By Ferris Jabr NEW YORK—When it comes to brain power, we humans like to think we're the animal kingdom's undisputed champions. But in the past few decades we've had to make a lot of room on our mantle place for shared trophies. Problem-solving? Sorry, but crows and octopuses do that too. Tool use? Primates, birds and even fish have learned that trick. It turns out our human cognitive abilities are just not as unique as we once thought. The collapsing divisions between animal and human minds is exactly what a group of scientists gathered to discuss on Saturday, June 5, at a World Science Festival panel, "All Creatures Great and Smart." WNYC radio host Jad Abumrad mediated the talk. The first topic of conversation was a behavior known as altruism: selflessly helping a stranger. Brian Hare, who studies ape psychology at Duke University, described a recent experiment on this kind of cooperation in bonobos—primates that are in the same genus as chimpanzees. "We wanted to challenge that notion that humans are unique and test whether one of our closest relatives is capable of voluntarily sharing," Hare said. In the study, published earlier this year in Current Biology, researchers showed a bonobo into a room with some food inside. Instead of hogging all the grub, the bonobo consistently chose to unlock the door of an adjacent room and share the food with an unfamiliar bonobo. © 2010 Scientific American,

Keyword: Evolution
Link ID: 14167 - Posted: 06.24.2010

By Katherine Harmon When the body does not properly manage insulin levels, diabetes and other metabolic disorders are familiar outcomes. That hormonal imbalance, however, has also been linked to a higher risk for psychiatric disorders, such as schizophrenia. And a new study has uncovered a potential pathway by which this metabolic hormone can upset the balance of a key neurotransmitter. "We know that people with diabetes have an increased incidence of mood and other psychiatric disorders," Kevin Niswender, an endocrinologist at Vanderbilt University Medical Center and coauthor of the study, said in a prepared statement. Previous researchers, including Aurelio Galli, a neurobiologist at Vanderbilt, had found that insulin was affecting more than blood sugar levels. "Something goes wrong in the brain because insulin isn't signaling the way that it normally does," Galli, a coauthor of the new paper, published online June 8 in the journal PLoS Biology, said in a prepared statement. Although schizophrenia is a complex disease that is thought to have a variety of individual genetic and epigenetic causes, these researchers and others have proposed that a common thread is too little dopamine, a neurotransmitter that is involved in movement, reward and motivation. But just how, molecularly, insulin and dopamine dysfunctions might be linked has yet to be settled. © 2010 Scientific American,

Keyword: Schizophrenia
Link ID: 14166 - Posted: 06.24.2010

By Katherine Harmon Premature infants have a known higher risk for poor neurological development, often leading to developmental and educational issues. However, these babies, born before 37 weeks, make up a small number of any generation, and new research shows that the 40 percent of babies born any more than a week before a full 40-week term are also at higher risk for having special education needs during childhood. By analyzing the 2005 Scottish school census of 407,503 children and national birth records, researchers found that risk for special education needs steadily decreased with gestation duration all the way to 40 and 41 weeks—even though babies born between 37 weeks and 41 weeks are considered "at term." For the survey, special education needs included learning disabilities (such as autism, attention deficit hyperactivity disorder, dyslexia and others) and physical disabilities that can impair learning. The findings were published online June 8 in PLoS Medicine. "The tendency of most previous studies to treat gestation as a binary factor (preterm versus term) has masked a dose-effect across the whole range of gestation," noted the researchers, led by Daniel MacKay, of the University of Glasgow's Section of Public Health. And the sheer number of children who were born before 40 weeks (but after 37 weeks) mean that they constitute a greater percentage of special education children. Whereas preterm births accounted for about 5 percent of deliveries, they made up 3.5 percent of children needing special education. After adjusting for other factors, such as maternal demographics and mode of delivery, early term infants (delivered between 37 weeks and 39 weeks), had a 5.3 percent higher risk (than full term babies) for needing special education later. © 2010 Scientific American,

