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

Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior; Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 26107 - Posted: 04.03.2019

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

Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 25940 - Posted: 02.08.2019

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

Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 25916 - Posted: 01.31.2019

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

Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 25857 - Posted: 01.11.2019

Bruce Bower An ancient hominid skeleton dubbed Little Foot possessed a brain largely similar to that of modern chimpanzees and an inner ear with a mix of apelike and humanlike features, two studies suggest. These findings, along with other analyses of the adult female’s 3.67-million-year-old skeleton, point to the piecemeal evolution of humanlike traits in close relatives of our species, scientists say. The research is part of the first formal analyses of Little Foot’s skeleton, which was discovered more than 20 years ago in a South African cave but was recently removed from its rocky encasing. Other analyses of trunk and limb bones indicate that Little Foot, who lived perhaps a million years before the emergence of the human genus, Homo, already walked upright about as well as people today do (SN: 1/19/19, p.13). Although Little Foot consists of a nearly complete skeleton, her evolutionary identity is controversial. Paleoanthropologist Ronald Clarke of the University of the Witwatersrand in Johannesburg — Little Foot’s discoverer and a coauthor of the two new studies — assigns the find to Australopithecus prometheus, an early extinct hominid species that many scientists don’t regard as valid. Other researchers regard Little Foot as an early member of Australopithecus africanus, a species previously known from fossils discovered at several South African sites (SN: 1/19/19, p. 13). |© Society for Science & the Public 2000 - 2018

Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 25855 - Posted: 01.10.2019

Ewen Callaway No human has the brain of a Neanderthal — but some have hints of its shape. The brain shape of some people with European ancestry is influenced by Neanderthal DNA acquired through interbreeding tens of thousands of years ago, researchers report on 13 December in Current Biology1. These DNA variants seem to affect the expression of two genes in such a way as to make the brains of some humans slightly less round, and more like the Neanderthals’ elongated brains. “It’s a really subtle shift in the overall roundedness,” says team member Philipp Gunz, a palaeoanthropologist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. “I don’t think you would see it with your naked eye. These are not people that would look Neanderthal-like.” The Neanderthal DNA variants alter gene expression in brain regions involved in planning, coordination and learning of movements. These faculties are used in speech and language, but there is no indication that the Neanderthal DNA affects cognition in modern humans. Instead, the researchers say, their discovery points to biological changes that might have endowed the human brain with its distinct shape. Earlier this year, Gunz and two colleagues determined that the rounded brain shape of modern humans evolved gradually, reaching its current appearance between 35,000 and 100,000 years ago2. The earliest human fossils from across Africa, dating to around 200,000–300,000 years ago, have large yet elongated brains. “There really is something going on in the brain that changes over time in the Homo sapiens lineage,” says Gunz. © 2018 Springer Nature Publishing AG

Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 4: Development of the Brain
Link ID: 25787 - Posted: 12.15.2018

Bruce Bower A nearly complete hominid skeleton known as Little Foot has finally been largely freed from the stony shell in which it was discovered in a South African cave more than 20 years ago. And in the first formal analyses of the fossils, researchers say the 3.67-million-year-old Little Foot belonged to its own species. In four papers posted online at bioRxiv.org between November 29 and December 5, paleoanthropologist Ronald Clarke of the University of the Witwatersrand in Johannesburg and colleagues assign Little Foot to a previously proposed species, Australopithecus prometheus, that has failed to gain traction among many researchers. Clarke has held that controversial view for more than a decade (SN: 5/2/15, p. 8). He found the first of Little Foot’s remains in a storage box of fossils from a site called Sterkfontein in 1994. Excavations of the rest of the skeleton began in 1997. Many other researchers, however, regard Little Foot as an early member of a hominid species called Australopithecus africanus. Anthropologist Raymond Dart first identified A. africanus in 1924 from an ancient youngster’s skull called the Taung Child. Hundreds of A. africanus fossils have since been found in South African caves, including Sterkfontein. One of those caves, Makapansgat, produced a partial braincase that Dart assigned to A. prometheus in 1948. But Dart dropped that label after 1955, assigning the braincase and another Makapansgat fossil to A. africanus. |© Society for Science & the Public 2000 - 2018.

Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 25778 - Posted: 12.12.2018

One of the animals that's thought to give creatures like apes, dolphins and crows a run for their money when it comes to intelligence is the octopus. For those other animals, there's a pattern to how they evolved to be so smart — they live long, socially complex lives. But that's not the case for octopuses that live solitary lives for the year or two they usually survive. Now scientists think they've figured out how the octopus became so so smart, and it has to do with the loss of their shell through evolution. "Octopuses, unlike many other molluscs, they do not have a protective shell," said Piero Amodio, the lead author on the new study published in the journal Trends in Ecology & Evolution about how cephalopods (octopuses and their relatives) gained their intelligence. "So [octopuses] are very, very vulnerable to many kinds of predators — from fishes to marine mammals to birds — and the idea is that by becoming quite smart, this is a kind of weapon they can use to avoid being eaten." Amodio, a PhD student at the University of Cambridge, told Quirks & Quarks host Bob McDonald that this evolutionary process differs from those that led to intelligence in other groups of vertebrates. Intelligence in other vertebrates is thought to have arisen because they live long and socially complex lives. Building a brain is a metabolically labour intensive process, so it's a big investment for an animal to develop a big brain like in apes, dolphins, and crows — an investment they get a return on when they live a long time. ©2018 CBC/Radio-Canada.

Related chapters from BN: Chapter 17: Learning and Memory; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory and Learning
Link ID: 25763 - Posted: 12.08.2018

Bruce Bower Neandertals are shaking off their reputation as head bangers. Our close evolutionary cousins experienced plenty of head injuries, but no more so than late Stone Age humans did, a study suggests. Rates of fractures and other bone damage in a large sample of Neandertal and ancient Homo sapiens skulls roughly match rates previously reported for human foragers and farmers who have lived within the past 10,000 years, concludes a team led by paleoanthropologist Katerina Harvati of the University of Tübingen in Germany. Males suffered the bulk of harmful head knocks, whether they were Neandertals or ancient humans, the scientists report online November 14 in Nature. “Our results suggest that Neandertal lifestyles were not more dangerous than those of early modern Europeans,” Harvati says. Until recently, researchers depicted Neandertals, who inhabited Europe and Asia between around 400,000 and 40,000 years ago, as especially prone to head injuries. Serious damage to small numbers of Neandertal skulls fueled a view that these hominids led dangerous lives. Proposed causes of Neandertal noggin wounds have included fighting, attacks by cave bears and other carnivores and close-range hunting of large prey animals. Paleoanthropologist Erik Trinkaus of Washington University in St. Louis coauthored an influential 1995 paper arguing that Neandertals incurred an unusually large number of head and upper-body injuries. Trinkaus recanted that conclusion in 2012, though. All sorts of causes, including accidents and fossilization, could have resulted in Neandertal skull damage observed in relatively small fossil samples, he contended (SN: 5/27/17, p. 13). |© Society for Science & the Public 2000 - 2018.

Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress
Link ID: 25686 - Posted: 11.15.2018

