Chapter 6. Evolution of the Brain and Behavior
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By Maureen McCarthy October 30th marked the five-year anniversary of the death of my friend Washoe. Washoe was a wonderful friend. She was confident and self-assured. She was a matriarch, a mother figure not only to her adopted son but to others as well. She was kind and caring, but she didn’t suffer fools. Washoe also happened to be known around the world as the first nonhuman to acquire aspects of a human language, American Sign Language. You see, my friend Washoe was a chimpanzee. Washoe was born somewhere in West Africa around September 1965. Much like the chimpanzees I study here in Uganda, Washoe’s mother cared for her during infancy, nursing her, carrying her, and sharing her sleeping nests with her. That changed when her mother was killed so baby Washoe could be taken from her forest home, then bought by the US Air Force for use in biomedical testing. Washoe was not used in this sort of testing, however. Instead, Drs. Allen and Beatrix Gardner of the University of Nevada chose her among the young chimpanzees at Holloman Aeromedical Laboratory to be cross-fostered. Cross-fostering occurs when a youngster of one species is reared by adults of a different species. In this case, humans raised Washoe exactly as if she were a deaf human child. She learned to brush her teeth, drink from cups, and dress herself, in the same way a human child learns these behaviors. She was also exposed to humans using sign language around her. In fact, humans used only American Sign Language (ASL) to communicate in Washoe’s presence, avoiding spoken English so as to replicate as accurately as possible the learning environment of a young human exposed to sign language. © 2012 Scientific American
SAM KIM, Associated Press SEOUL, South Korea (AP) — An elephant in a South Korean zoo is using his trunk to pick up not only food, but also human vocabulary. An international team of scientists confirmed Friday what the Everland Zoo has been saying for years: Their 5.5-ton tusker Koshik has an unusual and possibly unprecedented talent. The 22-year-old Asian elephant can reproduce five Korean words by tucking his trunk inside his mouth to modulate sound, the scientists said in a joint paper published online in Current Biology. They said he may have started imitating human speech because he was lonely. Koshik can reproduce "annyeong" (hello), "anja" (sit down), "aniya" (no), "nuwo" (lie down) and "joa" (good), the paper says. One of the researchers said there is no conclusive evidence that Koshik understands the sounds he makes, although the elephant does respond to words like "anja." Everland Zoo officials in the city of Yongin said Koshik also can imitate "ajik" (not yet), but the researchers haven't confirmed the accomplishment. Koshik is particularly good with vowels, with a rate of similarity of 67 percent, the researchers said. For consonants he scores only 21 percent. Researchers said the clearest scientific evidence that Koshik is deliberately imitating human speech is that the sound frequency of his words matches that of his trainers. © 2012 Hearst Communications Inc.
By Michael Balter “What would you do with a brain if you had one?” Dorothy’s question to the Scarecrow in The Wizard of Oz elicited one of the movie’s most delightful songs, in which her straw-filled friend assured her that, among other things, he could “think of things I’d never thunk before.” But the Scarecrow seemed to do quite well without one, thus avoiding the high energy costs of fueling and cooling a human brain—which, with an average volume of about 1,400 cubic centimeters, is humongous relative to our body size. How did our brains get so big? Researchers have put forward a number of possible explanations over the years, but the one with the most staying power is an idea known as the social brain hypothesis. Its chief proponent, psychologist Robin Dunbar of Oxford University, has argued for the past two decades that the evolution of the human brain was driven by our increasingly complex social relationships. We required greater neural processing power so that we could keep track of who was doing what to whom. Our expanded brains could have been practical for other things, of course, such as innovations in tool use and food gathering. Most researchers, including Dunbar, agree that these hypotheses are not mutually exclusive. Whatever the reasons for the very large human noggin, there is a lot of explaining to do, because big brains have a lot going against them. The oversized Homo sapiens brain let us take over the planet, build cities, send space probes to Mars, and do all the other marvelous things that we humans are so proud of. But none of these things makes us much better at reproducing, and in terms of evolution, that’s really all that matters. © 2012 The Slate Group, LLC.