Keyword: Development of the Brain
Link ID: 14165 - Posted: 06.24.2010

by Ewen Callaway You spend more time window shopping than you may realise. Whether someone intends to buy a product or not can be predicted from their brain activity – even when they are not consciously pondering their choices. The ability to predict from brain scans alone what a person intends to buy, while leaving the potential buyer none the wiser, could bring much-needed rigour to efforts to meld marketing and neuroscience, says Brian Knutson, a neuroscientist at Stanford University in California who was not involved in the research. NeuromarketingMovie Camera, as this field is known, has been employed by drug firms, Hollywood studios and even the Campbell Soup Company to sell their wares, despite little published proof of its effectiveness. Rather than soup, John-Dylan Haynes at the Bernstein Center for Computational Neuroscience in Berlin, Germany, attempted to predict which cars people might unconsciously favour. To do so, he and colleague Anita Tusche used functional MRI to scan the brains of two groups of male volunteers, aged 24 to 32, while they were presented with images of a variety of cars. One group was asked to rate their impressions of the vehicles, while the second performed a distracting visual task while cars were presented in the background. Each volunteer was then shown three cars and asked which they would prefer to buy. © Copyright Reed Business Information Ltd.

Keyword: Emotions; Brain imaging
Link ID: 14164 - Posted: 06.24.2010

by Carlin Flora; Depression is a chemical imbalance, most people think. Researchers, drug manufacturers, and even the Food and Drug Administration assert that antidepressants work by “normalizing” levels of brain neurotransmitters—chemical messengers such as serotonin. And yet hard science supporting this idea is quite poor, says Irving Kirsch, professor of psychology at the University of Hull in the U.K. An expert on the placebo effect, Kirsch has unearthed evidence that antidepressants do not correct brain chemistry gone awry. More important, the drugs are not much more effective against depression than are sugar pills, he says. To support these controversial claims, Kirsch conducted a meta-analysis, digging up data from unpublished clinical trials. When all the evidence is weighed together, Prozac, Paxil, and other such popular pills seem to be at best weakly effective against depression—an argument Kirsch presses in his new book, The Emperor’s New Drugs. Some other research backs up his claims. A study published this winter in the Journal of the American Medical Association found that psychoactive drugs are no better than placebos for people suffering from mild to moderate depression. Where did the idea of depression as a chemical imbalance come from?
 The initial two drugs, imipramine and iproniazid, that were discovered and promoted as effective antidepressants both seemed to increase the amount of serotonin in the brain. It was discovered afterward that one of them seemed to block the reabsorption of serotonin, leaving it to linger longer at cell receptors, and the other blocked the destruction of the serotonin neurotransmitters in the synapses in the brain.

Keyword: Depression
Link ID: 14163 - Posted: 06.24.2010

by Jennifer Couzin-Frankel A new study of nearly 1000 people with autism has confirmed that the genetics of the disease are much more idiosyncratic than some had thought. Rather than a few genes that raise the risk of autism throughout the population, scientists are finding dozens of genes that spur disease, many of them in just one or two people. It appears that these variants do share certain characteristics, however: Many play a role in cell proliferation and cell signaling in the brain. Although scientists are heartened by this new map of autism genetics, they also say that they have a long road ahead in discerning how these genetic changes cause this particular disease. Over the past few years, researchers studying autism and schizophrenia have found that the genomes of patients with one or the other are riddled with so-called copy-number variants: deletions or duplications of stretches of DNA that can encompass many genes. Indeed, the most dramatic of these copy-number variants are even visible with a microscope, as abnormalities in the chromosomes of children afflicted with undiagnosed intellectual disabilities. Some of these disease-causing changes happen spontaneously during embryonic development, whereas others are inherited. The latest study, published online today in Nature, is the second phase of the Autism Genome Project consortium, which comprises more than 120 scientists in 11 countries in North America and Europe. (The first, published in 2007 in Nature Genetics, was a broad analysis of gene changes and copy-number variation, with fewer families and less detailed analysis of rare copy-number variants.) Here the scientists scanned the genomes of 996 children with autism-spectrum disorders, a group of conditions that affect social and communication skills, at high resolution and compared them with the genomes of the children's parents and to 1287 people without the disease. © 2010 American Association for the Advancement of Science.

