A new mouse model closely resembles how the human body reacts to early HIV infection and is shedding light on nerve cell damage related to the disease, according to researchers funded by the National Institutes of Health. The study in today’s Journal of Neuroscience demonstrates that HIV infection of the nervous system leads to inflammatory responses, changes in brain cells, and damage to neurons. This is the first study to show such neuronal loss during initial stages of HIV infection in a mouse model. The study was conducted by a team of scientists from the University of Nebraska Medical Center, Omaha, and the University of Rochester Medical Center, N.Y. It was supported by the National Institute on Drug Abuse (NIDA), the National Institute of Neurological Disorders and Stroke, the National Institute of Mental Health, and the National Center for Research Resources. "This research breakthrough should help us move forward in learning more about how HIV affects important brain functioning in its initial stages, which in turn could lead us to better treatments that can be used early in the disease process," said Dr. Nora D. Volkow, director of NIDA. "The work contained within this study is the culmination of a 20-year quest to develop a rodent model of the primary neurological complications of HIV infection in humans," said Dr. Howard Gendelman, one of the primary study authors. "Previously, the rhesus macaque was the only animal model for the study of early stages of HIV infection. However, its use was limited due to expense and issues with generalizing results across species. Relevant rodent models that mimic human disease have been sorely needed."

Keyword: Miscellaneous
Link ID: 15064 - Posted: 03.03.2011

By Tina Hesman Saey A naturally occurring genetic variant may predict who will do well after a stroke and who won’t. People who have two copies of a particular version of the Tp53 gene have a poor prognosis after stroke and brain hemorrhages, researchers in Spain report online February 28 in the Journal of Experimental Medicine. The difference between the two versions of the gene amounts to one small change: swapping proline out for arginine as the 72nd link in a chain of amino acids that make up a protein called p53. The arginine-containing variant of p53 had previously been shown to help protect against cancer by increasing apoptosis, a cell suicide program that gets rid of damaged cells before they can turn nasty. Brain cells can also undergo apoptosis after a stroke, but there it’s a bad thing, leading to more widespread damage. Angeles Almeida, a molecular biologist at the University Hospital of Salamanca, and her colleagues wanted to know if the variant works as vigorously in the brain as in cancer cells, so they tested nerve cells that make either the arginine variant or the proline version. “We saw that the difference was huge,” Almeida says. Cells with the arginine version of p53 had four times greater capacity to undergo apoptosis than cells with the proline variant did. And that molecular difference carries over into consequences for the whole brain. The researchers tested the DNA of stroke and brain hemorrhage victims to see if the version of p53 the people carried could affect their prognosis. The variant did not affect the chance of having a stroke or brain hemorrhage, but did correlate with how well patients had recovered three months after the brain injuries, the team found. © Society for Science & the Public 2000 - 2011

Keyword: Stroke; Genes & Behavior
Link ID: 15063 - Posted: 03.03.2011

by Andrew Moseman Ken Jennings and Brad Rutter are accustomed to making others feel the heat as they blaze through Jeopardy clue after Jeopardy clue. But tonight, the quiz show's two greatest champions will oppose a player who can't be psyched out. It's time for the world to meet Watson. IBM's Jeopardy-playing computer system appears to viewers at home as an avatar of the Earth on a black screen. In fact, it is a system years in the making, and perhaps the most impressive attempt ever to create a question-answering computer that understands the nuances of human language. Watson is not connected to the Internet, but its databases overflow with books, scripts, dictionaries, and whatever other material lead researcher David Ferrucci could pack in. Storing information is the computer's strong suit; the grand artificial intelligence challenge of Jeopardy is the subtlety of words. advertisement | article continues below When the bright lights of Jeopardy go up tonight, there will be no human handler to tell Watson where inside its mighty databases to seek the answers. It must parse each clue and category title to figure out what it's being asked. It must race through its databases, find relevant search terms, and pick out the right response with a high level of confidence. It must understand the puns and geeky quirks of America's Favorite Quiz Show. It must beat two Jeopardy champions to the buzzer. And it too must voice its responses in the form of a question. © 2011, Kalmbach Publishing Co.

