By Melissa Hogenboom Science reporter, BBC News An analysis of a Neanderthal's fossilised hyoid bone - a horseshoe-shaped structure in the neck - suggests the species had the ability to speak. This has been suspected since the 1989 discovery of a Neanderthal hyoid that looks just like a modern human's. But now computer modelling of how it works has shown this bone was also used in a very similar way. Writing in journal Plos One, scientists say its study is "highly suggestive" of complex speech in Neanderthals. The hyoid bone is crucial for speaking as it supports the root of the tongue. In non-human primates, it is not placed in the right position to vocalise like humans. An international team of researchers analysed a fossil Neanderthal throat bone using 3D x-ray imaging and mechanical modelling. This model allowed the group to see how the hyoid behaved in relation to the other surrounding bones. Stephen Wroe, from the University of New England, Armidale, NSW, Australia, said: "We would argue that this is a very significant step forward. It shows that the Kebara 2 hyoid doesn't just look like those of modern humans - it was used in a very similar way." He told BBC News that it not only changed our understanding of Neanderthals, but also of ourselves. "Many would argue that our capacity for speech and language is among the most fundamental of characteristics that make us human. If Neanderthals also had language then they were truly human, too." BBC © 2013

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior; Chapter 19: Language and Hemispheric Asymmetry
Related chapters from MM:Chapter 15: Brain Asymmetry, Spatial Cognition, and Language
Link ID: 19066 - Posted: 12.24.2013

By JOHN NOBLE WILFORD Early in the 20th century, two brothers discovered a nearly complete Neanderthal skeleton in a pit inside a cave at La Chapelle-aux-Saints, in southwestern France. The discovery raised the possibility that these evolutionary relatives of ours intentionally buried their dead — at least 50,000 years ago, before the arrival of anatomically modern humans in Europe. These and at least 40 subsequent discoveries, a few as far from Europe as Israel and Iraq, appeared to suggest that Neanderthals, long thought of as brutish cave dwellers, actually had complex funeral practices. Yet a significant number of researchers have since objected that the burials were misinterpreted, and might not represent any advance in cognitive and symbolic behavior. Now an international team of scientists is reporting that a 13-year re-examination of the burials at La Chapelle-aux-Saints supports the earlier claims that the burials were intentional. The researchers — archaeologists, geologists and paleoanthropologists — not only studied the skeleton from the original excavations, but found more Neanderthal remains, from two children and an adult. They also studied the bones of other animals in the cave, mainly bison and reindeer, and the geology of the burial pits. The findings, in this week’s issue of Proceedings of the National Academy of Sciences, “buttress claims for complex symbolic behavior among Western European Neanderthals,” the scientists reported. William Rendu, the paper’s lead author and a researcher at the Center for International Research in the Humanities and Social Sciences in New York, said in an interview that the geology of the burial pits “cannot be explained by natural events” and that “there is no sign of weathering and scavenging by animals,” which means the bodies were covered soon after death. © 2013 The New York Times Company

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 19041 - Posted: 12.17.2013

By CARL ZIMMER Scientists have found the oldest DNA evidence yet of humans’ biological history. But instead of neatly clarifying human evolution, the finding is adding new mysteries. In a paper in the journal Nature, scientists reported Wednesday that they had retrieved ancient human DNA from a fossil dating back about 400,000 years, shattering the previous record of 100,000 years. The fossil, a thigh bone found in Spain, had previously seemed to many experts to belong to a forerunner of Neanderthals. But its DNA tells a very different story. It most closely resembles DNA from an enigmatic lineage of humans known as Denisovans. Until now, Denisovans were known only from DNA retrieved from 80,000-year-old remains in Siberia, 4,000 miles east of where the new DNA was found. The mismatch between the anatomical and genetic evidence surprised the scientists, who are now rethinking human evolution over the past few hundred thousand years. It is possible, for example, that there are many extinct human populations that scientists have yet to discover. They might have interbred, swapping DNA. Scientists hope that further studies of extremely ancient human DNA will clarify the mystery. “Right now, we’ve basically generated a big question mark,” said Matthias Meyer, a geneticist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and a co-author of the new study. Hints at new hidden complexities in the human story came from a 400,000-year-old femur found in a cave in Spain called Sima de los Huesos (“the pit of bones” in Spanish). The scientific team used new methods to extract the ancient DNA from the fossil. “This would not have been possible even a year ago,” said Juan Luis Arsuaga, a paleoanthropologist at Universidad Complutense de Madrid and a co-author of the paper. © 2013 The New York Times Company

