Chapter 6. Evolution of the Brain and Behavior

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Links 1 - 20 of 2032

By Sam Roberts Ralph Solecki, an archaeologist whose research helped debunk the view of Neanderthals as heartless and brutish half-wits and inspired a popular series of novels about prehistoric life, died on March 20 in Livingston, N.J. He was 101. The cause was pneumonia, his son William said. Starting in the mid-1950s, leading teams from Columbia University, Dr. Solecki discovered the fossilized skeletons of eight adult and two infant Neanderthals who had lived tens of thousands of years ago in what is now northern Iraq. Dr. Solecki, who was also a Smithsonian Institution anthropologist at the time, said physical evidence at Shanidar Cave, where the skeletons were found, suggested that Neanderthals had tended to the weak and the wounded, and that they had also buried their dead with flowers, which were placed ornamentally and possibly selected for their therapeutic benefits. The exhumed bones of a man, named Shanidar 3, who had been blind in one eye and missing his right arm but who had survived for years after he was hurt, indicated that fellow Neanderthals had helped provide him with sustenance and other support. “Although the body was archaic, the spirit was modern,” Dr. Solecki wrote in the magazine Science in 1975. Large amounts of pollen found in the soil at a grave site suggested that bodies might have been ceremonially entombed with bluebonnet, hollyhock, grape hyacinth and other flowers — a theory that is still being explored and amplified. (Some researchers hypothesized that the pollen might have been carried by rodents or bees, but Dr. Solecki’s theory has become widely accepted.) “The association of flowers with Neanderthals adds a whole new dimension to our knowledge of his humanness, indicating he had a ‘soul,’ ” Dr. Solecki wrote. © 2019 The New York Times Company

Keyword: Evolution
Link ID: 26131 - Posted: 04.12.2019

By Carl Zimmer In a cave in the Philippines, scientists have discovered a new branch of the human family tree. At least 50,000 years ago, an extinct human species lived on what is now the island of Luzon, researchers reported on Wednesday. It’s possible that Homo luzonensis, as they’re calling the species, stood less than three feet tall. The discovery adds growing complexity to the story of human evolution. It was not a simple march forward, as it once seemed. Instead, our lineage assumed an exuberant burst of strange forms along the way. Our species, Homo sapiens, now inhabits a comparatively lonely world. “The more fossils that people pull out of the ground, the more we realize that the variation that was present in the past far exceeds what we see in us today,” said Matthew Tocheri, a paleoanthropologist at Lakehead University in Canada, who was not involved in the new discovery. In the early 2000s, Armand Salvador Mijares, a graduate student at the University of the Philippines, was digging at Callao Cave, on Luzon, for traces of the first farmers on the Philippines. Soon, he decided to dig a little deeper. Researchers on the Indonesian island of Flores had discovered the bones of an extraordinary humanlike species about 60,000 years old. The scientists named it Homo floresiensis. Some features were similar to ours, but in other ways Homo floresiensis more closely resembled other hominins (the term scientists use for modern humans and other species in our lineage). © 2019 The New York Times Company

Keyword: Evolution
Link ID: 26126 - Posted: 04.11.2019

/ By Richard Kemeny Northern Ethiopia was once home to a vast, ancient lake. Saber-toothed cats prowled around it, giant crocodiles swam within. The streams and rivers that fed it — over 3 million years ago, during the Pliocene — left behind trails of sediment that have now hardened into sandstone. Deposited within these layers are fossils: some of early hominins, along with the bones of hippos, antelope, and elephants. Anthropologist Jessica Thompson encountered two of these specimens, from an area named Dikika, in 2010. At the time, she was a visiting researcher at the Institute of Human Origins at Arizona State University. Given no explanation as to their history, she analyzed the bones and found signs of butchery. Percussion marks suggested someone may have accessed the marrow; cut marks hinted that flesh was stripped from bone. To her surprise, the specimens were 3.4 million years old, putting the butcher’s behaviors back 800,000 years earlier than conventional estimates would suggest. That fact got Thompson, now an assistant professor in the Department of Anthropology at Yale University, thinking there might be more traces of tool use from those early times. In a wide-ranging review published in February’s issue of Current Anthropology, Thompson joins a team of researchers to weave together several strands of recent evidence and propose a new theory about the transition to large animal consumption by our ancestors. The prevailing view, supported by a confluence of fossil evidence from sites in Ethiopia, is that the emergence of flaked tool use and meat consumption led to the cerebral expansion that kickstarted human evolution more than 2 million years ago. Thompson and her colleagues disagree: Rather than using sharpened stones to hunt and scrape meat from animals, they suggest, earlier hominins may have first bashed bones to harvest fatty nutrients from marrow and brains. Copyright 2019 Undark

