by Greg Miller Vampire bats must consume 70% to 80% of their body weight in blood almost every night. To satisfy this never-ending thirst, they bite their prey—typically sleeping livestock, but also the occasional human toe poking out from under the covers—in areas where warm blood courses close to the surface. Now scientists have discovered a molecular heat sensor that helps the bats home in on their dinner. Researchers led by neuroscientist David Julius of the University of California, San Francisco, searched for genes related to known molecular heat sensors in several bat species collected by colleagues in Venezuela. In the vampire bat Desmodus rotundus, the researchers found evidence of a change in how cells use the gene for an ion channel called TRPV1. This molecular pore resides on the surface of sensory neurons, and in other animals it stimulates the neurons in response to painful heat or capsaicin, the compound that gives chili peppers their sting. In Desmodus, neurons in the nerve connected to the small heat-sensing pits near the bat's nose splice together different parts of the Trpv1 gene to produce a version of the ion channel that's shorter at one end than the version made by other animals, including bats that feed on fruit, nectar, or insects, the team reports in tomorrow's Nature. To investigate the workings of the shorter TRPV1 channel, Julius and colleagues inserted the genetic instructions into frog egg cells, causing the cells to make the channels and stick them on their surface. Probing the egg cells with electrodes, the researchers discovered that the short version of TRPV1 opens at about 31˚C, which in a neuron would increase firing. That's well below the 40˚C or higher threshold for the long version of TRPV1. © 2010 American Association for the Advancement of Science.

Keyword: Pain & Touch; Animal Migration
Link ID: 15644 - Posted: 08.04.2011

By Jason Castro If you’ve never watched bees carefully, you’re missing out. Looking up close as they gently curl and uncoil their tapered mouths toward food, you sense that they’re not just eating, but enjoying. Watch a bit more, and the hesitant flicks and sags of their antennae seem to convey some kind of emotion. Maybe annoyance? Or something like agitation? Whether bees really experience any of these things is an open scientific question. It’s also an important one with implications for how we should treat not just bees, but the great majority of animals. Recently, studies by Geraldine Wright and her colleagues at Newcastle University in the UK have rekindled debate over these issues by showing that honeybees may experience something akin to moods. Using simple behavioral tests, Wright’s research team showed that like other lab-tested brooders -- which so far include us, monkeys, dogs, and starlings -- stressed bees tend to see the glass as half empty. While this doesn’t (and can’t) prove that bees experience human-like emotions, it does give pause. We should take seriously the possibility that it feels like something to be an insect. As invertebrates -- animals without backbones -- bees are representatives of a diverse group accounting for over 95 percent of animal species. But despite their prevalence, not to mention their varied and often nuanced behaviors, invertebrates are sometimes regarded as life’s second string, as a mindless and unfeeling band of alien critters. If that seems a bit melodramatic, just consider our willingness to boil some of them alive. © 2011 Scientific American,

Keyword: Emotions; Evolution
Link ID: 15643 - Posted: 08.04.2011

THE extraordinary success of Homo sapiens is a result of four things: intelligence, language, an ability to manipulate objects dexterously in order to make tools, and co-operation. Over the decades the anthropological spotlight has shifted from one to another of these as the prime mover of the package, and thus the fundament of the human condition. At the moment co-operation is the most fashionable subject of investigation. In particular, why are humans so willing to collaborate with unrelated strangers, even to the point of risking being cheated by people whose characters they cannot possibly know? Evidence from economic games played in the laboratory for real money suggests humans are both trusting of those they have no reason to expect they will ever see again, and surprisingly unwilling to cheat them—and that these phenomena are deeply ingrained in the species’s psychology. Existing theories of the evolution of trust depend either on the participants being relatives (and thus sharing genes) or on their relationship being long-term, with each keeping count to make sure the overall benefits of collaboration exceed the costs. Neither applies in the case of passing strangers, and that has led to speculation that something extraordinary, such as a need for extreme collaboration prompted by the emergence of warfare that uses weapons, has happened in recent human evolution to promote the emergence of an instinct for unconditional generosity. Leda Cosmides and John Tooby, two doyens of the field, who work at the University of California, Santa Barbara, do not agree. They see no need for extraordinary mechanisms and the latest study to come from their group (the actual work was done by Andrew Delton and Max Krasnow, who have just published the results in the Proceedings of the National Academy of Sciences) suggests they are right. It also shows the value of applying common sense to psychological analyses—but then of backing that common sense with some solid mathematical modelling. © The Economist Newspaper Limited 2011.