By Rachel Ehrenberg Chimps, gibbons and other primates are not just humans’ evolutionary cousins; a new analysis suggests they are also our blood brothers. The A, B and O blood types in people evolved at least 20 million years ago in a common ancestor of humans and other primates, new research suggests. The analysis deepens a mystery surrounding the evolutionary history of the ABO blood system, and should prompt further research into why the different blood groups have persisted over time, Laure Ségurel of the University of Chicago and colleagues report online October 22 in the Proceedings of the National Academy of Sciences. “Their evidence is rather convincing that this is a shared, very old capability that has remained throughout the divergence of the species,” says doctor and transfusion specialist Martin Olsson of Lund University in Sweden. Different forms of a single blood type gene determine what types of molecules sit on your red blood cells: type A molecules, type B molecules, A and B together, or no intact surface molecules in the case of type O (O was originally called type C, then was changed to O for the German “ohne,” meaning “without”). The A, B and O versions of the gene differ only slightly, and scientists have debated two scenarios to explain their evolution. One posits that the A version of the gene existed long ago, and the B and/or O versions later cropped up independently in several species (including humans, gorillas, baboons and chimps). Alternatively, all of those species may have inherited the A and B types from a single ancestor. © Society for Science & the Public 2000 - 2012
Link ID: 17418 - Posted: 10.25.2012
by Ann Gibbons Eating a raw food diet is a recipe for disaster if you're trying to boost your species' brainpower. That's because humans would have to spend more than 9 hours a day eating to get enough energy from unprocessed raw food alone to support our large brains, according to a new study that calculates the energetic costs of growing a bigger brain or body in primates. But our ancestors managed to get enough energy to grow brains that have three times as many neurons as those in apes such as gorillas, chimpanzees, and orangutans. How did they do it? They got cooking, according to a study published online today in the Proceedings of the National Academy of Sciences. "If you eat only raw food, there are not enough hours in the day to get enough calories to build such a large brain," says Suzana Herculano-Houzel, a neuroscientist at the Federal University of Rio de Janeiro in Brazil who is co-author of the report. "We can afford more neurons, thanks to cooking." Humans have more brain neurons than any other primate—about 86 billion, on average, compared with about 33 billion neurons in gorillas and 28 billion in chimpanzees. While these extra neurons endow us with many benefits, they come at a price—our brains consume 20% of our body's energy when resting, compared with 9% in other primates. So a long-standing riddle has been where did our ancestors get that extra energy to expand their minds as they evolved from animals with brains and bodies the size of chimpanzees? © 2010 American Association for the Advancement of Science.
Ewen Callaway “Who told me to get out?” asked a diver, surfacing from a tank in which a whale named NOC lived. The beluga’s caretakers had heard what sounded like garbled phrases emanating from the enclosure before, and it suddenly dawned on them that the whale might be imitating the voices of his human handlers. The outbursts — described today in Current Biology1 and originally at a 1985 conference — began in 1984 and lasted for about four years, until NOC hit sexual maturity, says Sam Ridgway, a marine biologist at National Marine Mammal Foundation in San Diego, California. He believes that NOC learned to imitate humans by listening to them speak underwater and on the surface. A few animals, including various marine mammals, songbirds and humans, routinely learn and imitate the songs and sounds of others. And Ridgway’s wasn’t the first observation of vocal mimicry in whales. In the 1940s, scientists heard wild belugas (Delphinapterus leucas) making calls that sounded like “children shouting in the distance”2. Decades later, keepers at the Vancouver Aquarium in Canada described a beluga that seemed to utter his name, Lagosi. Ridgway’s team recorded NOC, who is named after the tiny midges colloquially known as no-see-ums found near where he was legally caught by Inuit hunters in Manitoba, Canada, in the late 1970s. His human-like calls are several octaves lower than normal whale calls, a similar pitch to human speech. After training NOC to 'speak' on command, Ridgway’s team determined that he makes the sounds by increasing the pressure of the air that courses through his naval cavities. They think that he then modified the sounds by manipulating the shape of his phonic lips, small vibrating structures that sit above each nasal cavity. © 2012 Nature Publishing Group