Keyword: Evolution
Link ID: 26107 - Posted: 04.03.2019

By Veronique Greenwood The sun bears were making faces at each other. And that was a bit of a surprise. Comparative psychologists have been studying the facial expressions of primates like orangutans and gorillas for years. They have evolved in complex societies and thus need to be able to convey their joy, anger, and other emotions to their companions. But nobody had thought to look at creatures like sun bears, who live mostly solitary lives. Marina Davila-Ross, a primatologist at the University of Portsmouth in England, and her colleagues learned that a handful of the Southeast Asian bears, which primarily live alone in the wild, were in a rehabilitation center near the orangutan center in Malaysia where Dr. Davila-Ross was doing research. Curious about whether facial communication was more common in the animal kingdom that people thought, they deployed cameras to capture hours of footage of the bears interacting with each other. In a study published Thursday in Scientific Reports, they say that sun bears do use facial expressions to communicate, suggesting that the capacity to do so may be widespread, and that social creatures do not have a monopoly on expressing themselves this way. Sun bears are exceedingly solitary. A female’s one or two cubs will live with her for about two years, and then set off for lives on their own. Adults seem to rarely meet, except for mating. At the center, bears that cannot be released back into the wild live in enclosures in groups of five or six. For the bears, it was an unnatural setup — but it was perfect for the scientists. In their footage of 22 bears going about their daily lives, the scientists zeroed in on moments when the animals were playing, batting at each other and grappling good-humoredly. They watched for moments where the playing bears were looking into each other’s faces, and then they looked for certain facial expressions, like opening one’s mouth wide and showing teeth. © 2019 The New York Times Company

Keyword: Emotions; Evolution
Link ID: 26067 - Posted: 03.23.2019

Terry Gross When Frans de Waal started studying nonhuman primates, in the Netherlands more than 40 years ago, he was told not to consider the emotions of the animals he was observing. "Thoughts and feelings — the mental processes basically — were off limits," he says. "We were told not to talk about them, because they were considered by many scientists as 'inner states' and you only were allowed to talk about 'outer states.' " But over the course of his career, de Waal became convinced that primates and other animals express emotions similar to human emotions. He's now the director of the Living Links Center at the Yerkes National Primate Research Center in Atlanta, where his office window looks out on a colony of chimps. "I am now at the point that I think emotions are more like organs," he says. "All my organs are present in a rat's body, and the same way, I think, all my emotions are probably present in the rat." De Waal writes about primate empathy, rivalry, bonding, sex and murder in his new book, Mama's Last Hug. The title of the book was inspired by a tender interaction between a dying 59-year-old chimp named Mama and de Waal's mentor, Jan van Hooff, who had known Mama for more than 40 years. "People were surprised [by] how humanlike the expression of Mama was and how humanlike her gestures were," de Waal says of the interaction. "I thought, 'Well, everyone knows that chimps are our closest relative, so why wouldn't the way they express their emotions be extremely similar to ours?' But people were surprised by that." © 2019 npr

