Chapter 6. Evolution of the Brain and Behavior

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By Laura Sanders Brainlike blobs made from chimpanzee cells mature faster than those grown from human cells. That finding, described October 16 in Nature along with other clues to human brain development, is one of the latest insights from studies of cerebral organoids — three-dimensional clumps of cells that can mimic aspects of early brain growth (SN: 2/20/18). The new study “draws interesting parallels, but also highlights important differences” in the way that the brains of humans and chimpanzees develop, says Paola Arlotta, a neurobiologist at Harvard University who was not involved in the study. While “it’s still early days in the organoid world,” the results represent an important step toward understanding the particulars of the human brain, she says. To make cerebral organoids from chimpanzees, researchers use cells in blood left over from veterinarians’ routine blood draws. In the vials were white blood cells that could be reprogrammed into stem cells, which themselves were then coaxed into blobs of brain cells. “From that, we get something that really looks a lot like the early brain,” says Gray Camp, a stem cell biologist at the Institute of Molecular and Clinical Ophthalmology Basel in Switzerland. There were no obvious differences in appearance between the chimpanzee organoids and the human organoids, Camp says. But a close look at how genes behaved in the two organoids — and how that behavior changed over time — turned up a big difference in pacing. Chimpanzee organoids seemed to grow up faster than their human counterparts. © Society for Science & the Public 2000–2019

Keyword: Development of the Brain; Evolution
Link ID: 26713 - Posted: 10.17.2019

By Elizabeth Preston Heidi the octopus is sleeping. Her body is still, eight arms tucked neatly away. But her skin is restless. She turns from ghostly white to yellow, flashes deep red, then goes mottled green and bumpy like plant life. Her muscles clench and relax, sending a tendril of arm loose. From the outside, the cephalopod looks like a person twitching and muttering during a dream, or like a napping dog chasing dream-squirrels. “If she is dreaming, this is a dramatic moment,” David Scheel, an octopus researcher at Alaska Pacific University, said in the documentary. Heidi was living in a tank in his living room when her snooze was captured by the film crew, and he speculates that she is imagining catching and eating a crab. But an octopus is almost nothing like a person. So how much can anyone really say with accuracy about what Heidi was doing? When our two branches of the animal family tree diverged, backbones hadn’t been invented. Yet octopuses, cuttlefish and squid, on their own evolutionary path, developed impressive intelligence. They came up with their own way to build big brains. Much of an octopus’s brain is spread throughout its body, especially its arms. It makes sense to be cautious when we guess what’s going on in these animals’ minds. Looking at a behavior like Heidi’s is “a bit like going to a crime scene,” said Nicola Clayton, a psychologist at the University of Cambridge who studies comparative cognition. “You’ve got some evidence in front of you, but you’d need to know so much more to understand better what’s causing the behavior.” It’s only conjecture to say the octopus is dreaming without more data, she said. Does the sequence of Heidi’s color changes match an experience she had while awake? Dreaming in humans mostly happens during rapid-eye movement, or R.E.M., sleep. Could we observe something similar in octopuses? Dr. Clayton points out that a human sleeper might flush red because she’s overheated. © 2019 The New York Times Company

Keyword: Sleep; Evolution
Link ID: 26686 - Posted: 10.09.2019

Nicola Davis A possible explanation for one of biology’s greatest mysteries, the female orgasm, has been bolstered by research showing that rabbits given antidepressants release fewer eggs during sex. The human female orgasm has long proved curious, having no obvious purpose besides being pleasurable. The scientists behind the study have previously proposed it might have its evolutionary roots in a reflex linked to the release of eggs during sex – a mechanism that exists today in several animal species, including rabbits. Since humans have spontaneous ovulation, the theory goes that female orgasm may be an evolutionary hangover. They say the new experiment supports the idea. “We know there is a reflex [in rabbits], but the question [is] could this be the same one that has lost the function in humans?” said Dr Mihaela Pavličev a researcher at the University of Cincinnati who co-authored the study. To explore the question the team gave 12 female rabbits a two-week course of fluoxetine (trade name Prozac) – an antidepressant known to reduce the capacity for women to orgasm – and looked at the number of eggs released after the animals had sex with a male rabbit called Frank. The results, published in the Proceedings of the National Academy of Sciences, showed that rabbits given the antidepressants released 30% fewer eggs than nine rabbits that were not given Prozac but still mated with Frank. © 2019 Guardian News & Media Limited

