By SINDYA N. BHANOO Handsome men may turn the heads of women, but for those less attractive, sociability and friendliness also seem to seduce the fairer sex. The same is true for male house finches, according to a new study. Female house finches prefer to mate with males with the reddest feathers, but dull-colored males make themselves more appealing by acting more social before mating season, according to a study in the September issue of the American Naturalist. The researchers found that the duller a male bird was in color, the more likely he was to engage with multiple social groups. Birds in a social group flock and forage together and any bird can belong to multiple groups. Drab-looking male finches drifted from group to group in the winter, the researchers found. By mating season in the spring, the less attractive males tended to have the same level of mating success as the most colorful, attractive males. “Females have limited options to chose from and this is a way for males to manipulate their chances to find mates, by placing themselves in certain settings,” said Kevin Oh, an evolutionary biologist at Cornell University and the study’s lead author. The least attractive, or most yellow, males were four times as likely to interact with multiple social groups then the most attractive, or reddest, males, Dr. Oh said. House finches are found across North America, but Dr. Oh and his co-author, Alexander Badyaev of the University of Arizona, studied wild populations in Arizona. Copyright 2010 The New York Times Company

Keyword: Sexual Behavior; Evolution
Link ID: 14253 - Posted: 07.13.2010

by Linda Geddes A form of synaesthesia in which people experience letters or numbers in colour may be trainable. The discovery could shed new light on how such traits develop. Synaesthesia is thought to have a genetic component, but some people have reported synaesthetic experiences following hypnosis, so Olympia Colizoli at the University of Amsterdam in the Netherlands, and colleagues, wondered if it might also be possible to acquire synaesthesia through training. To test the idea, they gave seven volunteers a novel to read in which certain letters were always written in red, green, blue or orange (see picture). Before and after reading the book, the volunteers took a "synaesthetic crowding" test, in which they identified the middle letter of a grid of black letters which were quickly flashed onto a screen. Synaesthetes perform better on the test when a letter they experience in colour is the target letter. The volunteers performed significantly better on this test after training compared with people who read the novel in black and white. The findings suggest that natural synaesthesia may develop as a result of childhood experiences as well as genetics, says Colizoli, who presented the findings at the Forum of European Neuroscience in Amsterdam last week. © Copyright Reed Business Information Ltd.

Keyword: Miscellaneous
Link ID: 14252 - Posted: 07.13.2010

By Tina Hesman Saey Aging and wisdom are supposed to go together, but it turns out that a molecule that prevents one may actually play a role in the other. Researchers have discovered a new role for the famous antiaging protein SIRT1. It not only fends off aging, but also aids in learning and memory, a new study published online July 11 in Nature shows. Sirtuins, a family of proteins that includes SIRT1, help to regulate gene activity and have been implicated in governing metabolism and many of the biological processes that lead to aging. In the new study, Li-Huei Tsai, a neuroscientist and Howard Hughes Medical Institute investigator at MIT, finds that SIRT1 also plays a critical role in protecting learning and memory, at least in mice. Tsai and her colleagues had an inkling that SIRT1 might play some role in the brain from earlier experiments showing that resveratrol, an activator of sirtuins, could help neurons survive a mouse version of Alzheimer’s disease. Resveratrol also improved the animals’ ability to learn and remember. Since resveratrol can act on all seven of the sirtuins found in mammals and also affects other biological processes (SN Online: 6/28/10), the researchers didn’t know what role, if any, SIRT1 played in the process. To find out, Tsai and her colleagues put mice genetically engineered to lack SIRT1 in their brains through a series of learning and memory tests. The mice had trouble remembering the location of a submerged platform in a water maze, couldn’t tell the difference between a new object and an old one placed in their cages, and did poorly on other memory tests. “The ability for these animals to learn is clearly impaired,” Tsai says. © Society for Science & the Public 2000 - 2010

Keyword: Learning & Memory; Alzheimers
Link ID: 14251 - Posted: 07.13.2010

Mice might turn up their noses at alcohol, but not the prairie vole. This usually upstanding rodent, famous for mating for life and sharing pup-raising duties, apparently likes a stiff drink. “They not only drink alcohol, they prefer it over water,” Allison Anacker, a neuroscience graduate student at Oregon Health & Science University told The Oregonian. Anacker, working under behavioral neuroscience professor Andrey Ryabinin, was looking for a model organism to study some humans’ troubled relationship with alcohol. Mice and rats fail in this role–it’s unusual to find ones that want even a sip of the stuff. In a study published in Addiction Biology last month, Ryabinin’s team records the drunken misadventures of prairie voles. After chugging their preferred 6 percent alcohol drink (about the equivalent of beer), some thirsty voles shoved off parental responsibilities and even walked out on their mates. Though some drank responsibility, others drank to excess, stumbling away from the bar/spiked water bottle. The study suggests that like humans, the voles also make drinking buddies, seemingly encouraging each other to have another. When caged together, the voles appear to match one another drink for drink, a practice that apparently has nothing to do with who’s buying the next round.