Keyword: Autism; Genes & Behavior
Link ID: 14162 - Posted: 06.24.2010

By NICHOLAS WADE The glue that binds a human society together is trust. But people who trust others too much are likely to get taken for a ride. Both trust and distrust, it now seems, are influenced by hormones that can induce people to ratchet their feeling of trust up or down. The trust side of the equation is mediated by a brain hormone known as oxytocin. A soft touch or caress will send a pulse of oxytocin into a person’s bloodstream. Swiss researchers found in 2005 that a squirt of oxytocin would make players in an investment game more willing to hand over their money to strangers. It may seem strange that there is a hormonal influence in such a delicate calculation as to whether or not to trust someone. But perhaps trust is so important to a society’s survival that natural selection has generated a hormonal basis for it. In any event, trust has a downside — one may hand over too much money to a Mr. Madoff who promises to generate steady returns in both up and down markets. There needs to be an antidote to oxytocin that makes a person keep those warm, fuzzy feelings suppressed in the appropriate circumstances. Researchers at Utrecht University in Holland now report that they have identified this antidote: it is testosterone. They gave young women a dose of the hormone in the form of a drop of liquid placed under the tongue, then asked them to judge the trustworthiness of a series of men’s faces shown in photographs. The women were significantly less inclined to trust a face when given testosterone than when they had taken a placebo, the Dutch team reported last month in The Proceedings of the National Academy of Sciences. Copyright 2010 The New York Times Company

Keyword: Hormones & Behavior
Link ID: 14161 - Posted: 06.24.2010

By Katherine Harmon Veterans of war have been known to suffer from high incidence of post-traumatic stress disorder (PTSD), depression and traumatic brain injury in addition to any physical wounds. And a new study of thousands of U.S. Army soldiers returning from combat duty in Iraq found up to 31 percent reported symptoms of PTSD or depression as long as a year after returning from the battlefield. Between 2004 and 2007, 18,305 soldiers returning from Active Component and National Guard infantry brigade combat teams completed surveys that screened for PTSD, depression and other trends, such as alcohol abuse, aggression and general difficulties getting along in civilian life, three months and a year after the soldiers returned from deployment in Iraq. Based on general definitions of the disorders, the researchers found that 20.7 percent to 30.5 percent of soldiers met the criteria for PTSD, and 11.5 percent to 16 percent met the criteria for depression. And "using the strictest definitions with high symptom rates and serious functional impairment," the authors found up to 11.3 percent of soldiers had PTSD and up to 8.5 percent suffered from depression. Between 8.5 percent and 14 percent of soldiers reported "serious functional impairment" due to their symptoms, the authors noted in their study, which was led by Jeffrey Thomas, of the Division of Psychiatry and Neuroscience at Walter Reed Army Institute of Research, and published online June 7 in Archives of General Psychiatry. © 2010 Scientific American,

Keyword: Stress
Link ID: 14160 - Posted: 06.24.2010

By Ferris Jabr Our eyes swivel restlessly in their sockets during rapid eye movement (REM) sleep, an aptly named period of intense dreaming that makes up 20 to 25 percent of total sleep time. Whether this fidgeting is random or serves a function has never been clear, but a new study suggests that our eyes shift their gaze to fixate on the imagined people, places and actions in our sleep dreamscape. In other words, the movements of dreaming eyes mimic those of waking eyes. For more than 50 years neuroscientists have debated the reasons for REM during sleep, proposing all kinds of ideas: the eyes roll around to lubricate the inside of the eyelids; jiggling eyes warm the brain; eyes twitch randomly in response to stimulation from the brain stem. According to a study in the June issue of Brain, the most likely explanation is the "scanning hypothesis," which says that throughout REM sleep our eyes orient their gaze to scan the imagery of our dreams—just as eyes change their gaze in response to our environment when we're awake and moving around. But how do researchers know where someone is looking while they dream? And how do they test whether that has anything to do with what someone is dreaming about? In the study neuroscientists at Pitié-Salpêtrière Hospital in Paris turned to a unique group of subjects: individuals with REM sleep behavior disorder (RBD). During REM sleep, the limb muscles of most people enter a state of temporary paralysis that prevents any flailing about. People with RBD do not go into sleep paralysis and physically act out their dreams—often with dramatic and violent actions: They kick, scream, grab, reach, climb and jump, both in their dreams and in reality, allowing researchers to observe what normally remains inside a dreamer's head. © 2010 Scientific American,

