Links for Keyword: Evolution

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by Michael Balter The basic questions about early European cave art—who made it and whether they developed artistic talent swiftly or slowly—were thought by many researchers to have been settled long ago: Modern humans made the paintings, crafting brilliant artworks almost as soon as they entered Europe from Africa. Now dating experts working in Spain, using a technique relatively new to archaeology, have pushed dates for the earliest cave art back some 4000 years to at least 41,000 years ago*, raising the possibility that the artists were Neandertals rather than modern humans. And a few researchers say that the study argues for the slow development of artistic skill over tens of thousands of years. Figuring out the age of cave art is fraught with difficulties. Radiocarbon dating has long been the method of choice, but it is restricted to organic materials such as bone and charcoal. When such materials are lying on a cave floor near art on the cave wall, archaeologists have to make many assumptions before concluding that they are contemporary. Questions have even arisen in cases like the superb renditions of horses, rhinos, and other animals in France's Grotte Chauvet, the cave where researchers have directly radiocarbon dated artworks executed in charcoal to 37,000 years ago. Other archaeologists have argued that artists could have entered Chauvet much later and picked up charcoal that had been lying around for thousands of years. Now in a paper published online today in Science, applied a technique called uranium-series (U-series) dating to artworks from 11 Spanish caves. U-series dating has been around since the 1950s and is often used to date caves, corals, and other proxies for climate and sea level changes. But it has been used only a few times before on cave art, including by Pike and Pettit, who used it to date the United Kingdom's oldest known cave art at Cresswell Crags in England. © 2010 American Association for the Advancement of Science.

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 0:
Link ID: 16919 - Posted: 06.16.2012

by Ann Gibbons Chimpanzees now have to share the distinction of being our closest living relative in the animal kingdom. An international team of researchers has sequenced the genome of the bonobo for the first time, confirming that it shares the same percentage of its DNA with us as chimps do. The team also found some small but tantalizing differences in the genomes of the three species—differences that may explain how bonobos and chimpanzees don't look or act like us even though we share about 99% of our DNA. "We're so closely related genetically, yet our behavior is so different," says team member and computational biologist Janet Kelso of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. "This will allow us to look for the genetic basis of what makes modern humans different from both bonobos and chimpanzees." Ever since researchers sequenced the chimp genome in 2005, they have known that humans share about 99% of our DNA with chimpanzees, making them our closest living relatives. But there are actually two species of chimpanzees that are this closely related to humans: bonobos (Pan paniscus) and the common chimpanzee (Pan troglodytes). This has prompted researchers to speculate whether the ancestor of humans, chimpanzees, and bonobos looked and acted more like a bonobo, a chimpanzee, or something else—and how all three species have evolved differently since the ancestor of humans split with the common ancestor of bonobos and chimps between 5 million and 7 million years ago in Africa. © 2010 American Association for the Advancement of Science.

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 0:
Link ID: 16913 - Posted: 06.14.2012

By Gareth Cook How aware are plants? This is the central question behind a fascinating new book, “What a Plant Knows,” by Daniel Chamovitz, director of the Manna Center for Plant Biosciences at Tel Aviv University. A plant, he argues, can see, smell and feel. It can mount a defense when under siege, and warn its neighbors of trouble on the way. A plant can even be said to have a memory. But does this mean that plants think — or that one can speak of a “neuroscience” of the flower? Chamovitz answered questions from Mind Matters editor Gareth Cook. 1. How did you first get interested in this topic? My interest in the parallels between plant and human senses got their start when I was a young postdoctoral fellow in the laboratory of Xing-Wang Deng at Yale University in the mid 1990s. I was interested in studying a biological process that would be specific to plants, and would not be connected to human biology (probably as a response to the six other “doctors” in my family, all of whom are physicians). So I was drawn to the question of how plants sense light to regulate their development. It had been known for decades that plants use light not only for photosynthesis, but also as a signal that changes the way plants grow. In my research I discovered a unique group of genes necessary for a plant to determine if it’s in the light or in the dark. When we reported our findings, it appeared these genes were unique to the plant kingdom, which fit well with my desire to avoid any thing touching on human biology. But much to my surprise and against all of my plans, I later discovered that this same group of genes is also part of the human DNA. © 2012 Scientific American