Keyword: Intelligence; Robotics
Link ID: 15062 - Posted: 03.03.2011

By Laura Sanders SALT LAKE CITY — When the brain can’t nail an answer, it falls back on reasonable guesses. Now scientists have evidence that this strategy may happen very early in the processing of sensory inputs, a study presented February 27 at the Computational and Systems Neuroscience meeting suggests. The research took advantage of a common misperception of the human brain: People often think that hazy, ill-defined objects are moving more slowly than they really are. The brain’s rationale for this error: “Things in the world don’t tend to move very quickly,” said neuroscientist Ed Vul of the University of California, San Diego, who was not involved in the new study. “They’re not running past you at 60 miles per hour. For the most part, when things are moving, they’re moving slowly.” Researchers already knew that the brain relies on assumptions when it has trouble figuring something out, but it wasn’t clear where in the brain—and when—these assumptions get used. In the new study, Brett Vintch of New York University and Justin Gardner of Riken Brain Science Institute in Japan scanned people’s brains using functional MRI while they judged how fast black and white lines moved on a computer screen. At first, the researchers made the task relatively easy to see how participants’ brains would handle it under normal conditions. Some brain regions grew more active as the volunteers judged speed, and other regions grew less active. The team used a statistical model to decode these brain activity signals and found that some of the most important vision areas in the brain were used to gauge the speed of the object. © Society for Science & the Public 2000 - 2011

Keyword: Attention
Link ID: 15061 - Posted: 03.01.2011

By Bruce Bower A popular “club drug” promises to open a scientific window on the strange world of out-of-body experiences, researchers say. Recreational users of a substance called ketamine often report having felt like they left their bodies or underwent other bizarre physical transformations, according to an online survey conducted by psychologist Todd Girard of Ryerson University in Toronto and his colleagues. Ketamine, an anesthetic known to interfere with memory and cause feelings of detachment from one’s self or body, reduces transmission of the brain chemical glutamate through a particular class of molecular gateways. Glutamate generally jacks up brain activity. Ketamine stimulates sensations of illusory movement or leaving one’s body by cutting glutamate’s ability to energize certain brain areas, the researchers propose in a paper published online February 15 in Consciousness and Cognition. “Ketamine may disrupt patterns of brain activation that coalesce to represent an integrated body and self, leading to out-of-body experiences,” Girard says. National surveys indicate that 1.6 percent of high school seniors in Canada and the United States have used ketamine at least once. An estimated 70 percent of Toronto rave-goers now report taking ketamine at these all-night parties, Girard notes. © Society for Science & the Public 2000 - 2011

Keyword: Drug Abuse; Attention
Link ID: 15060 - Posted: 03.01.2011

by Ferris Jabr The mind's eye can develop a knack for language in people who have been blind since birth. Functional magnetic resonance imaging (fMRI) measures blood flow in the brain to determine which neurons are most active. Since the 1990s the technology has shown, surprisingly, that the visual cortex flares up even in blind people. More puzzlingly, this activity occurs when they were carrying out language tasks. Rebecca Saxe at the Massachusetts Institute of Technology says the result seemed implausible, because the visual cortex isn't thought to be useful for language tasks. So to investigate, Saxe's team invited both sighted adults and those who had been blind since birth to listen to speech while lying inside an fMRI scanner. The team found that the language processing centres in the brains of all participants behaved almost identically, but the visual cortices of blind participants buzzed with far more activity than those of sighted people. "This was kind of crazy," says team member Evelina Fedorenko, also at MIT. "You have a portion of the brain which is there from birth to do something, but apparently it can acquire a new high-level function like language, which involves super complex cognitive processing." Fedorenko thinks that blind people who get a linguistic boost from their visual cortex might be better at language tasks than sighted people. © Copyright Reed Business Information Ltd.

Keyword: Language; Vision
Link ID: 15059 - Posted: 03.01.2011

By CARL ZIMMER Charles Darwin considered the evolution of the human eye one of the toughest problems his theory had to explain. In “On the Origin of Species,” he wrote that the idea that natural selection could produce such an intricate organ “seems, I freely confess, absurd in the highest possible degree.” But Darwin dispelled that seeming absurdity by laying out a series of steps by which the evolution could take place. Making this sequence all the more plausible was the fact that some of the transitional forms Darwin described actually existed in living invertebrates. Now, a team of American and European researchers report that they have discovered an eye that could represent the first step in this evolution. They have found, in effect, a swimming eyeball. “This is in no way the ancestor of the human eye, but it’s the first time we have had a model of it,” said Yale Passamaneck, a postdoctoral researcher at the University of Hawaii. He and his colleagues report the discovery in the online journal EvoDevo. The researchers made the discovery while studying a species of brachiopods, or lamp shells, which live in shells but are marine worms unrelated to mollusks like clams and oysters. Lamp shells have existed for over half a billion years, but their biology has long remained a mystery — including the simple question of whether they can see. © 2011 The New York Times Company

