By Tara Parker-Pope Nobody likes going to the dentist, but redheads may have good reason. A growing body of research shows that people with red hair need larger doses of anesthesia and often are resistant to local pain blockers like Novocaine. As a result, redheads tend to be particularly nervous about dental procedures and are twice as likely to avoid going to the dentist as people with other hair colors, according to new research published in The Journal of the American Dental Association. Researchers believe redheads are more sensitive to pain because of a mutation in a gene that affects hair color. In people with brown, black and blond hair, the gene, for the melanocortin-1 receptor, produces melanin. But a mutation in the MC1R gene results in the production of a substance called pheomelanin that results in red hair and fair skin. The MC1R gene belongs to a family of receptors that include pain receptors in the brain, and as a result, a mutation in the gene appears to influence the body’s sensitivity to pain. A 2004 study showed that redheads require, on average, about 20 percent more general anesthesia than people with dark hair or blond coloring. And in 2005, researchers found that redheads are more resistant to the effects of local anesthesia, such as the numbing drugs used by dentists. Copyright 2009 The New York Times Company

Keyword: Pain & Touch; Genes & Behavior
Link ID: 13139 - Posted: 06.24.2010

Wisconsin researchers have released a free software tool that could help web surfers susceptible to certain seizures. An estimated one in 4,000 people has photosensitive epilepsy and could suffer a seizure when exposed to bright colours and rapidly flashing images. The condition gained prominence in 1997 when more than 800 Japanese children were hospitalized after viewing a cartoon. Since then, television directors, video-game makers and others have tested their content to make sure it doesn't reach seizure-inducing thresholds. Web developers, though, didn't have simple ways to run such tests. Researchers at the University of Wisconsin-Madison set out to change that. "On the web you really never know what's going to pop up on the screen until it does, and one second later you could be having a seizure," said Gregg Vanderheiden, the centre's director. Web developers can use the Photosensitive Epilepsy Analysis Tool, or PEAT, to determine how fast an image blinks, for example, and let developers know whether it poses a seizure risk. Content that doesn't pass the test isn't always risky. Researchers say flashy content that doesn't fill at least 10 per cent of a screen isn't a danger. © CBC 2009

Keyword: Epilepsy
Link ID: 13138 - Posted: 06.24.2010

By Katherine Harmon In the months after he had surgery to fix his defective heart valve, Bruce Stutz didn't feel quite the same. It wasn't his physical fitness that was subpar, although that did require some post-op retraining, but rather his mental capacity. "I couldn't muster the concentration to deal with the problem," he wrote in a 2003 article for Scientific American. During surgery, Stutz had been hooked up to a heart–lung machine, also called a cardiopulmonary-bypass pump, for the two-hours of a procedure to keep his blood oxygenated and flowing while his heart was stopped. He found that he was not the only one who, after time on the pump, had felt their brains bogged down by simple tasks. A 2001 study in The New England Journal of Medicine found that of 261 heart disease patients who had been kept alive during surgery with the pump, 42 percent showed cognitive decline five years after the surgery, even after adjusting for age. "Interventions to prevent or reduce short- and long-term cognitive decline after cardiac surgery are warranted," the authors, led by Mark Newman of the Duke University Medical Center, concluded. And a study published earlier this year in The Annals of Thoracic Surgery, led by James Slater, a cardiothoracic surgeon at the Mid-Atlantic Surgical Associates in Morristown, N.J., supported the previous findings, showing that lowered levels of oxygen in blood flowing to the brain during surgery did correlate to increased risk of suffering from the mental impairment dubbed "pump head". © 1996-2009 Scientific American Inc.

Keyword: Stroke
Link ID: 13137 - Posted: 06.24.2010

By Michael Torrice No one would confuse the pain of a bee sting with the itch of a mosquito bite. But neuroscientists have had a hard time figuring out how the body makes these distinctions. Now researchers have identified a previously unstudied set of spinal neurons in mice that communicates only itch. The discovery could lead to novel treatments for the irritating ailment. Prevailing theory suggests that pain and itch are linked in the nervous system. In fact, doctors often prescribe pain medication to patients with chronic itch. But some neuroscientists favor a "labeled-line" theory, in which itch signals have their own neural circuits--or lines--to the brain. In 2001, researchers supported this idea by claiming to find itch-only neurons in the spinothalamic tract (STT), a set of cells that travel up the spine to the brain's thalamus. Subsequent studies, however, revealed that these neurons also respond to the burning pain of capsaicin--the spicy chemical in chili peppers. Now, neuroscientist Zhou-Feng Chen of Washington University School of Medicine in St. Louis, Missouri, and colleagues believe they have found the most compelling evidence yet for an itch labeled line. Two years ago, the group discovered a gene necessary for itch, but not pain, called the gastrin-releasing peptide receptor (GRPR). In the new study, Chen and colleagues tried to figure out if cells expressing GRPR were the long-sought itch-only neurons. So they selectively killed GRPR cells in mice spines with a toxin called saporin tethered to a peptide that targets GRPR proteins. After 2 weeks, they had destroyed more than 75% of GRPR neurons. © 2009 American Association for the Advancement of Science.

