Chapter 6. Evolution of the Brain and Behavior

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Nicola Davis Dolphins, like humans, have a dominant right-hand side, according to research. About 90% of humans are right-handed but we are not the only animals that show such preferences: gorillas tend to be right-handed, kangaroos are generally southpaws, and even cats have preferences for a particular side – although which is favoured appears to depend on their sex. Now researchers have found common bottlenose dolphins appear to have an even stronger right-side bias than humans. “I didn’t expect to find it in that particular behaviour, and I didn’t expect to find such a strong example,” said Dr Daisy Kaplan, co-author of the study from the Dolphin Communication Project, a non-profit organisation in the US. Researchers studying common bottlenose dolphins in the Bahamas say the preference shows up in crater feeding, whereby dolphins swim close to the ocean floor, echolocating for prey, before shoving their beaks into the sand to snaffle a meal. Writing in the journal Royal Society Open Science, Kaplan and colleagues say the animals make a sharp and sudden turn before digging in with their beaks. Crucially, however, they found this turn is almost always to the left, with the same direction taken in more than 99% of the 709 turns recorded between 2012 and 2018. The researchers say the findings indicate a right-side bias, since a left turn keeps a dolphin’s right eye and right side close to the ocean floor. The team found only four turns were made to the right and all of these were made by the same dolphin, which had an oddly shaped right pectoral fin. However the Kaplan said it was unlikely this fin was behind the right turns: two other dolphins had an abnormal or missing right fin yet still turned left.

Keyword: Laterality; Evolution
Link ID: 26861 - Posted: 12.02.2019

Suzana Herculano-Houzel Here’s something new to consider being thankful for at the dinner table: the long evolutionary journey that gave you your big brain and your long life. Courtesy of our primate ancestors that invented cooking over a million years ago, you are a member of the one species able to afford so many cortical neurons in its brain. With them come the extended childhood and the pushing century-long lifespan that together make human beings unique. All these bequests of your bigger brain cortex mean you can gather four generations around a meal to exchange banter and gossip, turn information into knowledge and even practice the art of what-not-to-say-when. You may even want to be thankful for another achievement of our neuron-crammed human cortices: all the technology that allows people spread over the globe to come together in person, on screens, or through words whispered directly into your ears long distance. I know I am thankful. But then, I’m the one proposing that we humans revise the way we tell the story of how our species came to be. Back when I had just received my freshly minted Ph.D. in neuroscience and started working in science communication, I found out that 6 in 10 college-educated people believed they only used 10% of their brains. I’m glad to say that they’re wrong: We use all of it, just in different ways at different times. The myth seemed to be supported by statements in serious textbooks and scientific articles that “the human brain is made of 100 billion neurons and 10 times as many supporting glial cells.” I wondered if those numbers were facts or guesses. Did anyone actually know that those were the numbers of cells in the human brain? No, they didn’t. © 2010–2019, The Conversation US, Inc.

Keyword: Intelligence; Neurogenesis
Link ID: 26857 - Posted: 11.29.2019

By Veronique Greenwood A few years back, Ryan Herbison, then a graduate student in parasitology at the University of Otago, painstakingly collected about 1,300 earwigs and more than 2,500 sandhoppers from gardens and a beach in New Zealand. Then, he dissected and examined the insides of their heads. This macabre scavenger hunt was in search of worms that lay coiled within some of the insects. The worms are parasites that force earwigs and sandhoppers to march into bodies of water, drowning themselves so the worms’ aquatic offspring can thrive. “Like a back-seat driver, but a bit more sinister,” said Mr. Herbison, describing these mind-controlling parasites. “And sometimes they may just grab the steering wheel.” Just how they do that, though, has remained a bit of a mystery. But in a paper published Wednesday in Proceedings of the Royal Society B, Mr. Herbison and fellow researchers reported that the parasites seemed to be manipulating the production of host proteins involved in generating energy and movement in their unfortunate hosts. The analysis is limited, but the researchers speculated that the parasites may be affecting neuronal connections in the bugs’ brains and perhaps even interfering with memory in a way that puts the hosts at risk. Parasites use a variety of similar strategies. Some make cat urine suicidally attractive to mice, which are promptly eaten so that the parasites can go through the next phase of their life cycle in the cat. Others prompt ants to expose themselves on high tree branches, the better to be eaten by birds. And still others cause snails to hang out in open spaces, with swollen eyestalks pulsing like neon signs, for apparently the same reason. © 2019 The New York Times Company