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: 19001 - Posted: 12.05.2013

Ewen Callaway New genome sequences from two extinct human relatives suggest that these ‘archaic’ groups bred with humans and with each other more extensively than was previously known. The ancient genomes, one from a Neanderthal and one from a different archaic human group, the Denisovans, were presented on 18 November at a meeting at the Royal Society in London. They suggest that interbreeding went on between the members of several ancient human-like groups living in Europe and Asia more than 30,000 years ago, including an as-yet unknown human ancestor from Asia. “What it begins to suggest is that we’re looking at a ‘Lord of the Rings’-type world — that there were many hominid populations,” says Mark Thomas, an evolutionary geneticist at University College London who was at the meeting but was not involved in the work. The first Neanderthal1 and the Denisovan2 genome sequences revolutionized the study of ancient human history, not least because they showed that these groups interbred with anatomically modern humans, contributing to the genetic diversity of many people alive today. All humans whose ancestry originates outside of Africa owe about 2% of their genome to Neanderthals; and certain populations living in Oceania, such as Papua New Guineans and Australian Aboriginals, got about 4% of their DNA from interbreeding between their ancestors and Denisovans, who are named after the cave in Siberia’s Altai Mountains where they were discovered. The cave contains remains deposited there between 30,000 and 50,000 years ago. © 2013 Nature Publishing Group

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 18946 - Posted: 11.20.2013

By EMILY ANTHES Humans have no exclusive claim on intelligence. Across the animal kingdom, all sorts of creatures have performed impressive intellectual feats. A bonobo named Kanzi uses an array of symbols to communicate with humans. Chaser the border collie knows the English words for more than 1,000 objects. Crows make sophisticated tools, elephants recognize themselves in the mirror, and dolphins have a rudimentary number sense. Anolis evermanni lizards normally attack their prey from above. The lizards were challenged to find a way to access insects that were kept inside a small hole covered with a tightfitting blue cap. And reptiles? Well, at least they have their looks. In the plethora of research over the past few decades on the cognitive capabilities of various species, lizards, turtles and snakes have been left in the back of the class. Few scientists bothered to peer into the reptile mind, and those who did were largely unimpressed. “Reptiles don’t really have great press,” said Gordon M. Burghardt, a comparative psychologist at the University of Tennessee at Knoxville. “Certainly in the past, people didn’t really think too much of their intelligence. They were thought of as instinct machines.” But now that is beginning to change, thanks to a growing interest in “coldblooded cognition” and recent studies revealing that reptile brains are not as primitive as we imagined. The research could not only redeem reptiles but also shed new light on cognitive evolution. Because reptiles, birds and mammals diverged so long ago, with a common ancestor that lived 280 million years ago, the emerging data suggest that certain sophisticated mental skills may be more ancient than had been assumed — or so adaptive that they evolved multiple times. © 2013 The New York Times Company

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior; Chapter 17: Learning and Memory
Related chapters from MM:Chapter 13: Memory, Learning, and Development
Link ID: 18942 - Posted: 11.19.2013