Keyword: Drug Abuse
Link ID: 14250 - Posted: 07.13.2010

By GINA KOLATA If you had to choose one public health problem to attack, which would it be: teenage smoking or childhood obesity? To answer that question, you might want to pose another. Who will have the harder road in life, or indeed the longer one: the teenage puffer or the chubby child? Pitting smoking against obesity is tricky because it can mean comparing apples and bonbons, but there is some suggestion that a kind of weird zero-sum game is actually going on. And some smoking opponents fear that a choice has been made — with obesity the winner, quite possibly for the wrong reasons. “Obesity is the new kid on the block, relatively speaking,” said Kenneth E. Warner, dean of the University of Michigan’s school of public health. “Tobacco is old news.” When it comes to smoking, said Stanton A. Glantz, director of the University of California at San Francisco’s Center for Tobacco Control Research and Education, “we really haven’t had anyone pushing it to the top of the agenda.” That is a problem. “It’s not that I am for obesity,” he said, but he finds it less than encouraging, for example, that the hugely influential Robert Wood Johnson Foundation is pulling back from its anti-smoking efforts while directing its money and resources to preventing childhood obesity. Then there is Michelle Obama’s campaign, Let’s Move, to prevent childhood obesity. And in May, the White House Task Force on Childhood Obesity announced its goal — reduce the rate of childhood obesity, now 17 percent, to 5 percent by 2030. Copyright 2010 The New York Times Company

Keyword: Obesity; Drug Abuse
Link ID: 14249 - Posted: 07.12.2010

by Helen Thomson I'VE just had a brainwave. Oh, and there's another. And another! In fact, you will have had thousands of them since you started reading this sentence. These waves of electricity flow around our brains every second of the day, allowing neurons to communicate while we walk, talk, think and feel. Exactly where brainwaves are generated in the brain, and how they communicate information, is something of a mystery. As we begin to answer these questions, surprising functions of these ripples of neural activity are emerging. It turns out they underpin almost everything going on in our minds, including memory, attention and even our intelligence. Perhaps most importantly, haphazard brainwaves may underlie the delusions experienced by people with schizophrenia, and researchers are investigating this possibility in the hope that it will lead to treatments for this devastating condition. So what exactly is a brainwave? Despite the way it is bandied about in everyday chit-chat, the term "brainwave" has a specific meaning in neuroscience, referring to rhythmic changes in the electrical activity of a group of neurons. Each neuron has a voltage, which can change when ions flow in or out of the cell. This is normally triggered by stimulation from another cell, and once a neuron's voltage has reached a certain point, it too will fire an electrical signal to other cells, repeating the process. When many neurons fire at the same time, we see these changes in the form of a wave, as groups of neurons are all excited, silent, then excited again, at the same time. © Copyright Reed Business Information Ltd.

Keyword: Miscellaneous
Link ID: 14248 - Posted: 07.12.2010

By John Cloud Men who cheat on their spouses have always enjoyed an expedient explanation: Evolution made me do it. Many articles (here is one, and here is another), especially in recent years, have explored the theory that men sleep around because evolution has programmed them to seek fertile (and, conveniently, younger) wombs. (See the top 10 political sex scandals.) But what about women? If it's really true that evolution can cause a man to risk his marriage, what effect does it have on women's sexuality? A new journal article suggests that evolutionary forces also push women to be more sexual, although in some unexpected ways. University of Texas psychologist David Buss wrote the article, which appears in the July issue of Personality and Individual Differences, with the help of three grad students, Judith Easton (who is listed as lead author), Jaime Confer and Cari Goetz. Buss, Easton and their colleagues found that women in their 30s and early 40s are significantly more sexual than younger women. Women ages 27 through 45 report not only having more sexual fantasies (and more intense sexual fantasies) than women ages 18 through 26; the older women also report having more sex, period. And they are more willing than younger women to have casual sex, even one-night stands. In other words, despite the girls-gone-wild image of promiscuous college women, it is women in their middle years who are America's most sexually industrious. © 2010 Time Inc.

