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By Helen Briggs BBC News Humans may in part owe their big brains to a DNA "typo" in their genetic code, research suggests. The mutation was also present in our evolutionary "cousins" - the Neanderthals and Denisovans. However, it is not found in humans' closest living relatives, the chimpanzees. As early humans evolved, they developed larger and more complex brains, which can process and store a lot of information. Last year, scientists pinpointed a human gene that they think was behind the expansion of a key brain region known as the neocortex. They believe the gene arose about five or six million years ago, after the human line had split off from chimpanzees. Now, researchers have found a tiny DNA change - a point mutation - that appears to have changed the function of the gene, sparking the process of expansion of the neocortex. It may have paved the way for the brain's expansion by dramatically boosting the number of brain cells found in this region. Dr Wieland Huttner of the Max Planck Institute of Molecular Cell Biology and Genetics in Dresden, Germany, led the research. "A point mutation in a human-specific gene gave it a function that allows expansion of the relevant stem cells that make a brain big," he told BBC News. "This one, as it is fixed in the human genome - so all living humans have the gene - apparently gave a tremendous selection advantage, and that's why we believe it spread in the human population." Between two and six million years ago, the ancestors of modern humans began to walk upright and use simple tools.

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory, Learning, and Development
Link ID: 22965 - Posted: 12.08.2016

By Ann Gibbons On a promontory high above the sweeping grasslands of the Georgian steppe, a medieval church marks the spot where humans have come and gone along Silk Road trade routes for thousands of years. But 1.77 million years ago, this place was a crossroads for a different set of migrants. Among them were saber-toothed cats, Etruscan wolves, hyenas the size of lions—and early members of the human family. Here, primitive hominins poked their tiny heads into animal dens to scavenge abandoned kills, fileting meat from the bones of mammoths and wolves with crude stone tools and eating it raw. They stalked deer as the animals drank from an ancient lake and gathered hackberries and nuts from chestnut and walnut trees lining nearby rivers. Sometimes the hominins themselves became the prey, as gnaw marks from big cats or hyenas on their fossilized limb bones now testify. "Someone rang the dinner bell in gully one," says geologist Reid Ferring of the University of North Texas in Denton, part of an international team analyzing the site. "Humans and carnivores were eating each other." This is the famous site of Dmanisi, Georgia, which offers an unparalleled glimpse into a harsh early chapter in human evolution, when primitive members of our genus Homo struggled to survive in a new land far north of their ancestors' African home, braving winters without clothes or fire and competing with fierce carnivores for meat. The 4-hectare site has yielded closely packed, beautifully preserved fossils that are the oldest hominins known outside of Africa, including five skulls, about 50 skeletal bones, and an as-yet-unpublished pelvis unearthed 2 years ago. "There's no other place like it," says archaeologist Nick Toth of Indiana University in Bloomington. "It's just this mother lode for one moment in time." © 2016 American Association for the Advancement of Science.

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 22899 - Posted: 11.23.2016

By STEPH YIN Neanderthals and modern humans diverged from a common ancestor about half a million years ago. Living in colder climes in Eurasia, Neanderthals evolved barrel chests, large skulls and strong hands. In Africa, modern humans acquired shorter faces, a prominent chin and slender limbs. Then, roughly 50,000 years ago, the two species encountered one another and interbred, as modern humans spread out of Africa. The legacy of this interbreeding has been the subject of much scientific inquiry in the past few years. Today, up to 4 percent of the genes of non-Africans are Neanderthal in origin.. These may have influenced a diverse range of traits, including keratin production, disease risk and the propensity to sneeze after eating dark chocolate. Where did all the other Neanderthal DNA go? Why did a Neanderthal-human hybrid not prevail? Two recent studies converge on an explanation. They suggest the answer comes down to different population sizes between Neanderthals and modern humans, and this principle of population genetics: In small populations, natural selection is less effective. “Neanderthals have this small population over hundreds of thousands of years, presumably because they’re living in very rough conditions,” said Graham Coop, a genetics professor at the University of California, Davis, and an author of one of the studies, published Tuesday in PLOS Genetics. As a result, Neanderthals were more inbred than modern humans and accumulated more mutations that have a slightly adverse effect, such as increasing one’s risk of disease, but do not prevent one from reproducing (and thus, passing such mutations along). © 2016 The New York Times Company