Keyword: Evolution; Vision
Link ID: 15058 - Posted: 03.01.2011

By CLAUDIA DREIFUS Dr. Emery Neal Brown, 54, is a professor of anesthesiology at Harvard Medical School, a professor of computational neuroscience at M.I.T. and a practicing physician, seeing patients at Massachusetts General Hospital. Between all that, he heads a laboratory seeking to unravel one of medicine’s big questions: how anesthesia works. Q. Anesthesia — what drew you to it? A. I enjoyed my anesthesia rotation at medical school. I could see that it was very fast-paced and that you had to make important decisions quickly. That appealed. Plus: the regular hours. I saw myself doing research, as well as working with patients. You need a predictable schedule — which anesthesiologists have — to manage both. It’s also a very important piece of modern medicine. If you think about what occurs when we do surgery, it’s a very traumatic insult to the body. You’re cutting people open, removing organs or possibly even transplanting them. The anesthesiologist puts people into a condition where they can tolerate such extreme assaults. Q. Is anesthesia like a coma? A. It’s a reversible drug-induced coma, to simplify. As with a coma that’s the result of a brain injury, the patient is unconscious, insensitive to pain, cannot move or remember. However, with anesthesia, once the drugs wear off, the coma wears off. Q. Anesthesia was first demonstrated right here at Massachusetts General Hospital in 1846. Does that historical fact drive your research? A. I think about it a lot. Seriously! © 2011 The New York Times Company

Keyword: Sleep
Link ID: 15057 - Posted: 03.01.2011

By SINDYA N. BHANOO Pilot whales are highly social creatures that communicate extensively with one another through tonal calls. But their ability to make calls is severely diminished when they dive deeper than about 260 feet, researchers report in The Proceedings of The Royal Society B. Until this point, as the whales dive deeper, their calls grow louder, but beyond this the calls become softer. The whales often dive nearly 3,000 feet deep in order to capture their favorite prey — a large, calorie-rich squid. “If they want to be heard by other whales at the surface, you would expect that they would increase their volume, but that is not the case,” said Frants Jensen a biologist at Aarhus University in Denmark and the study’s lead author. Dr. Jensen and his colleagues attached tags to 12 short-finned pilot whales off the Canary Islands and logged the sound, depth and orientation of the animals. Despite the impairment due to depth, the whales continued to produce tonal calls at lower volumes until they reached about 2,600 feet. The researchers believe that at such depths the lungs of the whales collapse, severely reducing their air volume and restricting their ability to generate sound. Still, the whales find their cohorts when they reach the surface. “They manage to find their social group after each dive,” Dr. Jensen said. “It’s a highly effective social system.” © 2011 The New York Times Company

Keyword: Hearing; Animal Communication
Link ID: 15056 - Posted: 03.01.2011

By NICHOLAS BAKALAR Alzheimer’s disease is more common in people whose mothers had the illness than in those whose fathers had it — and the evidence can be found in the brains of people who are still healthy. Researchers studied 53 mentally healthy men and women over 60 years old. Ten had a father with Alzheimer’s, 11 a mother with the disease, and 32 had no family history of the illness. Each volunteer underwent an initial M.R.I. examination and was examined again two years later. All the volunteers were still cognitively normal at the two-year point, but those with a family history of Alzheimer’s had significantly more brain atrophy than those without a family history. And even after controlling for age and sex, the deterioration was significantly greater in those with a maternal history of Alzheimer’s than in those with a paternal one. The authors acknowledge that the study, published in Tuesday’s issue of Neurology, depended on volunteers reporting their parents’ illnesses accurately. Still, the lead author, Robyn A. Honea of the University of Kansas, said scientists were getting closer to quantifying risk with brain scans. “The goal is to do a scan on someone before they get the disease and be able to tell if they’re at higher risk or starting to deteriorate,” she said. “Can we do that now? No. We need more and larger studies.” © 2011 The New York Times Company

