By Gisela Telis Already famous for swimming through sewers and surviving under subway rails, rats can now claim a more sophisticated talent: thinking about thinking. It's not epistemology, but a study published today in Current Biology reports the first evidence that rats know the limits of their own knowledge--a capacity long thought to belong only to the animal kingdom's top brains. People experience metacognition, or gauging their own knowledge, on a daily basis; anyone who's ever had a sinking feeling during an exam knows it well. But attempts to detect metacognition in animals have met with little success, in large part because animals can't tell researchers what they're thinking. Scientists must instead rely on behavioral clues: Monkeys place lower bets on their answers when given a difficult test, for example, and dolphins waver when asked to distinguish between two similar sounds. Thus far, however, smaller-brained animals, such as pigeons, have shown no signs of metacognition in the lab. Would rats be any different? Neuroscientist Jonathon Crystal of the University of Georgia in Athens and his graduate student, Allison Foote, put the rodents to the self-knowledge test by asking them to classify sounds. First, the researchers trained the rats to associate a short burst of static--lasting about 2 seconds--with one lever, and a long burst of static--lasting about 8 seconds--with another lever. Pushing the correct lever yielded a tasty reward of six food pellets; pushing the incorrect lever yielded no food and no chance to try again. The rats also learned that they could get half the reward without making a choice, by poking their nose into a food trough. © 2007 American Association for the Advancement of Science

Keyword: Intelligence
Link ID: 10051 - Posted: 06.24.2010

By Greg Miller Chimpanzees and bonobos are our closest primate relatives, but the two apes have very different personalities. While primatologists have often noted nasty, competitive behavior among power-hungry chimps, bonobos have a reputation as free-loving peaceniks. Now, a behavioral study that directly compares the two apes suggests that the bonobos' more cordial nature enables them to cooperate more successfully than chimps in some situations. Most researchers believe that humans shared a common ancestor with chimpanzees and bonobos between 5 million and 7 million years ago (for a different take, see ScienceNOW, 27 February). Both of these apes may have something to tell us about the evolution of human behavior, yet most research has focused on chimps, in large part because bonobos are endangered--perhaps as few as 10,000 remain. In the new study, researchers worked with bonobos at a sanctuary in the Democratic Republic of Congo and with chimps at a Ugandan sanctuary. The different natures of the two apes became clear when the researchers, led by Brian Hare, a biological anthropologist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, presented pairs of bonobos and pairs of chimps with plates of fruit. Bonobo pairs reacted by playing with each other and even rubbing genitals--a frequent stress-reliever in bonobo society. They also shared the bounty more often than not. Chimps, on the other hand, generally avoided their partner and shared food less than half of the time. © 2007 American Association for the Advancement of Science

Keyword: Aggression; Evolution
Link ID: 10050 - Posted: 06.24.2010

Roxanne Khamsi How well people perform on tests after being deprived of sleep depends in part on their genes, new research suggests. After staying awake all night, individuals with a long version of the PER3 gene only scored half as well on cognitive tests as subjects with a short version. What is more, the greatest differences in performance were seen during the small hours – the time when most tiredness-related accidents happen and when shift-workers have most trouble staying awake. “It may be there are people who are genetically predisposed against shift work,” says Malcolm von Schantz, at the University of Surrey, UK. But he emphasises that gene tests should not be used to discriminate against such individuals. It is very possible that carriers of the long PER3 gene have advantages at other times, he notes. Von Schantz and his colleagues recruited 12 volunteers who carried two copies of the long version of PER3 and another dozen with two copies of the short version. Using electroencephalogram machines to record brain activity, researchers monitored the participants' sleep patterns. The recordings revealed that although both groups slept for about the same amount of time, subjects with the short PER3 gene spent roughly 15% of this time in deep sleep, also known as slow-wave sleep. Their counterparts with the long PER3, meanwhile, spent about 22% in this restorative sleep stage. © Copyright Reed Business Information Ltd

