by Anil Ananthaswamy Advocates of free will can rest easy, for now. A 30-year-old classic experiment that is often used to argue against free will might have been misinterpreted. In the early 1980s, Benjamin Libet, a neuroscientist at the University of California in San Francisco, used electroencephalography (EEG) to record the brain activity of volunteers who had been told to make a spontaneous movement. With the help of a precise timer that the volunteers were asked to read at the moment they became aware of the urge to act, Libet found there was a 200 millisecond delay, on average, between this urge and the movement itself. But the EEG recordings also revealed a signal that appeared in the brain even earlier, 550 milliseconds, on average, before the action. Called the readiness potential, this has been interpreted as a blow to free will, as it suggests that the brain prepares to act well before we are conscious of the urge to move. This conclusion assumes that the readiness potential is the signature of the brain planning and preparing to move. "Even people who have been critical of Libet's work, by and large, haven't challenged that assumption," says Aaron Schurger of the National Institute of Health and Medical Research in Saclay, France. One attempt to do so came in 2009. Judy Trevena and Jeff Miller of the University of Otago in Dunedin, New Zealand, asked volunteers to decide, after hearing a tone, whether or not to tap on a keyboard. The readiness potential was present regardless of their decision, suggesting that it did not represent the brain preparing to move. Exactly what it did mean, though, still wasn't clear. © Copyright Reed Business Information Ltd.

Keyword: Consciousness; Attention
Link ID: 17131 - Posted: 08.07.2012

By Laura Sanders When one monkey sees another monkey messing up, the event ignites a small cluster of nerve cells in the brain that are sensitively tuned to others’ failures. The results help explain why the members of another primate species are such exquisite connoisseurs of blame. “We humans are very sensitive to others’ mistakes,” says Masaki Isoda of the Okinawa Institute of Science and Technology in Japan. He and his colleagues describe the macaques’ blunder detectors online August 5 in Nature Neuroscience. Catching other people’s slipups isn’t just schadenfreude. Noting another’s lapse, be it a gymnast’s step out of bounds or another animal’s regurgitation of a poisonous berry, is a good way to learn about the world. “Everybody’s life is a bit of a trial-and-error game,” says neuroscientist Matthew Shane of the Mind Research Network in Albuquerque who was not involved in the new study. An ability to sense others’ errors helps to see what doesn’t work without suffering the consequences firsthand. Past studies have suggested that nerve cells in a brain region called the medial frontal cortex are general error catchers: The cells were thought to fire when a person makes a mistake and also when witnessing someone else err. But by listening in on single nerve cells in macaques, Isoda and his team found that some of these neurons don’t seem to care about a personal mistake. Instead, these neurons are exclusively trained on other animals’ errors. © Society for Science & the Public 2000 - 2012

Keyword: Attention
Link ID: 17130 - Posted: 08.07.2012

By Giulio Tononi When is an entity one entity? How can multiple elements be a single thing? A question simple enough— but one, thought Galileo, that had not yet been answered. Or perhaps, it had not been asked. The sensor of the digital camera certainly had a large repertoire of states— it could take any possible picture. But was it a single entity? You use the camera as a single entity, you grasp it with your hands as one. You watch the photograph as a single entity. But that is within your own consciousness. If it were not for you, the observer, would it still be a single entity? And what exactly would that mean? While musing such matters, Galileo was startled by a voice. J., a man with the forehead of an ancient god, addressed him in a polished tone: “Take a sentence of a dozen words, and take twelve men, and tell to each one word. Then stand the men in a row or jam them in a bunch, and let each think of his word as intently as he will; nowhere will there be a consciousness of the whole sentence. Or take a word of a dozen letters, and let each man think of his letter as intently as he will; nowhere will there be a consciousness of the whole word,” J. said. Or take a picture of one million dots, and take one million photodiodes, and show each photodiode its own dot. Then stand the photodiodes well ordered on a square array, and let each tell light from dark for its own dot, as precisely as it will; nowhere will there be a consciousness of the whole picture, said Galileo. “So you see that, Galileo,” J. continued. “There is no such thing as the spirit of the age, the sentiment of the people, or public opinion. The private minds do not agglomerate into a higher compound mind. They say the whole is more than the sum of its parts; they say, but how can it be so?” © 2012 Scientific American, Copyright © 2012 by Giulio Tononi