Keyword: Emotions; Evolution
Link ID: 26054 - Posted: 03.20.2019

Bruce Bower Humankind’s gift of gab is not set in stone, and farming could help to explain why. Over the last 6,000 years or so, farming societies increasingly have substituted processed dairy and grain products for tougher-to-chew game meat and wild plants common in hunter-gatherer diets. Switching to those diets of softer, processed foods altered people’s jaw structure over time, rendering certain sounds like “f” and “v” easier to utter, and changing languages worldwide, scientists contend. People who regularly chew tough foods such as game meat experience a jaw shift that removes a slight overbite from childhood. But individuals who grow up eating softer foods retain that overbite into adulthood, say comparative linguist Damián Blasi of the University of Zurich and his colleagues. Computer simulations suggest that adults with an overbite are better able to produce certain sounds that require touching the lower lip to the upper teeth, the researchers report in the March 15 Science. Linguists classify those speech sounds, found in about half of the world’s languages, as labiodentals. And when Blasi and his team reconstructed language change over time among Indo-European tongues (SN: 11/25/17, p. 16), currently spoken from Iceland to India, the researchers found that the likelihood of using labiodentals in those languages rose substantially over the past 6,000 to 7,000 years. That was especially true when foods such as milled grains and dairy products started appearing (SN: 2/1/03, p. 67). “Labiodental sounds emerged recently in our species, and appear more frequently in populations with long traditions of eating soft foods,” Blasi said at a March 12 telephone news conference. |© Society for Science & the Public 2000 - 2019

Keyword: Language; Evolution
Link ID: 26037 - Posted: 03.15.2019

By Elizabeth Pennisi Cowbirds are the quintessential deadbeat parents. They, and about 90 other bird species, abandon their eggs in other birds’ nests, leaving the burden of chick care to others. An arms race is the result: Cuckolded foster parents keep evolving ways to fight back, and deadbeats evolve countermeasures. Now, researchers have discovered how spots on an egg play a crucial role in a parent’s decision to keep an egg—or boot it from the nest. One of the shiny cowbird’s (Molothrus bonariensis) most common victims is the chalk-browed mockingbird (Mimus saturninus). The mockingbird’s eggs are blue-green and spotted, whereas the cowbird’s eggs vary from pure white to brown and spotted. Researchers had assumed mockingbirds reject cowbird eggs that don't look like their own, in pattern and color. But the new study finds it’s not that simple. To get a better sense of how mockingbirds decide which eggs to boot, evolutionary ecologist Daniel Hanley at Long Island University in Brookville, New York, and colleagues painted 70 3D-printed eggs a range of colors and put spots on half of them. They distributed these eggs among 85 mockingbird nests and checked several days later to see which eggs were still there. Spots tended to make the mockingbirds hedge their bets and keep an egg, even if the color wasn’t “right,” Hanley and his colleagues report in the April issue of the Philosophical Transactions of the Royal Society B. For example, the mockingbirds removed unspotted brown eggs—a “wrong” color and pattern—90% of the time. But the birds were less sure when the egg had spots. They removed brown eggs with spots just 60% of the time, for example. In general, mockingbirds were more accepting of very blue eggs, even those that were much bluer than their own eggs. And when these blue eggs had spots, parents kept them more than 90% of the time. © 2019 American Association for the Advancement of Science

Keyword: Sexual Behavior; Evolution
Link ID: 26014 - Posted: 03.07.2019

Carolyn Wilke Over the course of human evolution, our brains expanded massively. One of the areas that ballooned over the past few million years is the cerebral cortex, the wrinkly outer layer of the brain. It processes sensory information, coordinates our motion, and is in charge of our higher order functions, such as language processing and problem solving. Scientists are scrutinizing the structure of the cortex for clues about its development throughout our lives and our evolution as a species and to understand where heredity intersects with intelligence. A new study of hundreds of developing brains reveals a trifecta of overlap in regions of the cortical surface that develop from childhood to adulthood, expanded during evolution, and are connected to genetics. The scientists also found genetically mediated links between IQ test scores and surface area in regions related to intelligence, they report today (March 4) in the Journal of Neuroscience. “I think it’s a very, very strong work,” says Rachel Brouwer, a neuroscientist at University Medical Center Utrecht in the Netherlands who was not part of the study. The authors pick up which regions of the brain where variability is most explained by genes, but by looking for connections with evolutionary expansion and neurodevelopment, “it is an attempt to link [heritability] to what it actually means in a broader picture,” she says. © 1986 - 2019 The Scientist