Keyword: Sleep; Genes & Behavior
Link ID: 10049 - Posted: 06.24.2010

Kerri Smith It's often said that optimistic people look at the world through rose-tinted spectacles. Now it seems that rose-tinted smells can have benefits too. Taking a whiff of rose scent while learning a task and then being exposed to the same smell during sleep helps memories to set, researchers have found. The discovery could see students frantically spraying themselves with perfume before exams — although the effect is tricky to replicate at home. Jan Born of the University of Lübeck and his colleagues exposed people to the smell of roses one evening while they learned the locations of various picture cards laid in a square. Half of them were then given the same odour to smell as they slept, while the other half had an odour-free night. When they were tested the next day, those who'd had a rosy sleep remembered 97% of the locations — without the roses this figure was 86%. The team's findings, published in Science1, supports theories about how memories are solidified in the brain during sleep. Researchers think that a part of the brain called the hippocampus is like the scratch-pad of memory, where we put new things that have been experienced or learned until they can be filed for long-term storage. During sleep, these memories are 'reactivated' and transferred to the cortex. ©2007 Nature Publishing Group

Keyword: Sleep; Chemical Senses (Smell & Taste)
Link ID: 10048 - Posted: 06.24.2010

By Sally Squires A year-long, head-to-head study of four widely used diets found that overweight women who followed the very low-carbohydrate Atkins diet had no adverse health effects and lost slightly more weight than women on the other three. The study by Stanford University researchers compared the Atkins approach with three others: the standard low-fat, reduced-calorie regimen long recommended by many physicians and weight-loss experts; the Zone, a reduced-carbohydrate approach developed by author Barry Sears; and the very low-fat, high-carbohydrate regimen created by Dean Ornish. The latest findings add to a growing body of evidence that the high-protein Atkins diet does not cause the harmful heart and artery effects long feared by many researchers. Women who followed the Atkins plan had a significant drop in triglycerides, one of the unhealthful blood fats linked to a higher risk of heart disease. Their blood pressure also dropped the most of the four groups, a finding that the researchers think may relate to their slightly greater weight loss. Those in the Atkins group also experienced the largest increase in high-density lipoprotein (HDL), a protective type of cholesterol. Most important, the Atkins group did not develop the soaring levels of low-density lipoprotein (LDL) that some experts have thought might result from eating a diet rich in saturated fat and cholesterol found in fatty cuts of meat, butter and cream. © 2007 The Washington Post Company

Keyword: Obesity
Link ID: 10047 - Posted: 06.24.2010

Roger Highfield People who have out-of-body experiences near death, such as flying along a tunnel towards a heavenly light, are more likely to suffer a strange effect called sleep paralysis, according to a survey that adds to mounting evidence for a biological explanation for this mystical experience. During sleep paralysis, people experience a kind of breakdown between states of consciousness which takes place on the fringe of slumber, either when falling asleep or awakening. Because the brain turns off the body's ability to move during dreaming, muscles can lose their tone, or tension, causing the paralysis. advertisementThe details of sleep paralysis vary from person to person. Some hear vague rustling sounds, indistinct voices and demonic gibberish. Others see hallucinations of humans, animals and supernatural creatures. There is a striking inability to move or to speak, or a weight on the chest. Also common are feelings of rising off the bed, flying, or hurtling through spiral tunnels. In addition, people report out of body experiences, sometimes accompanied by "autoscopy" when they look down on themselves. Not surprisingly, these bizarre experiences - called REM intrusions by scientists - are accompanied by fear and terror. Throughout history, there have also been accounts of people experiencing visions on the brink of death, what are now called near-death experiences. Now the two odd effects are linked by a study that backs the idea that the near-death experience is a biological experience, rather than anything to do with a larger, spiritual dimension, a glimpse of heaven, or the existence of the soul. © Copyright of Telegraph Media Group Limited 2007.

Keyword: Sleep
Link ID: 10046 - Posted: 06.24.2010

A genetic variant of a receptor in the brain’s reward circuitry heightens the stimulating effects of early exposures to alcohol and increases alcohol consumption, according to a new study by researchers at the National Institute on Alcohol Abuse and Alcoholism (NIAAA), part of the National Institutes of Health (NIH). Conducted in rhesus monkeys, the study extends previous research that suggests an important role for a similar brain receptor variant in the development of human alcohol use disorders. A report of the findings is published in the March, 2007 issue of the Archives of General Psychiatry. “Although the pathway to alcoholism is influenced by many factors, our findings affirm that individuals who possess this receptor variant may experience enhanced pleasurable effects from alcohol that could increase their risk for developing alcohol abuse and dependence,” notes Markus Heilig, M.D., Ph.D., NIAAA Clinical Director and the study’s senior author. Molecules known as opioid peptides bind to opioid receptors in the brain to signal experiences of reward and reinforcement, as well as the euphoria and other positive subjective effects produced by alcohol. Previous studies have shown that, among the brain’s various subtypes of opioid receptors, the mu-subtype is most likely responsible for transmitting alcohol’s positive effects. “We also know that there are several genetic variants of the human mu-opioid receptor,” notes first author Christina Barr, V.M.D., Ph.D. “One of these, designated 118G, has a greatly enhanced ability to bind opioid peptides. People who have this variant of the receptor have reported increased euphoria following alcohol consumption.”