Keyword: Pain & Touch
Link ID: 13136 - Posted: 06.24.2010

A nurse-led behavioral intervention can reduce the incidence of depression in stroke survivors, according to the results of a study published in the recent issue of the journal Stroke. The intervention, called Living Well with Stroke (LWWS), provided individualized counseling sessions aimed at increasing pleasant social interactions and physical activity as a way to elevate mood, and was designed to be used alone or in conjunction with antidepressant medications. This study was funded by the National Institute of Nursing Research (NINR), a component of the National Institutes of Health (NIH). A stroke occurs when the blood supply to a part of the brain becomes blocked or interrupted, leading to brain damage in the affected area. Stroke survivors can experience a range of aftereffects, including impaired mobility or paralysis, pain, speech and language problems, and altered cognition. As many as one-third of stroke survivors also develop post-stroke depression (PSD), which may include intense feelings of loss, anger, sadness, and/or hopelessness. Compared to stroke survivors without depression, those with PSD tend to have a poorer response to rehabilitation, a longer delay in returning to work, more social withdrawal, and increased use of health care services. They are also at higher risk for subsequent strokes, cardiac events, and death. While antidepressant medications have shown varying degrees of short-term efficacy for PSD patients, few studies have examined non-pharmacologic interventions or long-term outcomes.

Keyword: Depression; Stroke
Link ID: 13135 - Posted: 08.07.2009

Malcolm Ritter, Associated Press -- From the goose that laid the golden egg to the race between the tortoise and the hare, Aesop's fables are known for teaching moral lessons rather than literally being true. But a new study says at least one such tale might really have happened. It's the fable about a thirsty crow. The bird comes across a pitcher with the water level too low for him to reach. The crow raises the water level by dropping stones into the pitcher. (Moral: Little by little does the trick, or in other retellings, necessity is the mother of invention.) Now, scientists report that some relatives of crows called rooks used the same stone-dropping strategy to get at a floating worm. Results of experiments with three birds were published online Thursday by the journal Current Biology. Christopher Bird of Cambridge University and a colleague exposed the rooks to a 6-inch-tall clear plastic tube containing water, with a worm on its surface. The birds used the stone-dropping trick spontaneously and appeared to estimate how many stones they would need. They learned quickly that larger stones work better. In an accompanying commentary, Alex Taylor and Russell Gray of the University of Auckland in New Zealand noted that in an earlier experiment, the same birds had dropped a single stone into a tube to get food released at the bottom. So maybe they were just following that strategy again when they saw the tube in the new experiment, the scientists suggested. © 2009 Discovery Communications, LLC.

Keyword: Intelligence; Evolution
Link ID: 13134 - Posted: 06.24.2010

by Ewen Callaway As wind instruments go, folded vegetation seems a little on the primitive side. Orang-utans have been found to blow through leaves to modulate the sound of their alarm calls, making them the only animal apart from humans known to use tools to manipulate sound. The orang-utan's music, if you can call it that, is actually an alarm call known as a "kiss squeak". "When you're walking the forest and you meet an orang-utan that not habituated to humans, they'll start giving kiss squeaks and breaking branches," says Madeleine Hardus, a primatologist at the University of Utrecht in the Netherlands, who documented the practice among wild apes in Indonesian Borneo. She contends that orang-utans use leaves to make kiss squeaks to deceive predators, such as leopards, snakes and tigers, as to their actual size – a deeper call indicating a larger animal. Baritone squeaks Orang-utans also produce kiss squeaks with their lips alone or with their hands. To determine if the leaves make a difference, Hardus's team recorded a total of 813 calls produced by nine apes, and then measured the pitch of the different kinds of kiss squeaks made by each animal. Across all nine orang-utans, the unaided kiss squeaks came out with the highest pitch, followed by calls produced when the apes put their hands over their mouths. But leaves lowered the high-pitched calls the most, Hardus' team found. © Copyright Reed Business Information Ltd