Keyword: Consciousness; Attention
Link ID: 17129 - Posted: 08.06.2012

By Susan E. Matthews The way people's pupils react when they see other people is an effective way to assess sexual orientation, according to a new study. The reactions of study participants' pupils revealed that heterosexual men responded most to images of women and homosexual men responded most to images of men. Additionally, researchers found that homosexual women responded most to images of women, and heterosexual women expressed arousal in response to both men and women, though they were more likely to choose to watch men. Previous studies have shown that people's pupils widen in response to seeing others who they find attractive; the new study showed that, indeed, a person's sexuality is evident in their pupils' responses. Results also revealed that bisexual men were attracted to both men and women, an idea that has been disputed, and that heterosexual women may be aroused by both genders, despite being straight. "The pupil reacts very quickly, and it is unconscious, so it's a method that gives us a subconscious indicator of sexuality," said lead study author Gerulf Rieger, a researcher at Cornell University. Sex researchers don't always want to rely on people's own reports about who they are sexually attracted to, because cultural and societal pressures can influence what people say, he explained. The findings are detailed today (Aug. 3) in the journal PLoS ONE. © 2012 NBCNews.com

Keyword: Sexual Behavior; Attention
Link ID: 17128 - Posted: 08.06.2012

by Will Ferguson Let's face it, child rearing isn't for everyone. Midnight diaper changes, a seriously compromised social life, and trading in the two-seater coupe for a mid-size sedan can be too much for some of us to handle. Readers who find themselves in this category might be reassured to know there's at least one other creature on the planet that is, in all likelihood, even more keen to shirk parental responsibility. The common cuckoo is notorious for pawning off its young on other birds, like the Eurasian Reed Warbler (Acrocephalus scirpaceus). Unfortunately for these more willing caregivers, the cuckoo is a ruthless parasite. Upon hatching, young cuckoos push their surrogate brothers and sisters from the nest, leaving the unsuspecting host with a single cuckoo chick rather than a brood of its own. For obvious reasons, reed warblers have never been happy with the arrangement. They will attack female cuckoos on sight, reducing the chance of their nest being targeted. However, the sly cuckoo has developed an innovative way to avoid hostilities. Female cuckoos have evolved two different guises to minimise the chance of being recognised and attacked by warblers. It's unusual for female birds of a single species to come in different colours, but the phenomenon is surprisingly common for female cuckoos. Some are brownish-red, while others have grey, hawk-like plumage that deters other birds from attacking them. © Copyright Reed Business Information Ltd.

Keyword: Sexual Behavior; Evolution
Link ID: 17127 - Posted: 08.06.2012

Exercise and behavioural therapies are the most cost-effective and successful ways to treat Chronic fatigue syndrome, also known as ME, an analysis shows. A study of 640 patients showed these treatments had the potential to save the economy millions of pounds if they were widely adopted. The findings were published in the journal PLoS ONE. However, another treatment favoured by patients' groups was shown to offer little value. Nobody knows what causes the condition, yet a quarter of a million people in the UK are thought to have it. The symptoms include severe tiredness, poor concentration and memory as well as muscle and joint pain and disturbed sleep. An earlier version of this research, published last year, showed that cognitive behavioural therapy (changing how people think about their symptoms) and graded exercise therapy (gradually increasing the amount of exercise) were the most effective treatments. However, the study provoked anger from many patients' groups which argued that pacing therapies (learning to live within limits) were both better and safer for patients. Using data from the same set of patients, researchers compared improvements in levels of fatigue and activity with the cost to the NHS of providing the treatments. It concluded that only cognitive behavioural therapy and graded exercise therapy could be considered cost-effective. BBC © 2012

Keyword: Depression
Link ID: 17126 - Posted: 08.06.2012

by Nicholas St. Fleur With their trumpet-like calls, elephants may seem like some of the loudest animals on Earth. But we can't hear most of the sounds they make. The creatures produce low-frequency noises between 1 to 20 Hertz, known as infrasounds, that help them keep in touch over distances as large as 10 kilometers. A new study reveals for the first time how elephants produce these low notes. Scientists first discovered that elephants made infrasounds in the 1980s. The head female in a herd may produce the noises to guide her group's movements, whereas a male who’s in a mating state called musth might use the calls to thwart competition from other males. Mother elephants even rely on infrasounds to keep tabs on a separated calf, exchanging "I'm here" calls with the wayward offspring in a fashion similar to a game of Marco Polo. These noises, which fall below the hearing range for humans, are often accompanied by strong rumbles with slightly higher frequencies that people can hear. By recording the rumbles and then speeding up the playback, the scientists can increase the frequency of the infrasounds, making them audible. Good vibrations. The vocal folds of the excised larynx vibrating according to the myoelastic-aerodynamic method. Researchers have speculated that the noises come from vibrations in the vocal folds of the elephant larynx. This could happen in two ways. In the first, called active muscular contraction (AMC), neural signals cause the muscles in the larynx to contract in a constant rhythm. Cats do this when they purr. The second possibility is known as the myoelastic-aerodynamic (MEAD) method, and it occurs when air flows through the vocal folds causing them to vibrate—this also happens when humans talk. © 2010 American Association for the Advancement of Science