Keyword: Alzheimers; Genes & Behavior
Link ID: 15055 - Posted: 03.01.2011

Cassandra Willyard On 17 February, retired American-football player Dave Duerson committed suicide. The 50-year-old former defensive back for the Chicago Bears left this haunting note for his family: "Please, see that my brain is given to the NFL's brain bank." Then he shot himself in the chest, leaving his brain intact. The brain bank Duerson referred to, located at Bedford VA Medical Center in Massachusetts, is funded by the US National Football League (NFL) and run by Ann McKee, co-director of the Center for the Study of Traumatic Encephalopathy at Boston University in Massachusetts. She and her colleagues have spent the past several years examining athletes' brains for signs of a neurodegenerative condition called chronic traumatic encephalopathy (CTE). Whether Duerson had the disease is still unknown. But his note seems to imply that he feared the worst. Nature examines what researchers know about CTE, what they have yet to understand and what is being done to protect athletes. What is chronic traumatic encephalopathy? CTE is a neurodegenerative disease caused by repeated trauma to the head. "The head trauma usually occurs years, maybe even decades before the person become symptomatic," McKee says. © 2011 Nature Publishing Group,

Keyword: Brain Injury/Concussion
Link ID: 15054 - Posted: 02.26.2011

by Sara Reardon On an African savanna 10 million years ago, our ancestors awoke to the sun rising over dry, rolling grasslands, vast skies, and patterned wildlife. This complex scenery influenced the evolution of our eyes, according to a new study, guiding the arrangement of light-sensitive cone cells. The findings might allow researchers to develop machines with more humanlike vision: efficient, accurate, and attuned to the natural world. The human retina contains three types of light-sensitive cone cells—responding to red, green, or blue light—that are arranged in a mosaic pattern. This pattern isn't random. Previous studies suggest that the retina adapts to an animal's surroundings, evolving to extract the most information. For instance, the retinas of fish living at different depths of a lake have distinct patterns because they are attuned to detecting wavelengths of light filtered and distorted to varying degrees by the water. Physicist and lead author Gasper Tkačik of the University of Pennsylvania (Penn) calls this the "efficient coding hypothesis." Are human eyes also efficiently coded? They don't seem to be. The sky and sea make up much of our natural scenes, yet only 6% of our cone cells detect blue, and they are mostly located around the edge of our retina. Of the remaining cones, the ratio of red to green cones varies wildly between individuals. © 2010 American Association for the Advancement of Science.

Keyword: Vision; Evolution
Link ID: 15053 - Posted: 02.26.2011

By Tina Hesman Saey Infectious proteins that cause brain-wasting conditions like mad cow disease appear to build up in the brain long before initiating the cascade of deterioration that leads to dementia and death, a new study of mice finds. The findings suggest that other factors besides the misshapen infectious proteins characteristic of prion diseases may control the lethality of the disease. If scientists can determine what those factors are, future treatments may be able to prevent the infectious protein diseases — which include mad cow disease, scrapie in sheep and Creutzfeldt-Jakob disease in people — from progressing to a fatal stage. “We don’t know what’s going on here, but we do know there’s something interesting,” says John Collinge, director of the United Kingdom Medical Research Council Prion Unit in London, who headed the new study. Findings reported by Collinge and his colleagues in the Feb. 24 Nature contradict the idea that infectious versions of a normal brain protein called PrP accumulate slowly, gradually twisting all of the healthy copies of the protein into a disease-causing form. Researchers have thought that the disease-causing prions slowly build up to toxic levels that spell the death of brain cells. But the new study shows that the process is anything but gradual, and that infection and toxicity are independent stages of the disease. Prions quickly build up in the brains of mice over the course of a month or two, Collinge and his colleagues found, peaking at about 100 million infectious particles per brain. © Society for Science & the Public 2000 - 2011