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 0: ; Chapter 2: Cells and Structures: The Anatomy of the Nervous System
Link ID: 16878 - Posted: 06.06.2012

by Michael Balter Three years ago, a stone-throwing chimpanzee named Santino jolted the research community by providing some of the strongest evidence yet that nonhumans could plan ahead. Santino, a resident of the Furuvik Zoo in Gävle, Sweden, calmly gathered stones in the mornings and put them into neat piles, apparently saving them to hurl at visitors when the zoo opened as part of angry and aggressive "dominance displays." But some researchers were skeptical that Santino really was planning for a future emotional outburst. Perhaps he was just repeating previously learned responses to the zoo visitors, via a cognitively simpler process called associative learning. And it is normal behavior for dominant male chimps to throw things at visitors, such as sticks, branches, rocks, and even feces. Now Santino is back in the scientific literature, the subject of new claims that he has begun to conceal the stones so he can get a closer aim at his targets—further evidence that he is thinking ahead like humans do. The debate over Santino is part of a larger controversy over whether some humanlike animal behaviors might have simpler explanations. For example, Sara Shettleworth, a psychologist at the University of Toronto in Canada, argued in a widely cited 2010 article entitled, "Clever animals and killjoy explanations in comparative psychology," that the zookeepers and researchers who observed Santino's stone-throwing over the course of a decade had not seen him gathering the stones, and thus could not know why he originally starting doing so. Santino, Shettleworth and some others argued, might have had some other reasons for caching the stones, and the stone throwing might have been an afterthought. © 2010 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 0: ; Chapter 14: Attention and Consciousness
Link ID: 16777 - Posted: 05.10.2012

Ewen Callaway Humans walk on two feet and (mostly) lack hair-covered bodies, but the feature that sets us furthest apart from other apes is a brain capable of language, art, science, and other trappings of civilisation. Now, two studies published online today in Cell1, 2 suggest that DNA duplication errors that happened millions of years ago might have had a pivotal role in the evolution of the complexity of the human brain. The duplications — which created new versions of a gene active in the brains of other mammals — may have endowed humans with brains that could create more neuronal connections, perhaps leading to greater computational power. The enzymes that copy DNA sometimes slip extra copies of a gene into a chromosome, and scientists estimate that such genetic replicas make up about 5% of the human genome. However, gene duplications are notoriously difficult to study because the new genes differ little from their forebears, and tend to be overlooked. Evan Eichler, a geneticist at the University of Washington in Seattle, and lead author of one of the Cell papers, previously found that humans have four copies of a gene called SRGAP2, and he and his colleagues decided to investigate. In their new paper, they report that the three duplicated versions of SRGAP2 sit on chromosome 1, along with the original ancestral gene, but they are not exact copies. All of the duplications are missing a small part of the ancestral form of the gene, and at least one duplicate, SRGAP2C, seems to make a working protein. Eichler’s team has also found SRGAP2C in every individual human genome his team has examined – more than 2,000 so far – underscoring its significance. © 2012 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 0: ; Chapter 13: Memory, Learning, and Development
Link ID: 16753 - Posted: 05.05.2012

William G. Eberhard, William T. Wcislo A basic fact of life is that the size of an animal’s brain depends to some extent on its body size. A long history of studies of vertebrate animals has demonstrated that the relationship between brain and body mass follows a power-law function. Smaller individuals have relatively larger brains for their body sizes. This scaling relationship was popularized as Haller’s Rule by German evolutionary biologist Bernhard Rensch in 1948, in honor of Albrecht von Haller, who first noticed the relationship nearly 250 years ago. Little has been known, however, about relative brain size for invertebrates such as insects, spiders and nematodes, even though they are among Earth’s more diverse and abundant animal groups. But a recent wave of studies of invertebrates confirms that Haller’s Rule applies to them as well, and that it extends to much smaller body sizes than previously thought. These tiny animals have been able to substantially shift their allometric lines—that is, the relationship between their brain size and their overall body size—from those of vertebrates and other invertebrates. Animals that follow a given allometric line belong to the same grade and changes from one grade to another are known as grade shifts. The result is that different taxonomic groups have different, variant, versions of Haller’s Rule. The mechanisms that are responsible for grade shifts are only beginning to be understood. But this combination of generality and variability in Haller’s Rule appears to call into question some basic assumptions regarding the uniformity of how the central nervous system functions among animals. It also reveals a number of overlooked design challenges faced by tiny organisms. Because neural tissue is metabolically expensive, minute animals must pay relatively higher metabolic costs to power their proportionally larger brains, and they thus face different ecological challenges. © Sigma Xi, The Scientific Research Society

