CBC News Keeping track of how much you eat by writing it down each day, rather than what you eat, is key for weight loss, a new U.S. study suggests. The No. 1 piece of advice would be to keep a food journal to document every morsel that passes your lips and thereby help monitor daily calorie intake, concluded researchers at the Fred Hutchinson Cancer Research Center in Seattle, Wash. “It is difficult to make changes to your diet when you are not paying close attention to what you are eating.” said lead investigator Anne McTiernan. Participants in the study were given a printed booklet to record their food and beverage consumption, but a food journal doesn't have to be fancy. "Any notebook or pad of paper that is easily carried or an online program that can be accessed any time through a smart phone or tablet should work fine," McTiernan said. Other specific behaviours that support weight loss include not skipping meals and avoiding eating in restaurants – especially at lunch. The findings were published online Friday in the Journal of the Academy of Nutrition and Dietetics The study focus was on how self-monitoring and other diet-related behaviors, as well as meal patterns, effect weight change in overweight and obese postmenopausal women. © CBC 2012

Keyword: Obesity
Link ID: 17045 - Posted: 07.16.2012

By Kay Lazar Mary Regan has witnessed a transformation outside the front door of her Union Square office in Somerville — new “corrals” provide more parking spaces for bicyclists, angled parking has replaced parallel parking for cars to keep doors from flying open into bicycle lanes, and those lanes have been freshly painted. At the nearby farmers’ market, $1 in food stamps is worth $2 in produce to help low-income customers afford fresh fruits and vegetables. “I’ve heard people here say that farmers’ markets used to seem like an elite, foreign thing,” said Regan, a community organizer at a nonprofit organization for affordable housing. “But now that they can use their [food stamps] and get twice as much for the same amount of money, they are buying more healthy foods.” A decade after an ambitious experiment dubbed Shape Up Somerville was launched to lower obesity rates in elementary school children, the campaign has been expanded and woven into the fabric of everyday life in this diverse city of 78,000, where 52 languages are spoken in the public schools and almost two-thirds of students come from families so poor that they receive free or reduced-price school lunches. City decisions about roads, bridges, other transportation projects, real estate development, and parks include an analysis of how the plans might affect residents’ physical activity or ability to shop for healthy food. Two city employees ensure healthy goals are considered at every step, particularly by collaborating with community groups. © 2012 NY Times Co.

Keyword: Obesity
Link ID: 17044 - Posted: 07.16.2012

Children who increase the number of hours of weekly television they watch between the ages of two and four years old risk larger waistlines by age 10. A Canadian study found that every extra weekly hour watched could add half a millimetre to their waist circumference and reduce muscle fitness. The study, in a BioMed Central journal, tracked the TV habits of 1,314 children. Experts say children should not watch more than two hours of TV a day. Researchers found that the average amount of television watched by the children at the start of the study was 8.8 hours a week. This increased on average by six hours over the next two years to reach 14.8 hours a week by the age of four-and-a-half. Fifteen per cent of the children in the study were watching more than 18 hours per week by that age, according to their parents. The study said the effect of 18 hours of television at 4.5 years of age would by the age of 10 result in an extra 7.6mm of waist because of the child's TV habit. As well as measuring waist circumference, the researchers also carried out a standing long jump test to measure each child's muscular fitness and athletic ability. An extra weekly hour of TV can decrease the distance a child is able to jump from standing by 0.36cm, the study said. BBC © 2012

Keyword: Obesity; Development of the Brain
Link ID: 17043 - Posted: 07.16.2012

Will Ferguson, reporter You can't visit this tropical jungle. It's a forest of neurons snaking through a pig's brain. The brain cells, enlarged and coloured here, are being investigated to give scientists a clearer view of the mechanics of brain matter when it is hit hard. Michel Destrade, an applied mathematician at the National University of Ireland, Galway, and colleagues obtained samples of pig brains from a local slaughterhouse to study the mechanics of brain matter undergoing rapid impacts. With the aim of improving the treatment of traumatic head injuries, they used the samples to create computer models of electrical signals inside the brain. But during the course of the experiment, Destrade's student Badar Rashid decided to find out what white and grey matter inside a brain look like. He started with an image of neuron bundles taken using scanning electron microscopy, and blew it up to 4,000 times its actual size. He then added colour to the black and white result according to his own aesthetic. The image appears in Physics Today (DOI:10.1063/PT.3.1651). © Copyright Reed Business Information Ltd.