Keyword: Prions
Link ID: 15052 - Posted: 02.26.2011

by Michael Marshall IN A memory contest between a chimpanzee and a bird, most of us would bet on the chimp. But if the bird in question were a scrub jay - and the task involved mental time travel - the chimp might just find itself outmatched. Episodic memories combine what happened, when and where. They are an essential part of visualising a different time, and were thought to be uniquely human until Nicola Clayton at the University of Cambridge proved that western scrub jays have simple episodic memories - allowing them to track how long it takes for food they have stashed to rot. Chimps can remember where they hid food, but it's not clear whether they can track the amount of time that has passed since a memory was formed. To investigate, Marusha Dekleva of Utrecht University in the Netherlands tested nine captive chimps on a task similar to the one Clayton used with scrub jays. She showed each chimp four containers: two were empty; one contained either apple sauce or yoghurt, which the chimps like; and one held red peppers, which they like less. Dekleva let the chimps pick a food container either 15 minutes, 1 hour or 5 hours later. But there was a twist: the apple sauce disappeared by the 1-hour mark, leaving the container empty, and by the 5-hour mark the yoghurt had gone, but the peppers were still available. Chimps are good learners and were expected to adjust their choice of containers over time. They didn't. Instead, they remembered which containers held more food early in the study, and picked those no matter how much time had passed. This got them some food, but far less than they could have obtained by adapting their behaviour (PLoS One, DOI: 10.1371/journal.pone.0016593). © Copyright Reed Business Information Ltd.

Keyword: Learning & Memory; Evolution
Link ID: 15051 - Posted: 02.26.2011

by Aria Pearson Newly hatched sea turtles can sense their longitudinal position – something that took sailors hundreds of years and many lost ships to figure out. Surprisingly, they do so using the Earth's magnetic field. Recently, it was discovered that a handful of species – including older sea turtles and migratory birds – seem able to perceive longitude. But it was unclear what cues they could be using. The Earth's magnetic field, which animals can use to gauge latitude, was considered an unlikely candidate because of how little it varies in the east-west direction around the globe. However, in certain parts of the world at the same latitude there are subtle differences in the intensity and angle of the magnetic field. Could these be used by animals to figure out longitude? One such area is in the Atlantic Ocean, where Puerto Rico in the western Atlantic and the Cape Verde Islands in the eastern Atlantic have the same latitude but different longitudes. In between these locations is the North Atlantic Gyre. Loggerhead sea turtles (Caretta caretta) in Florida navigate the North Atlantic Gyre during their five to 10 year migration around the Atlantic Ocean. During this trip the turtles manage to avoid areas where they would get swept up by other currents and ejected out of the gyre. © Copyright Reed Business Information Ltd.

Keyword: Animal Migration
Link ID: 15050 - Posted: 02.26.2011

By Laura Sanders The polite term for what Alzheimer’s disease does to the brain is “neurodegeneration.” In reality, it’s more like violent, indiscriminate devastation. Alzheimer’s scrambles communication channels, incites massive inflammation and demolishes entire brain regions as once plump cells shrivel and die, burying memories in the wreckage. As the attack intensifies, Alzheimer’s gradually strips away a person’s mind, and ultimately the cognitive abilities that permit a conversation with a loved one, a smile or a taste of food. A couple of decades ago, some researchers thought they knew the root cause of this brain invasion — dangerous buildups of a protein called amyloid-beta. Get rid of these big, sticky globs and cure the disease, the reasoning went. But in recent years, a deeper understanding of the disease, along with a few disappointing clinical trials, has challenged long-held assumptions and forced a reevaluation of this strategy. Many researchers are convinced that A-beta is still a key target. A litany of damning evidence from genetics, pathology reports and lab experiments makes that case. Yet recent results show that A-beta is not the same foe it was originally thought to be. Smaller pieces of A-beta — not the large plaques that were formerly indicted — are likely to be malicious, capable of destroying nerve cell connections, several new studies show. Other data coming from sophisticated imaging techniques may illuminate how, when and where A-beta accumulates in the brain, and how this buildup might relate to diminished mental powers. © Society for Science & the Public 2000 - 2011

Keyword: Alzheimers; Learning & Memory
Link ID: 15049 - Posted: 02.26.2011

By PAM BELLUCK In the Oscar-nominated movie “The King’s Speech,” King George VI begins stuttering at 4 and struggles with it throughout his life. But he rarely talks like the stereotypical stutterer, Porky Pig, rapidly repeating letter sounds; usually the king has trouble getting sounds out from the get-go, blocked by sputtering pauses. His stutter is aggravated by stressful situations, like confronting his brother or addressing the public. He speaks better when playing with his daughters, singing words or inserting profanity, or when music blaring in his ears keeps him from hearing himself. These are complicated symptoms, but experts say these details, devised by a screenwriter who stuttered, mirror many aspects of actual stuttering. In that complexity are clues to this often devastating disorder’s cause, say scientists who are starting to untangle the underpinnings of stuttering in hopes of finding better treatment. Dispelling longstanding misconceptions that the underlying causes of stuttering are language problems or psychological problems like anxiety or trauma, researchers say stuttering is really a speech-production problem: a snag in the cascade of steps that our brains and bodies undertake to move the proper muscles to produce words. “People who stutter have motor difficulties in producing fluent speech,” said Luc De Nil, a speech-language pathologist at the University of Toronto. “They don’t have difficulty developing words or syntax, although they may process language differently. They have difficulty with efficient coordination of motor movements, and speech is such a high-demand fine-motor skill that requires extremely fast sequencing and timing.” © 2011 The New York Times Company