Keyword: Hearing; Evolution
Link ID: 17125 - Posted: 08.04.2012

Scientists have discovered a biological marker that may help to identify which depressed patients will respond to an experimental, rapid-acting antidepressant. The brain signal, detectable by noninvasive imaging, also holds clues to the agent’s underlying mechanism, which are vital for drug development, say National Institutes of Health researchers. The signal is among the latest of several such markers, including factors detectable in blood, genetic markers, and a sleep-specific brain wave, recently uncovered by the NIH team and grantee collaborators. They illuminate the workings of the agent, called ketamine, and may hold promise for more personalized treatment. "These clues help focus the search for the molecular targets of a future generation of medications that will lift depression within hours instead of weeks," explained Carlos Zarate, M.D., of the NIH’s National Institute of Mental Health (NIMH). "The more precisely we understand how this mechanism works, the more narrowly treatment can be targeted to achieve rapid antidepressant effects and avoid undesirable side effects." Previous research had shown that ketamine can lift symptoms of depression within hours in many patients. But side effects hamper its use as a first-line medication. So researchers are studying its mechanism of action in hopes of developing a safer agent that works similarly. Ketamine works through a different brain chemical system than conventional antidepressants. It initially blocks a protein on brain neurons, called the NMDA receptor, to which the chemical messenger glutamate binds.

Keyword: Depression; Brain imaging
Link ID: 17124 - Posted: 08.04.2012

COFFEE can give you the shakes, but caffeine seems to have the opposite effect in people with Parkinson's disease, helping to relieve tremors and get them back on the move. In the past, caffeine has been shown to reduce the risk of Parkinson's, but its effects have never been tested in people who already have the disease. Ronald Postuma of McGill University in Montreal, Canada, and colleagues gave 61 people with Parkinson's a 6-week course of pills containing the caffeine equivalent of about three cups of coffee every day, or a placebo. Only people in the caffeine group showed a significant improvement in tests for motor problems, such as the severity of their tremors, and general mobility (Neurology, DOI: 10.1212/WNL.0b013e318263570d). Motor problems associated with Parkinson's are caused by a lack of dopamine in areas of the brain where dopamine-producing cells are destroyed. Adenosine receptors normally inhibit the production of dopamine. Caffeine blocks adenosine receptors and so acts to boost available dopamine. Drugs that target adenosine receptors are already in clinical trials but caffeine could provide a cheaper alternative. © Copyright Reed Business Information Ltd.

Keyword: Parkinsons
Link ID: 17123 - Posted: 08.04.2012

By Laura Sanders A much-maligned molecule that is devastating in the brain may have therapeutic potential outside it. The sticky amyloid-beta protein, which piles up in the brains of people with Alzheimer’s disease, actually reverses paralysis in mice with symptoms of multiple sclerosis. The unexpected finding, published in the Aug. 1 Science Translational Medicine, could mean that A-beta or molecules like it may one day form the basis of a treatment for multiple sclerosis in people. In MS, rogue immune cells penetrate the brain and spinal cord and attack myelin, a substance that is necessary to keep neural impulses moving at full speed. Damage and inflammation from this attack can leave a person with paralysis, numbness, vision problems and extreme fatigue. A-beta is found in the brains of people with MS, but scientists do not know precisely what effect it has there, if any. To investigate that question, study coauthor Lawrence Steinman of Stanford University and colleagues tried injecting A-beta into mice’s abdomens, thinking it would worsen symptoms. “We expected that either nothing would happen or the disease would worsen because this is an infamous, villainous molecule,” he says. Instead, the mice got better. In several different kinds of mice designed to have symptoms similar to the human disease, A-beta injections into the body reduced paralysis and lowered brain inflammation. “The outcome was unmistakable,” Steinman says. © Society for Science & the Public 2000 - 2012