Keyword: Sexual Behavior; Evolution
Link ID: 26659 - Posted: 10.01.2019

By Veronique Greenwood When the land-dwelling ancestors of today’s whales and dolphins slipped into the seas long ago, they gained many things, including flippers, the ability to hold their breath for long periods of time and thick, tough skin. Along the way they also discarded many traits that were no longer relevant or useful. In fact, as scientists reported in a study published Wednesday in Science Advances, the loss of some genes in the common ancestor of whales and dolphins allowed them to shed features that would have been liabilities beneath the waves, which may have contributed to the survival of future generations. As more species’ genomes are sequenced, researchers can begin to pick out which genes are shared among groups of organisms. Presumably, these genes were also found in the group’s last common ancestor. A team led by Michael Hiller, a geneticist at the Max Planck Institute of Molecular Cell Biology and Genetics and an author of the new paper, used this technique with modern cetaceans, the group that includes whales, dolphins and porpoises. Then they compared that set of genes to those of the cetaceans’ nearest relatives, the hippo family, and pinpointed 85 genes that were switched off or inactivated in the cetaceans’ ancestor during its move to the aquatic life. These genes were involved in a wide variety of processes, such as blood clotting, sleep and hair growth. Although some of the genes had been flagged before, others had not been identified. (Dr. Hiller and colleagues had previously found that genes necessary for the development of hair had been lost in cetaceans, which perhaps reduced drag as the animals swam through the water.) “Many of the things we found were at least for me quite unexpected,” said Dr. Hiller. For instance, one of the lost genes produces an enzyme involved in DNA repair. © 2019 The New York Times Company

Keyword: Sleep; Evolution
Link ID: 26648 - Posted: 09.27.2019

By Rachel Nuwer In the perennial battle over dogs and cats, there’s a clear public relations winner. Dogs are man’s best friend. They’re sociable, faithful and obedient. Our relationship with cats, on the other hand, is often described as more transactional. Aloof, mysterious and independent, cats are with us only because we feed them. Or maybe not. On Monday, researchers reported that cats are just as strongly bonded to us as dogs or infants, vindicating cat lovers across the land. “I get that a lot — ‘Well, I knew that, I know that cats like to interact with me,’” said Kristyn Vitale, an animal behavior scientist at Oregon State University and lead author of the new study, published in Current Biology. “But in science, you don’t know that until you test it.” Research into cat behavior has lagged that into dogs. Cats are not social animals, many scientists assumed — and not as easy to work with. But recent studies have begun to plumb the depth of cats’ social lives. “This idea that cats don’t really care about people or respond to them isn’t holding up,” Ms. Vitale said. In a study in 2017, Ms. Vitale and her colleagues found that the majority of cats prefer interacting with a person over eating or playing with a toy. In a 2019 study, the researchers found that cats adjust their behavior according to how much attention a person gives them. Other researchers have found that cats are sensitive to human emotion and mood, and that cats know their names. Scientists had arrived at conflicting findings about whether cats form attachments to their owners, however, so Ms. Vitale and her colleagues designed a study to more explicitly test the hypothesis. They recruited owners of 79 kittens and 38 adult cats to participate in a “secure base test,” an experiment commonly used to measure bonds that dogs and primates form with caretakers. © 2019 The New York Times Company

Keyword: Evolution; Aggression
Link ID: 26647 - Posted: 09.25.2019

By Eva Frederick There may be honor among thieves, but there certainly isn’t among parasitic wasps. A new study suggests the crypt keeper wasp, whose larvae burrow into the bodies of other wasps and live off their corpses, has more than half a dozen hosts—or, if you prefer, victims. Those victims are typically Bassettia pallida wasps, which lay their eggs in the stems and branches of oak trees, forming swollen bumps called galls or crypts. The crypt keeper wasp (Euderus set) then lays her eggs in the gall, where her larvae either camp out next to the host hatchlings or burrow into their bodies. When a hatchling is ready to chew its way out of the gall, the crypt keeper—through a feat of undiscovered mind control or through simply weakening the host—makes it chew a hole that is too small. That causes the host’s head to get stuck like a cork in a wine bottle. After snacking on the body of the host, the crypt keeper wasp escapes the gall by burrowing out through its host’s head, which is much softer than the tough stem of the plant. © 2019 American Association for the Advancement of Science.