Keyword: Evolution
Link ID: 15642 - Posted: 08.04.2011

By RICHARD A. FRIEDMAN, M.D. Shortly after the singer Amy Winehouse, 27, was found dead in her London home, the airwaves were ringing with her popular hit “Rehab,” a song about her refusal to be treated for drug addiction. The official cause of Ms. Winehouse’s death won’t be announced until October pending toxicology reports, but her highly publicized battle with alcohol and drug addiction seems to have played a significant role. Indeed, her mother echoed a sentiment heard everywhere when she told The Sunday Mirror that her daughter’s death was “only a matter of time.” But was it? Why is it that some people survive drug and alcohol abuse, even manage their lives with it, while others succumb to addiction? It’s a question scientists have been wrestling with for decades, but only recently have they begun to find answers. Illicit drug use in the United States, as in Britain, is very common and usually begins in adolescence. According to the 2008 National Survey of Drug Use and Health, 46 percent of Americans have tried an illicit drug at some point in their lives. But only 8 percent have used an illicit drug in the past month. By comparison, 51 percent have used alcohol in the past year. Most people who experiment with drugs, then, do not become addicted. So who is at risk? © 2011 The New York Times Company

Keyword: Drug Abuse
Link ID: 15641 - Posted: 08.02.2011

By PAM BELLUCK Many people consider dyslexia simply a reading problem in which children mix up letters and misconstrue written words. But increasingly scientists have come to believe that the reading difficulties of dyslexia are part of a larger puzzle: a problem with how the brain processes speech and puts together words from smaller units of sound. Now, a study published last week in the journal Science suggests that how dyslexics hear language may be more important than previously realized. Researchers at the Massachusetts Institute of Technology have found that people with dyslexia have more trouble recognizing voices than those without dyslexia. John Gabrieli, a professor of cognitive neuroscience, and Tyler Perrachione, a graduate student, asked people with and without dyslexia to listen to recorded voices paired with cartoon avatars on computer screens. The subjects tried matching the voices to the correct avatars speaking English and then an unfamiliar language, Mandarin. Nondyslexics matched voices to avatars correctly almost 70 percent of the time when the language was English and half the time when the language was Mandarin. But people with dyslexia were able to do so only half the time, whether the language was English or Mandarin. Experts not involved in the study said that was a striking disparity. © 2011 The New York Times Company

Keyword: Dyslexia; Hearing
Link ID: 15640 - Posted: 08.02.2011

Zoë Corbyn The placenta has long been thought of as a passive organ that simply enables a fetus to take up nutrients from its mother. But new research in mice shows that when calories are restricted, the placenta steps up to the plate – actively sacrificing itself to protect the fetal brain from damage. Researchers at Cambridge University, UK, examined what happened to 10 fetuses from 8 mice when their pregnant mothers were deprived of food for 24 hours – as might happen in the wild — about mid-way through gestation. This point in pregnancy is critical in the development of the hypothalamus, the part of the brain that controls primal urges, including maternal instincts. Behavioural neuroscientists Kevin Broad and Barry Keverne found that the placenta responded by breaking down its own tissues, recycling proteins inside its cells to provide a steady supply of nutrients to the developing hypothalamus despite the mother's interrupted food intake. Their study is published today in the Proceedings of the National Academy of Sciences1. "We didn't know before that this protection of the fetus goes on," says Keverne. "I expected the lack of food to affect the fetal brain and the placenta equally, but instead we see the placenta acting as an interface to make sure the fetuses' particular stage of brain development is protected." © 2011 Nature Publishing Group

Keyword: Development of the Brain
Link ID: 15639 - Posted: 08.02.2011

David Cyranoski The largest-ever study of the genetics of depression is set to go ahead in China, after a major survey found that the condition largely has the same triggers and symptoms there as in the West — albeit with a few startling exceptions. Previous studies on twins in Sweden have shown that genetics explains about 40% of a woman's risk of depression, and about 30% of a man's1. Finding the genes responsible may help to make treatments more targeted and thus more effective, but identifying those genes has proved exceedingly difficult. The sheer diversity of symptoms involved in depression can make it difficult to be sure that patients actually have the same underlying disorder, and any genetic contribution is likely to come from many genes, each having a small effect. "It was clear that we needed a very large sample, [one that was] ethically homogenous, and to do it cheaply," says molecular geneticist Jonathan Flint at the University of Oxford, UK. Flint is one of the leaders on the CONVERGE consortium, a collaboration between Oxford, the Virginia Commonwealth University in Richmond and 53 provincial mental-health centres in China. "The only place that fitted was China. Where else could we access that many people and have sufficient control over quality?" asks Flint. The consortium, which began in 2008 with a £1.5-million (US$2.5-million) grant from UK charitable funder the Wellcome Trust, chose to study only women, who are known to have a two-fold higher risk of depression across the globe than men. They also selected only patients whose four grandparents were all Han Chinese; and only those with recurrent depression, an indicator of a likely genetic component. © 2011 Nature Publishing Group,