Related chapters from BP7e: Chapter 13: Homeostasis: Active Regulation of the Internal Environment; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 16651 - Posted: 04.16.2012

by Helen Fields The average adult human's brain weighs about 1.3 kilograms, has 100 billion or so neurons, and sucks up 20% of the oxygen we breathe. It's much bigger than an animal our size needs. According to a new computer model, the brains of humans and related primates are so large because we evolved to be social creatures. If we didn't play well with others, our brains would be puny. The idea behind the so-called social intelligence hypothesis is that we need pretty complex computers in our skulls to keep track of all the complex relationships we have with each other—who's a friend, who's an enemy, who's higher in the social ranks. Some studies have supported this idea, showing for example that bigger-brained primates tend to live in bigger social groups. The same appears to hold true for dolphins. But these studies only identified associations between brain and group size; they don't show how evolution might have worked. Since they didn't have a few million years of time on their hands, Ph.D. student Luke McNally and colleagues at Trinity College Dublin simulated evolution on a computer. They started with 50 simple brains. Each had just three to six neurons. The researchers then made each brain challenge the others to one of two classic games: the prisoner's dilemma or the snowdrift game. In the prisoner's dilemma, two people have been taken in for questioning by the police. If both keep their mouths shut, they'll both be set free. If one sells out the other, the snitch will get off and the other will do a long stint in jail. If they tell on each other, both get shorter sentences. © 2010 American Association for the Advancement of Science.

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 0:
Link ID: 16640 - Posted: 04.12.2012

by Virginia Morell The male dolphins of Shark Bay, Australia, are known to marine biologists for their messy social entanglements. Their relationships with each other are so unusual—they're more like the intricate webs of the Mafia than the vertical hierarchies of chimpanzees—that, in a new paper, one team of scientists argues that the dolphins live in a social system that is "unique among mammals." Intriguingly, the researchers also suggest that these complex, and often cooperative, relationships may stem in part from one simple, unexpected factor: the dolphins' low cruising speed. Mammals have evolved a variety of social structures. For example, chimpanzees live in what ethologists call "semiclosed groups"—that is, a community comprised of individuals who are well-known to each other. The members generally aren't friendly to chimps in other communities; the males practice what's known as community defense, patrolling and guarding their territory and fighting their neighbors. Inside that tight group, the chimpanzees also have male-male alliances. At first glance, dolphins seem to have a somewhat similar social system. Two or three adult males form a tight alliance and cooperate to herd a female for mating. (Female dolphins rarely form strong alliances.) Other male teams may try to spirit away the female—particularly if she is in estrus. To fight back, the first-level alliances form partnerships with other first-level alliances, thus creating a larger second-level alliance. Some of these second-level alliances have as many as 14 dolphins and can last 15 years or more. On some occasions, the second-level alliance can call in the troops from yet another group, "a third-order alliance," as the researchers call them—leading to huge battles with more than 20 dolphins biting and bashing each other with their heads and tails over the right to keep or steal a single female. © 2010 American Association for the Advancement of Science.