by Bob Holmes When it comes to evolution, there is no such thing as perfection. Even in the simple, unchanging environment of a laboratory flask, bacteria never stop making small tweaks to improve their fitness. That's the conclusion of the longest-running evolutionary experiment carried out in a lab. In 1988, Richard Lenski of Michigan State University in East Lansing began growing 12 cultures of the same strain of Escherichia coli bacteria. The bacteria have been growing ever since, in isolation, on a simple nutrient medium – a total of more than 50,000 E. coli generations to date. Every 500 generations, Lenski freezes a sample of each culture, creating an artificial "fossil record". This allows him to resurrect the past and measure evolutionary progress by comparing how well bacteria compete against each other at different points in the evolutionary process. No upper limit After 10,000 generations, Lenski thought that the bacteria might approach an upper limit in fitness beyond which no further improvement was possible. But the full 50,000 generations of data show that isn't the case. When pitted against each other in an equal race, new generations always grew faster than older ones. In other words, fitness never stopped increasing. Their results fit a mathematical pattern known as a power law, in which something can increase forever, but at a steadily diminishing rate. "Even if we extrapolate it to 2.5 billion generations, there's no obvious reason to think there's an upper limit," says Lenski. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 18937 - Posted: 11.16.2013

Ed Yong Humanity's success depends on the ability of humans to copy, and build on, the works of their predecessors. Over time, human society has accumulated technologies, skills and knowledge beyond the scope of any single individual. Now, two teams of scientists have independently shown that the strength of this cumulative culture depends on the size and interconnectedness of social groups. Through laboratory experiments, they showed that complex cultural traditions — from making fishing nets to tying knots — last longer and improve faster at the hands of larger, more sociable groups. This helps to explain why some groups, such as Tasmanian aboriginals, lost many valuable skills and technologies as their populations shrank. “For producing fancy tools and complexity, it’s better to be social than smart,” says psychologist Joe Henrich of the University of British Columbia in Vancouver, Canada, the lead author of one of the two studies, published today in Proceedings of the Royal Society B1. “And things that make us social are going to make us seem smarter.” “There were some theoretical models to explain these phenomena but no one had done experiments,” says evolutionary biologist Maxime Derex of the University of Montpellier, France, who led the other study, published online today in Nature2. Derex’s team asked 366 male students to play a virtual game in which they gained points — and eventually money — by building either an arrowhead or a fishing net. The nets offered greater rewards, but were also harder to make. The students watched video demonstrations of the two tasks in groups of 2, 4, 8 or 16, before attempting the tasks individually. Their arrows and nets were tested in simulations and scored. After each trial, they could see how other group members fared, and watch a step-by-step procedure for any one of the designs. © 2013 Nature Publishing Group

Related chapters from BP7e: Chapter 17: Learning and Memory; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory, Learning, and Development
Link ID: 18926 - Posted: 11.14.2013

Sid Perkins One of the most complete early human skulls yet found suggests that what scientists thought were three hominin species may in fact be one. This controversial claim comes from a comparison between the anatomical features of a 1.8-million-year-old fossil skull with those of four other skulls from the same excavation site at Dmanisi, Georgia. The wide variability in their features suggests that Homo habilis, Homo rudolfensis and Homo erectus, the species so far identified as existing worldwide in that era, might represent a single species. The research is published in Science today1. The newly described skull — informally known as 'skull 5' — was unearthed in 2005. When combined with a jawbone found five years before and less than 2 metres away, it “is the most complete skull of an adult from this date”, says Marcia Ponce de León, a palaeoanthropologist at the Anthropological Institute and Museum in Zurich, Switzerland, and one of the authors of the study. The volume of skull 5’s braincase is only 546 cubic centimetres, about one-third that of modern humans, she notes. Despite that low volume, the hominin’s face was relatively large and protruded more than the faces of the other four skulls found at the site, which have been attributed to H. erectus. Having five skulls from one site provides an unprecedented opportunity to study variation in what presumably was a single population, says co-author Christoph Zollikofer, a neurobiologist at the same institute as Ponce de León. All of the skulls excavated so far were probably deposited within a 20,000-year time period, he notes. © 2013 Nature Publishing Group