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 22845 - Posted: 11.09.2016

Erin Wayman SALT LAKE CITY — The earliest primate was a tiny, solitary tree dweller that liked the night life. Those are just some conclusions from new reconstructions of the primate common ancestor, presented October 27 at the annual meeting of the Society of Vertebrate Paleontology. Eva Hoffman, now a graduate student at the University of Texas at Austin, and colleagues at Yale University looked at behavioral and ecological data from 178 modern primate species. Examining patterns of traits across the primate family tree, the researchers inferred the most likely characteristics of ancestors at different branching points in the tree — all the way back to the common ancestor. This ancient primate, which may have lived some 80 million to 70 million years ago, was probably no bigger than a guinea pig, lived alone and gave birth to one offspring at a time, the researchers suggest. Living in trees and active at night, the critter probably ventured out to the ends of tree branches to eat fruits, leaves and insects. But this mix of traits probably didn’t arise in primates, Hoffman says. After adding tree shrews and colugos — primates’ closest living relatives — to the analysis, the researchers concluded these same attributes were also present in the three groups’ common ancestor. So explanations of early primate evolution that rely on these features need to be reconsidered, Hoffman says. |© Society for Science & the Public 2000 - 2016.

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 22808 - Posted: 10.31.2016

Nicola Davis A brown, pebble-sized object found in a rock pool on a beach near Bexhill, Sussex bears the first evidence of fossilised dinosaur brain tissue, scientists say. Found in 2004 by an amateur fossil collector, the object is the cast of a dinosaur’s brain cavity, and appears to show a thin veneer of mineralised tissues on its surface. Scientists say the find is most likely from a relative of the Iguanodon, which lived around 125 million years ago. Large, hefty herbivores, Iguanodons reached up around eight metres in length, could walk on either two legs or all fours and boasted sharp spikes on their thumbs - a feature initially thought to be a horn on the nose and immortalised as such in the Victorian dinosaur sculptures of Crystal Palace Park. While casts of the inside of dinosaur brain cases have been found before, it is the first time fossilised brain soft tissue has been discovered for any land-living vertebrate. “The most striking thing is that something as delicate as brain tissue, and which you wouldn’t expect to ever see, has been preserved,” said Alex Liu, co-author of the research from the University of Cambridge. “It just speaks volumes [about] the spectacular preservational quality that can be obtained in the fossil record even 130 million years after this dinosaur is alive.” Writing in a special publication from the Geological Society of London to commemorate the work of the late co-author Martin Brasier, an international team of researchers describe how the cast was discovered near other dinosaur remains, including ribs and leg bones. “We can’t say it is from the same organism, but it is from a fairly large dinosaur,” said Liu. © 2016 Guardian News and Media Limited

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 22799 - Posted: 10.28.2016

By Brian Owens Chimpanzees and their relatives bonobos are closer than we thought. Bonobos seem to have donated genes to chimps at least twice in the roughly two million years since they last shared an ancestor. The two closely related apes have occasionally interbred in captivity, and bonobos are renowned for their free and easy sex life. But the finding that they interbred in the wild was unexpected. The two species split sometime between 1.5 and 2.1 million years ago, around the same time that the Congo River system formed. Wild bonobo populations are entirely contained in that river system, separated from two nearby subspecies of chimps, the eastern and central subspecies. Scientists assumed the river was an impenetrable barrier, says Christina Hvilsom from Copenhagen Zoo in Denmark, one of the researchers who worked on the genetic project. But it turns out that it must have been breached more than once – although it’s not clear how that happened. Hvilsom and her colleagues weren’t actually looking for genetic evidence of ancient interspecies erotica. They were mapping genetic markers that could be used to determine where illegally traded chimps came from so they could be returned to their homes in the wild. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 22798 - Posted: 10.28.2016