Keyword: Multiple Sclerosis; Alzheimers
Link ID: 17122 - Posted: 08.04.2012

by Michael S. Gazzaniga We humans think we make all our decisions to act consciously and willfully. We all feel we are wonderfully unified, coherent mental machines and that our underlying brain structure must reflect this overpowering sense. It doesn’t. No command center keeps all other brain systems hopping to the instructions of a five-star general. The brain has millions of local processors making important decisions. There is no one boss in the brain. You are certainly not the boss of your brain. Have you ever succeeded in telling your brain to shut up already and go to sleep? Even though we know that the organization of the brain is made up of a gazillion decision centers, that neural activities going on at one level of organization are inexplicable at another level, and that there seems to be no boss, our conviction that we have a “self” making all the decisions is not dampened. It is a powerful illusion that is almost impossible to shake. In fact, there is little or no reason to shake it, for it has served us well as a species. There is, however, a reason to try to understand how it all comes about. If we understand why we feel in charge, we will understand why and how we make errors of thought and perception. When I was a kid, I spent a lot of time in the desert of Southern California—out in the desert scrub and dry bunchgrass, surrounded by purple mountains, creosote bush, coyotes, and rattlesnakes. The reason I am still here today is because I have nonconscious processes that were honed by evolution. © 2012, Kalmbach Publishing Co.

Keyword: Consciousness; Attention
Link ID: 17121 - Posted: 08.04.2012

By Michael Slezak, Even though women live longer than men, their brains seem to age faster. The reason? Possibly a more stressful life. As people age, some genes become more active while others become less so. In the brain, these changes can be observed through the transcriptome, a set of RNA molecules that indicate the activity of genes within a population of cells. When Mehmet Somel, a computational biologist at the University of California at Berkeley, and his colleagues compared the transcriptome of 55 brains, they found that the pattern of gene activation and deactivation that occurs with aging appeared to progress faster in women. “This was just the opposite of what we’d originally expected,” says Somel. He says that because women have longer lives, his group had expected to see slower or later aging-related brain changes. “But it fits everyday observations on aging. Not all organs within an individual age at the same rate.” Somel’s team compared the expression of more than 13,000 genes in four brain regions. In the superior frontal gyrus, which has been associated with self-awareness, the researchers found 667 genes that were expressed differently in men and women. Of those, 98 percent were skewed toward faster aging in women. Some of these gene changes have been linked to general cognitive decline and degenerative disease. © 1996-2012 The Washington Post

Keyword: Sexual Behavior; Stress
Link ID: 17120 - Posted: 08.04.2012

Scientists believe they have discovered a clue to why women tend to live longer than men - by studying fruit flies. Writing in Current Biology, they focus on mutations in mitochondrial DNA - the power source of cells. Mitochondria are inherited only from mothers, never from fathers, so there is no way to weed out mutations that damage a male's prospects. But one ageing expert said there were many factors that explained the gender difference in life expectancy. By the age of 85, there are approximately six women for every four men in the UK, and by 100 the ratio is more than two to one. And females outlive males in many other species. In the research, experts from Australia's Monash University and the UK's Lancaster University analysed the mitochondria of 13 different groups of male and female fruit flies. Mitochondria, which exist in almost all animal cells, convert food into the energy that powers the body. Dr Damian Dowling, of Monash University who was one of the researchers, said the results point to numerous mutations within mitochondrial DNA that affect how long males live, and the speed at which they age. "Intriguingly, these same mutations have no effects on patterns of ageing in females," he said. BBC © 2012