Keyword: Intelligence; Evolution
Link ID: 13133 - Posted: 06.24.2010

By Stephen Smith Just the other day, a man weighing 470 pounds lumbered into Dr. Caroline Apovian’s office at Boston Medical Center. He was young - only 32 years old - but already, his heart had begun to fail him, a legacy of his extreme obesity. Maybe, he asked Apovian, I should have weight-loss surgery. She told him that first, he would need to alter what he eats - and drinks, especially the 2 liters of sugary soft drinks he drains every day. “I gave him a high-protein, low-fat diet,’’ Apovian recalled. “Everything was fine until I said, ‘No soda.’ And he said, ‘You don’t understand. The soda calls to me.’ ’’ Last week, federal disease investigators reported that the cost of treating obesity has doubled in the past decade, and they pointed to sugar-laden beverages - sodas, energy drinks, fruity libations - as a prime culprit. Three months earlier, one of the nation’s premier nutrition specialists, Dr. Walter Willett of the Harvard School of Public Health, embarked on a personal crusade to persuade consumers to forgo sugary drinks. Research conducted by Willett and other Boston scientists has shown that women who quaffed more than two sweetened beverages a day had an almost 40 percent higher risk of heart disease than those who rarely touched the drinks. © 2009 NY Times Co.

Keyword: Obesity; Chemical Senses (Smell & Taste)
Link ID: 13132 - Posted: 06.24.2010

By Maggie Fox WASHINGTON - Use of antidepressant drugs in the United States doubled between 1996 and 2005, probably because of a mix of factors, researchers reported on Monday. About 6 percent of people were prescribed an antidepressant in 1996 — 13 million people. This rose to more than 10 percent or 27 million people by 2005, the researchers found. "Significant increases in antidepressant use were evident across all sociodemographic groups examined, except African Americans," Dr. Mark Olfson of Columbia University in New York and Steven Marcus of the University of Pennsylvania in Philadelphia wrote in the Archives of General Psychiatry. Story continues below ↓advertisement | your ad here "Not only are more U.S. residents being treated with antidepressants, but also those who are being treated are receiving more antidepressant prescriptions," they added. More than 164 million prescriptions were written in 2008 for antidepressants, totaling $9.6 billion in U.S. sales, according to IMS Health. Drugs that affect the brain chemical serotonin like GlaxoSmithKline's Paxil, known generically as paroxetine, and Eli Lilly and Co's Prozac, known generically as fluoxetine, are the most commonly prescribed class of antidepressant. But the study found the effect in all classes of the drugs. Copyright 2009 Reuters.

Keyword: Depression
Link ID: 13131 - Posted: 06.24.2010

By Emily Anthes The surface of the brain is a complex landscape, featuring endless peaks and valleys. This intricately folded outer layer, known as the cerebral cortex, is one of the brain’s most noticeable features. But it’s also one of the least well understood. “There’s this large expanse of cortex, much of which is like South America to a 17th century cartographer,’’ said David Van Essen, a neurobiologist at Washington University in St. Louis. “It’s this big mass of land, and we know what the outlines are, but no one’s been able to chart the intricacies.’’ That’s beginning to change. Technological and computational advances have enabled researchers to image the brain’s wrinkled exterior in stunning detail, mapping the size and shape of each fold. Scientists pursuing this new discipline of “cortical cartography’’ expect it to yield insights into how the brain develops and what happens when things go awry. Researchers have already discovered that the cerebral cortex - which controls higher-level functions, including thought, emotion, and perception - is folded abnormally in disorders ranging from autism to depression. Such insights could lead to better and earlier diagnoses and perhaps even new clues to treatment. When the human brain develops in the womb, the outer surface is initially almost entirely smooth. But during the last few months of fetal development, the cortex begins to fold and wrinkle; by the time a full-term infant is delivered, most of the folding has been completed, though subtle refinements continue through early childhood. The folds create more surface area, increasing the size of the cerebral cortex that can fit in our skulls, and, it’s believed, partly accounting for the greater cognitive powers of humans compared with species with smoother brains. © 2009 NY Times Co.