Keyword: Sexual Behavior; Evolution
Link ID: 14247 - Posted: 07.12.2010

by Susan Heavey and Lisa Richwine WASHINGTON — The first of three new fat-fighting pills faces public scrutiny by U.S. regulatory advisers next week, as small biotechs target the growing number of obese Americans despite a checkered past for weight-loss drugs. Vivus Inc, Arena Pharmaceuticals Inc and Orexigen Therapeutics Inc are trying to succeed where earlier efforts flopped after several weight-loss drugs were linked to serious side effects. The U.S. Food and Drug Administration will seek input from outside advisers July 15 on Vivus' pill, Qnexa, for use with diet and exercise. If approved, it would be the first new prescription weight-loss drug in a decade in the United States, where two out of every three people are overweight. The FDA's review by a panel of outside experts follows a troubled history with obesity pills that either never gained approval, were pulled from the market after sales began, or were slapped with severe warnings. "The history of weight-loss drugs is such that it's a no-brainer that the FDA is going to take each and every one to an advisory panel," said analyst Ira Loss, who follows the agency for Washington Analysis Corp. An advisory panel is one of the last hurdles in a drug's route to market. The FDA will make the final decision, but usually follows the advice of its advisers. Copyright 2010 Reuters

Keyword: Obesity
Link ID: 14246 - Posted: 07.10.2010

Janelle Weaver Birds that spend less time parenting engage more frequently in homosexual behaviour, according to a study published this week. The findings offer a possible explanation for the evolution of homosexuality: parents that devote less time to their offspring have more time and energy to interact with members of the same sex while still producing offspring. Biologists had thought that homosexuality is disadvantageous on an evolutionary level because it distracts animals from pursuing sexual encounters that could result in offspring. Yet more than 130 species of birds participate in homosexual activity — and sometimes a lot of it. In the Laysan albatross (Phoebastria immutabilis), for example, up to 31% of pairs are female–female in some populations, and up to 20% of pairings in graylag geese (Anser anser) are male–male. Scientists have struggled to explain such patterns. But homosexuality may not be costly for birds that have plenty of mating opportunities because of lower parenting demands, says Geoff MacFarlane, an ecologist at the University of Newcastle in Callaghan, Australia. The less effort that females or males put into parental care, the more they participate in homosexual activities, according to a survey of the literature his team published this week in the journal Animal Behaviour1. Vincent Savolainen, a biologist at Imperial College London, says homosexual behaviour is sometimes considered a Darwinian paradox because it does not result in offspring. "This is one of the few studies that explains homosexual behaviour from the evolutionary point of view," he says. © 2010 Nature Publishing Group,

Keyword: Sexual Behavior; Evolution
Link ID: 14245 - Posted: 07.10.2010

By Larry Greenemeier For many, the warm glow of fireflies in the night air is a sure sign that summer has arrived. After dark, these bioluminescent beetles are generally visible only when they emit flashes of yellow, green or pale red from their lower abdomen as part of their mating ritual. Some species of firefly have found their own key to successful coupling— synchronous flashing patterns, a phenomenon that has attracted the attention of a team of researchers studying what pattern recognition tells us about how the brain is wired. To better understand how the brains of humans and other animals process visual signals, Andrew Moiseff, a professor of physiology and neurobiology at the University of Connecticut in Storrs, and Jonathan Copeland, a biology professor at Georgia Southern University in Statesboro, over the past four summers have studied the role that synchronized flashing plays in the mating of the Photinus carolinus species of firefly found in Tennessee's Smoky Mountains National Park.Firefly, bioluminescence, mating In synchronous flashing by P. carolinus fireflies, many males produce flashes simultaneously, rhythmically and repeatedly, according to the researchers, who published their findings in the July 9 issue of Science. These patterns consist of a burst of several flashes (typically six) followed by a period of no flashing that lasts about six-to-eight seconds. During these pauses, the female responds with two flashes in rapid succession, with the second flash beginning almost immediately after the first one is finished. The female may produce one to four of these "doublets" while perched on leaves or branches, says Moiseff, the study's lead author. © 2010 Scientific American,