Hannah Devlin Science correspondent Monkeys have been observed producing sharp stone flakes that closely resemble the earliest known tools made by our ancient relatives, proving that this ability is not uniquely human. Previously, modifying stones to create razor-edged fragments was thought to be an activity confined to hominins, the family including early humans and their more primitive cousins. The latest observations re-write this view, showing that monkeys unintentionally produce almost identical artefacts simply by smashing stones together. The findings put archaeologists on alert that they can no longer assume that stone flakes they discover are linked to the deliberate crafting of tools by early humans as their brains became more sophisticated. Tomos Proffitt, an archaeologist at the University of Oxford and the study’s lead author, said: “At a very fundamental level - if you’re looking at a very simple flake - if you had a capuchin flake and a human flake they would be the same. It raises really important questions about what level of cognitive complexity is required to produce a sophisticated cutting tool.” Unlike early humans, the flakes produced by the capuchins were the unintentional byproduct of hammering stones - an activity that the monkeys pursued decisively, but the purpose of which was not clear. Originally scientists thought the behaviour was a flamboyant display of aggression in response to an intruder, but after more extensive observations the monkeys appeared to be seeking out the quartz dust produced by smashing the rocks, possibly because it has a nutritional benefit. © 2016 Guardian News and Media Limited

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 22771 - Posted: 10.20.2016

By Emily Underwood When you let forth a big, embarrassing yawn during a boring lecture or concert, you succumb to a reflex so universal among animals that Charles Darwin mentioned it in his field notes. “Seeing a dog & horse & man yawn, makes me feel how much all animals are built on one structure,” he wrote in 1838. Scientists, however, still don’t agree on why we yawn or where it came from. So in a new study, researchers watched YouTube videos of 29 different yawning mammals, including mice, kittens, foxes, hedgehogs, walruses, elephants, and humans. (Here is a particularly cute montage used in the study.) They discovered a pattern: Small-brained animals with fewer neurons in the wrinkly outer layer of the brain, called the cortex, had shorter yawns than large-brained animals with more cortical neurons, the scientists report today in Biology Letters. Primates tended to yawn longer than nonprimates, and humans, with about 12,000 million cortical neurons, had the longest average yawn, lasting a little more than 6 seconds. African elephants, whose brains are close to the same weight as humans’ and have a similar number of cortical neurons, lasted about 6 seconds. The yawns of tiny-brained mice, in contrast, were less than 1.5 seconds in duration. The study lends support to a long-held hypothesis that yawning has an important physiological effect, such as increasing blood flood to the brain and cooling it down, the scientists say. © 2016 American Association for the Advancement of Science.

Related chapters from BP7e: Chapter 15: Emotions, Aggression, and Stress; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress
Link ID: 22723 - Posted: 10.05.2016

Carl Zimmer Modern humans evolved in Africa roughly 200,000 years ago. But how did our species go on to populate the rest of the globe? The question, one of the biggest in studies of human evolution, has intrigued scientists for decades. In a series of extraordinary genetic analyses published on Wednesday, researchers believe they have found an answer. In the journal Nature, three separate teams of geneticists survey DNA collected from cultures around the globe, many for the first time, and conclude that all non-Africans today trace their ancestry to a single population emerging from Africa between 50,000 and 80,000 years ago. “I think all three studies are basically saying the same thing,” said Joshua M. Akey of the University of Washington, who wrote a commentary accompanying the new work. “We know there were multiple dispersals out of Africa, but we can trace our ancestry back to a single one.” The three teams sequenced the genomes of 787 people, obtaining highly detailed scans of each. The genomes were drawn from people in hundreds of indigenous populations: Basques, African pygmies, Mayans, Bedouins, Sherpas and Cree Indians, to name just a few. The DNA of indigenous populations is essential to understanding human history, many geneticists believe. Yet until now scientists have sequenced entire genomes from very few people outside population centers like Europe and China. © 2016 The New York Times Company