By Erin Wayman Rusty red stains on the head of a fossilized segmented creature found in southwestern China are a paleontological record-breaker: They are the remains of the oldest arthropod brain ever found. The imprint of the 520-million-year-old critter’s three-part brain indicates that complex nervous systems evolved fairly early in animal evolution, among the ancestors of insects, centipedes and crustaceans. The roughly 7-centimeter-long specimen includes the entire body of Fuxianhuia protensa. The species lived during the Cambrian period, before modern arthropod lineages evolved. The fossil shows F. protensa had a brain composed of three sections that sat in front of the animal’s gut. That’s the same setup seen today in insects, crabs, lobsters and many other arthropods, researchers report in the Oct. 11 Nature. “It was very fascinating and very exciting,” says study coauthor Nicholas Strausfeld, a neuroscientist at the University of Arizona. “It suggests that the organization we see in the modern [arthropod] brains is very ancient.” Scientists had thought early arthropods had simpler brains like those of modern water fleas, fairy shrimp and other tiny freshwater crustaceans called branchiopods. The branchiopod brain consists of two connected parts with a third mass of nervous tissue sitting behind the stomach. Sometime after the branchiopod lineage split from the other arthropods, scientists had assumed, the nervous tissue behind the gut migrated up and connected with the other parts of the brain, Strausfeld says. © Society for Science & the Public 2000 - 2012
Link ID: 17357 - Posted: 10.11.2012
By Bruce Bower A new study suggests that present-day Europeans share more genes with now-extinct Neandertals than do living Africans, at least partly because of interbreeding that took place between 37,000 and 86,000 years ago. Cross-species mating occurred when Stone Age humans left Africa and encountered Neandertals, or possibly a close Neandertal relative, upon reaching the Middle East and Europe in the latter part of the Stone Age, says a team led by geneticist Sriram Sankararaman of Harvard Medical School. The new study, published online October 4 in PLOS Genetics, indicates that at least some interbreeding must have occurred between Homo sapiens and Neandertals, Sankararaman says. But it’s not yet possible to estimate how much of the Neandertal DNA found in modern humans comes from that interbreeding and how much derives from ancient African hominid populations ancestral to both groups. A separate analysis of gene variants in Neandertals and in people from different parts of the world also found signs of Stone Age interbreeding outside Africa. That study, published online April 18 in Molecular Biology and Evolution, was led by evolutionary geneticist Melinda Yang of the University of California, Berkeley. Results from Sankararaman and Yang’s groups “convincingly show that the finding of a higher proportion of Neandertal DNA in non-Africans compared to Africans can be best explained by gene flow from Neandertals into modern humans,” says evolutionary geneticist Johannes Krause of the University of Tübingen in Germany. © Society for Science & the Public 2000 - 2012
by Michael Marshall THE human brain might be the most complex object in the known universe, but a much simpler set of neurons is also proving to be a tough nut to crack. A tiny wasp has brain cells so small, physics predicts they shouldn't work at all. These miniature neurons might harbour subtle modifications, or they might work completely differently from all other known neurons - mechanically. The greenhouse whitefly parasite (Encarsia formosa) is just half a millimetre in length. It parasitises the larvae of whiteflies and so it has long been used as a natural pest-controller. To find out how its neurons have adapted to miniaturisation, Reinhold Hustert of the University of Göttingen in Germany examined the insect's brain with an electron microscope. The axons - fibres that shuttle messages between neurons - were incredibly thin. Of 528 axons measured, a third were less than 0.1 micrometre in diameter, an order of magnitude narrower than human axons. The smallest were just 0.045 μm (Arthropod Structure & Development, doi.org/jfn). That's a surprise, because according to calculations by Simon Laughlin of the University of Cambridge and colleagues, axons thinner than 0.1 μm simply shouldn't work. Axons carry messages in waves of electrical activity called action potentials, which are generated when a chemical signal causes a large number of channels in a cell's outer membrane to open and allow positively charged ions into the axon. At any given moment some of those channels may open spontaneously, but the number involved isn't enough to accidentally trigger an action potential, says Laughlin - unless the axon is very thin. An axon thinner than 0.1 μm will generate an action potential if just one channel opens spontaneously (Current Biology, doi.org/frfwpz). © Copyright Reed Business Information Ltd