Keyword: Intelligence; Evolution
Link ID: 26010 - Posted: 03.06.2019

Susan Milius Cheating pays, sort of. But for a glossy blue-black bird with a bright yellow eye, cheating doesn’t outdo regular honest parenting. The greater ani, a type of cuckoo found from Panama to the Amazon Basin, usually starts out as a dutiful parent. Two or three male-female pairs typically build and fill a communal nest “like a big basket of eggs,” says behavioral ecologist Christina Riehl of Princeton University. But if a snake or some other disaster kills the young, a bereft female sometimes gets sneaky. She slips into neighboring ani nests and leaves an egg here and there that she won’t care for, but the rightful nest owners might. Not all females from trashed nests do that. Some just wait for the next breeding season, when all the birds get a fresh start building another nest. Greater anis’ sporadic cheating offers a rare chance to compare the success of egg-sneaks with honest mothers in the same species. Over 11 breeding seasons, Riehl and colleagues determined the parentage of more than 1,700 eggs and found 65 eggs in foster nests. Mothers that parasitize other nests in this way seem to lay more eggs a year, on average, Riehl says. “It’s actually kind of hard to be a parasite,” she says. But the average number of chicks that survived to flutter out of the nest on their own frantic wing power was about the same for all females, Riehl and Princeton colleague Meghan Strong report online February 27 in Nature. The mothers that always cooperated averaged about one fledgling a year, and so did the females that laid stealth eggs. |© Society for Science & the Public 2000 - 2019

Keyword: Sexual Behavior; Evolution
Link ID: 25991 - Posted: 02.28.2019

Erin Wayman During the last few weeks of her life, Mama, an elderly chimpanzee at a zoo in the Netherlands, received a special visitor. As Mama lay curled up on a mound of straw, biologist Jan van Hooff entered her enclosure. Van Hooff, who had known Mama for more than 40 years, knelt down and stroked the arm of the listless chimp. When Mama looked up, her vacant face erupted into a smile. She reached out to van Hooff, calling out as she patted his face and neck. For primatologist Frans de Waal, this touching scene isn’t difficult to interpret: Mama was happy to see her old friend. But such an interpretation has been taboo among many behavioral scientists, who have claimed nonhuman animals are like unthinking, emotionless machines that react to situations with preprogrammed instincts. In the thought-provoking Mama’s Last Hug, de Waal dismantles that view. He presents piles of evidence that animals are emotional beings. The book is a companion to Are We Smart Enough to Know How Smart Animals Are?, in which he explored animal intelligence (SN: 12/24/16 & 1/7/17, p. 40). Emotions, de Waal writes, “are bodily and mental states — from anger and fear to sexual desire and affection and seeking the upper hand — that drive behavior.” On page after page, he tells of depressed fish, empathetic rats, envious monkeys and other emotional creatures. More than a collection of fascinating anecdotes, Mama’s Last Hug weaves together formal observations of animals in the wild and in captivity, behavioral experiments and neuroscience research. |© Society for Science & the Public 2000 - 2019.

Keyword: Emotions; Evolution
Link ID: 25982 - Posted: 02.26.2019

Nicole Creanza and Kate Snyder How do individuals choose their mates? Why are some more successful at attracting mates than others? These age-old questions are broadly relevant to all animals, including human beings. Darwin’s theory of natural selection offers one way to answer them. Sometimes phrased as “survival of the fittest,” the theory can also apply to mate choice, predicting that it’s beneficial to choose the mate who’s best adapted to surviving in its environment — the fastest runner, the best hunter, the farmer with the highest yields. That’s a bit simplistic as a summary of human sexuality, of course, since people pair up in the context of complex social norms and gender roles that are uniquely human. Researchers like us do think, though, that mate choice in other animals is influenced by these kinds of perceived adaptations. It fits with scientists’ understanding of evolution: If females choose to mate with well-adapted males, their offspring might have a better chance of surviving as well. Advantageous traits wind up passed down and preserved in future generations. But in many species, males try to attract mates by displaying characteristics that seem to be decidedly non-adaptive. These signals – such as a dazzling tail on a peacock or a beautiful tune from a songbird – were originally a big wrench thrown into Darwin’s theory of natural selection. Traits like these seem to do the opposite of making an animal more likely to survive in its environment. A flashy tail display or a showy melody is cumbersome, and it announces you to predators as well as love interests. Darwin got so upset by this inconsistency that he said “The sight of a feather in a peacock’s tail, whenever I gaze at it, makes me sick.” © 2010–2019, The Conversation US, Inc.