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 22682 - Posted: 09.22.2016

Laurel Hamers The brains of human ancestors didn’t just grow bigger over evolutionary time. They also amped up their metabolism, demanding more energy for a given volume, a new study suggests. Those increased energy demands might reflect changes in brain structure and organization as cognitive abilities increased, says physiologist Roger Seymour of the University of Adelaide in Australia, a coauthor of the report, published online August 31 in Royal Society Open Science. Blood vessels passing through bones leave behind holes in skulls; bigger holes correspond to bigger blood vessels. And since larger vessels carry more blood, scientists can use hole size to estimate blood flow in extinct hominids’ brains. Blood flow in turn indicates how much energy the brain consumed. (In modern humans, the brain eats up 20 to 25 percent of the energy the body generates when at rest.) Seymour and colleagues focused on the carotid arteries, the vessels that deliver the bulk of the brain’s blood. The team looked at nearly three dozen skulls from 12 hominid species from the last 3 million years, including Australopithecus africanus, Homo neanderthalensis and Homo erectus. In each, the researchers compared the brain’s overall volume with the diameter of the carotid artery’s tiny entrance hole at the base of the skull. “We expected to find that the rate of blood flow was proportional to the brain size,” Seymour says. “But we found that wasn’t the case.” Instead, bigger brains required more blood flow per unit volume than smaller brains. |© Society for Science & the Public 2000 - 2016.

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior; Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior
Related chapters from MM:Chapter 2: Cells and Structures: The Anatomy of the Nervous System
Link ID: 22616 - Posted: 08.31.2016

By Lydia Pyne | On August 3, 1908, the first near-complete Neanderthal skeleton was discovered in a cave near the village of La Chapelle-aux-Saints in south central France, during a survey of the region’s Paleolithic archaeological sites. For decades prior, prehistorians had collected bits and pieces of curious but not-quite-human fossils from museums and excavations alike—the odd skull here, a scrap of tooth there. In 1863, the mélange of bones was finally given its own species designation, Homo neanderthalensis. Forty-five years later, the La Chapelle discovery was the first Neanderthal specimen found in an original archaeological context and the first to be expertly excavated and carefully studied. Because the body was arranged in a flexed, fetal position and carefully placed in the floor of the cave, excavators argued that fossil—nicknamed the Old Man—had been purposefully buried by his Neanderthal contemporaries. More than any other single individual, the Old Man of La Chapelle has shaped the way that science and popular culture have thought about Neanderthals. But why? What is it about this Neanderthal’s story that is so special? In short, the Old Man was the right fossil found at the right time. He was—and still is—offered as a key bit of evidence in debates about evolution and human origins. He quickly became a scientific touchstone, an archetype for how science and popular culture create celebrity fossils. I explore the stories of similarly spectacular paleoanthropological finds in my new book Seven Skeletons: The Evolution of the World’s Most Famous Human Fossils. © 1986-2016 The Scientist