Keyword: Depression
Link ID: 15638 - Posted: 08.02.2011

By DAN HURLEY Early in the evening of June 25, 1995, hours after the birth of his first and only child, the course of Dr. Alberto Costa’s life and work took an abrupt turn. Still recovering from a traumatic delivery that required an emergency Caesarean section, Costa’s wife, Daisy, lay in bed, groggy from sedation. Into their dimly lighted room at Methodist Hospital in Houston walked the clinical geneticist. He took Costa aside to deliver some unfortunate news. The baby girl, he said, appeared to have Down syndrome, the most common genetic cause of cognitive disabilities, or what used to be called “mental retardation.” Costa, himself a physician and neuroscientist, had only a basic knowledge of Down syndrome. Yet there in the hospital room, he debated the diagnosis with the geneticist. The baby’s heart did not have any of the defects often associated with Down syndrome, he argued, and her head circumference was normal. She just didn’t look like a typical Down syndrome baby. And after all, it would take a couple weeks before a definitive examination would show whether she had been born with three copies of all or most of the genes on the 21st chromosome, instead of the usual two. Costa had dreamed that a child of his might grow up to become a mathematician. He had even prevailed upon Daisy to name their daughter Tyche, after the Greek goddess of fortune or chance, and in honor of the Renaissance astronomer Tycho Brahe. Now he asked the geneticist what the chances were that Tyche (pronounced Tishy) really had Down syndrome. “In my experience,” he said, “close to a hundred percent.” © 2011 The New York Times Company

Keyword: Development of the Brain; Neurogenesis
Link ID: 15637 - Posted: 08.02.2011

By Laura Sanders In a fast-moving car, the brain can hit the brakes faster than the foot. By relying on brain waves that signal the intent to jam on the brakes, a new technology could shave critical milliseconds off the reaction time, researchers report online July 28 in the Journal of Neural Engineering. The work adds to a growing trend in car technology that assists drivers. Though it may eventually lead to improvements in emergency braking, the new brain signal technology isn’t ready for the road. “As a basic science study, I was quite impressed with it,” says cognitive neuroscientist Raja Parasuraman of George Mason University in Fairfax, Va. “I just think a lot more needs to be done.” In the study, computer scientist Stefan Haufe of the Berlin Institute of Technology in Germany and his colleagues measured brain wave changes while participants drove in a car simulator. The participants drove around 60 miles per hour, following a lead car on a curvy road with heavy oncoming traffic. Every so often the lead car would slam on its brakes, so that the participant would have to either do the same or crash. For most drivers, the lag between the lead car stopping and themselves slamming the brakes was around 700 milliseconds. Particular neural signatures were evident during this lag time, and they could be early indicators that the drivers wanted to brake. “Our approach was to obtain the intention of the driver faster than he could actually act,” Haufe says. “That’s what the neural signature is good for.” © Society for Science & the Public 2000 - 2011

Keyword: Robotics; Attention
Link ID: 15636 - Posted: 07.30.2011

By Laura Sanders Though the diagnostic code scrawled on a doctor’s chart might suggest otherwise, each person who lives with an autism spectrum disorder has a very private disease. An avalanche of new genetic data shows clearly that there is no single culprit in autism. Each case stems from a unique jumble of genetic and environmental triggers, which makes figuring out one clear cause for every person’s disorder impossible. This news may sound grim, but it contains a glimmer of hope. By uncovering huge numbers of genetic aberrations, scientists say, they have the opportunity to begin piecing together all of the disparate threads weaving through autism to find the commonalities. A suite of new studies have identified numerous genetic changes that may have a role in the disorder, some of which could help scientists understand why boys are more vulnerable than girls, for instance. And some of the genes affected by these changes appear to be players in common networks of molecular activity in the brain. New work shows that many genetic changes impair nerve cell communication. Understanding this process and finding other common cellular activities that go awry may lead to powerful ways to combat autism, regardless of what caused it. “Parents and families have been tremendously patient,” says child psychiatrist and geneticist Matthew State of the Yale University School of Medicine. “They’ve been promised a lot by geneticists for a long time, and it’s been tougher than any of us expected to deliver.” But the flood of studies in the last few months reflects tremendous progress, he says. “These are all, in their own way, making a chink in the armor.” © Society for Science & the Public 2000 - 2011