by Elizabeth Norton Baboons, like people, really do get by with a little help from their friends. Humans with strong social ties live longer, healthier lives, whereas hostility and "loner" tendencies can set the stage for disease and early death. In animals, too, strong social networks contribute to longer lives and healthier offspring—and now it seems that personality may be just as big a factor in other primates' longevity status. A new study found that female baboons that had the most stable relationships with other females weren't always the highest up in the dominance hierarchy or the ones with close kin around—but they were the nicest. Scientists are increasingly seeing personality as a key factor in an animal's ability to survive, adapt, and thrive in its environment. But this topic isn't an easy one to study scientifically, says primatologist Dorothy Cheney of the University of Pennsylvania. "Research in mammals, birds, fish, and insects shows individual patterns of behavior that can't be easily explained. But the many studies of personality are based on human traits like conscientiousness, agreeableness, or neuroticism. It isn't clear how to apply those traits to animals," Cheney says. Along with a group of scientists—including co-authors Robert Seyfarth, also at the University of Pennsylvania, and primatologist Joan Silk of Arizona State University, Tempe—Cheney has studied wild baboons at the Moremi Game Reserve in Botswana for almost 20 years. Besides providing detailed, long-term observations of behavior in several generations of baboons, the research has yielded a wealth of biological and genetic information. © 2010 American Association for the Advancement of Science.
FRANK JORDANS, Associated Press BERLIN (AP) — More than half the cases of severe intellectual disability caused by genetic defects are the result of random mutations, not inherited, a European study published Thursday suggests. The findings of the small-scale study give hope to parents of children born with a severe intellectual disabilities who are worried about having another baby with the same condition, said Anita Rauch, a researcher at the Institute of Medical Genetics in Zurich who was one of the study's lead authors. It examined the genetic makeup of 51 children, both of their parents and a control group. The study concluded that in at least 55 percent of cases there was no evidence that parents carried faulty genes responsible for the disability. "The average chances of having another child with the same disability are usually estimated at eight percent, but if we know that it was caused by a random mutation the chances of recurrence drop dramatically," Rauch said. Hans-Hilger Ropers, the director of Berlin's Max Planck Institute for Molecular Genetics, who was not involved in the study, said the basic science appeared sound but noted that it excluded children whose parents were blood relatives and so the results could be biased toward random mutations. Ropers said a larger study that included subjects from parts of the world where marriage between blood relatives is more common could produce different results. © 2012 Hearst Communications Inc.
by Emily Underwood A human newborn's brain is uniquely impressionable, allowing social interactions and the environment to shape its development. But this malleability may come with a price, a new study finds. A comparison of juvenile chimpanzee and human brains suggests that differences in the development of myelin—the fatty sheath that surrounds nerve fibers—may contribute not only to our unusual adaptability, but also to our vulnerability to psychiatric diseases that start in early adulthood. Research increasingly suggests that psychiatric illnesses like depression and schizophrenia may involve problems with the timing of neural signals, says Douglas Fields, a neuroscientist at the National Institutes of Health in Bethesda, Maryland, who was not involved in the study. The nerve fibers, or axons, that connect neurons are usually protected by myelin, which enhances the neural relay of information throughout the brain. "Myelin speeds transmission of information [by] at least 50 times," Fields says, "so it matters a great deal whether or not an axon becomes myelinated." Humans start out with comparatively few myelinated axons as newborns. We experience a burst of myelin development during infancy that is followed by a long, slow growth of myelin that can last into our thirties, says Chet Sherwood, a neuroscientist at George Washington University in Washington, D.C., and a co-author of the new study. In contrast, other primates, such as macaques, start out with significantly more myelin at birth, but stop producing it by the time they reach sexual maturity. However, Sherwood says, "extraordinarily little data exists" on brain growth and the development of myelin in our closest genetic relatives, chimpanzees. © 2010 American Association for the Advancement of Science.