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 16588 - Posted: 03.29.2012

By Bruce Bower An ancient member of the human evolutionary family has put what’s left of a weird, gorillalike foot forward to show that upright walking evolved along different paths in East Africa. A 3.4 million-year-old partial fossil foot unearthed in Ethiopia comes from a previously unknown hominid species that deftly climbed trees but walked clumsily, say anthropologist Yohannes Haile-Selassie of the Cleveland Museum of Natural History and his colleagues. Their report appears in the March 29 Nature. To the scientists’ surprise, this creature lived at the same time and in the same region as Australopithecus afarensis, a hominid species best known for a partial skeleton dubbed Lucy. Another recent fossil discovery in Ethiopia suggests that Lucy’s kind walked much as people do today (SN: 7/17/10, p. 5). “For the first time, we have evidence of another hominid lineage that lived at the same time as Lucy,” says anthropologist and study coauthor Bruce Latimer of Case Western Reserve University in Cleveland. “This new find has a grasping big toe and no arch, suggesting [the species] couldn’t walk great distances and spent a lot of time in the trees.” Lucy’s flat-footed compatriot adds to limited evidence that some hominids retained feet designed for adept tree climbing several million years after the origin of an upright gait, writes Harvard University anthropologist Daniel Lieberman in a comment published in the same issue of Nature. © Society for Science & the Public 2000 - 2012

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior; Chapter 11: Motor Control and Plasticity
Related chapters from MM:Chapter 0: ; Chapter 5: The Sensorimotor System
Link ID: 16583 - Posted: 03.29.2012

By Eric Michael Johnson In my cover article out this week in Times Higher Education I featured the life and work of famed primatologist and evolutionary theorist Sarah Blaffer Hrdy. While she never intended to be a radical, she has nevertheless had a radical influence on how primatology and evolutionary biology address female strategies as well as the evolutionary influences on infants. Hrdy graduated summa cum laude from Radcliffe College in Cambridge, Massachusetts and received her Ph.D. in anthropology from Harvard. She is a former Guggenheim fellow and a member of the National Academy of Sciences, the American Academy of Arts and Sciences, and the California Academy of Sciences. She is currently professor emeritus at the University of California, Davis. In our discussion, Hrdy explores both her own life as well as how her personal experiences inspired her to ask different questions than many of her scientific colleagues. While it may not seem like a particularly dramatic idea to emphasize the evolutionary selection pressures on mothers and their offspring, it is a telling insight into the unconscious (and at times fully conscious) sexism that has long been a part of the scientific process. Through her work, in books such as The Woman that Never Evolved, selected by the New York Times as one of its Notable Books of 1981, Mother Nature: A History of Mothers, Infants and Natural Selection, chosen by both Publisher’s Weekly and Library Journal as one of the “Best Books of 1999″ and, her latest, Mothers and Others: The Evolutionary Origins of Mutual Understanding, Hrdy has challenged, and transcended, many of the flawed assumptions that biologists have held dating back to the Victorian era. It is a body of work that continues to provoke and inspire a new generation of scientists and was highly influential in my own scientific work. © 2012 Scientific American,

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 16541 - Posted: 03.19.2012

By Tina Hesman Saey Reading the genetic instruction books of gorillas and chimpanzees has provided more insight into what sets humans apart from their closest primate relatives. The two new studies also provide details about how these primate species may have evolved. Comparing a newly compiled genetic blueprint, or genome, of a western lowland gorilla named Kamilah with the genomes of humans and chimpanzees has revealed that the three species didn’t make a clean break when splitting from a common ancestor millions of years ago. Although humans are more closely related to chimps over about 70 percent of the human genome, about 15 percent of the human genome bears a closer relationship to gorillas. An international group of researchers reports the findings, which come from the first gorilla genome to be deciphered, in the March 8 Nature. A separate study of western chimpanzees, published online March 15 in Science, also has implications for understanding the human-chimp split. The new work shows that humans and chimps have different strategies for shuffling their genetic decks before dealing genes out to their offspring. Neither humans nor chimps shuffle genetic material randomly across the genome. Instead, both species have what are called hot spots, locations in the genetic material where matching sets of chromosomes recombine most often, Gil McVean, a statistical geneticist at the University of Oxford in England and colleagues report. © Society for Science & the Public 2000 - 2012