Keyword: Evolution
Link ID: 26644 - Posted: 09.25.2019

Daniel Pfau I came out to a Christian counselor during a therapy session in 2001 when I was 14. He convinced me to engage in conversion therapy, a pseudoscientific practice to change an individual’s sexual orientation based in the assumption that such behaviors are “unnatural.” He produced an article describing a talk at that year’s American Psychological Association conference that indicated the therapy worked. This painful experience encouraged me, when I started my scientific career, to examine queerness in biology. The queer community, 25 million years (or more) in the making Understanding how complex human relationships developed requires a complete picture of our social behavior during evolution. I believe leaving out important behaviors, like same-sex sexual behavior, can bias the models we use to explain social evolution. Many researchers have postulated how queer behaviors, like same-sex sexual behavior, may have developed or how they are expressed. Recently, scientists at the Broad Institute of Harvard and MIT published a paper suggesting a genetic component to same-sex sexual behavior expression in modern humans. However, no studies provide an argument of when queer behavior may have arisen during humans’ evolution. Such research would push back against the assertions I encountered during my youth, that queerness is a modern aberration. © 2010–2019, The Conversation US, Inc.

Keyword: Sexual Behavior; Evolution
Link ID: 26632 - Posted: 09.21.2019

Shawna Williams Pain, unpleasant though it may be, is essential to most mammals’ survival, a warning to back off before we lose a limb or worsen a wound. So it was curious when, in a 2008 study, molecular physiologist Gary Lewin and his colleagues found that, unlike most mammals, naked mole rats (Heterocephalus glaber) didn’t lick or flick a limb that had been injected with a small amount of capsaicin—the hot in hot chili pepper. The mole rats turned out to be similarly nonchalant when exposed to dilute hydrochloric acid. “We wondered, first of all, how they became insensitive to these things,” says Lewin, who heads up a lab at Berlin’s Max Delbrück Center for Molecular Medicine. The team took an evolutionary approach to finding the answer. Several group members traveled to the naked mole rat’s native territory of East Africa to try out three common pain-causing substances on seven other mole rat species, plus the more distantly related East African root rat. They found that, in addition to the naked mole rat, the Natal mole rat was insensitive to capsaicin, while the Cape mole rat and the root rat didn’t seem to feel a burn from the hydrochloric acid. Most startlingly, one species, the highveld mole rat (Cryptomys hottentotus pretoriae), didn’t flinch when injected with a few milliliters of a highly diluted solution of an irritant present in mustard and wasabi known as AITC—an agent that even the naked mole rat reacted to. When team member Karlien Debus donned a gas mask to inject a similar amount of 100 percent AITC under the skin of a highveld mole rat, there was still no response. “Probably the AITC was the most interesting because AITC is a substance that actually every [other] animal in the entire animal kingdom avoids,” Lewin says. An electrophilic compound, AITC can crosslink an animal’s proteins and damage its cells. © 1986–2019 The Scientist.

Keyword: Pain & Touch; Evolution
Link ID: 26623 - Posted: 09.19.2019

By Laura Sanders Dog breeders have been shaping the way the animals look and behave for centuries. That meddling in canine evolution has sculpted dogs’ brains, too. A brain-scanning study of 62 purebred dogs representing 33 breeds reveals that dog brains are not all alike — offering a starting point for understanding how brain anatomy relates to behavior. Different breeds had different shapes of various brain regions, distinctions that were not simply the result of head shape or the size of the dogs’ brains or bodies, researchers report September 2 in the Journal of Neuroscience. Through selective breeding, “we have been systematically shaping the brains of another species,” Erin Hecht, an evolutionary neuroscientist at Harvard University, and colleagues conclude. The MRI scans were taken of dogs with normal brain anatomy at the Veterinary Teaching Hospital at the University of Georgia at Athens. While the study wasn’t designed to directly link brain shape to behavior, the results offer some hints. Researchers identified groups of brain areas, such as smell and taste regions, that showed the most variability between breeds. Those groups are involved in specialized behaviors that often serve humans, such as hunting by smell, guarding and providing companionship to people, earlier studies have suggested. © Society for Science & the Public 2000–2019