By Virginia Morell When wild orangutans spot a predator, they let out a loud “kiss-squeak,” a call that sounds like a human smooching. That noise tells tigers and other enemies, “I’ve seen you,” scientists believe, and it also lets other orangutans know danger is near. Now, researchers report having heard orangutans making this call long after predators have passed—the first evidence that primates other than humans can “talk” about the past. “The results are quite surprising,” says Carel van Schaik, a primatologist at the University of Zurich in Switzerland who was not involved in the work. The ability to talk about the past or the future “is one of the things that makes language so effective,” he says. That suggests, he adds, that the new findings could provide clues to the evolution of language itself. Many mammals and birds have alarm calls, some of which include information on the type and size of a predator, its location and distance, and what level of danger it poses. But until now, researchers have never heard wild animals announcing danger after the fact. Adriano Reis e Lameira, a postdoctoral student at the University of St. Andrews in the United Kingdom, was examining alarm calls in orangutans in Sumatra’s dense Ketambe forest, where the primates have been observed for nearly 40 years. He set up a simple experiment to investigate their alarm calls: A scientist draped in a tiger-striped, spotted, or plain sheet walked on all fours along the forest floor, right underneath lone female orangutans sitting in trees at heights of 5 to 20 meters above the ground. © 2018 American Association for the Advancement of Science

Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior; Chapter 19: Language and Lateralization
Related chapters from MM:Chapter 15: Language and Lateralization
Link ID: 25685 - Posted: 11.15.2018

By Neil Genzlinger Dorothy L. Cheney, whose careful research into how primates live and communicate revealed the surprising complexity of their thought processes and social structures, died on Friday at her home in Devon, Pa. She was 68. Her husband and research partner, Robert M. Seyfarth, said the cause was breast cancer. “Cheney was a spectacular scientist,” Robert M. Sapolsky, a professor of biology and neurology at Stanford University and the author of books like “A Primate’s Memoir,” said by email. “Along with Robert Seyfarth, she did wonderfully clever, elegant field experiments that revealed how other primates think about the world — showing that they think in far more sophisticated and interesting ways than people anticipated.” Rather than doing their research in laboratories, Dr. Cheney and Dr. Seyfarth spent long stretches in the wilds of Africa and elsewhere, studying gorillas, baboons, vervet monkeys and other animals. One of their best-known experiments, conducted in Kenya in 1977, showed that vervets made distress sounds not just involuntarily, out of fear, but to convey a specific message about a given threat. They hid loudspeakers in bushes, played recorded sounds of vervets and watched the reaction. A particular bark sent the animals scurrying up trees because it was a warning about leopards; a low-pitched staccato noise had them looking skyward for predatory eagles. They summarized their research in their first book, “How Monkeys See the World: Inside the Mind of Another Species” (1990). Later research in Botswana included insights into the hierarchical nature of baboon societies and its possible evolutionary effects. “Because Western scientists learned about primates by examining corpses or observing single animals brought home as pets,” they wrote in their 2007 book, “Baboon Metaphysics: The Evolution of a Social Mind,” “few if any ever learned what can be discovered only through long, patient observation: that the most human features of monkeys and apes lie not in their physical appearance but in their social relationships.” © 2018 The New York Times Company

Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 25683 - Posted: 11.15.2018

David Sington Aubrey Manning’s hugely popular 1998 BBC series Earth Story, about the evolution and shaping of the planet Earth, inspired a generation and led to a noticeable increase in students applying to read earth sciences. Yet, Aubrey, who has died aged 88, was not a geologist, but an ethologist, whose work made an important contribution to the understanding of how animal behaviour plays a role in the evolution of new species. In a series of experiments at Oxford and Edinburgh universities – he was professor of natural history (1973-97) at the latter – Aubrey showed how mutations in genes that affect the behaviour of fruit flies could lead to reproductive isolation, a key mechanism in the creation of new species. This work laid the foundation for the modern study of the evolutionary genetics of behaviour. His 1967 publication An Introduction to Animal Behaviour, now in its sixth edition, is still the standard textbook in its field, and his lectures were so popular – packed with students from many other courses – that the university took to scheduling them for 9am on Mondays as the most effective way to get undergraduates out of bed. It was this reputation as a superb communicator of science that led the BBC to his door. When as its producer I approached him in 1997 to present Earth Story, Aubrey, with typical modesty, protested that I had the wrong man and insisted on introducing me to his geological colleagues. However, it was the very fact that the subject was new to him that was the secret of the ventures success. © 2018 Guardian News and Media Limited

Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 25667 - Posted: 11.12.2018

By Carl Zimmer People of Asian and European descent — almost anyone with origins outside of Africa — have inherited a sliver of DNA from some unusual ancestors: the Neanderthals. These genes are the result of repeated interbreeding long ago between Neanderthals and modern humans. But why are those genes still there 40,000 years after Neanderthals became extinct? As it turns out, some of them may protect humans against infections. In a study published on Thursday, scientists reported new evidence that modern humans encountered new viruses — including some related to influenza, herpes and H.I.V. — as they expanded out of Africa roughly 70,000 years ago. Some of those infections may have been picked up directly from Neanderthals. Without immunity to pathogens they had never encountered, modern humans were particularly vulnerable. “We were actually able to not only say, ‘Yes, modern humans and Neanderthals exchanged viruses,’” said David Enard, an evolutionary biologist at the University of Arizona and co-author of the new paper, published in the journal Cell. “We are able to start saying something about which types of viruses were involved.” But if Neanderthals made us sick, they also helped keep us well. Some of the genes inherited from them through interbreeding also protected our ancestors from these infections, just as they protected the Neanderthals. Lluis Quintana-Murci, a geneticist at the Pasteur Institute in Paris who was not involved in the new research, said that until now, scientists had not dreamed of getting such a glimpse at the distant medical history of our species. “Five years ago, we would never have imagined that,” he said. © 2018 The New York Times Company

Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 4: Development of the Brain
Link ID: 25533 - Posted: 10.05.2018

By JoAnna Klein Plants have no eyes, no ears, no mouth and no hands. They do not have a brain or a nervous system. Muscles? Forget them. They’re stuck where they started, soaking up the sun and sucking up nutrients from the soil. And yet, when something comes around to eat them, they sense it. And they fight back. How is this possible? “You’ve got to think like a vegetable now,” says Simon Gilroy, a botanist who studies how plants sense and respond to their environments at the University of Wisconsin-Madison. “Plants are not green animals,” Dr. Gilroy says. “Plants are different, but sometimes they’re remarkably similar to how animals operate.” To reveal the secret workings of a plant’s threat communication system for a study published Thursday in Science, Masatsugu Toyota (now a professor at Saitama University in Japan) and other researchers in Dr. Gilroy’s lab sent in munching caterpillars like in the video above. They also slashed leaves with scissors. They applied glutamate, an important neurotransmitter that helps neurons communicate in animals. In these and about a dozen other videos, they used a glowing, green protein to trace calcium and accompanying chemical and electrical messages in the plant. And they watched beneath a microscope as warnings transited through the leafy green appendages, revealing that plants aren’t as passive as they seem. The messages start at the point of attack, where glutamate initiates a wave of calcium that propagates through the plant’s veins, or plumbing system. The deluge turns on stress hormones and genetic switches that open plant arsenals and prepare the plant to ward off attackers — with no thought or movement. © 2018 The New York Times Company

Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior; Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Related chapters from MM:Chapter 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Link ID: 25450 - Posted: 09.14.2018

By Jake Buehler Whether it’s avoiding the slap of a flyswatter or shooting a tongue out at just the right moment to capture prey, fast reflexes can mean the difference between life and death in the animal kingdom. But a new study finds that not all reflexes are created equal: Larger animals are slower on the draw than smaller ones and because of that, they can’t move nearly as fast as they should be able to. When it comes to reflexes, there’s no doubt that bigger animals are a little slower. Big animals have longer neurons, and that means more time for a signal to travel from the spine to a leg muscle, for example. But nerve speed isn’t the only thing that slows down reflexes. So in the new study, researchers decided to look at myriad factors, like how fast muscles can generate force. They combed through data from other studies on electrically stimulated nerves and muscles in animals as small as shrews to as large as elephants. They also looked at the gaits of these mammals to calculate how long their stride and foot-down positions were in relation to their body size, which allowed researchers to look at how relatively quick their reflexes are. As size scales up, so does the total time it takes for muscles to respond, the team reported yesterday in the Proceedings of the Royal Society B. Large mammals experience a delay between nerve firing and muscle movement that is more than 15 times longer than small mammals. But, relative to the speed of their body movements, that delay is only twice as long—which means to compensate for slow signals, they’re moving more slowly. If this didn’t happen, a running 250-kilogram elk would be a cartoonish blur of legs, taking steps far faster than its reflexes could ever respond to. Call it a biological speed limit. © 2018 American Association for the Advancement of Science