Keyword: Brain imaging
Link ID: 17042 - Posted: 07.16.2012

By Jason G. Goldman The idea behind quantifying personality is deceptively simple: personality refers to predictable differences in behavior between people. Those differences should be reasonably reliable. That is, they ought to hold constant across different types of situations. Those differences should also be reasonably stable, which means they should be consistent over time. For example, you might score high on the openness factor if you answer “yes” to questions like “I spend time reflecting on things,” and you might score low on the extraversion scale if you answer “no” to questions like “I talk to a lot of different people at parties.” According to personality theory, your answers to those questions shouldn’t change all that much as you grow older, nor should they be different if you complete the survey at home or at the office or at a shopping mall. Based on this definition of personality, it should be obvious that personality is not limited to humans. Indeed, animal behavior researchers are also interested in defining and quantifying personality. If measuring and describing personality is complicated for humans, it becomes vastly more so for animals. How are these individual differences in predictable responses measured, and classified? How are they even identified? What measurements should be used, and what traits do they measure? In a new paper in press in the journal Behavioural Processes, Noelle M. Watanabe and colleagues from the UCLA Departments of Ecology & Evolutionary Biology and Psychology explore these questions using an unlikely animal model: the Caribbean hermit crab (Coenobita clypeatus). © 2012 Scientific American,

Keyword: Emotions
Link ID: 17041 - Posted: 07.14.2012

Ed Yong Uri Simonsohn, the researcher who flagged up questionable data in studies by social psychologist Dirk Smeesters, has revealed the name of a second social psychologist whose data he believes to be suspiciously perfect. That researcher is Lawrence Sanna, whose former employer, the University of Michigan in Ann Arbor, tells Simonsohn that he resigned his professorship there at the end of May. The reasons for Sanna's resignation are not known, but it followed questions from Simonsohn and a review by Sanna’s previous institution, the University of North Carolina in Chapel Hill (UNC). According to the editor of the Journal of Experimental Social Psychology, Sanna has also asked that three of his papers be retracted from the journal. In both Smeesters’ and Sanna’s work, odd statistical patterns in the data raised concerns with Simonsohn, at the University of Pennsylvania in Philadelphia. But the similarity between the cases ends there. Smeesters’ resignation was announced on 25 June by his institution, Erasmus University Rotterdam in the Netherlands, which undertook a review and concluded that two of his papers should be retracted. Sanna’s resignation, by contrast, remains mysterious: UNC did not release the results of its review, and the University of Michigan will not explain why Sanna resigned. Sanna’s research covers areas of psychology including judgement, decision-making and morality. Last year, his work attracted media coverage (and so far, four citations) for showing that people behave more altruistically if they are physically elevated, for example by riding an ascending escalator1. This link between physical height and moral virtue is an example of embodied cognition, a growing area of psychology that looks at how the body and environment influence the mind. © 2012 Nature Publishing Group,

Keyword: Emotions
Link ID: 17040 - Posted: 07.14.2012

By Ruth Williams Until recently, most scientists believed that neurons were the all-important brain cells controlling mental functions and that the surrounding glial cells were little more than neuron supporters and “glue.” Now research published in March in Cell reveals that astrocytes, a type of glia, have a principal role in working memory. And the scientists made the discovery by getting mice stoned. Marijuana impairs working memory—the short-term memory we use to hold on to and process thoughts. Think of the classic stoner who, midsentence, forgets the point he was making. Although such stupor might give recreational users the giggles, people using the drug for medical reasons might prefer to maintain their cognitive capacity. To study how marijuana impairs working memory, Giovanni Marsicano of the University of Bordeaux in France and his colleagues removed cannabinoid receptors—proteins that respond to marijuana's psychoactive ingredient THC—from neurons in mice. These mice, it turned out, were just as forgetful as regular mice when given THC: they were equally poor at memorizing the position of a hidden platform in a water pool. When the receptors were removed from astrocytes, however, the mice could find the platform just fine while on THC. The results suggest that the role of glia in mental activity has been overlooked. Although research in recent years has revealed that glia are implicated in many unconscious processes and diseases, this is one of the first studies to suggest that glia play a key role in conscious thought. “It's very likely that astrocytes have many more functions than we thought,” Marsicano says. “Certainly their role in cognition is now being revealed.” © 2012 Scientific American,