Keyword: Autism; Genes & Behavior
Link ID: 15635 - Posted: 07.30.2011

Sandrine Ceurstemont, video producer Can you trust a moving shadow? Not according to this dramatic illusion created by animator David Phillips (see video above). If you follow the shadow as it moves around, it will look like the ball is bouncing all over the place. But try looking at the animation again - this time while fixing your eyes on the ball's trajectory - and you'll see that it's always following the same route. So why is an artificial shadow able to trick our brain and override an object's actual motion? Back in 1997, Daniel Kersten and his team from University of Minnesota first studied the effect and found that it is consistent with how our visual system uses shadows to determine the layout of a scene. We assume a fixed viewpoint illuminated by a stationary light source, where an object is paired with its shadow. So when a fake shadow is introduced into an animation, our brain is primed to link it to the moving object above since in the real world this type of motion wouldn't arise from independent objects. "The robustness of this illusion may in fact be a consequence of perception's ability to use global constraints which are needed to cope with the complexity and ambiguity of natural viewing," write Kersten and colleagues. "Specifically, this may owe in part to the fact that dynamic displays contain an important piece of information not available in static scenes: the correlation between the motion of an object and its shadow." The team found that the effect persists even when the shadow has the wrong contrast polarity or brightness. © Copyright Reed Business Information Ltd.

Keyword: Vision
Link ID: 15634 - Posted: 07.30.2011

By SINDYA N. BHANOO The Marcgravia evenia plant has dish-shaped leaves that bounce back echoes that bats can identify through echolocation. The vine, Marcgravia evenia, has dish-shaped leaves that bounce back echoes that are easy for the bats to identify through echolocation. “They have a very special kind of echo,” said the lead author, Ralph Simon, a biologist at the University of Ulm in Germany. “This echo is very loud and has a constant signature from different angles.” Dr. Simon and his colleagues trained bats in the laboratory to look for a feeder. They then placed it in different locations — attached to a dish-shaped leaf, an ordinary leaf or no leaf. The bats located the feeder in half the time when it was attached to a dish-shaped leaf. And that was good for the bats and the vine. “For the plants, it increases the success of pollination,” Dr. Simon said. “For the bats, it’s good because it helps them find the flowers faster — they have to make several hundred visits to flowers every night.” The study, which appears in the current issue of the journal Science, is one of the first to focus on the evolution of echo-acoustic signals in plants. Several hundred species of plants in the Neotropics rely on about 40 nectar-feeding bat species for pollination, Dr. Simon said. © 2011 The New York Times Company

Keyword: Hearing; Evolution
Link ID: 15633 - Posted: 07.30.2011

by Anil Ananthaswamy THINK for a moment about a time before you were born. Where were you? Now think ahead to a time after your death. Where will you be? The brutal answer is: nowhere. Your life is a brief foray on Earth that started one day for no reason and will inevitably end. But what a foray. Like the whole universe, your consciousness popped into existence out of nothingness and has evolved into a rich and complex entity full of wonder and mystery. Contemplating this leads to a host of mind-boggling questions. What are the odds of my consciousness existing at all? How can such a thing emerge from nothingness? Is there any possibility of it surviving my death? And what is consciousness anyway? Answering these questions is incredibly difficult. Philosopher Thomas Nagel once asked, "What is it like to be a bat?" Your response might be to imagine flying around in the dark, seeing the world in the echoes of high-frequency sounds. But that isn't the answer Nagel was looking for. He wanted to emphasise that there is no way of knowing what it is like for a bat to feel like a bat. That, in essence, is the conundrum of consciousness. Neuroscientists and philosophers fall into two broad camps. One thinks that consciousness is an emergent property of the brain and that once we fully understand the intricate workings of neuronal activity, consciousness will be laid bare. The other doubts it will be that simple. They agree that consciousness emerges from the brain, but argue that Nagel's question will always remain unanswered: knowing every detail of a bat's brain cannot tell us what it is like to be a bat. This is often called the "hard problem" of consciousness, and seems scientifically intractable - for now. © Copyright Reed Business Information Ltd.