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 0: ; Chapter 13: Memory, Learning, and Development
Link ID: 16528 - Posted: 03.17.2012

by Michael Marshall DON'T be offended, but you have the brain of a worm. Clusters of cells that are instrumental in building complex brains have been found in a simple worm that barely has a brain at all. The discovery suggests that, around 600 million years ago, primitive worms had the machinery to develop complex brains. They may even have had complex brains themselves - which were later lost. Vertebrates, such as humans and fish, have the biggest and most complex brains in the animal kingdom. Yet all their closest non-vertebrate relatives, such as the eel-like lancelets and sea squirts, have simple brains that lack the dozens of specialised nerve centres typical of complex brains. As a result, evolutionary biologists have long thought that complex brains only evolved after animals with backbones appeared. Not so, says Christopher Lowe of Stanford University in California. His team studies a species of acorn worm, Saccoglossus kowalevskii, which has a rudimentary nervous system made up of two nerve cords and nerves spread out in its skin. The worms live in burrows in the seabed and pull in passing particles of food. Lowe found that young S. kowalevskii have three clusters of cells identical to the ones vertebrates use to shape their brains. In developing vertebrate brains, these clusters - called signalling centres - make proteins that orchestrate the formation of specialised brain regions. The acorn worm, Lowe found, produces the same proteins, and they spread through its developing body in patterns similar to those they follow in the developing vertebrate brain (Nature, DOI: 10.1038/nature10838). © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 0:
Link ID: 16518 - Posted: 03.15.2012

by Elizabeth Pennisi Ever since the human genome was sequenced a decade ago, researchers have dreamed about deciphering DNA from our three great ape cousins as well. Now the final remaining genome, that of the gorilla, is in hand, and it reveals interesting connections between us and them. Surprisingly, parts of our genome are more similar to the gorilla's than they are to the chimp's, and a few of the same genes previously thought key to our unique evolution are key to theirs, too. Today there are four groups of great apes: chimps and bonobos, humans, gorillas, and orangutans. The genome of the chimp—our closest relative—was published in 2005; the orangutan sequence came out in early 2011. Now researchers have analyzed the DNA of a western lowland gorilla named Kamilah, who lives at the San Diego Zoo. In addition, they sequenced DNA from three other gorillas, including one eastern lowland gorilla, a rare species estimated at only 20,000 individuals. "It's essential to have all of the great ape genomes in order to understand the features of our own genome that make humans unique," says Gregory Wray, an evolutionary biologist at Duke University in Durham, North Carolina, who was not involved in the study. Adds paleoanthropologist David Begun of the University of Toronto in Canada: "It will allow us to begin to identify genetic changes specific to humans since our divergence from chimps." Humans and apes are nearly identical in the vast majority of base pairs, or letters of the genetic code: The human genome is 1.37% different from the chimp's; 1.75% different from the gorilla's; and 3.4% different from the orangutan's, researchers from the Wellcome Trust Sanger Institute in Hinxton, U.K., and their colleagues report today in Nature. Although chimps and humans are indeed closest kin, 15% of the human genome more closely matches the gorilla's. Those genes' activity patterns are similar too, says Sanger evolutionary genomicist and lead author of the study Aylwyn Scally: "Some of our functional biology is more gorillalike than chimplike." © 2010 American Association for the Advancement of Science.

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 0: ; Chapter 13: Memory, Learning, and Development
Link ID: 16491 - Posted: 03.08.2012

By NATALIE ANGIER You may think you’re pretty familiar with your hands. You may think you know them like the back of your hand. But as the following exercises derived from the latest hand research will reveal, your pair of bioengineering sensations still hold quite a few surprises up their sleeve. • Make a fist with your nondominant hand, knuckle side up, and then try to extend each finger individually while keeping the other digits balled up tight. For which finger is it extremely difficult, maybe even impossible, to comply? • Now hold your hand palm up, fingers splayed straight out, and try curling your pinky inward without bending the knuckles of any other finger. Can you do it? • Imagine you’re an expert pianist or touch-typist, working on your chosen keyboard. For every note or letter you strike, how many of your fingers will move? • You’re at your desk and, without giving it much thought, you start reaching over for your water bottle, or your pen. What does your hand start doing long before it makes contact with the desired object? And a high-five to our nearest nonhuman kin: • What is the most important difference between a chimpanzee’s hands and our own? (a) the chimpanzee’s thumbs are not opposable; (b) the chimpanzee’s thumbs are shorter than ours; or (c) the chimpanzee’s thumbs are longer than ours. © 2012 The New York Times Company

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior; Chapter 11: Motor Control and Plasticity
Related chapters from MM:Chapter 0: ; Chapter 5: The Sensorimotor System
Link ID: 16443 - Posted: 02.28.2012