Keyword: Drug Abuse; Learning & Memory
Link ID: 17039 - Posted: 07.14.2012

Analysis by Sheila Eldred If you've seen "Silence of the Lambs," you probably remember the scene where the lights go out on Jodie Foster and the unseen Buffalo Bill reaches out to her. That's because at that moment, your brain was probably at its peak of engagement, according to a study by a team of researchers from The City College of New York and Columbia University. "Peak correlations of neural activity across viewings can occur in remarkable correspondence with arousing moments of the film," the researchers wrote in the journal "Moreover, a significant reduction in neural correlation occurs upon a second viewing of the film or when the narrative is disrupted by presenting its scenes scrambled in time." Tense scenes present prime conditions for peak brain activity. They usually contain at least two of the three components identified by the researchers as most engaging: powerful visual cues, ominous music, and meaningful scene changes. To make the correlation, the researchers hooked 20 subjects up to EEG devices (electroencephalography measures electrical activity across the scalp) as they showed scenes from three films: Alfred Hitchcock's "Bang! You're Dead," Sergio Leone's "The Good, the Bad and the Ugly," and an amateur film of people walking on a college campus as a control. © 2012 Discovery Communications, LLC

Keyword: Emotions; Brain imaging
Link ID: 17038 - Posted: 07.14.2012

By Susan Milius OTTAWA — Some of the animal kingdom’s showiest extremes, from deer antlers to the outsized horn of the male rhinoceros beetle, may be natural insulin meters. As an animal grows, the nubbins of tissue that will form its big weapons or displays may be more sensitive to insulin than other developing body parts, Douglas Emlen of the University Montana said July 10 at the Evolution Ottawa scientific congress. The proposal “potentially narrows the range of explanations for the evolution of ornaments and weapons,” said Bob Montgomerie of Queen’s University in Kingston, Ontario, who studies courtship-related features in birds. Insulin orchestrates growth in tune with how much food a young animal gets, Emlen explained. A well-fed youngster flush with insulin will grow the most spectacular horns or other paraphernalia, while underfed rivals remain stunted. If the growing antlers or other extreme structures are supersensitive to insulin, they will supersize out of proportion to less sensitive tissue. That’s the case for the horns of the rhinoceros beetle, Trypoxylus dichotomus. Males of the species grow horns about two-thirds as long as the rest of their bodies. They use these fearsome weapons to knock rivals away from sap-oozing wounds on trees where females go to feed. The horns are eight times more responsive to insulin or insulin-like growth factors than some other body parts, Emlen said. That sensitivity fits with reports from other researchers that insulin or related signals affect development of antlers in red deer and the outsized male claws in a type of shrimp and one kind of crab. For those animals though, researchers haven’t yet explored how the weaponry tissues’ sensitivity compares with that of other body parts. © Society for Science & the Public 2000 - 2012

Keyword: Hormones & Behavior; Sexual Behavior
Link ID: 17037 - Posted: 07.14.2012

by Kat McGowan When she’s looking for a mate, how does a female know what she likes? Macho mating displays—turkeys strutting, lions roaring, bighorn sheep colliding—quickly tell her who is biggest and burliest. But some females prefer a more subtle approach. Evolutionary ecologist John Endler of Deakin University in Australia discovered that among great bowerbirds, pigeon-size birds native to northern Australia, females are dazzled by craftsmanship. In nearly every species of bowerbird, males impress females by building elaborate structures called bowers: long, twiggy corridors that open to a courtyard decorated with small objects. Great bowerbirds go one step further, creating optical illusions to intrigue the ladies and make them more likely to mate. Endler realized the wooer uses a trick called forced perspective. The birds arrange objects by size, so the smallest are closest to the entrance and larger pieces farther away. From the female’s point of view inside the corridor, the bigger, more distant items look about the same size as the nearby smaller ones. The courtyard may appear smaller, potentially making the male seem larger to deliberating females. Photographers regularly use the same trick. If you stand some distance from the Leaning Tower of Pisa, a friend can take a picture that looks as if you are propping up the tower. Creating this illusion is a priority for great bowerbirds. When Endler rearranged their objects, they put their courtyards back in order within three days. © 2012, Kalmbach Publishing Co.