Keyword: Drug Abuse
Link ID: 10045 - Posted: 06.24.2010

Roxanne Khamsi A high-fat diet can desensitise the brain to appetite-suppressing hormones, effectively leaving the brain unaware of obesity, a study in mice has found. The research shows why the brain cells of obese mice stop responding to one such hormone, called leptin. According to scientists, drugs that help the brain to respond to leptin might one day treat obesity in humans by decreasing appetite. In both humans and mice, fat cells throughout the body release leptin. The hormone travels to a part of the brain known as the hypothalamus, which regulates sensations such as appetite and thirst. In theory, when fat increases in the body so do levels of leptin, causing a decrease in appetite. But scientists have found that administering leptin does not reliably work to treat obesity. The new study by Michael Cowley at the Oregon National Primate Research Center, US, and colleagues suggests that failure is because the brain has become insensitive to leptin. In their experiment, researchers fed a group of genetically identical mice either a high-calorie diet rich in fats or a low-calorie diet. All of the mice on the low-calorie diet remained lean. © Copyright Reed Business Information Ltd.

Keyword: Obesity
Link ID: 10044 - Posted: 06.24.2010

Roxanne Khamsi The female wasp spider dwarfs her male counterpart (Image: Sebastian Funke)Some male spiders up-and-leave right after sex for good reason – they risk being eaten by their female partners if they linger too long. In the process of making a swift exit, many leave part of their genitalia inside their mates. Now a new study reveals that detaching part of the genital organ is not a means to help the male escape a murderous attack. Instead, the abandoned genitals act as "chastity belts" and block the entry of sperm from competitors into the female. Gabriele Uhl at the University of Bonn, Germany, and colleagues watched wasp spiders (Argiope bruennichi) mate. During the act, a male must insert one of its two sperm-carrying organs, known as pedipalps, into the female’s genital openings. After delivering the sperm, the tip of the pedipalp becomes stuck inside the female, forming a plug in her reproductive tract. To find out if leaving behind part of the pedipalp helped the males escape death, researchers compared the damage to this organ during first-time sexual encounters with damage sustained in subsequent encounters. The experienced males monitored in the experiment had mated once before and only had a single remaining pedipalp intact. These males would enjoy no evolutionary benefit from surviving after mating a second time because they have generally lost both of their pedipalps at this point, and can therefore no longer inseminate females. © Copyright Reed Business Information Ltd.

Keyword: Sexual Behavior; Evolution
Link ID: 10043 - Posted: 06.24.2010

A US study appears to back previous research suggesting underweight babies are at a greater risk of depression. Researchers found girls who had been born weighing under 2.5kg (5.5lb) were more prone to depression aged 13 to 16 than those born at a normal weight. The Archives of General Psychiatry study, led by Duke University, examined data on more than 1,400 children, aged nine to 16. They said further investigation was needed to pin down possible reasons. Previous studies have said a potential for depression may lie dormant in small babies, before emerging later under stressful conditions. The Duke University study found that among girls, 5.7% were born weighing less than 2.5kg, and of these 38% experienced depression at least once between the ages of 13 and 16. This compared with 8.4% of those born at a normal weight. On average, 23.5% of teenage girls with a low birth weight were depressed each year, compared with 3.4% of those born at a normal weight. Regardless of their birth weight, no more than 4.9% of the boys experienced depression. Low birth weight was not linked to an increased risk of any other psychiatric condition, including anxiety disorders, in either boys or girls. The researchers' favoured theory for the link to depression is that the changes a foetus has to make to compensate for a harsh environment in the womb may in some way leave it poorly prepared for the conditions it will encounter in later life. It is also possible that low birth weight is indicative of harsh living conditions, such as poverty, which may make a child experiencing them more likely to be depressed. Alternatively, a depressed mother may be more likely to produce a child who is prone to depression - and to have a low birth weight baby because they may be more likely to smoke and drink during pregnancy. However, the latest study found no evidence to support these later two ideas. (C)BBC