Keyword: Sexual Behavior; Evolution
Link ID: 14244 - Posted: 07.10.2010

by Linda Geddes, Amsterdam THE discovery of an antibody that binds to certain brain receptors could reduce the side effects of a common stroke drug and buy additional time in which to use it. The preferred treatment for ischaemic stroke, in which a blood clot cuts off the blood supply to brain tissue, is a drug called rtPA, which dissolves the clot. However, that drug has to be given within the first few of hours of a stroke, otherwise the risks of treatment outweigh the benefits. Dissolving the clot can lead to a sudden rise in blood pressure, increasing the chance that a blood vessel will rupture and bleed into the brain. Only 5 to 10 per cent of people who suffer a stroke make it to hospital early enough to be treated with rtPA, says Denis Vivien of the University of Caen Basse-Normandie in France. The rest are given drugs that do not destroy the initial clot but reduce the chance of further clots forming. One reason for a delay in administering rtPA is that a brain scan must be carried out to determine the nature of the stroke. People with haemorrhagic stroke, in which a blood vessel in the brain bursts, should not receive rtPA as it increases the risk of bleeding. Now a startling discovery by Vivien has put a different perspective on this relatively simple picture: rtPA is actually released by brain cells. "This was completely unexpected," he says. © Copyright Reed Business Information Ltd.

Keyword: Stroke
Link ID: 14243 - Posted: 07.10.2010

by Andy Coghlan A GENE has been discovered that appears to dictate the sexual preferences of female mice. Delete the gene and the modified mice reject the advances of the males and attempt to mate with other females instead. While it is impossible to say whether the finding has any relevance for human sexuality, it provides a clue as to how sexuality develops in mammals. Chankyu Park and colleagues at the Korea Advanced Institute of Science and Technology in Daejon, South Korea, deleted the FucM gene in mouse embryos to see what effect it would have on behaviour. Female mice lacking the gene avoided the advances of males, stopped sniffing male urine and attempted to mate with other females, though their ability to have pups was unaffected (BMC Genetics, DOI: 10.1186/1471-2156-11-62). The gene the team deleted is for an enzyme called fucose mutarotase, which adds the sugar fucose to proteins. Park believes that disabling the gene exposes parts of the developing mouse brain linked with sexual preference in adult life to extra oestrogen. The hormone masculinises the brain in mice - though not in people. In a normal female mouse fetus, this extra oestrogen would be "filtered out" by a substance called alpha-fetoprotein. But AFP only functions properly when adorned with fucose. So without the gene that makes the enzyme, AFP cannot keep the flood of oestrogen at bay. © Copyright Reed Business Information Ltd.

Keyword: Sexual Behavior
Link ID: 14242 - Posted: 07.10.2010

By James Dao NEW YORK — The government is preparing to issue new rules that will make it substantially easier for veterans who have been found to have posttraumatic stress disorder to receive disability benefits for the illness, a change that could affect hundreds of thousands of veterans from the wars in Iraq, Afghanistan, and Vietnam. The regulations from the Department of Veterans Affairs— which will take effect as early as Monday and cost as much as $5 billion over several years, according to congressional analysts — will essentially eliminate a requirement that veterans document specific events like bomb blasts, firefights, or mortar attacks that might have caused post-traumatic stress disorder, an illness characterized by emotional numbness, irritability, and flashbacks. For decades, veterans have complained that finding such records was extremely time consuming and sometimes impossible. And in the wars in Afghanistan and Iraq, veterans groups assert, the current rules discriminate against tens of thousands of service members — many of them women — who did not serve in combat roles but nevertheless suffered traumatic experiences. Under the new rule, which applies to veterans of all wars, the department will grant compensation to those with the illness if they can simply show that they served in a war zone and in a job consistent with the events that they say caused their conditions. They would not have to prove, for instance, that they came under fire, served in a front-line unit, or saw a friend killed. © Copyright 2010 Globe Newspaper Company.

Keyword: Stress
Link ID: 14241 - Posted: 07.08.2010

By Lindsey Tanner Want happier, more alert teenagers? Let them sleep in a little. A new study reveals that delaying the school day by 30 minutes results in teens who are less sleepy and depressed. Scientists say that teens tend to be in their deepest sleep around dawn, when they typically need to arise for school. Interrupting that sleep can leave them groggy. Giving teens 30 extra minutes to start their school day leads to more alertness in class, better moods, less tardiness, and even healthier breakfasts, a small study found. "The results were stunning. There's no other word to use," said Patricia Moss, academic dean at the Rhode Island boarding school where the study was done. "We didn't think we'd get that much bang for the buck." The results appear in July's Archives of Pediatrics & Adolescent Medicine. The results mirror those at a few schools that have delayed starting times more than half an hour. Researchers say there's a reason why even 30 minutes can make a big difference. Teens tend to be in their deepest sleep around dawn -- when they typically need to arise for school. Interrupting that sleep can leave them groggy, especially since they also tend to have trouble falling asleep before 11 p.m. © 2010 Associated Press/AP Online