Keyword: Learning & Memory; Evolution
Link ID: 26845 - Posted: 11.22.2019

By Susana Martinez-Conde The many evils of social media notwithstanding, millions of users agree that some of its most delightful aspects include viral illusions and cute cat videos. The potential for synergy was vast in retrospect—but only realized in 2013, when Rasmus Bååth, a cognitive scientist from Lund University in Sweden, blended both elements in a YouTube video of his kitten attacking a printed version of Akiyoshi Kitaoka’s famous “Rotating Snakes” illusion. The clip, which has been viewed more than 6 million times as of this writing, led to subsequent empirical research and an internet survey of cat owners, where 29% of respondents answered that their pets reacted to the Rotating Snakes. The results, published in the journal Psychology in 2014, indicated—though not conclusively—that cats experience illusory motion when they look at the Rotating Snakes pattern, much as most humans do. Now, a team of researchers from University of Padova, Italy, Queen Mary University of London in the UK, and the Parco Natura Viva—Garda Zoological Park in Bussolengo, Italy, has collected additional evidence that cats—in this case, big cats—find the Rotating Snakes Illusion fascinating. Advertisement Intrigued by the earlier study on house cats, Christian Agrillo of the University of Padova and his collaborators set out to determine whether lions at Parco Natura Viva were similarly susceptible to motion illusions, as well as explore the possibility that such patterns might serve as a source of visual enrichment for zoo animals. Their findings were published last month in Frontiers in Psychology. © 2019 Scientific American,

Keyword: Vision; Evolution
Link ID: 26826 - Posted: 11.18.2019

By Bruce Bower An ancient ape that was larger than a full-grown male gorilla has now revealed molecular clues to its evolutionary roots. Proteins extracted from a roughly 1.9-million-year-old tooth of the aptly named Gigantopithecus blacki peg it as a close relative of modern orangutans and their direct ancestors, say bioarchaeologist Frido Welker of the University of Copenhagen and his colleagues. Protein comparisons among living and fossil apes suggest that Gigantopithecus and orangutan forerunners diverged from a common ancestor between around 10 million and 12 million years ago, Welker’s group reports November 13 in Nature. Since it was first described in 1935, based on a molar purchased from a traditional Chinese drugstore in Hong Kong, G. blacki has stimulated debate over its evolutionary links to other ancient apes. Almost 2,000 isolated teeth and four partial jaws of G. blacki have since been found in southern China and nearby parts of Southeast Asia. G. blacki fossils date from around 2 million to almost 300,000 years ago. The sizes of individual teeth and jaws indicate that G. blacki weighed between 200 and 300 kilograms. Proteins preserve better in teeth and bones than DNA does, but both molecular forms break down quickly in hot, humid settings. “We were surprised to find any proteins this old at all, especially in a fossil from a subtropical environment,” Welker says. Proteins consisting of chains of amino acids can be used to sort out living and fossil species of various animals, including hominids (SN: 5/1/19). © Society for Science & the Public 2000–2019