Keyword: Depression; Development of the Brain
Link ID: 10042 - Posted: 03.06.2007

By Dennis Drabelle The insomniac as hero -- that's how I think of W.C. Fields. When chronic lack of sleep wore the comedian down during a film shoot, he would repair to his trailer for a few winks (supplemented, no doubt, by a few swigs from the bottle). For Fields, who wrote his own scripts, sleep was the Great Eluder, and his struggles to catch up with it inspired an unforgettable scene in his best movie, "It's a Gift" (1934). One night, Harold Bissonette (Fields) sneaks out on his nagging wife and beds down on the porch swing outside their apartment. In the next dozen minutes, he becomes a nocturnal Job, beleaguered by animate and inanimate forces: The swing collapses; the grocer's boy delivers clinking bottles of milk; a coconut bounces down the stairs; a salesman comes looking for a Carl La Fong, whose name he spells out repeatedly and loudly. The cacophony goes on, and poor Bissonette never does get to sleep. The film's title can be puzzling unless taken ironically, as a comment on Bissonette's ability to slough off irritations by the score -- all contributing to the scourge of sleeplessness -- without losing his temper. Yet there's another possible reading. Whether a habitually sound sleeper could have thought up that series of anti-sleep roadblocks is dubious. Working as a creative artist, Fields might be hinting that a condition most of us would regard as a curse can actually be a help. © 2007 The Washington Post Company

Keyword: Sleep
Link ID: 10041 - Posted: 06.24.2010

By MARIA CHENG BERLIN (AP) - At a laboratory in Germany, volunteers slide into a donut-shaped MRI machine and perform simple tasks, such as deciding whether to add or subtract two numbers, or choosing which of two buttons to press. They have no inkling that scientists in the next room are trying to read their minds _ using a brain scan to figure out their intention before it is turned into action. In the past, scientists had been able to detect decisions about making physical movements before those movements appeared. But researchers at Berlin's Bernstein Center for Computational Neuroscience claim they have now, for the first time, identified people's decisions about how they would later do a high-level mental activity _ in this case, adding versus subtracting. While still in its initial stages, the techniques may eventually have wide-ranging implications for everything from criminal interrogations to airline security checks. And that alarms some ethicists who fear the technology could one day be abused by authorities, marketers, or employers. Tanja Steinbach, a 21-year-old student in Leipzig who participated in the experiment, found it a bit spooky but wasn't overly concerned about the civil liberties implications. "It's really weird," she said. "But since I know they're only able to do this if they have certain machines, I'm not worried that everybody else on the street can read my mind." Copyright 2006 Associated Press.

Keyword: Brain imaging; Attention
Link ID: 10040 - Posted: 03.06.2007

Rachel Nowak Tooth brushing can induce seizures in people with epilepsy, a new case study of three people with the condition has found. “Brushing your teeth is very rhythmic. Our idea is that it causes a rhythmic over-activity in the brain, which feeds back on itself – similar to the effect of strobe lighting on people with photosensitive epilepsy,” says neurologist Wendyl D’Souza of St Vincent’s Hospital in Melbourne, Australia, one of the team reporting the cases. Epilepsy occurs when nerve cells in an area of the brain fire more rapidly than usual and in synchrony with one another. This causes seizures that range from “grand mal” seizures – the old term for extreme convulsions and loss of consciousness – to short bouts of staring that may wrongly be blamed on lack of concentration. Seizures bought on by a benign stimulus such as tooth brushing, reading or strobe lighting – called “reflex” seizures – are rare, D’Souza notes. Each of the patients in the new study had been diagnosed with epilepsy, and had suffered full-blown convulsive seizures. The tooth-brushing seizures were smaller and included jerking of the mouth, eyes, and face; tongue cramping; and excessive salivation, lasting for up to 90 seconds. © Copyright Reed Business Information Ltd.