Keyword: Biological Rhythms; Development of the Brain
Link ID: 14240 - Posted: 07.08.2010

By GRETCHEN REYNOLDS What goes on inside your brain when you exercise? That question has preoccupied a growing number of scientists in recent years, as well as many of us who exercise. In the late 1990s, Dr. Fred Gage and his colleagues at the Laboratory of Genetics at the Salk Institute in San Diego elegantly proved that human and animal brains produce new brain cells (a process called neurogenesis) and that exercise increases neurogenesis. The brains of mice and rats that were allowed to run on wheels pulsed with vigorous, newly born neurons, and those animals then breezed through mazes and other tests of rodent I.Q., showing that neurogenesis improves thinking. But how, exactly, exercise affects the staggeringly intricate workings of the brain at a cellular level has remained largely mysterious. A number of new studies, though, including work published this month by Mr. Gage and his colleagues, have begun to tease out the specific mechanisms and, in the process, raised new questions about just how exercise remolds the brain. Some of the most reverberant recent studies were performed at Northwestern University’s Feinberg School of Medicine in Chicago. There, scientists have been manipulating the levels of bone-morphogenetic protein or BMP in the brains of laboratory mice. BMP, which is found in tissues throughout the body, affects cellular development in various ways, some of them deleterious. In the brain, BMP has been found to contribute to the control of stem cell divisions. Your brain, you will be pleased to learn, is packed with adult stem cells, which, given the right impetus, divide and differentiate into either additional stem cells or baby neurons. As we age, these stem cells tend to become less responsive. They don’t divide as readily and can slump into a kind of cellular sleep. It’s BMP that acts as the soporific, says Dr. Jack Kessler, the chairman of neurology at Northwestern and senior author of many of the recent studies. The more active BMP and its various signals are in your brain, the more inactive your stem cells become and the less neurogenesis you undergo. Your brain grows slower, less nimble, older. Copyright 2010 The New York Times Company

Keyword: Learning & Memory; Neurogenesis
Link ID: 14239 - Posted: 07.08.2010

The undersea world isn't as quiet as we thought, according to a New Zealand researcher who found fish can "talk" to each other. Fish communicate with noises including grunts, chirps and pops, University of Auckland marine scientist Shahriman Ghazali has discovered according to newspaper reports Wednesday. "All fish can hear, but not all can make sound -- pops and other sounds made by vibrating their swim bladder, a muscle they can contract," Ghazali told the New Zealand Herald. Fish are believed to communicate with each other for different reasons, including attracting mates, scaring off predators or orienting themselves. The gurnard species has a wide vocal repertoire and keeps up a constant chatter, Ghazali found after studying different species of fish placed into tanks. On the other hand, cod usually kept silent, except when they were spawning. "The hypothesis is that they are using sound as a synchronization so that the male and female release their eggs at the same time for fertilization," he said. Some reef fish, such as the damselfish, made sounds to attempt to scare off threatening fish and even divers, he said. But anyone hoping to strike up a conversation with their pet goldfish is out of luck. © 2010 Discovery Communications, LLC.

Keyword: Animal Communication; Hearing
Link ID: 14238 - Posted: 07.08.2010

by Linda Geddes, Amsterdam When children learn to read and write, they often get things back to front: confusing the letters "b" and "d", and sometimes even writing their entire names in the mirror image. This strange phenomenon might be a consequence of children "recycling" an area of the brain that recognises shapes and patterns as they learn to read, says Stanislas Dehaene of INSERM, the National Institute of Health and Medical Research in Saclay, France. Previous studies in macaques have shown that individual neurons in an area of the brain's left hemisphere fire in response to pictures and patterns. We also know that animals and human infants alike find it hard to distinguish between mirror images of the same picture. Still other studies have established that this brain region, called the visual word form area (VWFA), is activated as people learn to read. To investigate what happens in the VWFA when humans look at words and pictures and their mirror images, Dehaene used functional magnetic resonance imaging to record the brain activity of adults when they were shown pictures, written words and letters both in the normal and the reverse orientation. © Copyright Reed Business Information Ltd.