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 18806 - Posted: 10.19.2013

by Denise Chow, LiveScience The discovery of a fossilized brain in the preserved remains of an extinct "mega-clawed" creature has revealed an ancient nervous system that is remarkably similar to that of modern-day spiders and scorpions, according to a new study. The fossilized Alalcomenaeus is a type of arthropod known as a megacheiran (Greek for "large claws") that lived approximately 520 million years ago, during a period known as the Lower Cambrian. The creature was unearthed in the fossil-rich Chengjiang formation in southwest China. VIDEO: Bugs, Arthropods, and Insects! Oh My! Researchers studied the fossilized brain, the earliest known complete nervous system, and found similarities between the extinct creature's nervous system and the nervous systems of several modern arthropods, which suggest they may be ancestrally related. [Photos of Clawed Arthropod & Other Strange Cambrian Creatures] Living arthropods are commonly separated into two major groups: chelicerates, which include spiders, horseshoe crabs and scorpions, and a group that includes insects, crustaceans and millipedes. The new findings shed light on the evolutionary processes that may have given rise to modern arthropods, and also provide clues about where these extinct mega-clawed creatures fit in the tree of life. "We now know that the megacheirans had central nervous systems very similar to today's horseshoe crabs and scorpions," senior author Nicholas Strausfeld, a professor in the department of neuroscience at the University of Arizona in Tucson, said in a statement. "This means the ancestors of spiders and their kin lived side by side with the ancestors of crustaceans in the Lower Cambrian." © 2013 Discovery Communications, LLC.

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 18804 - Posted: 10.17.2013

by Bob Holmes The great flowering of human evolution over the past 2 million years may have been driven not by the African savannahs, but by the lakes of that continent's Great Rift Valley. This novel idea, published this week, may explain why every major advance in the evolution of early humans, from speciation to the vast increase in brain size, appears to have taken place in eastern Africa. Anthropologists have surmised for several years that early humans, or hominins, might have evolved their unusually large, powerful brains to cope with an increasingly variable climate over the past few million years. However, studies testing this hypothesis have been equivocal, perhaps because most use global or continental-scale measures of climate, such as studying trends in the amount of airborne dust from dry earth that is blown into the ocean and incorporated into deep-sea sediments. Mark Maslin, a palaeoclimatologist at University College London, and his colleague Susanne Shultz at the University of Manchester, UK, have taken a local approach instead, by studying whether the presence or absence of lakes in the Rift Valley affected the hominins living there. Maslin's hunch is that relatively short periods of extreme variability 2.6, 1.8, and 1 million years ago – which are important periods for human evolution – corresponded to times of rapid change in the large lakes of the Great Rift Valley. Because the valley concentrates rainfall from a wide area into relatively small basins, these lakes are unusually sensitive to rainfall and swell or disappear depending on climate. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 18802 - Posted: 10.17.2013

by Erika Engelhaupt Could I interest you in eating the partially digested stomach contents of a porcupine? No? Maybe a spot of reindeer stomach, then. Still no? Well, that’s curious. The Western aversion to these dishes is odd, because people around the world have long partaken of — even delighted in — the delicacy known to medical science as chyme. That’s what becomes of food after it’s chewed, swallowed and mushed around in the stomach for a while with a healthy dose of hydrochloric acid. And, researchers now suggest, Neandertals were no exception. Eating chyme may even explain the presence of some puzzling plant matter found in Neandertal’s tartar-crusted teeth. Neandertals didn’t have great dental care, and in the last few years anthropologists have begun to take advantage of monstrous tartar buildup on fossilized teeth to figure out what the hominids ate. Various chemical signatures, starch grains and even tiny plant fossils called phytoliths get preserved in the tartar, also known as calculus. Just what Neandertals ate has been more of a puzzle than paleo dieters might have you believe. Isotope analyses of fossilized bones and teeth suggest Neandertals ate very high on the food chain, with high-protein diets akin to those of wolves or hyenas. But wear marks on their teeth suggest the Neandertal diet consisted of more animals in colder high-latitude areas, and more of a mix of plants and animals in warmer areas. Tartar analyses support the idea that Neandertals ate their veggies, and have also suggested the presence of plants considered inedible, or at least unpalatable and non-nutritious. These include some plants like yarrow and chamomile with medicinal value, so one team suggested Neandertals self-medicated. © Society for Science & the Public 2000 - 2013