Sandrine Ceurstemont, editor, New Scientist TV Chimps may be similar to us in many ways but they can't compete when it comes to brain size. Now for the first time we can see when the differences emerge by tracking the brain development of unborn chimps. As seen in this video, Tomoko Sakai and colleagues from Kyoto University in Japan subjected a pregnant chimp to a 3D ultrasound to gather images of the fetus between 14 and 34 weeks of development. The volume of its growing brain was then compared to that of an unborn human. The team found that brain size increases in both chimps and humans until about 22 weeks, but after then only the growth of human brains continues to accelerate. This suggests that as the brain of modern humans rapidly evolved, differences between the two species emerged before birth as well as afterwards. The researchers now plan to examine how different parts of the brain develop in the womb, particularly the forebrain, which is responsible for decision-making, self-awareness and creativity. If you enjoyed this post, watch the first video MRI of unborn twins or the first MRI movie of a baby's birth. © Copyright Reed Business Information Ltd.
by Virginia Morell Bumblebees foraging in flowers for nectar are like salesmen traveling between towns: Both seek the optimal route to minimize their travel costs. Mathematicians call this the "traveling salesman problem," in which scientists try to calculate the shortest possible route given a theoretical arrangement of cities. Bumblebees, however, take the brute-force approach: For them, it's simply a matter of experience, plus trial and error, scientists report in the current issue of PLoS Biology. The study, the first to track the movements of bumblebees in the field, also suggests that bumblebees aren't using cognitive maps—mental recreations of their environments—as some scientists have suggested, but rather are learning and remembering the distances and directions that need to be flown to find their way from nest to field to home again. A team of researchers from Queen Mary, University of London outfitted seven bumblebees with tiny radar transponders, which they stuck on the bees' backs with double-sided tape. They trained the bees to forage nectar from five blue artificial flowers (see video). Each artificial flower had a yellow landing platform and a single drop of sucrose, just enough to fill one-fifth of a bumblebee's tank capacity, to ensure that the bees would visit all five flowers on each foraging bout. The scientists placed the flowers in a field at Rothamsted Research, a biological research station north of London, in October—a time of year when there are few natural sources of nectar and pollen and the bees are more likely to focus on the artificial flowers. They arranged the flowers in a pentagon and spaced them 50 meters apart; that distance is more than three times as far as bumblebees can see, so the bees must actively fly around to locate their next target. A motion-triggered Webcam was attached to each flower to record the bees' visits. Then, every day for a month, each bee was freed to forage for 7 hours. © 2010 American Association for the Advancement of Science
by Virginia Morell Imagine hearing a distant roll of thunder and wondering what caused it. Even asking that question is a sign that you, like all humans, can perform a type of sophisticated thinking known as "causal reasoning"—inferring that mechanisms you can't see may be responsible for something. But humans aren't alone in this ability: New Caledonian crows can also reason about hidden mechanisms, or "causal agents," a team of scientists report today in the Proceedings of the National Academy of Sciences. It's the first time that this cognitive ability has been experimentally demonstrated in a species other than humans, and the method may help scientists understand how this type of reasoning evolved, the researchers say. Causal reasoning is "one of the most powerful human abilities," says Alison Gopnik, a psychologist at the University of California, Berkeley, who was not involved in the study. "It's at the root of our understanding of the world and one another." Indeed, it is the key mental ability for many things humans do, including inventing, making, and using tools. We develop this ability early in life: A 2007 study in Developmental Psychology reported that human infants as young as 7 months old understand that when a beanbag is tossed from behind a screen, something or someone must have thrown it. The infants infer that a "causal agent" must be involved in the motion of the flying beanbag. But why should this ability be limited to humans? "It seems like it would make good sense for crows and many other animals to be able to distinguish between the wind rustling tree limbs and an unseen animal crashing through the canopy," says Alex Taylor, an evolutionary psychologist at the University of Auckland in New Zealand and the lead author of the new study. Because New Caledonian crows are also inventive and skillful tool-users, Taylor and his colleagues thought the birds might have causal reasoning skills similar to those of humans. © 2010 American Association for the Advancement of Science