Keyword: Language
Link ID: 15048 - Posted: 02.26.2011

By Linda Carroll With disturbing before and after photos of drug users’ faces, a new anti-drug campaign may succeed where others have failed, grabbing teens’ attentions by appealing to their vanity. The pairs of mug shots, which graphically display the damage drugs can do to the face, were collected by the sheriff’s office in Multnomah County, Ore. Faces that were normal — even attractive — in initial photos, shot when addicts were first arrested, metamorphose over years, and sometimes just months, into gaunt, pitted, even toothless wrecks. The photos are part of a 48-minute documentary called “From Drugs to Mugs,” created by Deputy Bret King. King hopes that the documentary, which is available on a DVD along with a CD of mug shots, will help scare kids straight by showing them concrete evidence of damage that can occur within months from using meth, heroin or cocaine. “The thinking is that this will give kids a tangible image of what can happen if they get involved in using hard drugs,” King says. “We did want to appeal to their sense of vanity.” King understands the power of that teen vanity. “I remember in high school you had to have the right clothes, the right shoes, the right look,” he says. Perhaps the most stunning feature of the photos is how quickly the face is damaged. © 2011 msnbc.com.

Keyword: Drug Abuse
Link ID: 15047 - Posted: 02.26.2011

By MARIA CHENG LONDON — You are awake, aware and probably unable to move or talk — but you are not necessarily unhappy, says the largest study of locked-in syndrome ever conducted. A surprising number of patients with the condition say they are happy, despite being paralyzed and having to communicate mainly by moving their eyes. Most cases are caused by major brain damage, often sustained in traumatic accidents. As part of the study — published in the online journal BMJ Open on Wednesday, Dr. Steven Laureys of the Coma Science Group at the University Hospital of Liege in Belgium and colleagues sent questionnaires to 168 members of the French Association for Locked-in Syndrome, asking them about their medical history, their emotional state and views on euthanasia. Sixty-five patients used a scale to indicate their sense of well-being, with 47 saying they were happy and 18 unhappy. They were also asked a variety of questions about their lives, including their ability to get around or participate in social functions, or if they had ever considered euthanasia. Only a handful of patients said they often had suicidal thoughts. The patients responded to questions largely by blinking. Adrian Owen, a neuroscientist at the University of Western Ontario in Canada, said of the results: "We cannot and should not presume to know what it must be like to be in one of these conditions... Many patients can find happiness in ways that we simply cannot imagine," he said via e-mail. He was not linked to the study. Copyright 2011 The Associated Press.

Keyword: Emotions
Link ID: 15046 - Posted: 02.24.2011

By Matt Walker Capuchin monkeys have what at first glance appears to be an odd habit: they urinate onto their hands then rub their urine over their bodies into their fur. Now scientists think they know why the monkeys "urine wash" in this way. A new study shows that the brains of female tufted capuchins become more active when they smell the urine of sexually mature adult males. That suggests males wash with their urine to signal their availability and attractiveness to females. Details of the finding are published in the American Journal of Primatology. A number of New World monkey species, including mantled howler monkeys, squirrel monkeys and the few species of capuchins, regularly "urine wash", urinating into the palm of the hand, then vigorously rubbing the urine into the feet and hindquarters. Several hypotheses have been put forward as to why they do it, including that it may somehow help maintain body temperature or allow other monkeys to better identify an individual by smell. Most studies into the behaviour have been inconclusive. "But one study reported that when being solicited by a female, adult males increased their rate of urine-washing," said Dr Kimberley Phillips, a primatologist at Trinity University in San Antonio, Texas, US. BBC © MMXI

Keyword: Sexual Behavior; Chemical Senses (Smell & Taste)
Link ID: 15045 - Posted: 02.24.2011