Related chapters from BP7e: 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: 18776 - Posted: 10.12.2013

By CARL ZIMMER Evolutionary biologists have come to recognize humans as a tremendous evolutionary force. In hospitals, we drive the evolution of resistant bacteria by giving patients antibiotics. In the oceans, we drive the evolution of small-bodied fish by catching the big ones. In a new study, a University of Minnesota biologist, Emilie C. Snell-Rood, offers evidence suggesting we may be driving evolution in a more surprising way. As we alter the places where animals live, we may be fueling the evolution of bigger brains. Dr. Snell-Rood bases her conclusion on a collection of mammal skulls kept at the Bell Museum of Natural History at the University of Minnesota. Dr. Snell-Rood picked out 10 species to study, including mice, shrews, bats and gophers. She selected dozens of individual skulls that were collected as far back as a century ago. An undergraduate student named Naomi Wick measured the dimensions of the skulls, making it possible to estimate the size of their brains. Two important results emerged from their research. In two species — the white-footed mouse and the meadow vole — the brains of animals from cities or suburbs were about 6 percent bigger than the brains of animals collected from farms or other rural areas. Dr. Snell-Rood concludes that when these species moved to cities and towns, their brains became significantly bigger. Dr. Snell-Rood and Ms. Wick also found that in rural parts of Minnesota, two species of shrews and two species of bats experienced an increase in brain size as well. Dr. Snell-Rood proposes that the brains of all six species have gotten bigger because humans have radically changed Minnesota. Where there were once pristine forests and prairies, there are now cities and farms. In this disrupted environment, animals that were better at learning new things were more likely to survive and have offspring. © 2013 The New York Times Company

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: 18555 - Posted: 08.24.2013

By Jessica Shugart Sometimes it pays to be mediocre. A new study shows that sheep with a 50/50 blend of genes for small and big horns pass along more of their genes over a lifetime than their purely big-horned brethren, who mate more often. The finding offers rare insight into an enduring evolutionary paradox—why some traits persist despite creating a reproductive disadvantage. The results, published online August 21 in Nature, reveal that while big-horned sheep mated most successfully each season, small-horned sheep survived longer. Rams who inherited one of each type of gene from their parents got the best of both worlds: they lived longer than bigger-horned sheep and mated more successfully than those with the smallest horns. As a result, middle-of-the-road sheep passed on more of their genes over time. “They’re the fittest of them all,” says Jon Slate of the University of Sheffield in Scotland, who led the study. “This is a marvelous combination of using the most modern tools available to confirm classic older views of sexual selection,” says evolutionary geneticist Allen Moore of the University of Georgia in Athens, who was not involved in the study. Traits such as bold peacock feathers and giant antlers evolved to garner the attention of prospective females and boost reproductive success. Yet if each generation of females continues to pick the most stellar males, Charles Darwin wondered, how do sub-par versions of a trait continue to persist? “It’s something that has preoccupied evolutionary biologists ever since,” Slate says. © Society for Science & the Public 2000 - 2013

Related chapters from BP7e: 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: 18550 - Posted: 08.22.2013

By Melissa Hogenboom Science reporter, BBC News Several ancient dinosaurs evolved the brainpower needed for flight long before they could take to the skies, scientists say. Non-avian dinosaurs were found to have "bird brains", larger than that of Archaeopteryx, a 150 million-year-old bird-like dinosaur. Once regarded as a unique transition between dinosaurs and birds, scientists say Archaeopteryx has now lost its pivotal place. The study is published in Nature. A recent discovery in China which unveiled the earliest creature yet discovered on the evolutionary line to birds, also placed Archaeopteryx in less of a transitional evolutionary place. Bird brains tend to be more enlarged compared to their body size than reptiles, vital for providing the vision and coordination needed for flight. Scientists using high-resolution CT scans have now found that these "hyper-inflated" brains were present in many ancient dinosaurs, and had the neurological hardwiring needed to take to the skies. This included several bird-like oviraptorosaurs and the troodontids Zanabazar junior, which had larger brains relative to body size than that of Archaeopteryx. This latest work adds to previous studies which found the presence of feathers and wishbones on ancient dinosaurs. BBC © 2013