Keyword: Sexual Behavior; Vision
Link ID: 17036 - Posted: 07.12.2012

People who are born deaf process the sense of touch differently than people who are born with normal hearing, according to research funding by the National Institutes of Health. The finding reveals how the early loss of a sense — in this case hearing — affects brain development. It adds to a growing list of discoveries that confirm the impact of experiences and outside influences in molding the developing brain. The study is published in the July 11 online issue of The Journal of Neuroscience. The researchers, Christina M. Karns, Ph.D., a postdoctoral research associate in the Brain Development Lab at the University of Oregon, Eugene, and her colleagues, show that deaf people use the auditory cortex to process touch stimuli and visual stimuli to a much greater degree than occurs in hearing people. The finding suggests that since the developing auditory cortex of profoundly deaf people is not exposed to sound stimuli, it adapts and takes on additional sensory processing tasks. "This research shows how the brain is capable of rewiring in dramatic ways," said James F. Battey, Jr., M.D., Ph.D., director of the NIDCD. "This will be of great interest to other researchers who are studying multisensory processing in the brain." Previous research, including studies performed by the lab director, Helen Neville Ph.D., has shown that people who are born deaf are better at processing peripheral vision and motion. Deaf people may process vision using many different brain regions, especially auditory areas, including the primary auditory cortex. However, no one has tackled whether vision and touch together are processed differently in deaf people, primarily because in experimental settings, it is more difficult to produce the kind of precise tactile stimuli needed to answer this question.

Keyword: Hearing; Pain & Touch
Link ID: 17035 - Posted: 07.12.2012

Gary W. Lewandowski, Jr., When you see someone coughing, you reflexively know to steer clear of his or her germs. When you observe someone who is cranky or complaining, it is less obvious what to do. Studies suggest, however, that others' moods may be as easy to catch as their germs. Psychologists call this phenomenon emotional contagion, a three-step process through which one person's feelings transfer to another person. The first stage involves nonconscious mimicry, during which individuals subtly copy one another's nonverbal cues, including posture, facial expressions and movements. In effect, seeing my frown makes you more likely to frown. People may then experience a feedback stage--because you frowned, you now feel sad. During the final contagion stage, individuals share their experiences until their emotions and behaviors become synchronized. Thus, when you encounter a co-worker on a bad day, you may unknowingly pick up your colleague's nonverbal behaviors and begin to morph into an unhappy state. Mimicry is not all bad, however; a person can also adopt a friend or colleague's good mood, which can help enhance their bond. Although mimicry often occurs outside of our awareness, sometimes we can observe it. Let us say you see someone across from you on the train yawn. Often you cannot help but yawn as well. Recent research suggests that this type of mimicry is more common when the person yawning is someone close to you, such as a family member, good friend or romantic partner. Another study revealed that nonconscious mimicry, also dubbed the chameleon effect, occurs more often in more empathetic people. © 2012 Scientific American,

Keyword: Emotions
Link ID: 17034 - Posted: 07.12.2012

By Myron Levin and Stuart Silverstein For several years, doctors and medical spas around the country have touted a fat-melting device called the LipoTron 3000, or Lipo-Ex, as a revolutionary way for people to slim down. Signature Medical Spa in Tampa, Fla., in an online pitch for its “Lipo-Ex Spring Fling Fat-Off!,” described the technology as “truly the only non-invasive way to reduce fat.” Praise also came from Sculpt Medical Spa in Chicago, which called the procedure “the most innovative, effective, and technologically advanced” non-surgical method of removing fat. These testimonials have translated into millions of dollars in sales for physicians, med spas, and the device’s manufacturer, RevecoMED International of Fullerton, Calif. But there’s a problem: The LipoTron, which targets fat with radiofrequency waves, has never been cleared or approved by the U.S. Food and Drug Administration, which would make it illegal under federal law to sell or promote it for weight loss. The FDA is aware of the activity. But an investigation by FairWarning found that the agency has not taken enforcement action — even though it has known about the situation at least since January, 2010. At that time, two whistleblowers, one a former LipoTron distributor, provided sales records and a trove of other documents to an FDA criminal investigator. © 2012 msnbc.com

Keyword: Obesity
Link ID: 17033 - Posted: 07.12.2012

Ewen Callaway Almost 30 million people live with Alzheimer’s disease worldwide, a staggering health-care burden that is expected to quadruple by 2050. Yet doctors can offer no effective treatment, and scientists have not been able definitively to pin down the underlying mechanism of the disease. Research published this week offers some hope on both counts, by showing that a lucky few people carry a genetic mutation that naturally prevents them from developing the condition1. The discovery not only confirms the principal suspect that is responsible for Alzheimer’s, it also suggests that the disease could be an extreme form of the cognitive decline seen in many older people. The mutation — the first ever found to protect against the disease — lies in a gene that produces amyloid-β precursor protein (APP), which has an unknown role in the brain and has long been suspected to be at the heart of Alzheimer’s. APP was discovered 25 years ago in patients with rare, inherited forms of Alzheimer’s that strike in middle age2–5. In the brain, APP is broken down into a smaller molecule called amyloid-β. Visible clumps, or plaques, of amyloid-β found in the autopsied brains of patients are a hallmark of Alzheimer’s, but scientists have long debated whether the plaques are a cause of the neuro­degenerative condition or a consequence of other biochemical changes associated with the disease. The latest finding supports other genetics studies blaming amyloid-β, and it makes the protein “the prime therapeutic target”, says Rudolph Tanzi, a neurologist at the Massachusetts General Hospital in Boston and a member of one of the four teams that discovered APP’s role in the 1980s. © 2012 Nature Publishing Group,