Keyword: Development of the Brain; Evolution
Link ID: 13130 - Posted: 06.24.2010

By TARA PARKER-POPE Married people tend to be healthier than single people. But what happens when a marriage ends? New research shows that when married people become single again, whether by divorce or a spouse’s death, they experience much more than an emotional loss. Often they suffer a decline in physical health from which they never fully recover, even if they remarry. And in terms of health, it’s not better to have married and lost than never to have married at all. Middle-age people who never married have fewer chronic health problems than those who were divorced or widowed. The findings, from a national study of 8,652 men and women in their 50s and early 60s, suggest that the physical stress of marital loss continues long after the emotional wounds have healed. While this does not mean that people should stay married at all costs, it does show that marital history is an important indicator of health, and that the newly single need to be especially vigilant about stress management and exercise, even if they remarry. “When your spouse is getting sick and about to die or your marriage is getting bad and about to die, your stress levels go up,” said Linda Waite, a sociology professor at the University of Chicago and an author of the study, which appears in the September issue of The Journal of Health and Social Behavior. “You’re not sleeping well, your diet gets worse, you can’t exercise, you can’t see your friends. It’s a whole package of awful events.” Copyright 2009 The New York Times Company

Keyword: Stress
Link ID: 13129 - Posted: 06.24.2010

By C. CLAIBORNE RAY Q. After a five-day cruise, I felt the ground ashore rolling under my legs for days, as if I were still at sea. What’s going on? A. It is a condition that has been called mal de débarquement, like a sort of mal de mer after debarking. Timothy C. Hain, an expert on dizziness disorders in Chicago, and others published a study of the condition in Archives of Otolaryngology in 1999, finding that 26 of 27 sufferers responding to a survey of passengers about severe post-cruise symptoms were women ages 40 to 50. Most people suffer for a month or less, though the subjects of the study had it for months or years. Mal de débarquement is not linked to any injury to the ear or brain and is generally described as a variant of motion sickness, though most motion-sickness medications do not work once it starts. There is no proof of any cause. Because of the preponderance of premenopausal women with symptoms, there is some suspicion that the problem could be linked to hormones. Other suggestions for a cause include a type of migraine or the results of overcompensation for sensory input while trying to maintain balance on a boat. Another possible cause is the adaptation to rolling, that is, rocking side to side, while rotating the head. A study could investigate whether people who do a lot of head rotation on a boat are more likely to develop it. Copyright 2009 The New York Times Company

Keyword: Miscellaneous
Link ID: 13128 - Posted: 06.24.2010

by Colin Barras Epilepsy may be sparked by a metal imbalance in the brain caused by a single gene mutation, a study in mice suggests. The finding could help develop new treatments in humans who suffer from the condition. Steven Clapcote's team at the University of Leeds, UK, pinpointed a gene that seems to play an important part in the genesis of epileptic seizures, which result from abnormal bursts of electrical activity in the brain and can occur even when there is no underlying neurological condition. The Atp1a3 gene is one of three that produce a chemical pump mechanism to keep sodium and potassium levels in brain nerve cells and the surrounding tissue at the levels needed for normal activity. "It's been known for a long time that injecting the sodium/potassium pump inhibitor ouabain into the brain can induce seizures in rats," says Clapcote, and it's also known that mice lacking two of three forms of the pump – either the "alpha1" or "alpha2" forms – are free from seizures. Cured offspring Clapcote's team have now determined that mice with a mutated copy of the Atp1a3 gene and reduced activity of the "alpha3" pump were prone to epileptic seizures. The mouse strain has been dubbed Myshkin after a Dostoevsky character in The Idiot, who suffered from epilepsy. "Mysh" also comes from the Russian for mouse. © Copyright Reed Business Information Ltd.

Keyword: Epilepsy; Genes & Behavior
Link ID: 13127 - Posted: 06.24.2010

By Greg Miller In people suffering from glaucoma, damage to the optic nerve can slowly degrade peripheral vision and, in the worst cases, eventually lead to blindness. But eyedrops containing nerve growth factor (NGF)--a protein that promotes the survival and growth of neurons in the developing brain--appear to prevent nerve damage in rats and restore some vision in three human glaucoma patients, the authors of a new study claim. Not everyone thinks the reported effect is real, however. For the study, ophthalmologist Alessandro Lambiase of the University of Rome Campus Bio-Medica and colleagues first mimicked glaucoma in rats. The researchers recreated the most common form of the disease, in which increased fluid pressure inside the eye damages nerves, by injecting saline solution into a vein in the eye. They kept the intraocular pressure up for 7 weeks, killing about 40% of the neurons in the retina whose tail-like axons give rise to the optic nerve, which conveys visual information to the brain. However, in rats treated four times daily with NGF-laced eyedrops during the 7-week period, the death of these "retinal ganglion cells" was reduced by about 25%, the team reports online today in the Proceedings of the National Academy of Sciences. Encouraged by these findings, the researchers asked three patients with advanced glaucoma to take the drops four times daily for 3 months. Peripheral vision, one of the main visual functions impaired by glaucoma, improved in two of the patients and got no worse in the third, the researchers report in the same paper. They also report improvements in visual acuity, contrast sensitivity, and in electrophysiological measures of nerve conduction in the visual system in some or all of the patients. © 2009 American Association for the Advancement of Science.