Related chapters from BN: Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Link ID: 25398 - Posted: 08.31.2018

By Carl Zimmer In a limestone cave nestled high above the Anuy River in Siberia, scientists have discovered the fossil of an extraordinary human hybrid. The 90,000-year-old bone fragment came from a female whose mother was Neanderthal, according to an analysis of DNA discovered inside it. But her father was not: He belonged to another branch of ancient humanity known as the Denisovans. Scientists have been recovering genomes from ancient human fossils for just over a decade. Now, with the discovery of a Neanderthal-Denisovan hybrid, the world as it was tens of thousands of years ago is coming into remarkable new focus: home to a marvelous range of human diversity. In 2010, researchers working in the Siberian cave, called Denisova, announced they had found DNA from a scrap of bone representing an unknown group of humans. Subsequent discoveries in the cave confirmed that the Denisovans were a lineage distinct from modern humans. Scientists can’t yet say what Denisovans looked like or how they behaved, but it’s clear they were separated from Neanderthals and modern humans by hundreds of thousands of years of evolution. Until now, scientists had indirect clues that Neanderthals, Denisovans and modern humans interbred, at least a few times. But the new study, published on Wednesday in the journal Nature, offers clear evidence. “They managed to catch it in the act — it’s an amazing discovery,” said Sharon Browning, a statistical geneticist at the University of Washington who was not involved in the new study. © 2018 The New York Times Company

Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 25367 - Posted: 08.23.2018

James R. Howe VI In May 2007, Wim Hof went on a short hike in well-worn summer clothes, a pair of shorts and open-toed sandals. But it may have been a poor choice: his foot started to hurt and he had to turn back after four and a half miles. There are two crucial details to this story: Hof began his hike at Base Camp on Mount Everest, and the pain in his foot was caused by severe frostbite. He had reason to think he could withstand the extreme conditions; Wim Hof is also known as “The Iceman,” holder of 26 world records and one of the most successful extreme athletes of all time. He attributes his success to a breathing method that he thinks exploits his “reptilian brain,” helping him acquire a superhuman tolerance to punishing cold. According to some, tricks like these fool the lizard part of your brain – the more primitive, unconscious mind – and can be used to make us vulnerable to marketing, lose us money, or maybe even elect Donald Trump. Paul MacLean first proposed the idea of the “lizard brain” in 1957 as part of his triune brain concept, theorizing that the human brain supposedly consists of three sections, nested based on their evolutionary age. He believed the neocortex, which he thought arose in primates, is the largest, outermost, and newest part of the human brain: It houses our conscious mind and handles learning, language, and abstract thought. MacLean thought the older, deeper limbic system – which mediates emotion and motivation – began in mammals. Finally, he traced the brainstem and basal ganglia back to primordial reptiles, theorizing that they controlled our reflexes, as well as our four major instincts: to fight, flee, feed, and fornicate.

Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior; Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System
Related chapters from MM:Chapter 1: Cells and Structures: The Anatomy of the Nervous System
Link ID: 25356 - Posted: 08.21.2018

By Carl Zimmer In 2003, researchers digging in a mountain cave on the Indonesian island of Flores discovered astonishing fossils of a tiny, humanlike individual with a small, chimp-sized brain. They called the species Homo floresiensis. These relatives of modern humans stood just over three feet tall. Several villages in the area, scientists noted, are inhabited by people whose average height is 4 feet 9 inches. Was this the result of interbreeding long ago between taller modern humans and shorter Homo floresiensis? Fifteen years after the bones’ discovery, a study of the DNA of living people on Flores has delivered a verdict. “It’s rare in science that you set about to answer a question and you get something of a definitive answer and it’s the end,” said Richard E. Green, a geneticist at the University of California, Santa Cruz, and a co-author of the study, published on Thursday in Science. “The answer is a clear enough ‘no’ that I’m done with it.” But as often happens in science, the answer to one question raises new ones. The study shows that at least twice in ancient history, humans and their relatives (known as hominins) arrived on Flores and then grew shorter. And not just humans: Other research has shown that elephants also arrived on Flores twice, and both times the species evolved into dwarves. So what mysterious power does this island have to shrink the body? When the fossils of Homo floresiensis first came to light, many researchers hoped they might still hold fragments of DNA. They were encouraged by the initial dating of the fossils — an estimated age of perhaps just 13,000 years. © 2018 The New York Times Company

Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 25288 - Posted: 08.03.2018

by Sarah Kaplan For years, scientists at the Smithsonian Tropical Research Institute in Panama had whispered about the remote island where monkeys used stone tools. A botanist had witnessed the phenomenon during a long-ago survey — but, being more interested in flora than fauna at the time, she couldn't linger to investigate. A return to the site would require new funds, good weather for a treacherous 35-mile boat ride, and days of swimming, hiking and camping amid rocky, wave-pounded shorelines and dense tropical forest. “For while, it kind of just stayed a rumor,” said Brendan Barrett, a behavioral ecologist at the Max Planck Institute in Germany and a visiting researcher at STRI. But when Barrett and his colleagues finally arrived at Jicarón Island in Panama's Coiba National Park last year, what they found was well-worth the effort: Tiny white-faced capuchin monkeys were using stones almost half their body weight as hammers to smash open shellfish, nuts and other foods. “We were stunned,” said Barrett, the lead author of a new paper on the discovery posted on the preprint website bioRxiv. The capuchins are the first animals of their genus observed using stone tools, and only the fourth group of nonhuman primates known to do so. Sophisticated, social, and tolerant of observation, they also provide scientists with an ideal system for studying what causes a species to venture into the stone age — and could help researchers understand how and why our own ancestors first picked up stone tools more than 2 million years ago. © 1996-2018 The Washington Post

Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 25175 - Posted: 07.06.2018

By Elizabeth Gamillo Why does a wild rabbit flee when a person approaches it, but a domestic rabbit sticks around for a treat? A new study finds that domestication may have triggered changes in the brains of these—and perhaps other—animals that have helped them adapt to their new, human-dominated environment. The new study provides “specific and new insights” into the ongoing debate over the physiological factors shaping domestication and evolution, says Marcelo Sánchez-Villagra, a professor of paleobiology at the University of Zurich in Switzerland who was not involved with the work. The leader of the research team, animal geneticist Leif Andersson of Uppsala University in Sweden and Texas A&M University in College Station, thinks the process of domestication has led to changes in brain structure that allow the rabbit to be less nervous around humans. To find out, he and colleagues took MRI scans of the brains of eight wild and eight domestic rabbits and compared the results. The team found that the amygdala, a region of the brain that processes fear and anxiety, is 10% smaller in domesticated rabbits than in wild rabbits. Meanwhile, the medial prefrontal cortex, which controls responses to aggressive behavior and fear, is 11% larger in domesticated rabbits. The researchers also found that the brains of domesticated rabbits are less able to process information related to fight-or-flight responses because they have less white matter than their feral cousins do. White matter handles information processing. When a wild rabbit is in danger, more white matter is needed for faster reflexes and for learning what to be afraid of. © 2018 American Association for the Advancement of Science.

Related chapters from BN: 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: 25142 - Posted: 06.26.2018