Keyword: Epilepsy
Link ID: 10039 - Posted: 06.24.2010

By HENRY FOUNTAIN There are patterns everywhere in nature, but sometimes they are hard to find. A group of researchers at Cornell, for example, had to look through the transparent tissues of a larval zebra fish as neurons in its spinal cord fired away. But the pattern they found is remarkable and offers insight into how developing nervous systems are organized. Neurons on the cord’s ventral side — near the bottom when the cord is viewed in cross-section — fire when the fish swims slowly, while those on the dorsal side, or top, fire when it swims fast. It’s “a very simple pattern that no one had seen before,” said Joseph R. Fetcho, in whose laboratory the initial discovery was made, by another researcher, David L. McLean. They are among the authors of a paper describing the finding in Nature. Zebra fish larvae make excellent subjects for studying neurons as the basis of behavior. By making the neurons fluoresce when they fire, either through injection of chemicals or by genetically modifying the fish to produce a fluorescent protein, researchers can link individual neurons to specific behaviors. The Cornell researchers were able to see which neurons fired when the fish were engaged in slow-swimming movements (activating muscles in the tail only) or fast-swimming movements (involving muscles that make the whole body bend). Copyright 2007 The New York Times Company

Keyword: Development of the Brain
Link ID: 10038 - Posted: 06.24.2010

Andy Coghlan Marlon Brando eat your heart out. Around the world, parasitic birds such as cuckoos and cowbirds are displaying the same mixture of guile, ruthlessness and brutality as any self-respecting Godfather. Using a delicate mixture of intimidation and retribution, they "persuade" other birds to accept their eggs and raise their chicks. Ten years ago, Anders Pape Møller at Copenhagen University in Denmark and colleagues discovered that great spotted cuckoos (Clamator glandarius) run a mafia-style protection racket against magpies living in Andalucia, Spain. If a magpie rejects a cuckoo egg laid in its nests, the cuckoo promptly returns to destroy the magpie's own eggs or kill its chicks. Not to be outdone, American cowbirds, which are not related to cuckoos, employ an even more forceful racket against warblers. "The cowbird has much more sophisticated predatory behaviours than we thought," says James Hoover at the Illinois Natural History Survey in Champaign, US, who has been monitoring brown-headed cowbirds (Molothrus ater) for four years in the swamps of the Cache River in southern Illinois. Wild warblers are very compliant with cowbirds, and are not known to recognise and eject cowbird eggs. But Hoover and Robinson wanted to find out what would happen if they did. To mimic this situation, they provided artificial nests for 180 pairs of prothonotary warblers (Protonotaria citrea), waited for the cowbirds to cuckold them, then selectively removed the cowbird eggs. © Copyright Reed Business Information Ltd

Keyword: Sexual Behavior; Aggression
Link ID: 10037 - Posted: 06.24.2010

Heidi Ledford The long-term mental anguish caused by psychological torture and humiliating treatment is comparable to that caused by physical torture, a new study indicates. The results, say the study's authors, support the prohibition of psychological torture by international law. The findings are particularly important given recent debate over how the United States defines torture. The United Nations Convention Against Torture and Other Cruel, Inhuman, or Degrading Treatment or Punishment defines it as "severe suffering, whether physical or mental". But the US Department of Defense has argued for a definition of torture that does not include many acts of psychological abuse, including humiliating treatment, isolation, or deprivation of sleep, food, or medical care. The implication is that these psychological acts aren't as serious, says Metin Basoglu of King's College University in London, lead author of the new study. To investigate this point, Basoglu and his colleagues studied the effects of psychological abuse in 279 survivors of torture during the war in former Yugoslavia. Nearly all of the participants had been beaten, humiliated and threatened with death. Participants were asked to rank the distress caused by different assaults on a scale of zero to four. ©2007 Nature Publishing Group

Keyword: Stress
Link ID: 10036 - Posted: 06.24.2010

High levels of stress may physically scar a child's brain, a study suggests. US scientists discovered a brain structure involved with memory and emotion had shrunk in children with post-traumatic stress disorder (PTSD). A withered hippocampus may make a child less able to deal with stress and raise anxiety, Pediatrics journal reports. The children in the study also had higher blood levels of a stress hormone called cortisol, which has been shown to kill hippocampal cells in animals. This could set up a vicious cycle, where high cortisol causes more hippocampal damage, which in turn raises the anxiety. The Stanford University Medical Center scientists speculate that the ensuing damage could prolong the stress symptoms and also interfere with therapy. Lead researcher Victor Carrion explained: "One common treatment for PTSD is to help a sufferer develop a narrative of the traumatic experience. But if the stress of the event is affecting areas of the brain responsible for processing information and incorporating it into a story, that treatment may not be as effective." He said stress had to be extreme to cause the damage. "We are not talking about the stress of doing your homework or fighting with your dad," Dr Carrion said. The 15 children he and his team studied all had PTSD as a result of physical, emotional or sexual abuse, witnessing violence or experiencing lasting separation and loss. Dr Carrion said it would now be important to understand why some children appear to be more resilient to stress than others, and what the long-term effects of extreme stress are. (C)BBC