Keyword: Sexual Behavior; Evolution
Link ID: 25979 - Posted: 02.22.2019

By Veronique Greenwood Sleep — that absurd, amazing habit of losing consciousness for hours on end — is so universal across the animal kingdom that we usually assume it is essential to survival. Now, however, scientists who repeatedly disturbed the sleep of more than a thousand fruit flies are reporting that less slumber may be necessary for sustaining life than previously thought, at least in one species. A handful of studies involving dogs and cockroaches going back to the late 19th century suggest that being deprived of sleep can result in a shortened life span. But the methods behind some of these studies can make it difficult to say whether the test subjects were harmed by sleep deprivation itself, or by the stress of the treatment they were given — such as being shaken constantly. The new study took a milder approach, in hope of seeing the true effects of sleep deprivation. The automated system the researchers developed for monitoring the flies kept track of their movements with cameras, scoring any extended period without movement as sleep. When they were not being awakened repeatedly, the males slept about 10 hours a day, females about five on average. To keep the flies awake, the researchers equipped the system with tiny motors that would gently tip the flies any time they went still for at least 20 seconds. With this method, researchers deprived flies of rest over the course of their entire lifetimes, tipping them hundreds of times a day such that if they were snoozing during those periods of stillness, they might have been able to sleep around 2.5 hours a day on average. “When the results came from that experiment, it was very surprising,” said Giorgio Gilestro, a professor at Imperial College London who is a co-author of the study, which was published Wednesday in Science Advances. © 2019 The New York Times Company

Keyword: Sleep; Evolution
Link ID: 25978 - Posted: 02.21.2019

Nicola Davis The mystery of how the zebra got its stripes might have been solved: researchers say the pattern appears to confuse flies, discouraging them from touching down for a quick bite. The study, published in the journal Plos One, involved horses, zebras, and horses dressed as zebras. The team said the research not only supported previous work suggesting stripes might act as an insect deterrent, but helped unpick why, revealing the patterns only produced an effect when the flies got close. Dr Martin How, co-author of the research from the University of Bristol, said: “The flies seemed to be behaving relatively naturally around both [zebras and horses], until it comes to landing. “We saw that these horseflies were coming in quite fast and almost turning away or sometimes even colliding with the zebra, rather than doing a nice, controlled flight.” Researchers made their discovery by spending more than 16 hours standing in fields and noting how horseflies interacted with nine horses and three zebras – including one somewhat bemusingly called Spot. While horseflies circled or touched the animals at similar rates, landing was a different matter, with a lower rate seen for zebras than horses. To check the effect was not caused by a different smell of zebras and horses, for example, the researchers put black, white and zebra-striped coats on seven horses in turn. While there was no difference in the rate at which the flies landed on the horses’ exposed heads, they touched and landed on the zebra coat far less often than either the black or white garment. © 2019 Guardian News & Media Limited

Keyword: Vision; Evolution
Link ID: 25977 - Posted: 02.21.2019

Jules Howard It’s a bit garbled but you can definitely hear it in the mobile phone footage. As the chimpanzees arrange their branches into a makeshift ladder and one of them makes its daring escape from its Belfast zoo enclosure, some words ring out loud and clear: “Don’t escape, you bad little gorilla!” a child onlooker shouts from the crowd. And … POP … with that a tiny explosion goes off inside my head. Something knocks me back about this sentence. It’s a “kids-say-the-funniest things” kind of sentence, and in any other situation I’d offer a warm smile and a chuckle of approval. But not this time. This statement has brought out the pedant in me. At this point, you may wonder if I’m capable of fleshing out a 700-word article chastising a toddler for mistakenly referring to a chimpanzee as a gorilla. The good news is that, though I am more than capable of such a callous feat, I don’t intend to write about this child’s naive zoological error. In fact, this piece isn’t really about the (gorgeous, I’m sure) child. It’s about us. You and me, and the words we use. So let’s repeat it. That sentence, I mean. “Don’t escape, you bad little gorilla!” the child shouted. The words I’d like to focus on in this sentence are the words “you” and “bad”. The words “you” and “bad” are nice examples of a simple law of nearly all human languages. They are examples of Zipf’s law of abbreviation, where more commonly used words in a language tend to be shorter. It’s thought that this form of information-shortening allows the transmission of more complex information in a shorter amount of time, and it’s why one in four words you and I write or say is likely to be something of the “you, me, us, the, to” variety. © 2019 Guardian News & Media Limited