Keyword: Attention
Link ID: 15632 - Posted: 07.30.2011

by Cian O'Luanaigh Here's a piece of good news for people who have had a gastric bypass – not only will you eat less, you may also start to eat more healthily. The most common form of bariatric – anti-obesity – surgery is the "Roux-en-Y" gastric bypass, which involves stapling the stomach so a small pouch is made at the top, which is then connected directly to the small intestine. This bypasses most of the stomach and the duodenum so the patient feels full quicker. The vertical-banded gastroplasty is an alternative technique which reduces the volume of the stomach without bypassing any part of the intestine, restricting how much the patient can eat at any one time. After people undergo gastric bypass operations, it is not uncommon for them to report that their eating habits have changed. To investigate these claims, Carel le Roux and colleagues from Imperial College London asked 16 people who had undergone either type of bariatric surgery six years before to fill in a survey about their dietary preferences after the operation. People who had had a gastric bypass reported eating a lower proportion of fat after surgery than those with a vertical-banded gastroplasty. To find out why this was so, the team carried out either a gastric bypass or a sham operation on 26 rats. © Copyright Reed Business Information Ltd.

Keyword: Obesity; Hormones & Behavior
Link ID: 15631 - Posted: 07.30.2011

by Andy Coghlan A hereditary form of blindness has been delayed or reversed for the first time by a daily drug treatment. The drug is the first to benefit people with a disease of their mitochondria, the energy powerhouses of cells. There had been no way to halt the rapid onset of blindness in people with the most common mitochondrial disease, called Leber's hereditary optic neuropathy. It strikes men in their twenties, leading to total blindness within three to six months of the first symptoms appearing. But after receiving a drug called idebenone for six months, some people whose sight had begun to deteriorate reported drastic improvements in their vision that continued after the trial ended. In the trial, 55 people received idebenone and 30 were given a placebo. After six months, 11 people who received idebenone could read an extra two lines on a standard vision chart – and nine people who could not read any letters at the outset could by the end. "This is not a cure, but it's a significant effect," says team leader Patrick Chinnery of Newcastle University in the UK. It is also the first time that an inherited mitochondrial disease has been successfully treated. "This trial tells us there's hope for this and other mitochondrial diseases," says Chinnery. © Copyright Reed Business Information Ltd.

Keyword: Vision
Link ID: 15630 - Posted: 07.30.2011

By Rachael Rettner Amy Winehouse's family has reportedly said the singer may have died from alcohol withdrawal. The family believes withdrawal may have induced fatal seizures in the singer, according to Entertainment Weekly. But is it really possible to die from alcohol withdrawal? Yes, experts say — though it's not common. "Somebody who's been a drinker and consumed a lot of alcohol for a number of years probably could have severe seizures," said Dr. Robert Schwartz, chairman of family medicine at the University of Miami Miller School of Medicine. Such seizures may cause an individual to aspirate food (inhale it through the trachea) that comes up from their stomach, possibly leading to choking and death, Schwartz said. Hitting your head during a seizure can also be lethal. Common withdrawal symptoms from alcohol include difficulty sleeping, sweating and heart palpitations. Withdrawal can also cause delirium, hallucinations, rapid heart rate, high blood pressure and hyperventilation, Schwartz said. Alcohol is toxic to the body, causing changes to a person's metabolism and central nervous system, Schwartz said. But the body of an alcoholic has adapted to this new environment, Schwartz said. So abstaining from the drug completely can be dangerous. "Your body develops a homeostasis with alcohol," Schwartz said. "As soon as you take it away, you're upsetting that balance," Schwartz said. © 2011 msnbc.com

Keyword: Drug Abuse
Link ID: 15629 - Posted: 07.30.2011

By Cari Nierenberg It's truly a sob story for those prone to waterworks displays: Shedding tears only improved mood in one-third of cryers who kept tabs of their bawling behaviors, finds recent research. Apparently weeping isn't the cathartic emotional release it's often cracked up to be, sniff, sniff. Please pass the tissues. Science has previously looked into boo-hooing with mixed results: After viewers in a lab setting watched a sad film clip, weeping was rarely found to boost mood -- but this might not be the best place to burst into heartfelt tears. Other studies have asked participants to recall past crying episodes. But retrospective surveys might not necessarily reflect actual behavior since memory can be selective, and people might not remember those times when wailing made them feel worse. This new study, currently published online in the Journal of Research in Personality, asked 97 women aged 18 to 48 in the Netherlands to keep a daily crying and mood diary over a two-to three-month period. Men were not included in this experiment because the data was originally collected as part of a larger trial exploring the link between crying and the menstrual cycle. Each night, participants logged their daily mood, their urge to cry, and whether they shed any tears. If they wept, they kept further details of each sob session, such as the reason for it, how long it lasted, how intensely they bawled, where it occurred, whether other people were around and how they felt afterward. © 2011 msnbc.com