Keyword: Vision; Trophic Factors
Link ID: 13126 - Posted: 06.24.2010

By NEIL AMDUR The three new movies would seem to have little in common: a romantic comedy about Upper West Side singles, a biopic about a noted animal science professor, and an animated film about an extended pen-pal relationship. But all three revolve around Asperger’s syndrome, the complex and mysterious neurological disorder linked to autism. Their nearly simultaneous appearance — two open this summer, and the third is planned for next year — underscores how much Asperger’s and high-functioning autism have expanded in the public consciousness since Dustin Hoffman’s portrayal of an autistic savant in “Rain Man” 21 years ago. “The more I learned about Asperger’s,” said Max Mayer, the writer and director of the romance, “Adam,” which opened last week, “the better metaphor it felt like for the condition of all of us in terms of a desire for connection to other people.” People with Asperger’s may have superior intelligence and verbal skills, and they often have an obsessive interest in a particular topic (astronomy, in the case of the title character in “Adam,” played by Hugh Dancy). But they tend to be self-defeatingly awkward in social situations, and romantic relationships can leave them at sea. The syndrome is generally considered a high-functioning form of autism, which in recent years has been diagnosed in more and more children. While the reasons for the explosion in diagnoses are unclear, increased awareness may be part of the explanation, and one reason for the growth in awareness is the rise of online parent communities. Copyright 2009 The New York Times Company

Keyword: Autism
Link ID: 13125 - Posted: 06.24.2010

By Charles Q. Choi Breathing in the hormone oxytocin has been shown in recent years to trigger all kinds of feel-good emotions in people, such as trust, empathy and generosity. Now scientists find it might have a dark side: Snorting oxytocin might also incite envy and gloating. Past studies have shown that oxytocin plays a wide role in social bonding in mammals—between mates, for instance, or mother and child—and recent work suggested the hormone was linked with pro-social behavior in people, such as altruism. Still, neuroscientist Simone Shamay-Tsoory in University of Haifa in Israel and her colleagues noted that oxytocin was found to raise aggression in rodents, suggesting the hormone might play a wider role in social emotions in humans. The researchers decided to investigate envy and gloating—feelings related to the tendency to compare oneself with others—to see if oxytocin ramped up these emotions or dialed them down. The researchers gave 56 volunteers either oxytocin or a placebo and paid them to take part in a game of chance with another participant which, unknown to them, was a computer. They were shown three doors on a video screen, either red, blue or yellow, and told that behind each door was a different sum of money they could keep after the game. The computer was programmed to either win more money than the players to trigger feelings of envy, lose more money to elicit a form of gloating known as schadenfreude (delight over another's misfortune) or to win or lose equal amounts of money. To encourage these negative emotions, the researchers gave the computer player an arrogant "personality". © 1996-2009 Scientific American Inc.

Keyword: Aggression; Hormones & Behavior
Link ID: 13124 - Posted: 06.24.2010

Sue Barry is a neuroscientist at Mount Holyoke College. She's also the author of the newly released book Fixing My Gaze, which tells the story of how Barry, at the age of 48, finally learned to see in 3-D. Mind Matters editor Jonah Lehrer chats with Barry about what a flat world looks like and what her own experience can teach us about brain plasticity and education. LEHRER: You begin your new book, Fixing My Gaze, by describing the moment you realized that you lacked stereoscopic vision, which underlies the ability to see in 3-D. Could you describe that moment? BARRY: I was sitting in my college neurobiology class, somewhat bored and distracted, when the professor began to describe experiments done on wall-eyed and cross-eyed cats. He mentioned that vision in these cats had not developed normally and that these animals probably lacked stereovision or the ability to see in 3D. What's more, these animals could never gain stereovision because this skill developed only during a "critical period" in early life. What was true for cats was also thought to be true for people. The professor's words jerked me right out of my daydream. I realized that I was like the cats in the scientists' experiments, since I had been cross-eyed since early infancy. Three childhood surgeries made my eyes look normal so I assumed that I saw normally as well. Yet, I had just learned in class that I lacked a fundamental way of seeing. After class, I went straight to the college library and read up on stereovision. I searched out and tried every stereovision test I could find and flunked them all. This is how I learned that I was stereoblind. © 1996-2009 Scientific American Inc.