Keyword: Language; Evolution
Link ID: 25971 - Posted: 02.18.2019

By Lee Dugatkin Like many breakthroughs in science, Dmitri Belyaev’s silver fox domestication experiment began with a thunderbolt: one simple, powerful, new idea. Born of a parish priest in early 20th century Russia, the geneticist proposed that all domestic animals were tamed through a generations-long process in which our distant ancestors repeatedly chose the calmest animals — those that were friendliest to people — for breeding. Whether horses for transport, dogs for protection, pigs for food, or oxen for labor, the essential trait was that the animals not try to bite the hand that fed them. Belyaev went on to speculate that all of the other characteristics we tend to see in domesticated species — their curly tails, floppy ears, juvenile facial, and body features — were somehow byproducts of this selection for the friendliest of the friendly. As a test, Belyaev decided that he would build a dog out of a fox, in real time, to understand how man’s best friend came to be. No one had ever attempted anything like it. No matter, he would try. At the time, in Stalinist Russia, the idea was considered radical and out of line with State orthodoxy. There were men who might very well have thrown the scientist in prison for what he was dreaming. But he would perform his magic in a far off, frozen land: The Siberian town of Novosibirsk, where winter temperatures can plummet to a bone-chilling -50 degrees Fahrenheit. Some 60 years later, his experiment is still going. It is one of the longest running science experiments ever, having outlived even its creator. And after all this time, it is still shaping the way we think about fundamental questions in biology — and even influencing the way we understand our own evolutionary trajectory. Copyright 2019 Undark

Keyword: Evolution
Link ID: 25940 - Posted: 02.08.2019

By Alex Fox If math is the language of the universe, bees may have just uttered their first words. New research suggests these busybodies of the insect world are capable of addition and subtraction—using colors in the place of plus and minus symbols. In the animal kingdom, the ability to count—or at least distinguish between differing quantities—isn’t unusual: It has been seen in frogs, spiders, and even fish. But solving equations using symbols is rare air, so far only achieved by famously brainy animals such as chimpanzees and African grey parrots. Enter the honey bee (Apis mellifera). Building on prior research that says the social insects can count to four and understand the concept of zero, researchers wanted to test the limits of what their tiny brains can do. Scientists trained 14 bees to link the colors blue and yellow to addition and subtraction, respectively. They placed the bees at the entrance of a Y-shaped maze, where they were shown several shapes in either yellow or blue. If the shapes were blue, bees got a reward if they went to the end of the maze with one more blue shape (the other end had one less blue shape); if the shapes were yellow, they got a reward if they went to the end of the maze with one less yellow shape. © 2018 American Association for the Advancement of Science

Keyword: Attention; Evolution
Link ID: 25938 - Posted: 02.08.2019

By Jordana Cepelewicz Genitals are among the fastest-evolving features in the animal kingdom. They’re also among the most diverse, arrayed in all shapes and sizes, adorned with spines, hooks and even teeth. Ducks have corkscrew-shaped genitalia. The male sea horse has a brood pouch that receives his mate’s eggs for fertilization and in which he nurtures the resulting offspring until birth. Female cabbage white butterflies have a hinged jaw inside their genital tract. Nature is full of strange reproductive organs with unusual uses. For the most part, though, certain genital morphologies are associated with males, others with females. But in 2014, a tiny insect called the barklouse broke even that rule when researchers reported that the females of all four species of a genus found in the caves of Brazil had a penis. It didn’t just look like a penis but acted like one, too: a penetrative organ the female insects used to anchor themselves to their mates during copulation. Moreover, complementary changes in the genitalia of the males had left them with a small pumping mechanism inside a membranous “vagina-like” cavity. Content from The Coca-Cola Company Sustainability and closed-loop recycling systems must now become a global priority, from emerging nations to the world's largest economies. Read More The finding not only piqued widespread interest (and amusement — the team was awarded a comedic Ig Nobel Prize in 2017), but also led to a debate about whether the scientists involved were correct to refer to the structure, called a gynosome, as a “female penis.” (Some experts, for instance, disagree with that characterization because the gynosome collects sperm rather than delivering it.) © 1996-2019 The Washington Post