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 22585 - Posted: 08.23.2016

By Katherine S. Pollard When the first human genome sequence was published in 2001,1 I was a graduate student working as the statistics expert on a team of scientists. Hailing from academia and biotechnology, we aimed to discover differences in gene expression levels between tumors and healthy cells. Like many others, I had high hopes for what we could do with this enormous text file of more than 3 billion As, Cs, Ts, and Gs. Ambitious visions of a precise wiring diagram for human cells and imminent cures for disease were commonplace among my classmates and professors. But I was most excited about a different use of the data, and I found myself counting the months until the genome of a chimpanzee would be sequenced. Chimps are our closest living relatives on the tree of life. While their biology is largely similar to ours, we have many striking differences, ranging from digestive enzymes to spoken language. Humans also suffer from an array of diseases that do not afflict chimpanzees or are less severe in them, including autism, schizophrenia, Alzheimer’s disease, diabetes, atherosclerosis, AIDS, rheumatoid arthritis, and certain cancers. I had long been fascinated with hominin fossils and the way the bones morphed into different forms over evolutionary time. But those skeletons cannot tell us much about the history of our immune system or our cognitive abilities. So I started brainstorming about how to extend the statistical approaches we were using for cancer research to compare human and chimpanzee DNA. My immodest goal was to identify the genetic basis for all the traits that make humans unique. © 1986-2016 The Scientist

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory, Learning, and Development
Link ID: 22502 - Posted: 08.02.2016

By Lizzie Wade Neandertals and modern humans had a lot in common—at least enough to have babies together fairly often. But what about their brains? To answer that question, scientists have looked at how Neandertal and modern human brains developed during the crucial time of early childhood. In the first year of life, modern human infants go through a growth spurt in several parts of the brain: the cerebellum, the parietal lobes, and the temporal lobes—key regions for language and social interaction. Past studies suggested baby Neandertal brains developed more like the brains of chimpanzees, without concentrated growth in any particular area. But a new study casts doubt on that idea. Scientists examined 15 Neandertal skulls, including one newborn and a pair of children under the age of 2. By carefully imaging the skulls, the team determined that Neandertal temporal lobes, frontal lobes, and cerebellums did, in fact, grow faster than the rest of the brain in early life, a pattern very similar to modern humans, they report today in Current Biology. Scientists had overlooked that possibility, the researchers say, because Neandertals and Homo sapiens have such differently shaped skulls. Modern humans’ rounded skull is a telltale marker of the growth spurt, for example, whereas Neandertals’ skulls were relatively flat on the top. If Neandertals did, in fact, have fast developing cerebellums and temporal and frontal lobes, they might have been more skilled at language and socializing than assumed, scientists say. This could in turn explain how the children of Neandertal–modern human pairings fared well enough to pass down their genes to so many us living today. © 2016 American Association for the Advancement of Science

Related chapters from BP7e: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory, Learning, and Development
Link ID: 22473 - Posted: 07.26.2016

By Bret Stetka Beloved crank and Seinfeld co-creator Larry David once told an interviewer that he tolerates people like he tolerates lactose — which is to say, I'm assuming, not well. David's particular degree of grumpiness might be extreme, and perhaps embellished in the interest his shtick, but his social misgivings echo those of many in their dotage who’d rather spend time with old friends than deal with the sweat and small talk required to go out and make new ones. Humans may not be alone here. According to new research, our primate cousins also become more socially selective with age, preferring the companionship of their “friends” to monkeys that are less familiar (or maybe just a drag at parties). The findings also hint at a possible evolutionary explanation for why our social preferences change over the years. The work, conducted primarily by researchers from the German Primate Center in Göttingen, Germany, was recently published in the journal Current Biology and entailed observing the behaviors of over 100 Barbary macaque monkeys, an out-going, some might say "screechy," species hailing from North Africa. To get a sense of how interest in non-social vs social stimulation changes over the course of their lifetimes, monkeys of varying ages were observed in the presence of both inanimate objects and other monkeys. They were first presented with three novel objects: animal toys, a see-through cube filled with glitter in a viscous liquid, and a tube baited with food. Those that had reached early adulthood were not interested in the objects without a reward. The younger ones were intrigued by all three. © 2016 Scientific American

Related chapters from BP7e: Chapter 15: Emotions, Aggression, and Stress; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress
Link ID: 22396 - Posted: 07.05.2016