Keyword: Alzheimers; Genes & Behavior
Link ID: 17032 - Posted: 07.12.2012

By JoNel Aleccia Steve and Dawn Thomas rarely saw their son Brandon blush, and if they did, it wasn’t a worry. Brandon was blond and fair, like his twin brother, Devin, and an occasional flush of color didn’t seem concerning. “We wouldn’t have witnessed it,” said Steve Thomas. “It wasn’t even happening here at home. I think this was his place of comfort.” So they were stunned last fall when Brandon, a friendly, well-liked University of Washington student, confessed to his mother he’d been struggling with crippling, chronic blushing for four years. Steve and Dawn Thomas are speaking out about their son Brandon's death to raise awareness of the little-known disorder estimated to affect between 5 percent and 7 percent of the population. And they were devastated on May 29, when Brandon jumped from the 11th floor balcony of his Seattle dormitory, leaving behind a five-page note blaming his suicide on despair caused by the little-known disorder. “When Brandon finally let us in to his secret life of torment, we were obviously way behind,” his mother said. Six weeks later, the Thomases are speaking out about Brandon’s death to honor his last wish. In the letter, the young man who hid the problem from his friends, his family -- even his twin -- wanted the world to know that there’s nothing trivial about turning red. © 2012 msnbc.com

Keyword: Emotions
Link ID: 17031 - Posted: 07.12.2012

By Laura Sanders In a paradoxical twist, people with amnesia can get bogged down by too many memories. Unwanted, irrelevant information crowds in and prevent amnesiac patients from recognizing objects, scientists report in the July 12 Neuron. The finding suggests that amnesia isn’t strictly a memory problem, and it may even point out ways to help people with the disorder live more normally. Most people consider amnesia a breakdown of memory that leaves people unable to recall a conversation they had minutes earlier, says study coauthor Morgan Barense of the University of Toronto. While it’s true that people with amnesia have striking memory deficits, “the real picture is more complicated,” she says. People with amnesia caused by damage to a brain region near the ears called the perirhinal cortex also have problems recognizing objects, Barense and colleagues found. In the study, two people with this form of amnesia assessed a series of pictures of two objects — squiggly blobs with distinctive patterns of lines. The objects, shown at different rotations, were either identical or slightly different. At first, people with amnesia were just as good as people with functioning recall at deciding whether the two objects were the same. But as the experiment wore on, participants’ performance started to crash. “They’re doing fine, they’re doing fine — and then all of a sudden, it was like a switch flipped,” says Barense. After ruling out other possibilities, the researchers landed on what Barense calls a “wildly paradoxical conclusion” to explain the crash: too many memories. © Society for Science & the Public 2000 - 2012

Keyword: Learning & Memory
Link ID: 17030 - Posted: 07.12.2012

By GRETCHEN REYNOLDS Much has been studied and reported, particularly in this newspaper, about the short-term effects of concussions on young athletes, as well as the potential longer-term outcomes for professional athletes who engage in high-level contact sports like football and ice hockey for many years, putting themselves at risk for multiple concussions and the lesser but still consequential subconcussive injuries. But until recently, far less has been understood about the long-term implications, if any, of concussions experienced years ago by recreational athletes. Does a 55-year-old man who played high school football in the ’70s and perhaps grew dizzy or “had his bell rung” after a tackle or two need to worry about the state of his brain today, even if he never had a formal diagnosis of concussion? Or do I, because I bounced my head hard against the slopes several times while learning to snowboard 10 years ago? The emerging answer, according to recent research, would seem to be a cautious “probably not,” although there may be reason to monitor how easily names and places come to mind. For a study published in May in the journal Cerebral Cortex, researchers at the University of Montreal examined the brains of a group of healthy, middle-aged former athletes, all of whom had played contact sports in college about 30 years ago and some of whom had sustained concussions while doing so. In the years since, the athletes had stopped competing but had remained physically active. None complained of failing memories or other symptoms of cognitive impairment — or at least, not more so than any group of 50- and 60-year-olds would be expected to complain. Copyright 2012 The New York Times Company