Keyword: Sexual Behavior; Evolution
Link ID: 25928 - Posted: 02.04.2019

Jon Hamilton For comedian Lewis Black, anger is a job. Black is famous for his rants about stuff he finds annoying or unfair or just plain infuriating. Onstage, he often looks ready for a fight. He leans forward. He shouts. He stabs the air with an index finger, or a middle finger. To a scientist, Black looks a lot like a belligerent dog, or an irritated gerbil. "Practically every sexually reproducing, multicellular animal shows aggressive behavior," says David Anderson, a professor of biology at Caltech and co-author of the book The Neuroscience of Emotion. "Fruit flies show aggression." When I relay that last bit to Black, he's skeptical. "Really?" he says. "Come on." But Anderson, whose lab studies fruit flies, says the evidence is compelling. "They fight over females, they fight over food, they threaten each other, they put their wings up in the air, they charge at each other," he says. But does aggressive behavior mean a fruit fly gets angry the way Black does? Anderson says that depends on how you define the term. "We use anger subjectively to refer to our experience, our conscious experience, of rage, the feeling that you are about to explode, the feeling of irritation," he says. Black feels that way a lot. And he has spent decades thinking about how anger works in his own brain. "My anger comes from a collection of things that occur during the course of a day that build up," he says. "So by the end of a day, six or seven things have happened to me that have gone into my anger bank." © 2019 npr

Keyword: Emotions; Evolution
Link ID: 25917 - Posted: 01.31.2019

Ewen Callaway Neanderthals and Denisovans might have lived side by side for tens of thousands of years, scientists report in two papers in Nature1,2. The long-awaited studies are based on the analysis of bones, artefacts and sediments from Denisova Cave in southern Siberia, which is dotted with ancient-human remains. They provide the first detailed history of the site’s 300,000-year occupation by different groups of ancient humans. “We can now tell the whole story of the entire cave, not just bits and pieces,” says Zenobia Jacobs, a geochronologist at the University of Wollongong, Australia, who co-led one of the studies. Soviet archaeologists began unravelling the story of Denisova Cave, at the foot of the Altai Mountains, in the early 1980s. Since then, scientists have found the fragmentary remains of nearly a dozen ancient humans at the site. The cave became world famous in 2010, after an analysis of the DNA from a tiny hominin finger bone found that the creature was distinct from both modern humans and Neanderthals3. It belonged to a previously unknown hominin group, later named Denisovans. Additional sequencing of the DNA in bone remains from the cave found that Denisovans were a sister group to Neanderthals, and might once have lived across Asia — where they interbred with the ancestors of some humans now living there4. © 2019 Springer Nature Publishing AG

Keyword: Evolution
Link ID: 25916 - Posted: 01.31.2019

By Elizabeth Pennisi TAMPA, FLORIDA—Swimming through the oceans, voraciously consuming plankton and other small creatures—and occasionally startling a swimmer—the beautiful gelatinous masses known as comb jellies won’t be joining Mensa anytime soon. But these fragile creatures have nerve cells—and they offer insights about the evolutionary origins of all nervous systems, including our own. Inspired by studies of a glue-secreting cell unique to these plankton predators, researchers have now proposed that neurons emerged in the last common ancestor of today’s animals—and that their progenitors were secretory cells, whose primary function was to release chemicals into the environment. Joseph Ryan, a computational evolutionary biologist the University of Florida Whitney Laboratory for Marine Bioscience in St. Augustine, suggested that scenario last year after tracing the development of nerve cells in embryos of comb jellies, among the most ancient animals. Earlier this week at the annual meeting of the Society for Integrative and Comparative Biology (SICB) here, he marshaled evidence from developmental studies of other animals, all pointing to common origins for some neuron and secretory cells. “What Ryan is proposing is novel and important,” says David Plachetzki, an evolutionary biologist at the University of New Hampshire in Durham. Among other mysteries, it could resolve a long debate about whether the nervous system evolved twice early in animal life. © 2018 American Association for the Advancement of Science

Keyword: Evolution
Link ID: 25857 - Posted: 01.11.2019