By NATALIE ANGIER At birth, the least weasel is as small and light as a paper clip, and the tiny ribs that press visibly against its silvery pink skin give it a segmented look, like that of an insect. A newborn kit is exceptionally underdeveloped, with sealed eyes and ears that won’t open for five or six weeks, an age when puppies and kittens are ready to be weaned. A mother weasel, it seems, has no choice but to deliver her young half-baked. As a member of the mustelid clan — a noble but often misunderstood family of carnivorous mammals that includes ferrets, badgers, minks and wolverines — she holds to a slender, elongated body plan, the better to pursue prey through tight spaces that most carnivores can’t penetrate. Bulging baby bumps would jeopardize that sylphish hunting physique. The solution? Give birth to the equivalent of fetuses and then finish gestating them externally on mother’s milk. “If you want access to small environments, you can’t have a big belly,” said William J. Zielinski, a mustelid researcher with the United States Forest Service in Arcata, Calif. “You don’t see fat weasels.” For Dr. Zielinski and other mustelid-minded scientists, weasels exemplify evolutionary genius and compromise in equal measure, the piecing together of exaggerated and often contradictory traits to yield a lineage of fierce, fleet, quick-witted carnivores that can compete for food against larger celebrity predators like the big cats, wolves and bears. Researchers admit that wild mustelids can be maddening to study. Most species are secretive loners, shrug off standard radio collars with ease, and run close to the ground “like small bolts of brown lightning,” as one team noted. Now you see them, no, you didn’t. Nevertheless, through a mix of dogged field and laboratory studies, scientists have lately made progress in delineating the weasel playbook, and it’s a page turner, or a page burner. © 2016 The New York Times Company

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 22321 - Posted: 06.14.2016

By Devi Shastri Calling someone a “bird brain” might not be the zinger of an insult you thought it was: A new study shows that—by the total number of forebrain neurons—some birds are much brainier than we thought. The study, published online today in the Proceedings of the National Academy of Sciences, found that 28 bird species have more neurons in their pallial telencephalons, the brain region responsible for higher level learning, than mammals with similar-sized brains. Parrots and songbirds in particular packed in the neurons, with parrots (like the gray parrot, above) ranging from 227 million to 3.14 billion, and songbirds—including the notoriously intelligent crow—from 136 million to 2.17 billion. That’s about twice as many neurons as primates with brains of the same mass and four times as many as rodent brains of the same mass. To come up with their count, the researchers dissected the bird brains and then dissolved them in a detergent solution, ensuring that the cells were suspended in what neuroscientist Suzana Herculano-Houzel of Vanderbilt University in Nashville calls “brain soup.” This allowed them to label, count, and estimate how many neurons were in a particular brain region. The region that they focused on allows some birds to hone skills like tool use, planning for the future, learning birdsong, and mimicking human speech. One surprising finding was that the neurons were much smaller than expected, with shorter and more compact connections between cells. The team’s next step is to examine whether these neurons started out small or instead shrank in order to keep the birds light enough for flights. One thing, at least, is clear: It’s time to find a new insult for your less brainy friends. © 2016 American Association for the Advancement of Science

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior; Chapter 18: Attention and Higher Cognition
Related chapters from MM:Chapter 14: Attention and Consciousness
Link ID: 22315 - Posted: 06.14.2016

By C. CLAIBORNE RAY Q. Does the size of an animal’s brain really correlate with intelligence on a species-by-species basis? A. “It’s not necessarily brain size but rather the ratio of brain size to body size that really tells the story,” said Rob DeSalle, a curator at the Sackler Institute for Comparative Genomics at the American Museum of Natural History. Looking at this ratio over a large number of vertebrate animals, he said, scientists have found that “brain size increases pretty linearly with body size, except for some critical species like Homo sapiens and some cetaceans,” the order of mammals that includes whales, dolphins and porpoises. “So if there is a deviation from this general ratio, one can predict how smart a vertebrate might be,” Dr. DeSalle continued. Therefore, living vertebrates that deviate so that their brains are inordinately bigger compared with their bodies are for the most part smarter, he said. As for dinosaurs, he said, scientists really can’t tell how smart they may have been. “But the Sarmientosaurus, with its lime-sized brain, was a big animal, so the extrapolation is that it would have been pretty dense,” he said. “On the other hand, Troodon, a human-sized dinosaur, had a huge brain relative to its body size and is widely considered the smartest dinosaur ever found.” © 2016 The New York Times Company