Keyword: Evolution
Link ID: 26566 - Posted: 09.03.2019

Colin Barras An ancient face is shedding new light on our earliest ancestors. Archaeologists have discovered a 3.8-million-year-old hominin skull in Ethiopia — a rare and remarkably complete specimen that could change what we know about the origins of one of humanity’s most famous ancestors, Lucy. The researchers who discovered the skull say it belongs to a species called Australopithecus anamensis, and it gives scientists their first good look at the face of this hominin. This species was thought to precede Lucy’s species, Australopithecus afarensis. But features of the latest find now suggest that A. anamensis shared the prehistoric Ethiopian landscape with Lucy’s species for at least 100,000 years, the researchers say. This hints that the early hominin evolutionary tree was more complicated than scientists had thought — but other researchers say the evidence isn’t yet conclusive. “Fossil hominin crania are exceptionally rare treasures,” says Carol Ward, a palaeoanthropologist at the University of Missouri in Columbia who wasn’t involved in the analysis. “This to me is the specimen we have been waiting for.” An analysis of the skull is published in Nature1 . Exceptionally preserved A. afarensis lived in East Africa between about 4 million and 3 million years ago. It is important to the understanding of human evolution because it might have been the ape-like species from which the ‘true’ human genus, Homo, evolved about 2.8 million years ago. Over the past few decades, researchers have discovered dozens of fragments of australopithecine fossils in Ethiopia and Kenya that date back more than 4 million years. Most researchers think these older fossils belong to the earlier species, A. anamensis. It’s generally thought that A. anamensis gradually morphed into A. afarensis, implying that the two species never coexisted.

Keyword: Evolution
Link ID: 26551 - Posted: 08.29.2019

By Cara Giaimo Peppered moth caterpillars live across the Northern Hemisphere, from the forests of China to the backyards of North America. But if you’ve never seen one, don’t feel bad: They’re experts at blending in. Each caterpillar mimics the twig it perches on, straightening its knobbly body into a stick-like shape. It also changes its hue to match the twig’s color, whether birch white, willow green or dark oak brown. They’re so good at this, in fact, that they can do it blindfolded — literally. According to a paper published in Communications Biology in early August, the caterpillars sense the color of their surroundings not only with their eyes, but also with their skin. While other animals, including cuttlefish and lizards, have similar abilities, this is “the most complete demonstration so far that color change can be controlled by cells outside the eyes,” said Martin Stevens, a professor of sensory and evolutionary ecology at the University of Exeter. Dr. Stevens, who was not involved in the study, added that the exact mechanism remains a mystery. The adult peppered moth is famous for a completely different color journey; After soot from the Industrial Revolution darkened tree bark in Britain, peppered moths there evolved to be darker, too. Ilik Saccheri, a professor of ecological genetics at the University of Liverpool and an author of the new paper, normally studies the adult moth. This requires keeping a lot of caterpillars around. Years of observation sparked his curiosity about their color-changing abilities, which happen individually and in a matter of minutes rather than over generations. Each caterpillar hatches tiny and black, and in its early days is blown around by the wind. Once it falls on a plant, it must camouflage itself to avoid being spotted by hungry birds. This process, which involves producing new pigments, plays out over a period of days or weeks. “I was a bit disbelieving that they could change that accurately only using their eyes,” which are quite simple at the larval stage, Dr. Saccheri said. © 2019 The New York Times Company

Keyword: Vision; Evolution
Link ID: 26547 - Posted: 08.27.2019

By James Gorman Here are three good things about gulls: They are devoted parents. Males share child care equally with females. That includes sitting on the eggs during incubation. And they have figured out a way — actually many ways — to survive in a harsh and unforgiving world. Some eat clams, some eat fish, some are attracted to landfills. Of course, a few will divebomb you at the beach or boardwalk to steal a French fry, or the cheese on your cracker, or an entire slice of pizza. The beach pirate approach to survival is, of course, where humans and gulls clash. And the outcry from humans is almost as loud and outraged as the cries of the gulls themselves. Several recent news articles have chronicled the predations of gulls and some possible remedies. Ocean City, N.J., is bringing in hawks, and some scientists have suggested staring directly at gulls to fend them off. Though that is hard to do when the birds sneak up behind you as you are putting cheese on a cracker. There are some reports of more serious trouble. In England, a woman said a gull carried off her Chihuahua, and in Russia a pilot was hailed as a hero for safely landing his plane after a collision with a flock of gulls. In the New York area, thousands of birds, including gulls, have been killed in the decade since the Miracle on the Hudson crash to clear the skies for airplanes, without an apparent reduction in bird strikes. But it’s at the beach where tempers flare most predictably. And in times like these, with heightened human-gull tensions, very little has been written about the gulls’ point of view. Is there a Lorax who speaks for the gulls? Admittedly, gulls have quite a strong voice of their own, it’s just that it’s pretty unintelligible to most of us. An ornithologist would seem to be the obvious choice. They like birds. I called Christopher Elphick at the University of Connecticut. He spends a lot of time studying sparrows, but has a soft spot for gulls. © 2019 The New York Times Company