Keyword: Stress; Learning & Memory
Link ID: 10035 - Posted: 03.06.2007

Physical differences in the brain may increase the chances of a person choosing to take drugs, say Cambridge University scientists. A study of rats showed variations in brain structure pre-dated their first exposure to narcotics, and made them more likely to opt for cocaine. Writing in Science, the team say genes may affect these differences in humans. Treatments to reduce their effect may be found - but a test of vulnerability to drugs is unlikely, they add. Up to 500,000 people are currently addicted to Class A drugs such as cocaine, heroin and amphetamines, according to government figures. One of the most important questions in the science of addiction surrounds the origin of differences noticed in the brains of human drug users. While these differences are thought to be important in the way humans respond to drugs, it is difficult to prove whether they are a part of the natural brain chemistry of that individual, or have developed as a result of taking the drugs themselves. To unravel this problem, the Cambridge researchers scanned the brains of rats, and found similar differences in 'neurotransmitter receptors' in certain parts of the brain. Some of the animals had far fewer 'dopamine receptors' - the brain structures onto which drugs such as cocaine and heroin latch to produce their effect. The scientists used a game in which the rats had to wait to press a button and receive a reward, coupled with detailed brain scans, to see if those with the fewest dopamine receptors were impulsive, a type of behaviour often linked with drug use in humans. This was the case - even in rats which had no contact with drugs. (C)BBC

Keyword: Drug Abuse; ADHD
Link ID: 10034 - Posted: 03.03.2007

By William J. Kole VIENNA, Austria - Abuse of prescription drugs is about to exceed the use of illicit street drugs worldwide, and the shift has spawned a lethal new trade in counterfeit painkillers, sedatives, and other medicines potent enough to kill, a global watchdog warned yesterday. Prescription drug abuse already has outstripped traditional illegal drugs such as heroin, cocaine and ecstasy in parts of Europe, Africa and South Asia, the U.N.-affiliated International Narcotics Control Board said. In the United States, the abuse of painkillers, stimulants, tranquilizers, and other prescription medications has gone beyond "practically all illicit drugs with the exception of cannabis," with users increasingly turning to them first, the Vienna-based group said in its annual report. Unregulated markets in many countries make it easy for traffickers to peddle a wide variety of counterfeit drugs using courier services, the mail and the Internet. "Gains over the past years in international drug control may be seriously undermined by this ominous development if it remains unchecked," Narcotics Control Board president Philip O. Emafo said.

Keyword: Drug Abuse
Link ID: 10033 - Posted: 03.03.2007

By Michael Balter In the classic 1969 buddy movie Butch Cassidy and the Sundance Kid, the Kid gets the girl, but Butch still does some courting, especially when he takes Etta on a bicycle ride while the soundtrack plays "Raindrops Keep Falling on My Head." It's that way too with lance-tailed manakins, a bird found in South America. Two males team up to woo the female, but the alpha male is the only one who scores. A new study suggests that the beta male benefits from this supporting role, although the payoff can take a long time. The evolutionary advantage of cooperative behavior is often a mystery, especially when there is no immediate perk to being someone's buddy. To see why beta males might lend a helping wing to their alpha pals, behavioral ecologist Emily DuVal, now at the Max Planck Institute for Ornithology in Seewiesen, Germany, spent several years studying lance-tailed manakins on a small island off the coast of Panama. The males of this species team up in pairs and perform elaborate duets and dances to attract females, including leapfrogging over each other and showing off with short, swooping flights. Between 1999-2004, DuVal captured 457 birds, banded them for identification, and took blood samples from their wing veins for DNA analysis. DuVal wanted to test three hypotheses for why the beta male would help the alpha even though he never gets to mate with the female: The beta's own immediate reproductive chances could increase; the beta male could be a close relative of the alpha, thus helping to pass on related genes; or the beta male might be increasing his own chances of reproducing sometime down the line. © 2007 American Association for the Advancement of Science

Keyword: Sexual Behavior
Link ID: 10032 - Posted: 06.24.2010