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior; Chapter 11: Motor Control and Plasticity
Related chapters from MM:Chapter 5: The Sensorimotor System
Link ID: 18439 - Posted: 08.01.2013

Andrew Curry In the 1970s, archaeologist Peter Bogucki was excavating a Stone Age site in the fertile plains of central Poland when he came across an assortment of odd artefacts. The people who had lived there around 7,000 years ago were among central Europe's first farmers, and they had left behind fragments of pottery dotted with tiny holes. It looked as though the coarse red clay had been baked while pierced with pieces of straw. Looking back through the archaeological literature, Bogucki found other examples of ancient perforated pottery. “They were so unusual — people would almost always include them in publications,” says Bogucki, now at Princeton University in New Jersey. He had seen something similar at a friend's house that was used for straining cheese, so he speculated that the pottery might be connected with cheese-making. But he had no way to test his idea. The mystery potsherds sat in storage until 2011, when Mélanie Roffet-Salque pulled them out and analysed fatty residues preserved in the clay. Roffet-Salque, a geochemist at the University of Bristol, UK, found signatures of abundant milk fats — evidence that the early farmers had used the pottery as sieves to separate fatty milk solids from liquid whey. That makes the Polish relics the oldest known evidence of cheese-making in the world1. © 2013 Nature Publishing Group

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: 18438 - Posted: 08.01.2013

John Hawks Humans are known for sporting big brains. On average, the size of primates' brains is nearly double what is expected for mammals of the same body size. Across nearly seven million years, the human brain has tripled in size, with most of this growth occurring in the past two million years. Determining brain changes over time is tricky. We have no ancient brains to weigh on a scale. We can, however, measure the inside of ancient skulls, and a few rare fossils have preserved natural casts of the interior of skulls. Both approaches to looking at early skulls give us evidence about the volumes of ancient brains and some details about the relative sizes of major cerebral areas. For the first two thirds of our history, the size of our ancestors' brains was within the range of those of other apes living today. The species of the famous Lucy fossil, Australopithecus afarensis, had skulls with internal volumes of between 400 and 550 milliliters, whereas chimpanzee skulls hold around 400 ml and gorillas between 500 and 700 ml. During this time, Australopithecine brains started to show subtle changes in structure and shape as compared with apes. For instance, the neocortex had begun to expand, reorganizing its functions away from visual processing toward other regions of the brain. The final third of our evolution saw nearly all the action in brain size. Homo habilis, the first of our genus Homo who appeared 1.9 million years ago, saw a modest hop in brain size, including an expansion of a language-connected part of the frontal lobe called Broca's area. The first fossil skulls of Homo erectus, 1.8 million years ago, had brains averaging a bit larger than 600 ml. © 2013 Scientific American

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior; Chapter 1: Biological Psychology: Scope and Outlook
Related chapters from MM:Chapter 1: An Introduction to Brain and Behavior
Link ID: 18418 - Posted: 07.29.2013

By Cristy Gelling Lemur species that live in large groups can tell when to steal food from a competitor in a lab experiment, researchers report June 26 in PLOS ONE. The finding supports the idea that brainpower in primates evolved to fit their complex social lives. Because the sneakier lemurs don't have bigger brains than less sneaky ones living in smaller groups, researchers suggest that social smarts don’t always depend on brain size. Much of the evidence for sociality’s role in the evolution of intelligence comes from indirect measures such as brain size, says study coauthor Evan MacLean of Duke University. But brain size does not always correspond to brainpower, so MacLean uses behavioral tests. He and his colleagues tested the social intelligence of six species of lemur, primates from Madagascar distantly related to monkeys and apes. Each of the species lives in social groups ranging from families of just three, mongoose lemurs’ preferred posse, to gangs of about 16, a typical size for a group of ring-tailed lemurs. The researchers trained lemurs to view humans as competitors for food, then presented the animals with a choice between pilfering treats from one of two people: one facing the animals or another with his or her back turned. Species that live in small groups reached for the food under a competitor’s nose as often as they did behind people’s backs. But the ring-tailed lemurs were much more likely to choose the unguarded food. © Society for Science & the Public 2000 - 2013