Keyword: Sexual Behavior; Evolution
Link ID: 26537 - Posted: 08.24.2019

Jon Hamilton In mice, scientists have used a variety of drugs to treat brain disorders including murine versions of Alzheimer's disease, depression and schizophrenia. But in people, these same treatments usually fail. And now researchers are beginning to understand why. A detailed comparison of the cell types in mouse and human brain tissue found subtle but important differences that could affect the response to many drugs, a team reports Wednesday in the journal Nature. "If you want to develop a drug that targets a specific receptor in a specific disease, then these differences really matter," says Christof Koch, an author of the study and chief scientist and president of the Allen Institute for Brain Science in Seattle. One key difference involved genes that cause a cell to respond to the chemical messenger serotonin, says Ed Lein, a study author and investigator at the institute. "They're expressed in both mouse and human, but they're not in the same types of cells," Lein says. As a result, "serotonin would have a very different function when released into the cortex of the two species." That's potentially a big deal because antidepressants like Prozac act on the brain's serotonin system. So testing these drugs on mice could be misleading, Lein says. The comparison was possible because of new technology that allows scientists to quickly identify which of the hundreds of types of brain cells are present in a particular bit of brain tissue. © 2019 npr

Keyword: Brain imaging; Evolution
Link ID: 26530 - Posted: 08.22.2019

By Bruce Bower A 20-million-year-old monkey skull that fits in the palm of an adult’s hand may contain remnants of piecemeal brain evolution in ancient primates. Neural landmarks preserved on the skull fit a scenario in which specific primate brain regions expanded or, at times, contracted while other regions remained unchanged, a new study finds. In an early clue to that evolutionary process, researchers say, a small part of the monkey’s brain devoted to odor perception was not counterbalanced by an enlarged visual system, as is typical of primates today. Primate visual systems expanded in size and complexity over millions of years without requiring substantial changes elsewhere in the brain, contend paleontologist Xijun Ni of the Chinese Academy of Sciences in Beijing and colleagues. And comparisons of the skull with fossils of African primates from 30 million years ago or more indicate that major brain structures evolved at different rates in different primate lineages, as did increases in brain size relative to body size, the team reports August 21 in Science Advances. The study adds evidence to the idea that the brains of primates, a group that includes humans, evolved in a piecemeal way, instead of progressively getting bigger overall as time passed. The skull, from an extinct monkey called Chilecebus carrascoensis, was reported discovered in Chile’s Andes Mountains in 1995 by a team led by paleontologist John Flynn of the American Museum of Natural History in New York City. In the new study, Flynn and colleagues used high-resolution scanning and a digital, 3-D cast of the inner surface of the skull’s tiny braincase to reveal impressions made by a set of neural folds. © Society for Science & the Public 2000–2019.

Keyword: Evolution
Link ID: 26528 - Posted: 08.22.2019

Laura Sanders The golf ball–sized chunk of brain is not cooperating. It’s thicker than usual, and bloodier. One side has a swath of tissue that looks, to my untrained eye, like gristle. Nick Dee, the neuroscientist charged with quickly cutting the chunk into neat pieces, confers with his colleagues. “We can trim off that ugliness on the side,” he says. The “ugliness” is the brain’s connective tissue called white matter. To produce useful slices for experiments, the brain tissue must be trimmed, superglued to a lipstick-sized base and then fed into a lab version of a deli slicer. But this difficult chunk isn’t cutting nicely. Dee and colleagues pull it off the base, trim it again and reglue. Half an hour earlier, this piece of neural tissue was tucked inside a 41-year-old woman’s head, on her left side, just above the ear. Surgeons removed the tissue to reach a deeper part of her brain thought to be causing severe seizures. Privacy rules prevent me from knowing much about her; I don’t know her name, much less her first memory, favorite meal or sense of humor. But within this piece of tissue, which the patient generously donated, are clues to how her brain — all of our brains, really — create the mind. Dee’s team is working fast because this piece of brain is alive. Some of the cells can still behave as if they are a part of a person’s brain, which means they hold enormous potential for scientists who want to understand how we remember, plan, behave and feel. After Dee and his team do their part, pieces of the woman’s brain will be whisked into the hands of eager scientists, where the cells will be photographed, zapped with electricity, relieved of their genetic material and even infected with viruses that make them glow green and red. © Society for Science & the Public 2000 - 2019