Keyword: Vision
Link ID: 13123 - Posted: 06.24.2010

By Sandra G. Boodman Although he had never seen a case like it in his career, cardiologist David Lomnitz felt certain he knew why his new patient kept blacking out when she ate. At the time of her first appointment in September 2004, Martha Bryce, then a 36-year-old health-care consultant, was feeling desperate. Four years earlier she had been given a diagnosis of epilepsy, and had taken medication to prevent seizures. But doctors had been unable to explain the frequent swooning episodes that occurred when she started to eat, forcing her to put her head down on the table in an intermittently successful attempt to avoid passing out. Doctors seemed unconcerned and told her the episodes might be a symptom of her seizure disorder. Bryce, a registered nurse, wasn't so sure. But after a frightening incident drove home the potential danger of the baffling condition, she made an appointment with Lomnitz, now assistant chief of cardiology at Norwalk Hospital in Norwalk, Conn. "Her story rang a bell for me," he said. His hunch about her condition, triggered by cases he heard about during his training years earlier, would upend her diagnosis and radically alter her treatment. The first sign something was wrong was dramatic. While on a business trip to Las Vegas in January 2000, Bryce, who lives in Ridgefield, Conn., decided to visit the Hoover Dam before catching a red-eye flight home. Standing at an overlook preparing to photograph the concrete behemoth, Bryce recalled, "all of a sudden I felt a way I'd never felt before." She fainted and, after regaining consciousness, learned she had suffered a grand mal seizure during which she had bitten her tongue. © 2009 The Washington Post Company

Keyword: Epilepsy
Link ID: 13122 - Posted: 06.24.2010

By JOHN MARKOFF LOS ANGELES — As a promising Caltech graduate student in applied physics, Stephen Kurtin could have taken a job offer from Intel at the dawn of the microelectronics era 40 years ago. Instead he followed the path of a lone inventor, gaining more than 30 patents in fields including word processing software and sound systems, culminating in the pair of glasses resting on his nose, which he believes can free nearly two billion people around the world from bifocals, trifocals and progressive lenses. The glasses have a tiny adjustable slider on the bridge of the frame that makes it possible to focus alternately on the page of a book, a computer screen or a mountain range in the distance. Dr. Kurtin, 64, has spent almost 20 years of his career on a quest to create a better pair of spectacles for people who suffer from presbyopia — the condition that affects almost everyone over the age of 40 as they progressively lose the ability to focus on close objects. After many false turns and dead ends, he has succeeded in creating glasses with a mechanically adjustable focus. He says they are better than other glasses and some forms of Lasik surgery. And they make an intriguing fashion statement: a bit of Harry Potter with a dash of “Revenge of the Nerds.” Copyright 2009 The New York Times Company

Keyword: Vision
Link ID: 13121 - Posted: 06.24.2010

Matt Kaplan Finches instinctively avoid competitors coloured red, rather than learning to fear the colour during their upbringing, Australian research concludes.1 The results are tempting researchers to suspect that in other animals, including ourselves, red's aggressive and intimidating character might also be hard-wired into brains from birth. Dozens of experiments have shown that red intimidates competitors. In humans, wearing red improves chances of winning at sports.2 Studies have also revealed that red is associated with aggression and dominance in fish, reptiles and birds.3,4 But whether fear of red is innate or learned is an "unresolved mystery", says Robert Barton, an anthropologist at the University of Durham, UK. Sarah Pryke of Macquarie University in Sydney tested this question in Australian Gouldian finches (Erythrura gouldiae). As adults, the finches develop either red or black heads, a genetically determined trait. The red-headed birds are aggressive, dominant and avoided by others. To find out whether these traits were learned or inborn, Pryke examined competition between young Gouldian finches — whose heads, yet to blossom into coloured adulthood, are all dull grey. She first raised finches that were genetically destined to be red-headed with black-headed parents, raised others that were genetically destined to be black-headed with red-headed parents, and left still other finches to be raised by parents of the same colour group. In contests staged between these young birds over food, it was body size rather than genetic destiny or rearing environment that decided the winner. © 2009 Nature Publishing Group,

Keyword: Vision; Evolution
Link ID: 13120 - Posted: 06.24.2010