Keyword: Emotions
Link ID: 15628 - Posted: 07.30.2011

NIH-funded scientists have developed a strain of mice with a built-in off switch that can selectively shut down the animals’ serotonin-producing cells, which make up a brain network controlling breathing, temperature regulation, and mood. The switch controls only the serotonin-producing cells, and does not affect any other cells in the animal’s brains or bodies. When the researchers powered down the animals’ serotonin cells, the animals failed to sufficiently step up their breathing to compensate for an increase of carbon dioxide in the air, and their body temperatures dropped to match the surrounding temperature. The finding has implications for understanding sudden infant death syndrome, or SIDS, which has been linked to low serotonin levels, and is thought to involve breathing abnormalities and problems with temperature control. The finding may also provide insight into depressive disorders, which also involve serotonin metabolism. The study results appear in the current issue of the journal Science. SIDS is the death of an infant before his or her first birthday that cannot be explained after a complete autopsy, an investigation of the scene and circumstances of the death, and a review of the medical history of the infant and of his or her family. According to the National Center for Health Statistics, SIDS is the third leading cause of infant death. To conduct the study, the researchers developed mice with a unique molecule, or receptor, on the surface of their serotonin-producing brain cells, or neurons. Typically, cells communicate via chemicals that bind to receptors on their surfaces, with the molecules binding to their receptors in much the same way a key fits into a lock.

Keyword: Sleep
Link ID: 15627 - Posted: 07.30.2011

When people recognize voices, part of what helps make voice recognition accurate is noticing how people pronounce words differently. But individuals with dyslexia don't experience this familiar language advantage, say researchers. The likely reason: "phonological impairment." Tyler Perrachione with the Massachusetts Institute of Technology explains, "Even though all people who speak a language use the same words, they say those words just a little bit differently from one another--what is called 'phonetics' in linguistics." Phonetics is concerned with the physical properties of speech. Listeners are sensitive to phonetic differences as part of what makes a person's voice unique. But individuals with dyslexia have trouble recognizing these phonetic differences, whether a person is speaking a familiar language or a foreign one, Perrachione says. As a Ph.D. candidate in Neuroscience at MIT, Perrachione recently examined the impacts of phonological impairment through experiments funded by the National Science Foundation's Directorate for Education and Human Resources. He and colleague Stephanie Del Tufo as well as Perrachione's MIT research advisor John Gabrieli hypothesized that if voice recognition by human listeners relies on phonological knowledge, then listeners with dyslexia would be impaired when identifying voices speaking their native language as compared to listeners without dyslexia. © 2011 U.S.News & World Report LP

Keyword: Dyslexia; Language
Link ID: 15626 - Posted: 07.30.2011

by Michael Balter "This town ain't big enough for the both of us," says ranch foreman Nick Grindell to lawman Tim Barrett in the 1932 film The Western Code. Biologists know the principle well: Two animal species can rarely occupy the same niche. The same, it seems, goes for human populations. A new study of Neandertal and modern human sites in the south of France concludes that the moderns so greatly outnumbered their evolutionary cousins that Neandertals had little choice but to go extinct. For more than 100,000 years, Neandertals had Europe all to themselves. Then, beginning roughly 40,000 years ago, modern humans—Homo sapiens—began migrating into the continent from Africa. Although researchers debate how long the Neandertals hung around, these ancient humans probably did not survive much longer than 5000 years. Just why they disappeared is also a matter of contention, but most experts agree that H. sapiens was able to outgun its rival in either direct or indirect competition for food and other resources. Some genetic studies, based on both modern and ancient DNA sequences, have suggested that modern human population growth quickly outstripped that of Neandertals, but estimating population levels from these kinds of data is very difficult and inexact. So Paul Mellars and Jennifer French, archaeologists at the University of Cambridge in the United Kingdom, decided to look directly at the archaeological evidence for the presence of both groups in the region where the most excavations have taken place: southwestern France, including the lush Dordogne region, as well known for its prehistoric sites as for its wine and foie gras. © 2010 American Association for the Advancement of Science

Keyword: Evolution
Link ID: 15625 - Posted: 07.30.2011