Keyword: Brain imaging; Evolution
Link ID: 26490 - Posted: 08.12.2019

By Iliana Magra LONDON — On a spring afternoon last year, Neil Fraser was walking down the main shopping street in Aberdeen, a port city in northeastern Scotland, when something strange happened. The bacon-and-chicken sandwich he was halfway through eating suddenly vanished from his hand. The culprit? A hungry bird he hadn’t seen coming. “The sea gull flew in from behind me,” Mr. Fraser, a manager at the Old Schoolhouse pub in the city, said by phone on Wednesday. The bird knocked down his hand and, before he realized what was happening, it was all over: “The sandwich and the sea gull were both gone.” Aggressive gulls trying to snatch people’s food, and at times succeeding, have been a longstanding nuisance in Britain, and various solutions have been proposed over the years, including not feeding the birds, holding a stick or umbrella overhead and installing wires on roofs that they use for nesting. The Old Schoolhouse pub even reportedly offered customers water pistols to deflect the birds. Now, new research proposes a different approach: staring them down. A study published in the journal Biology Letters on Wednesday by the Royal Society, the world’s oldest continuous scientific society, suggested that making eye contact might be key to fending off herring gulls, a familiar sight in British seaside towns. The study, conducted late last year in coastal towns in Cornwall, in southwestern England, focused on that species, which are white-, gray- and black-feathered, with beaks of yellow and red. The researchers tried to test 74 birds by placing potato chips in front of an experimenter. Just 27 of the gulls bit the bait — a factor that the research team attributed to whether the experimenter was facing toward or away from the gull. © 2019 The New York Times Company

Keyword: Aggression; Evolution
Link ID: 26486 - Posted: 08.12.2019

By Knvul Sheikh It’s a myth that black widow female spiders always kill and consume their mates. But courtship remains perilous for males, cannibalism or no. The terrain, navigated in the dark, is challenging. The female’s web releases come-hither pheromones, but only about 12 percent of prospective males manage to reach it. And once there, they can expect to face male rivals competing to pass their genes on to the next generation. Usually, this results in wild displays of machismo. The males slash the female’s webs to make them less enticing to others. They deposit “mating plugs” in the female’s body to block rival sperm. Why not simply avoid the competition and seek out females’ webs empty of other males? But male black widows actually seem to thrive on the competition, according to a study published Wednesday in the Proceedings of the Royal Society B: Biological Sciences. Researchers found that male black widows find potential mates faster by following the silk trails left behind by other males. “Males have to race to find females,” said Catherine Scott, an arachnologist at the University of Toronto Scarborough in Canada and the study’s lead author. “It makes sense for them to try to use all the tricks they can to find females as soon as possible, even if there are other males that have already found her.” If a male arrives an hour or two late at a female’s web, he still has a chance to interrupt the courting rituals of other males, and could still be the first to mate with the female, Ms. Scott said. Males typically make their way to a rendezvous by following female pheromones back to their source. But those signals must be at just the right distance, and uninterrupted by shifting winds and other factors. © 2019 The New York Times Company