Keyword: Sexual Behavior; Genes & Behavior
Link ID: 17119 - Posted: 08.04.2012

By Judy Stone As expected, the FDA recently announced approval of a second drug for obesity within a month, Vivus’ Qnexa, now renamed Qsymia. This approval is less of a surprise, as the data appeared somewhat stronger than that for Arena’s lorcaserin (Belviq). What was rather curious is that USA Today broke news of the drug’s approval before the FDA had announced their decision. The FDA is responding to the growing crisis of obesity. As noted in my post, “A Glut of Obesity Drugs?” the Centers for Disease Control and Prevention has established that more than one-third of adults in the United States are obese, defined as having a Body-Mass Index of ­> 30. In the U.S. alone, 78 million U.S. adults are obese; another 34% of adults are overweight > 25-29. So 70% of US adults have a problem with weight. This results in an estimated 300,000 deaths per year. And the burden of obesity is increasing, expected to rise to 42% by 2030, with an additional 11% prevalence of severe obesity (BMI >40, or ~80+ lbs overweight). Obesity is the second cause of preventable deaths, after smoking. The costs of obesity are also staggering, and may be as high as $147 billion per year, or roughly 9% of U.S. annual medical expenditures. The health crisis from obesity is drawing increasing attention, as outlined in the documentary, “The Weight of the Nation,” a project of HBO, the Institute of Medicine (IOM), the Centers for Disease Control and Prevention (CDC) the National Institutes of Health (NIH), the Michael & Susan Dell Foundation, and Kaiser Permanente. In my previous post, we looked at how obesity drugs work and how there are many different targets that are under study. Lorcaserin (Belviq) works by targeting the activation of the serotonin 5HT2C receptor in the brain. © 2012 Scientific American,

Keyword: Obesity
Link ID: 17118 - Posted: 08.04.2012

By Melissa Healy Los Angeles Times Measuring human intelligence may be controversial and oh-so-very-tricky to do. But like obscenity, we think we know it when we see it. A new study, however, demonstrates a more rigorous way to see and measure differences in intelligence between individuals. It finds that connectedness among the brain's disparate regions is a key factor that separates the plodding from the penetrating. As many researchers have long suspected, intelligence does have a "seat" in the human brain: an area just behind each of the temples called the lateral prefrontal cortex. But researchers writing in the journal Neuroscience found that human behavior that is exceptionally flexible, responsive and capable of navigating complexity requires something beyond a strong and active prefrontal cortex: strong and agile runners must link that seat to brain regions involved in perception, memory, language and mobility. The researchers estimate that the strength of those connections, as measured when subjects rested between mental tasks, explains about 10% of differences in intelligence among individuals. That makes this measure an even better predictor of intelligence than brain size -- a measure that scientists believe may explain about 7% of the variation in intelligence among individuals. To detect this relationship, the Neuroscience study compared functional magnetic resonance imaging (fMRI) brain scans of 78 men and women between 18 and 40 years old with those subjects' performance on tests of cognitive performance that required "fluid intelligence" and "cognitive control." Subjects, for instance, were asked to count backwards by, say, nine, or to watch a series of visual images and then indicate whether a single image shown had been among them. Copyright 2012

Keyword: Intelligence; Brain imaging
Link ID: 17117 - Posted: 08.04.2012

Published by scicurious under Behavioral Neuro Imagine for a minute. You're in a coffeeshop, or a bar, or at a swanky cocktail party (whichever you prefer). There are people around, chatting nearby. But you're speaking to the person directly across from you. Somehow, you can pick their voice out of the chatter and attend to what they are saying, even though the conversations around you might be just as loud or louder (especially in a bar!) than the one you're interested in. Have you ever wondered how you do that? I know I have. It's kind of a mind-boggling problem (and is, in fact, called the Cocktail party problem), trying to separate out speech, and make sense of it, in comparison to all the noise. And it's not just something to think about for us humans. Voice recognition technology and recording wrestles with this all the time: how to pick out the voice from the crowd? As it turns out, it's all about attention, and how that attention can change your brain. The authors of this study were interested in what happens in the brain when someone tries to pick out a single speaker in a room full of people. To look at this, they actually used electrodes implanted subdurally (beneath the tough dura mater on the outside of the brain) in three human patients. Three is a really small number, but they had to use patients who were receiving this electrode implant clinically, in this case for treatment of epilepsy, and who were known to have normal hearing and language skills. Copyright © 2012

Keyword: Attention; Hearing
Link ID: 17116 - Posted: 08.04.2012

By Emily Selvadurai Health reporter, BBC News online People with mild mental illnesses such as anxiety or depression are more likely to die early, say researchers. They looked at the premature deaths from conditions such as heart disease and cancer of 68,000 people in England. The research suggested low level distress raised the risk by 16%, once lifestyle factors such as drinking and smoking were taken into account. More serious problems increased it by 67%, the University College London and Edinburgh University team said. The risk among those with severe mental health problems is already well documented. But researchers said the finding among those with milder cases - thought to be one in every four people - was concerning, as many would be undiagnosed. The Wellcome Trust-funded study, published in the British Medical Journal, looked at data over 10 years and matched it to information on death certificates. This is the largest study so far to show an association between psychological distress and death, according to scientists. Lead author Dr Tom Russ said: "The fact that an increased risk of mortality was evident, even at low levels of psychological distress, should prompt research into whether treatment of these very common, minor symptoms can modify this increased risk of death." BBC © 2012

