time. Smaller subsets of the dogs, including Hana, will participate in more focused studies and more extensive evaluations. From all of this, scientists hope to spot patterns and find links between lifestyles and health from puppyhood through the golden years. The effort joins that of an earlier one: the Family Dog Project, spearheaded in the 1990s at Eötvös Loránd University (ELTE) in Budapest to study “the behavioral and cognitive aspects of the dog-human relationship,” with tens of thousands of canines participating through the decades. The two projects have begun collaborating across continents, and the scientists hope that such a large combined group of dogs can help them tease out genetic and environmental factors that affect how long dogs live, and how much of that time is spent in good health. © 2022 Annual Reviews

Keyword: Alzheimers; Development of the Brain
Link ID: 28411 - Posted: 07.30.2022

ByVirginia Morell We swat bees to avoid painful stings, but do they feel the pain we inflict? A new study suggests they do, a possible clue that they and other insects have sentience—the ability to be aware of their feelings. “It’s an impressive piece of work” with important implications, says Jonathan Birch, a philosopher and expert on animal sentience at the London School of Economics who was not involved with the paper. If the study holds up, he says, “the world contains far more sentient beings than we ever realized.” Previous research has shown honey bees and bumble bees are intelligent, innovative, creatures. They understand the concept of zero, can do simple math, and distinguish among human faces (and probably bee faces, too). They’re usually optimistic when successfully foraging, but can become depressed if momentarily trapped by a predatory spider. Even when a bee escapes a spider, “her demeanor changes; for days after, she’s scared of every flower,” says Lars Chittka, a cognitive scientist at Queen Mary University of London whose lab carried out that study as well as the new research. “They were experiencing an emotional state.” To find out whether these emotions include pain, Chittka and colleagues looked at one of the criteria commonly used for defining pain in animals: “motivational trade-offs.” People will endure the pain of a dentist’s drill for the longer term benefits of healthy teeth, for example. Similarly, hermit crabs will leave preferred shells to escape an electric shock only when given a particularly high jolt—an experiment that demonstrated crabs can tell the difference between weak and strong painful stimuli, and decide how much pain is worth enduring. That suggests crabs do feel pain and don’t simply respond reflexively to an unpleasant stimulus. Partly as a result of that study, crabs (and other crustaceans, including lobsters and crayfish) are recognized as sentient under U.K. law. © 2022 American Association for the Advancement of Science

Keyword: Pain & Touch; Evolution
Link ID: 28410 - Posted: 07.30.2022

By Laura Sanders A dog’s brain is wired for smell. Now, a new map shows just how extensive that wiring is. Powerful nerve connections link the dog nose to wide swaths of the brain, researchers report July 11 in the Journal of Neuroscience. One of these canine connections, a hefty link between areas that handle smell and vision, hasn’t been seen before in any species, including humans. The results offer a first-of-its-kind anatomical description of how dogs “see” the world with their noses. The new brain map is “awesome, foundational work,” says Eileen Jenkins, a retired army veterinarian and expert on working dogs. “To say that they have all these same connections that we have in humans, and then some more, it’s going to revolutionize how we understand cognition in dogs.” In some ways, the results aren’t surprising, says Pip Johnson, a veterinary radiologist and neuroimaging expert at Cornell University College of Veterinary Medicine. Dogs are superb sniffers. Their noses hold between 200 million and 1 billion odor molecule sensors, compared with the 5 million receptors estimated to dwell in a human nose. And dogs’ olfactory bulbs can be up to 30 times larger than people’s. But Johnson wanted to know how smell information wafts to brain regions beyond the obvious sniffing equipment. To build the map, Johnson and colleagues performed MRI scans on 20 mixed-breed dogs and three beagles. The subjects all had long noses and medium heads, and were all probably decent sniffers. Researchers then identified tracts of white matter fibers that carry signals between brain regions. A method called diffusion tensor imaging, which relies on the movement of water molecules along tissue, revealed the underlying tracts, which Johnson likens to the brain’s “road network.” © Society for Science & the Public 2000–2022.

Keyword: Chemical Senses (Smell & Taste); Evolution
Link ID: 28405 - Posted: 07.22.2022