By Robin Anne Smith Recently while visiting the National Museum of Natural History in Washington, D.C., I found myself pondering the noggins of some very, very, old apes. Along one wall of the Hall of Human Origins — an exhibit on human evolution that opened in 2010 — were 76 fossil skulls from 15 species of early humans. Looking at these skulls, one thing was clear: millions of years of evolution have given us much bigger brains. In the 8 million to 6 million years since the ancestors of humans and chimps went their separate ways, the human brain more than tripled in size. If the earliest humans had brains the size of oranges, today’s human brains are more akin to cantaloupes. As for our closest primate relatives, the chimps? Their brains haven’t budged. With our big brains we compose symphonies, write plays, carve sculptures and do math. But our big brains came at a cost, some scientists say. In two recent studies, researchers from Duke University suggest the human brain boost may have been powered by a metabolic shift that meant more fuel for brains, and less fuel for muscles. Co-author Olivier Fedrigo told me the full story one morning over coffee near his home in Durham, North Carolina. The human brain isn’t just big, he explained. It’s also hungry. © 2012 Scientific American

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 0:
Link ID: 16421 - Posted: 02.23.2012

Christian Keysers Every time my 18-month-old daughter sees me using a tool, she tries to copy me. She steals my pen to write, and excitedly brushes the few teeth she has when I brush mine. Such a capacity for connecting with and learning from other minds also manifests itself in the empathy we feel with other people's emotions, and in our ability to understand others' goals and help them. Through that ability, we can create and manage the complex social world that is arguably the key to our species' dominance. Ten years ago, human minds were thought to be unique in their ability to connect. But as The Primate Mind shows, there has been a revolution in our understanding. This collection of essays, the result of a 2009 conference organized by primatologist Frans de Waal and ethologist Pier Francesco Ferrari, presents an authoritative, surprising and enriching picture of our monkey and ape cousins. We now know that they have remarkably sophisticated social minds, and that their poor performance in social tasks set by humans was more a result of researchers asking the wrong questions than deficiencies in their experimental subjects. For example, a chapter by psychologists April Ruiz and Laurie Santos explores whether non-human primates can monitor where others are looking and use that information in their own decision-making — a test of whether the animal understands what another perceives. Primatologists first tested this by seeing whether monkeys followed an experimenter's gaze to find a box containing food. The animals performed unexpectedly poorly. But changing the task from cooperation to competition unleashed the primates' true potential: macaques readily stole food from humans who looked away, but refrained from doing so when watched. Placing the task in a setting more relevant to macaque social life, which is less cooperative than our own, emphasized the continuity between our social mind and that of our primate ancestors. © 2012 Nature Publishing Group,

Related chapters from BP7e: Chapter 18: Attention and Higher Cognition; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 14: Attention and Consciousness
Link ID: 16365 - Posted: 02.11.2012

by Lisa Grossman Clint Eastwood might sound an unlikely candidate to help investigate the evolution of the brain, but he has lent a helping hand to researchers doing just that. It turns out that brain regions that do the same job in monkeys and humans aren't always found in the same part of the skull. Previous studies comparing brains across species tended to assume that human brains were just blown-up versions of monkey brains and that functions are carried out by anatomically similar areas. To test this idea, Wim Vanduffel of Harvard Medical School in Boston and the Catholic University of Leuven (KUL) in Belgium, and colleagues scanned the brains of 24 people and four rhesus monkeys while they watched The Good, The Bad and The Ugly. They compared the brain responses of each individual to the same sensory stimulation, and identified which brain areas had similar functions. The majority of the human and monkey brain maps lined up, but some areas with a similar function were in completely different places. The team say the discovery is crucial to building more accurate models of our evolution. "You can't assume that because A and B are close together in the monkey brain, they need to be close together in the human brain," Vanduffel says. Journal reference: Nature Methods, DOI: 10.1038/nmeth.1868 © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior; Chapter 18: Attention and Higher Cognition
Related chapters from MM:Chapter 0: ; Chapter 14: Attention and Consciousness
Link ID: 16355 - Posted: 02.07.2012