By Susan Milius Male killer whale thirtysomethings appear to live longer when mom’s nearby, especially if mom has stopped reproducing. This survival bonus for mama’s boys could be the first evidence from nonhuman animals for an evolutionary advantage to living long after reproduction stops. In the Pacific Northwest, a male killer whale’s risk of disappearing, presumably from dying, seems to jump almost 14-fold if he’s older than 30 and his post-reproductive mom dies, says marine biologist Emma Foster of the University of Exeter in England. Daughters get a more modest fivefold boost, Foster and her colleagues report in the Sept. 14 Science. Both sons and daughters typically spend their lives swimming with mom and other maternal relatives. Even though a female killer whale may stop having babies in her 30s or 40s, she can live into her 90s. Males typically don’t live as long, but they can keep siring offspring throughout their lives. Keeping sons alive as long as possible should therefore maximize the chances that the mom’s genes will be carried into further generations. So, Foster says, the whale survival boost may help explain how female killer whales have evolved the longest post-reproductive life span known among nonhuman animals. “Menopause is still one of the great mysteries of biology,” Foster says. Evolution works as genes for traits multiply through greater numbers of offspring, so what drives the evolution of a no-babies phase of adulthood has been a puzzle. Some theorists have argued that this post-reproductive life span is just a side effect of other survival-boosting traits, but other biologists have searched for some benefit in staying alive post-baby-bearing. The evidence is “quite heavily debated,” as Foster puts it. © Society for Science & the Public 2000 - 2012
by Carrie Arnold More than a kilometer below the ocean's surface, where the sunless water is inky black, scientists have documented one of nature's most spectacular living light shows. An underwater survey has found that roughly 20% of bottom-dwelling organisms in the Bahamas produce light. Moreover, all of the organisms surveyed by the researchers proved to have visual senses tuned to the wavelengths of light generated by this bioluminescence. The work speaks to the important role self-generated light plays in deep-sea communities, marine biologists say. Bioluminescence has evolved many times in marine species and may help organisms find mates and food or avoid predators. In the middle depths of the ocean—the mesopelagic zone that is located 200 to 1000 meters below the surface—the vast majority of organisms can bioluminesce. Much less was known about bioluminescence in organisms living close to the sea floor. Such benthic organisms are harder to visit or sample and therefore study, says Sönke Johnsen, a marine biologist at Duke University in Durham, North Carolina. With Tamara Frank, a marine biologist at Nova Southeastern University in Florida, and colleagues, Johnsen recently explored four sites in the northern Bahamas in a submersible. The researchers collected the benthic organisms by suctioning them gently into a lightproof box with a vacuum hose. Once back in their shipboard labs, they stimulated bioluminescence in the captured organisms by softly prodding the animals. Those that glowed were tested further to determine the exact wavelength of light emitted. © 2010 American Association for the Advancement of Science
by Colin Barras ON THE face of it, the placebo effect makes no sense. Someone suffering from a low-level infection will recover just as nicely whether they take an active drug or a simple sugar pill. This suggests people are able to heal themselves unaided - so why wait for a sugar pill to prompt recovery? New evidence from a computer model offers a possible evolutionary explanation, and suggests that the immune system has an on-off switch controlled by the mind. It all starts with the observation that something similar to the placebo effect occurs in many animals, says Peter Trimmer, a biologist at the University of Bristol, UK. For instance, Siberian hamsters do little to fight an infection if the lights above their lab cage mimic the short days and long nights of winter. But changing the lighting pattern to give the impression of summer causes them to mount a full immune response. Likewise, those people who think they are taking a drug but are really receiving a placebo can have a response which is twice that of those who receive no pills (Annals of Family Medicine, doi.org/cckm8b). In Siberian hamsters and people, intervention creates a mental cue that kick-starts the immune response. There is a simple explanation, says Trimmer: the immune system is costly to run - so costly that a strong and sustained response could dangerously drain an animal's energy reserves. In other words, as long as the infection is not lethal, it pays to wait for a sign that fighting it will not endanger the animal in other ways. © Copyright Reed Business Information Ltd.