Keyword: Language; Dyslexia
Link ID: 14237 - Posted: 07.08.2010

By Tina Hesman Saey Little things can make a big difference in the brain. Case in point: A tiny snippet of RNA may help guard cocaine-using rats against addiction to the drug, a new study shows. The minuscule molecular guard is a hairpin-shaped piece of RNA known as a microRNA. Raising levels of a microRNA called miR-212 in the brains of cocaine-using rats led the animals to take less of the drug than rats with normal microRNA levels, researchers report in the July 8 Nature. Similarly, blocking the microRNA’s action increased the rats’ cocaine use. If the results hold true in people, researchers may be able to develop new therapies for treating addiction to cocaine and other drugs of abuse. “Once you get out of whack, this is something that might help bring you back,” says Yale neuroscientist Marina Picciotto, who was not involved in the study. It’s unlikely that the research will lead to gene therapy to raise levels of microRNAs in people’s brains. But small-molecule drugs that mimic the microRNA’s action might be helpful. Just 21 to 23 RNA units long, microRNAs are major regulatory molecules (SN: 3/1/08, p. 136) that govern part of the process by which instructions contained in DNA are transformed into proteins. The molecules generally block protein production. So it was a surprise to find levels of a protein called CREB increase with rising levels of miR-212, says Paul Kenny, a neuroscientist at the Scripps Research Institute in Jupiter, Fla. © Society for Science & the Public 2000 - 2010

Keyword: Drug Abuse
Link ID: 14236 - Posted: 07.08.2010

By Steve Connor, Science Editor Aggressive teenagers with severe behavioural problems may have developed a biological abnormality in their brain, causing them to be aggressive and anti-social, a study has found. Scientists believe they have discovered the first hard evidence showing that conduct disorder in adolescents has a biological basis connected with brain chemistry, rather than being the result of the desire in teenagers to ape their badly-behaved peers. The findings suggest that it may be possible to diagnose a predisposition to conduct disorder in early childhood so that child psychologists could intervene before the behaviour starts to deteriorate. Conduct disorder affects five per cent of teenagers and costs society millions of pounds in terms of remedial education. "Detecting conduct disorder in adolescence may be too late to do anything about it. Early identification of a biological abnormality may be a route to take in terms of early intervention," said Andy Calder of the Medical Research Council's Cognition and Brain Sciences Unit in Cambridge, where the study was carried out. "These are pretty severe kids. They are frequently excluded from school over and over again. Some of them will go into young offenders institutions, so they are not just badly behaved kids," Dr Calder said. "Psychiatrists in the past have not really considered conduct disorder as a medical condition. This is research that's saying that actually it has a biological basis and this is soomething we should consider as a medical issue," he said. ©independent.co.uk

Keyword: Aggression; Development of the Brain
Link ID: 14235 - Posted: 07.06.2010

By Patrick House What if I told you that last week I predicted all eight winners of a round of the World Cup? And that instead of rankings or divination all I did was look up how many people in each team's home country had a tiny parasite lurking in their amygdalas? Would you believe me? A decade ago, Discover Magazine concluded that parasites ruled the world, and now I'm going to try to tell you that, at the very least, parasites rule the World Cup. Toxo is one of the most successful parasites in the world and is found in almost every type of mammal. Goats, cows, pigs, sheep, humans. But it spends its time trying to get into the stomach of a cat, the only place where it can successfully reproduce. Thus the organism has evolved an unusual lifecycle relating to the brains of rats and mice. Rodents ingest little bits of Toxo from cat feces and Toxo goes straight to their heads. Once there, it scrambles the neurons around and reverses the animals' natural aversion to cat urine. Soon after, a recently relieved cat returns to the scene and takes its supper. In other words, the rat plays taxi to the parasite, finding it a new feline host and completing the Toxo lifecycle. Livestock fields are full of fertilizer made from, you guessed it, bits of cat feces. When the cows and goats graze, they ingest Toxo, and it sneaks its way into their brains. Eat one of these livestock uncooked and you'll get Toxo in your brain, too. Thanks to the urbanization of cats (and their feces), almost a third of the human population now has a chronic, latent, and seemingly innocuous Toxo infection. This is, of course, an average: Rates vary a great deal from one country to another, from 6 percent in South Korea to 92 percent in Ghana. © Copyright 2010 Washington Post.Newsweek Interactive Co. LLC

Keyword: Emotions
Link ID: 14234 - Posted: 07.06.2010