Keyword: Depression
Link ID: 17115 - Posted: 08.01.2012

By Maria Konnikova It’s 1879, and psychology is just about to be born. The place: the University of Leipzig. The birth parent: Wilhelm Wundt. The deed: establishing the first official university laboratory for the study of psychology, an event taken by many as the line that marks unofficial explorations from empirical, accepted science. The laboratory has four rooms and a handful of students. By the early 1880s, it will grow to an astounding six rooms—and a total of 19 students. In 1883, it will award its first doctoral degree, to the first of Wundt’s advisees, Max Friedrich, on the topic of the time-course of individual psychological processes. That same year will see the publication of the first issue of the Journal Philosophische Studien, the first journal of experimental psychology, established—fittingly—by none other than Wundt. From that point on, the future of the discipline will be assured: psychology will survive, and perhaps even flourish, with the dawn of the new century. It will not be just another experiment gone wrong. That, at least, is the most straightforward story. It’s difficult to pinpoint a date for the birth of Psychology as such. That 1879 laboratory is but one contender, and Wundt, but one possible father. But just think of how many paved the way for Wundt’s achievements. Is it fair to call him the start, or is he rather more of a point of coalescence (if that)? And how far back must we go, if we’re to be really fair? © 2012 Scientific American,

Keyword: Miscellaneous
Link ID: 17114 - Posted: 08.01.2012

By RONI CARYN RABIN Older people who have eye surgery to remove cataracts and improve their vision also significantly reduce their risk of breaking a hip in a fall, with the sickest among them and those in their early 80s experiencing nearly 30 percent fewer hip fractures in the first year, a large study reports. The study adds to findings from earlier papers indicating that the benefits of cataract surgery, a relatively safe outpatient procedure with a high success rate, may significantly enhance the quality of life for the elderly, improving sleep, enabling them to be more engaged and mentally alert and curbing depression. “This is elective surgery, and sometimes people think, ‘I’m too sick to have my cataracts out,’ or ‘I’m too old,’ ” said Dr. Anne L. Coleman, the study’s lead author and a professor of ophthalmology at the Jules Stein Eye Institute at the University of California, Los Angeles. “But the take-home message from this study is that if you’re starting to have vision problems and the doctor says you have cataracts, you should probably think of having them removed.” Hip fractures, which become more common with age, are serious injuries for elderly people, with complications that can be life-threatening. The new study, published on Tuesday in The Journal of the American Medical Association, examined the incidence of hip fractures within a year of cataract surgery in a random sample of 1.1 million Medicare beneficiaries age 65 and older who were given a cataract diagnosis from 2002 to 2009. © 2012 The New York Times Company

Keyword: Vision; Development of the Brain
Link ID: 17113 - Posted: 08.01.2012

By Tina Hesman Saey Expeditions to Africa may have brought back evidence of a hitherto unknown branch in the human family tree. But this time the evidence wasn’t unearthed by digging in the dirt. It was found in the DNA of hunter-gatherer people living in Cameroon and Tanzania. Buried in the genetic blueprints of 15 people, researchers found the genetic signature of a sister species that branched off the human family tree at about the same time that Neandertals did. This lineage probably remained isolated from the one that produced modern humans for a long time, but its DNA jumped into the Homo sapiens gene pool through interbreeding with modern humans during the same era that other modern humans and Neandertals were mixing in the Middle East, researchers report in the August 3 Cell. The evidence for ancient interbreeding is surprisingly convincing, says Richard “Ed” Green, a genome biologist at the University of California, Santa Cruz. “There is a signal that demands explanation, and archaic admixture seems to be the most reasonable one at this point,” he says. Scientists have discovered that some people with ancestry outside Africa have DNA inherited from Neandertals or Denisovans, a mysterious group known only through DNA derived from a fossil finger bone found in a Siberian cave (SN: 6/5/10, p. 5; SN: 1/15/11, p.10). But those researchers had DNA from fossils to guide their research. This time, researchers led by Sarah Tishkoff at the University of Pennsylvania in Philadelphia didn’t have fossil DNA, or even fossils. © Society for Science & the Public 2000 - 2012

Keyword: Evolution
Link ID: 17112 - Posted: 08.01.2012