by Sarah C. P. Williams To run or to hide? For an elk trying to avoid a gun-wielding hunter, the choice depends on personality. Gutsy, bold elk are more likely to sprint faster and farther when they encounter a threat. Others shy away from danger in the first place, shunning human-frequented areas and exploring new places less often. Human hunters more often kill animals that fall into the bolder group, new research has found. And this tendency could put evolutionary pressure on elk populations to become more skittish, the scientists hypothesize. "There has been a lot of work in the past on humans selecting for appearance of animals," says biologist John Fryxell of the University of Guelph in Canada, who was not involved in the study. "What really distinguishes this paper is the fact that it focuses on selecting behavior." Previous studies have found that hunters are most likely to target animals that are the biggest or have the largest antlers. To test whether hunting also selected for elk with certain behavioral traits, researchers led by biologist Simone Ciuti of the University of Alberta in Edmonton, Canada, put GPS collars on 122 male and female elk (Cervus elaphus) in the Canadian Rockies and monitored their movement throughout the year. By the end of hunting season, 25 elk had been killed by hunters. The researchers analyzed the GPS data to determine whether the way elk move correlated with whether they’d been killed. Hunters, they found, typically picked the elk that moved more often and traveled longer distances and that were more likely to spend time in open areas. The trend was particularly noticeable for male elk, which had larger variation in their movement patterns. The researchers found much less difference in movement patterns between the killed and nonkilled females. © 2010 American Association for the Advancement of Science.
By Gary Stix Evolutionary psychology has typically tried to identify the piece parts of human cognition shaped by the rigors of natural selection. New questions have arisen in this contentious discipline about what exactly is on that parts list—or whether the list itself really exists. One of the foremost debating points centers on whether the brain consists of a series of Lego-like modules, each one produced from evolutionary adaptations that resulted in mental tools for things like going after Mastodons, forming clans and communicating the daily incidentals related to food, shelter and mating. Another way to think about all this is to invoke the metaphor of a Swiss-Army knife, with each adaptive module the equivalent of a corkscrew, nail clipper or a myriad of cutting implements. The revisionist viewpoint rejects this neat tailoring of mental functioning championed by psychologists like Leda Cosmides and John Tooby. Instead, upstarts trot out the human hand as a replacement analogy for the pocket knife, a single all-purpose implement that can poke, prod, pull and push. A walk through the new thinking on evolutionary psychology appears in the Aug. 5 edition of the Philosophical Transactions of the Royal Society of London B. (The original journal, founded in 1665, was the first anywhere to deal solely with science—and this issue is open to everyone for a download.) The metaphor of the hand, notes Cecilia Heyes of Oxford in an introductory article, alludes to the ability of a limb extension that can “strip the defensive spines from a piece of fruit, making it safe to eat, but in Thai dancing it can also signal the smallest nuances of emotion. The human hand performs with equal facility a vast array of tasks that natural selection did and did not ‘foresee’.” © 2012 Scientific American,
Link ID: 17218 - Posted: 08.30.2012