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 22261 - Posted: 05.30.2016

By Emily Benson Baby birds are sometimes known to shove their siblings out of the nest to gain their parents’ undivided attention, but barn owl chicks appear to be more altruistic. Scientists recorded the hissing calls of hungry and full barn owl nestlings (Tyto alba, pictured), then played the sounds back to single chicks settled in nests stocked with mice. The young owls that heard the squawks of their hungry kin delayed eating each rodent by an average of half an hour; those that heard cries indicating their invisible nest-mate was full ate the mice more quickly. The findings suggest that barn owl chicks give hungrier siblings a chance to eat first even when the nest is full of food, the researchers will report in an upcoming issue of Behavioral Ecology and Sociobiology. So is it true altruism? Maybe not. Nestlings may share food in exchange for help with grooming or to get the first crack at a later meal, the team says, suggesting a possible ulterior motive. © 2016 American Association for the Advancement of Science

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 22174 - Posted: 05.04.2016

By Sarah Kaplan We know where the human story started: In Africa, millions of years ago, with diminutive people whose brains were just a third of the size of ours. And we know where it ended: with us. Yet a lot of what happened in between is still debated, including the question of how humans' bodies and noggins got so much bigger than our ancestors'. The traditional thinking is that the growth of both was spurred by the process of natural selection. The evolutionary advantages of a big body and a big brain are plentiful, so it seems reasonable to think that each developed independent of the other in response to the demands of survival in a hostile world. But a new study in the journal Current Anthropology suggests that, while our brains are certainly an advantageous adaptation, our imposing physiques (such as they are) are more of an evolutionary fluke. That's because the genes that determine brain and body size are the same, argues Mark Grabowski, a fellow at the American Museum of Natural History. So as humans evolved bigger and bigger brains, our bodies "just got pulled along." Grabowski acknowledges that it may seem like a counterintuitive conclusion — most of us learned in high school biology that evolution is about adapting to circumstances and that only the fittest survive. We're not used to thinking of traits as a product of happenstance. But evolutionary scientists know that lots of traits — even ultimately beneficial ones — are just the luck of the draw.

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 22119 - Posted: 04.20.2016

By Virginia Morell Moths have an almost fatal attraction to lights—so much so that we say people are drawn to bad ends “like moths to a flame.” But in this age of global light pollution, that saying has a new poignancy: Moths, which are typically nocturnal insects, are dying in droves at artificial lights. The high levels of mortality should have evolutionary consequences, leading to moths that avoid lights, biologists say. To find out, two scientists tested the flight-to-light behavior of 1048 adult ermine moths (Yponomeuta cagnagella, shown above) in Europe. The researchers collected the insects in 2007 as larvae that had just completed their first molt. Three hundred and twenty came from populations that lived where the skies were largely dark; 728 were gathered in light polluted areas. They were raised in a lab with 16 hours of daylight and 8 hours of darkness daily while they completed their life stages. Two to 3 days after emerging as moths, they were released in a flight cage with a fluorescent tube at one side. Moths from high light pollution areas were significantly less attracted to the light than those from the darker zones, the scientists report in today’s issue of Biology Letters. Overall, moths from the light-polluted populations had a 30% reduction in the flight-to-light behavior, indicating that this species is evolving, as predicted, to stay away from artificial lights. That change should increase these city moths’ reproductive success. But their success comes at a cost: To avoid the lights, the moths are likely flying less, say the scientists, so they aren’t pollinating as many flowers or feeding as many spiders and bats. © 2016 American Association for the Advancement of Science.

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 22100 - Posted: 04.13.2016