Related chapters from BP7e: 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: 18324 - Posted: 06.29.2013

Sid Perkins Sporting feats such as baseball's 100-mile-per-hour fastball are made possible by a suite of anatomical features that appeared in our hominin ancestors about 2 million years ago, a video study of college athletes suggests. And this ability to throw projectiles may have been crucial for human hunting, which in turn may have had a vital role in our evolution. “Throwing projectiles probably enabled our ancestors to effectively and safely kill big game,” says Neil Roach, a biological anthropologist at George Washington University in Washington DC, who led the work. Eating more calorie-rich meat and fat would have helped early hominins' brains and bodies to grow, enabling our ancestors to expand into new regions of the world, he suggests. The study is published today in Nature1. Although some primates occasionally throw objects, and with a fair degree of accuracy, only humans can routinely hurl projectiles with both speed and accuracy, says Roach. Adult male chimpanzees can throw objects at speeds of around 30 kilometres per hour, but even a 12-year-old human can pitch a baseball three times faster than that, he notes. In fact, the quickest motion that the human body produces — rotation of the humerus, the long bone in the upper arm, at a rate that is briefly equivalent to 25 full rotations in a single second — occurs while a person is throwing a projectile. © 2013 Nature Publishing Group,

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior; Chapter 11: Motor Control and Plasticity
Related chapters from MM:Chapter 5: The Sensorimotor System
Link ID: 18323 - Posted: 06.29.2013

By Melissa Hogenboom Science reporter, BBC News The social brain theory - that animals in large social groups have bigger brains - has now been supported by a computer model. For animals in smaller social groups, the cost of having a large brain outweighs the benefits. Scientists used a simulation modelling technique to confirm that large social groups are only possible through sophisticated communication. The study is published in Proceedings of the Royal Society B. The human brain is a very costly organ which consumes a lot of energy. Animals that live in small social groups could therefore be at a disadvantage if they had large brains taking up processing power that could better be used elsewhere. A team at Oxford University has now looked at the cognitive demands of making social decisions using a method called agent-based modelling, which models simplified representations of reality. As expected, they found that more complex social decisions take up more 'brain' power. The cognitive complexity of language evolved as social groups became larger and more complex, said lead author of the study Tamas David-Barrett from the University of Oxford. He explained that a group of five is an ideal number to coordinate an event such as a hunt, but as the group size increases, the coordination involved would become increasingly complex. BBC © 2013

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: 18312 - Posted: 06.26.2013

Sid Perkins The near-complete fossil of a tiny creature unearthed in China in 2002 has bolstered the idea that the anthropoid group of primates — whose modern-day members include monkeys, apes and humans — had appeared by at least 55 million years ago. The fossil primate does not belong to that lineage, however: it is thought to be the earliest-discovered ancestor of small tree-dwelling primates called tarsiers, showing that even at this early time, the tarsier and anthropoid groups had split apart. The slender-limbed, long-tailed primate, described today in Nature1, was about the size of today’s pygmy mouse lemur and would have weighed between 20 and 30 grams, the researchers estimate. The mammal sports an odd blend of features, with its skull, teeth and limb bones having proportions resembling those of tarsiers, but its heel and foot bones more like anthropoids. “This mosaic of features hasn’t been seen before in any living or fossil primate,” says study author Christopher Beard, a palaeontologist at the Carnegie Museum of Natural History in Pittsburgh, Pennsylvania. By analysing almost 1,200 morphological aspects of the fossil and comparing them to those of 156 other extant and extinct mammals, the team put the ancient primate near the base of the tarsier family tree. The creature is dubbed Archicebus achilles, in which the genus name Archicebus roughly translates as 'original long-tailed monkey', while the species name achilles is a wry nod to the primate's anthropoid-like heel bone. © 2013 Nature Publishing Group

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 18240 - Posted: 06.06.2013