By Bruce Bower A chimpanzee in need gets help indeed, on two conditions. Another chimp must both see his or her predicament and receive a blatant help request from the needy animal, a new study finds. Observations in the wild and in previous experiments indicate that chimps seldom help others (SN: 8/27/11, p. 10), but that’s not because the chimps don’t understand their peers’ motivations, as some researchers suspect, says primatologist Shinya Yamamoto of Kyoto University in Japan. In a series of lab tests, chimps who saw one of their relatives unsuccessfully reach for a juice box and then request help picked out a useful tool and passed it to their kin, Yamamoto and colleagues report online February 6 in the Proceedings of the National Academy of Sciences. “Chimpanzees can understand others’ goals from obvious cues and then provide help,” Yamamoto says. This ability to grasp that another individual has a goal in mind based on his or her behavior represents one element of what psychologists call theory of mind — an ability to attribute beliefs, desires, pretending and other mental states to oneself and others. Until now, scientists had studied chimps’ understanding of other chimps’ goals only in competitive situations, such as clashes over food and mates. That fueled suspicion that chimps discern others’ goals only in the heat of such struggles. © Society for Science & the Public 2000 - 2012

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior; Chapter 18: Attention and Higher Cognition
Related chapters from MM:Chapter 0: ; Chapter 14: Attention and Consciousness
Link ID: 16351 - Posted: 02.07.2012

Brian Switek The largest mammals to walk Earth evolved from shrew-like creatures that proliferated after the dinosaurs died out, 65 million years ago. But the change from pipsqueak to behemoth took a while: 24 million generations. Researchers led by Alistair Evans, an evolutionary biologist at Monash University in Clayton, Australia, investigated how maximum body mass increased among 28 orders of mammals on multiple continents during the past 70 million years. By comparing the sizes of the largest members of mammal groups at different points in time, and using modern mammals to estimate the length of a generation for each group, Evans and colleagues tracked the speed at which mammals expanded. Their work is published online in the Proceedings of the National Academy of Sciences1 today. The top speed of mammal inflation was slower than had been thought. Previous estimates of the time it takes for a mouse-sized mammal to grow to the size of an elephant — a 100,000-fold size increase — had been based on observations of much smaller, 'microevolutionary' changes in mice, and ranged from 200,0002 to 2 million generations. “This tells us how much slower so-called macroevolution is compared to microevolution,” says Evans, explaining that small size changes can occur quickly, but larger-scale alterations require more time. To put this into perspective, “if we wiped out everything above the size of a rabbit, it would take at least 5 million generations to get to elephant-sized animals”, a 1,000-fold increase. That translates to about 20 million years. Bucking the trend But not all groups followed the same rule. Whales, the largest mammals ever, grew much more quickly than land-dwelling mammals, needing only about 3 million generations for a 1,000-fold size increase. Evans says that the difference was probably the result of different evolutionary constraints of life in the sea, such as the need to retain body heat, which is easier with a larger body mass. © 2012 Nature Publishing Group

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 0:
Link ID: 16326 - Posted: 01.31.2012

By NATALIE ANGIER Meet the African crested rat, or Lophiomys imhausi, a creature so large, flamboyantly furred and thickly helmeted it hardly seems a member of the international rat consortium. Yet it is indeed a rat, a deadly dirty rat, its superspecialized pelt permeated with potent toxins harvested from trees. As a recent report in the journal Proceedings of the Royal Society B makes clear, the crested rat offers one of the most extreme cases of a survival strategy rare among mammals: deterring predators with chemical weapons. Venoms and repellents are hardly rare in nature: Many insects, frogs, snakes, jellyfish and other phyletic characters use them with abandon. But mammals generally rely, for defense or offense, on teeth, claws, muscles, keen senses or quick wits. Every so often, however, a mammalian lineage discovers the wonders of chemistry, of nature’s burbling beakers and tubes. And somewhere in the distance a mad cackle sounds. Skunks and zorilles mimic the sulfurous, anoxic stink of a swamp. The male duck-billed platypus infuses its heel spurs with a cobralike poison. The hedgehog declares: Don’t quite get the point of my spines? Allow me to sharpen their sting with a daub of venom I just chewed off the back of a Bufo toad. © 2012 The New York Times Company

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior; Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 0: ; Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 16324 - Posted: 01.31.2012