Keyword: Brain Injury/Concussion
Link ID: 17029 - Posted: 07.12.2012

Many people who abused the painkiller OxyContin by inhaling or injecting it switched to heroin after the prescription's formula changed, U.S. researchers say. OxyContin was designed to slowly release the opioid drug oxycodone. After people started abusing it by crushing the pills and inhaling the powder or dissolving the pills in water and injecting it to get a rush, the drug maker introduced a new formula in the U.S. in 2010 to make inhaling and injecting more difficult. The new pills are harder to crush and dissolve more slowly. In Wednesday's issue of the New England Journal of Medicine, investigators in the U.S. said use of OxyContin by inhalation and injection has dropped significantly since the abuse-deterrent form went on the market. "In that sense, the new formulation was very successful," said author and principal investigator Theodore Cicero, a professor of neuropharmacology in psychiatry at Washington University School of Medicine in St. Louis, Mo. "The most unexpected, and probably detrimental, effect of the abuse-deterrent formulation was that it contributed to a huge surge in the use of heroin," he added in a release. OxyContin was a popular drug in suburban and urban areas, where drug abusers have now shifted either to more potent opioids if they can find them or to heroin, he said. © CBC 2012

Keyword: Drug Abuse
Link ID: 17028 - Posted: 07.12.2012

By Kara Rogers The honeybee brain is dynamic and full of surprises. For instance, much like the human brain, its neurons not only modulate their activity in response to sensory stimuli but also alter their gene and protein expression patterns—changes that in bees are so dramatic as to essentially rewire the brain. And even more remarkable is that this plasticity is strongly influenced by social environment, a feature that was underscored recently by the discovery that bees who changed social roles effectively reversed the aging of their brains. The reversal, described in terms of recovery of learning ability, occurred when older honeybees reverted from foraging tasks to caring for newborn bees and was linked to increased brain levels of stress response and antioxidant proteins, which serve important cellular maintenance and repair functions. One of the proteins was similar to the mammalian enzyme peroxiredoxin-6 (Prx6). In humans, Prx6 defends against oxidative stress and inflammation associated with Alzheimer disease and Huntington disease, indicating that a better understanding of the molecules involved in brain plasticity and cognitive recovery in honeybees could inform research on dementia and related conditions. The new findings are especially intriguing for what they suggest about the influence of social environment on cognitive function. Studies in humans have linked strong social relationships with increased likelihood for survival and declining social engagement in mid- to late-life with increasing risk of dementia. However, relatively little is known about the significance of social environment in the context of human cognitive function and aging. © 2012 Scientific American,

Keyword: Learning & Memory; Development of the Brain
Link ID: 17027 - Posted: 07.12.2012

by Elizabeth Pennisi OTTAWA—With big brains comes big intelligence, or so the hypothesis goes. But there may be trade-offs as well. Humans and other creatures with large brains relative to their body size tend to have smaller guts and possibly fewer offspring. Scientists have debated for decades whether the two phenomena are related. Now a team of researchers says that they are—and that big brains do indeed make us smart. The finding comes thanks to an unusual experiment reported here yesterday at the Evolution Ottawa evolutionary biology meeting in which scientists shrank and grew the brains of guppies over several generations. "This is a real experimental result," says David Reznick, an evolutionary biologist at the University of California, Riverside, who was not involved in the study. "The earlier results were just correlations." Researchers first began to gather evidence that big brains were advantageous after 19th century U.S. biologist Hermon Bumpus examined the brains of sparrows, some of whom had succumbed in a blizzard and some of whom survived. The survivors had relatively larger brains. More recently, evolutionary biologist Alexei Maklakov from Uppsala University in Sweden found evidence that songbirds that colonize cities tend to have larger brains relative to their body size than species still confined to the countryside. The challenge of urban life might require bigger brains, he and his colleagues concluded last year in Biology Letters. Yet in humans and in certain electric fish, larger brain size seems to have trade-offs: smaller guts and fewer offspring. That's led some scientists to suggest there are constraints on how big brains can become because they are expensive to build and maintain. © 2010 American Association for the Advancement of Science.

Keyword: Evolution; Intelligence
Link ID: 17026 - Posted: 07.11.2012