Keyword: Evolution
Link ID: 26818 - Posted: 11.14.2019

By Karinna Hurley Part of the Museum of Natural History in Paris, the Jardin des Plantes, on the left bank of the Seine River, hosts a collection of galleries and gardens. A couple of miles away, the larger museum also includes the Museum of Mankind, which is, in part, an exploration of what it means to be human. There, like in many other museums worldwide, you can view a collection of stone tools used by the earliest humans. Tool use was long believed to be unique to our species—a defining feature, like language. Utilizing objects to achieve goals is not just a demonstration of advanced cognitive capabilities; it is largely through our symbolic and material tools that we share and transmit culture. In 1960 primatologist Jane Goodall observed wild chimpanzees making and using tools. A connection between humans and other animals, in how we think and learn, was captivating news. Since then, scientists have gone on to establish tool use in a relatively small number of other species. And observations of learning to use a tool from other group members, rather than instinctively, have been even more rare—until now. The Jardin des Plantes is also home to a special couple, Priscilla and Billie. Along with at least one of their daughters, these Visayan warty pigs—residents of the garden’s zoo—are the first in any pig species to be identified using tools and, even more remarkably, to apparently transmit this behavior through social learning. The discovery was made by chance by ecologist Meredith Root-Bernstein, who was watching the family from outside its enclosure. Priscilla, working on building a nest, picked up a piece of bark in her mouth and used it to aid her digging. For six weeks Root-Bernstein frequently returned to the zoo to try to again catch her in the act. Although she didn’t do so, she did notice the digging tool moved among different areas of the enclosure and always near a recently constructed nest. © 2019 Scientific American

Keyword: Evolution; Intelligence
Link ID: 26817 - Posted: 11.14.2019

By Elizabeth Preston A pack of baldheaded, boldly plumaged birds steps through the grass shoulder to shoulder, red eyes darting around. They look like middle schoolers seeking a cafeteria table at lunchtime. Perhaps they’re not so different. A study published Monday in Current Biology shows that the vulturine guineafowl of eastern Africa, like humans, have many-layered societies. In the past, scientists hypothesized that such social structures require a lot of brainpower. But the pea-brained guineafowl are revealing the flaws in that assumption. Damien Farine, who led the research and is an ornithologist at the Max Planck Institute of Animal Behavior who studies collective behavior, first worked in Kenya during his postdoctoral research on baboon societies. Baboons are a model for researchers trying to understand how human society evolved. Some kinds of baboons live in groups within groups, a structure that’s called a multilevel society. “Humans are the classic multilevel society,” Dr. Farine said. Imagine a human family living in a village: The family might be friendly with other families within the village, which in turn might have ties to neighboring villages, and so on. “People have long hypothesized that living in complex society is one of the reasons why we’ve evolved such large brains,” Dr. Farine said. Researchers have found evidence for multilevel societies in some other large-brained mammals, such as monkeys, elephants, giraffes and sperm whales. But as Dr. Farine studied baboons, he also watched the vulturine guineafowl wandering around his study site. “I was really struck by the social behavior that they exhibited,” he said. These hefty birds can fly, but rarely choose to. Instead, they stroll across the landscape in packs, often walking so closely that their bodies touch. They may chase each other or fight to maintain their strict hierarchies. But at other times they engage in friendly behaviors like sharing food. Their groups are unusually large for birds, sometimes including 60 or more individuals. And while most other social birds are very territorial, Dr. Farine says, groups of vulturine guineafowl don’t mind sharing turf. © 2019 The New York Times Company