Keyword: Sexual Behavior; Evolution
Link ID: 26476 - Posted: 08.01.2019

Bruce Bower Monkeys can keep strings of information in order by using a simple kind of logical thought. Rhesus macaque monkeys learned the order of items in a list with repeated exposure to pairs of items plucked from the list, say psychologist Greg Jensen of Columbia University and colleagues. The animals drew basic logical conclusions about pairs of listed items, akin to assuming that if A comes before B and B comes before C, then A comes before C, the scientists conclude July 30 in Science Advances. Importantly, rewards given to monkeys didn’t provide reliable guidance to the animals about whether they had correctly ordered pairs of items. Monkeys instead worked out the approximate order of images in the list, and used that knowledge to make choices in experiments about which of two images from the list followed the other, Jensen’s group says. Previous studies have suggested that a variety of animals, including monkeys, apes, pigeons, rats and crows, can discern the order of a list of items (SN: 7/5/08, p. 13). But debate persists about whether nonhuman creatures do so only with the prodding of rewards for correct responses or, at least sometimes, by consulting internal knowledge acquired about particular lists. Jensen’s group designed experimental sessions in which four monkeys completed as many as 600 trials to determine the order of seven images in a list. Images included a hot air balloon, an ear of corn and a zebra. Monkeys couldn’t rely on rewards to guide their choices. In some sessions, animals usually received a larger reward for correctly identifying which of two images came later in the list and a smaller reward for an incorrect response. In other sessions, incorrect responses usually yielded a larger reward than correct responses. Rewards consisted of larger or smaller gulps of water delivered through tubes to the moderately thirsty primates. |© Society for Science & the Public 2000 - 2019

Keyword: Attention; Evolution
Link ID: 26475 - Posted: 08.01.2019

Carolyn Wilke Most frogs lay oodles of eggs and quickly hop away. But some poison dart frogs baby their offspring, cleaning and hydrating eggs laid on land and piggybacking hatched tadpoles to water. A peek inside the brains of these nurturing amphibians reveals that in males and females, two regions linked with caring for young are the same — a finding that may provide clues to the neural underpinnings of parental behavior, researchers report online July 17 in Proceedings of the Royal Society B. From humans to crocodiles, many creatures tend to their young. “But we actually understand very little about how the brain makes parental behaviors,” says Eva Fischer, a neuroethologist at Stanford University. To study how such care is wired into the amphibian brain, Fischer and her colleagues looked at neural activity in three poison dart frog species with different parenting strategies: Dendrobates tinctorius, among whom the males take care of the young; Oophaga sylvatica, whose females do the parenting; and Ranitomeya imitator, whose offspring are cared for by a monogamous male and female pair. The researchers collected and quickly killed 25 frogs while the amphibians were toting their tadpoles to water, in order to study the brain while it was still influenced by the parental task. Another 59 brains from non-caregiving frog species or caregivers’ partners were also included in the study. The researchers froze the frog brains and sliced them like loaves of bread. They stained the layers of tissue to pinpoint which nerve cells, or neurons, were turned on. In all three species, a brain region called the preoptic area was lit up with activity in caregiving frogs, but not in those of non-caregiving animals. |© Society for Science & the Public 2000 - 2019.

Keyword: Sexual Behavior; Evolution
Link ID: 26451 - Posted: 07.26.2019

By Virginia Morell A bold claim about gorilla societies is drawing mixed reviews. Great apes, humans’ closest evolutionary relatives, were thought to lack our social complexity. Chimpanzees, for example, form only small bands that are aggressive toward strangers. But based on years of watching gorillas gather in food-rich forest clearings, a team of scientists has concluded the apes have hierarchical societies similar to those of humans, perhaps to help them exploit rich troves of food. The finding, reported in the current issue of the Proceedings of the Royal Society B, challenges the prevailing notion that such sophisticated societies evolved relatively recently, after humans split from chimpanzees. Instead, these researchers say, the origins of such social systems extend at least as far back as the common ancestor of humans and gorillas, but were lost in chimpanzees. The group has presented “a pretty convincing case for a hierarchical social structure in gorillas,” says Richard Connor, a cetacean biologist and expert on dolphin society at the University of Massachusetts in Dartmouth. But because other primates that are not great apes—notably baboons, geladas, and colobine monkeys—show similar hierarchies, he’s not surprised they have turned up in gorillas, too. Gorillas spend most of their time in dense forests, travel great distances to a new home spot daily, and are slow to get used to observers, making their social lives hard to study. But western gorillas in the Republic of Congo gather periodically at swampy clearings in the forests to feed primarily on the highly abundant vegetation, but also on favorite and rare foods such as certain fig trees that produce massive amounts of fruit only every 3 to 5 years, says Robin Morrison, a zoologist at the University of Cambridge in the United Kingdom and the study’s lead author. © 2019 American Association for the Advancement of Science.

Keyword: Evolution
Link ID: 26428 - Posted: 07.18.2019