Keyword: Evolution
Link ID: 26789 - Posted: 11.05.2019

By Carl Zimmer Evolutionary biologists retrace the history of life in all its wondrous forms. Some search for the origin of our species. Others hunt for the origin of birds. On Thursday, a team of researchers reported an important new insight into the origin of zombies — in this case, ants zombified by a fungus. Here’s how it works: Sometimes an ant, marching about its business outdoors, will step on a fungal spore. It sticks to the ant’s body and slips a fungal cell inside. The fungus, called Ophiocordyceps, feeds on the ant from within and multiplies into new cells. But you wouldn’t know it, because the ant goes on with its life, foraging for food to bring back to the nest. All the while, the fungus keeps growing until it makes up nearly half of the ant’s body mass. When Ophiocordyceps is finished feeding on its host, the fungal cells gather inside the ant’s body. They form a mat and push needlelike projections into the ant’s muscle cells. The fungal cells also send chemical signals to the ant’s brain, causing the host to do something strange. The ant departs its nest and climbs a nearby plant. In the tropics, where many species of Ophiocordyceps live, the fungus drives ants upward, to a leaf above the ground. The ant bites down, its jaws locking as it dies. The fungus sends out sticky threads that glue the corpse to the leaf. And now it is ready to take the next step in its life cycle: Out of the ant’s head bursts a giant stalk, which showers spores onto the ant trails below. “The ants are walking over a minefield,” said David Hughes, an expert on Ophiocordyceps at Pennsylvania State University. © 2019 The New York Times Company

Keyword: Evolution
Link ID: 26754 - Posted: 10.25.2019

By Veronique Greenwood To the rippling sound of an aquarium pump, a small crab comes around the corner. It moves sideways, sticking close to the walls. But when it catches sight of a mussel — laid as a reward at the end of the maze it has just walked — the crab breaks into a skipping run, throwing itself on the treat with abandon. This crustacean, one of many shore crabs scooped by researchers from under a pier in Swansea, Wales, had just completed an intriguing feat: Without any guidance from researchers, it found its way to the end of a small maze. According to a paper in Biology Letters on Wednesday, shore crabs can learn to navigate a lab-rat-style maze and remember it weeks later. While crabs that have never seen the maze before bump around aimlessly, experienced crabs race to the finish line with no wrong turns. The study, one of the few to look at whether crustaceans can perform such feats, suggests that crabs are quite capable of remembering routes. Maze running could also be a way to measure the effects of changes in the sea, like ocean acidification and warming, on crabs’ cognitive abilities. Crabs often clamber through complex landscapes in their daily lives, says Edward Pope, a marine biologist at Swansea University who is an author of the new study. So, it is not particularly surprising that crabs would be able to find their way through a maze and even be able to remember it later. What was surprising, however, was just how clear the results of the study were. During the first week of the experiment, no crabs got to the end of the maze without taking wrong turns, some of them detouring six or seven times. By week four, some could race to the end flawlessly. Even the worst-performing crab took no more than three wrong turns. To see how the crabs would perform when there was no food in the maze, and thus no trace in the water of a snack to guide them, the researchers waited a couple of weeks and put the crabs back in the maze. They also tested crabs that had never seen the maze. “The conditioned animals all ran to the end of the maze expecting there to be food,” Dr. Pope said. © 2019 The New York Times Company

Keyword: Learning & Memory; Evolution
Link ID: 26751 - Posted: 10.25.2019

Tara Boyle Some of Laurie Santos's most insightful research was sparked by an embarrassing incident. One day, monkeys — her research subjects — stole all the fruit she needed to run a study. She left the research site early for the day. On the boat ride home from Cayo Santiago, the island where the monkeys lived, Santos reflected on the monkeys' mischief. "It's not just that we're dumb researchers and they can outsmart us," she says. "They're specifically trying to steal from us when we're not aware of what they're doing." Santos, a professor of psychology at Yale University, decided to study the monkeys' theft. She found that they selectively stole from the person who couldn't see them. "In other words, they're rationally calculating whether or not someone could detect that they're about to do something dastardly," she says. It was behavior befitting a human. Over the years Santos has discovered other similarities in how humans and non-human primates act. She's also pinpointed important differences, helping us understand which capacities are unique to humans. This comparison between humans and other animals, Santos says, is essential for making any claims that humans are unique. "There's no way to study what makes humans special if you only study humans. You actually have to turn to all the other critters in the animal kingdom," she says. © 2019 npr

Keyword: Evolution
Link ID: 26739 - Posted: 10.23.2019

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