Keyword: Sleep; Vision
Link ID: 14159 - Posted: 06.24.2010

By Bruce Bower Where there’s secondhand cigarette smoke, there’s emotional fire. As exposure to cigarette fumes increases among nonsmokers, so does their risk of developing serious psychological distress and of being hospitalized for mental ailments, a new study finds. Cigarette smokers have been shown to have more psychological problems than nonsmokers do, and new evidence suggests that nonsmokers who inhale high levels of secondhand smoke may experience nearly as much psychological distress as smokers, say epidemiologist Mark Hamer of University College London and his colleagues. Overall, these findings support the view, largely based on animal studies, that nicotine administered in large enough doses can induce sadness and other negative moods, the researchers propose in the August Archives of General Psychiatry. “Our data are preliminary, but there is a strong possibility that the observed association reflects a causal link,” Hamer says. Previous research suggests that nicotine alters mood by disrupting immune responses, stress-hormone regulation and the transmission of dopamine, a chemical messenger in the brain. But little is known about nicotine’s possible relationship to specific psychiatric disorders. The link between nicotine exposure and mood held up after statistically accounting for participants’ social status, alcohol use, physical activity level, body mass index, chronic physical illness, level of psychological distress upon entering the study and previous hospitalizations for mental illness. © Society for Science & the Public 2000 - 2010

Keyword: Drug Abuse; Stress
Link ID: 14158 - Posted: 06.24.2010

by Linda Geddes Children with autism appear to have a characteristic chemical signature in their urine which might form the basis of an early diagnostic test for the condition. The finding also adds weight the hypothesis that substances released by gut bacteria are contributing to the onset of the condition. Autism has previously been linked to metabolic abnormalities and gastrointestinal problems such as gut pain and diarrhoea. Several studies have also hinted at changes in gut bacteria in the faeces of children with autism. To investigate whether signs of these metabolic changes might be detectable in children's urine, Jeremy Nicholson and colleagues at Imperial College London investigated 39 children with autism, 28 of their non-autistic siblings and 34 unrelated children. Using nuclear magnetic resonance (NMR) spectroscopy to analyse the children's urine, they found that each of these groups had a distinct chemical fingerprint, with clear and significant differences between children with autism and unrelated controls. "The signature that comes up is related to gut bacteria," says Nicholson. It is not yet clear whether the bacteria's metabolic products contribute to the development of autism, but it is a possibility worth investigating, he adds. A large proportion of autistic children have severe gastrointestinal problems that tend to appear at about the same time as the behavioural symptoms. © Copyright Reed Business Information Ltd.

Keyword: Autism
Link ID: 14157 - Posted: 06.24.2010

by Jim Giles The children of lesbian parents outscore their peers on academic and social tests, according to results from the longest-running study of same-sex families. The researchers behind the National Longitudinal Lesbian Family Study say the results should change attitudes to adoption of children by gay and lesbian couples, which is prohibited in some parts of the US. The finding is based on 78 children who were all born to lesbian couples who used donor insemination to become pregnant and were interviewed and tested at age 17. The new tests have left no doubt as to the success of these couples as parents, says Nanette Gartrell at the University of California, San Francisco, who has worked on the study since it began in 1986. Compared with a group of control adolescents born to heterosexual parents with similar educational and financial backgrounds, the children of lesbian couples scored better on academic and social tests and lower on measures of rule-breaking and aggression. A previous study of same-sex parenting, based on long-term health data, also found no difference in the health of children in either group. "This confirms what most developmental scientists have suspected," says Stephen Russell, a sociologist at the University of Arizona in Tucson. "Kids growing up with same-sex parents fare just as well as other kids." © Copyright Reed Business Information Ltd.

Keyword: Development of the Brain; Sexual Behavior
Link ID: 14156 - Posted: 06.24.2010

Answered by: Professor Andrew Smith Caffeine – 1,3,7-trimethylxanthine, to give it its chemical name – is a member of a group of naturally occurring substances called methylxanthines. These compounds are similar in structure to adenosines, naturally occurring molecules in our bodies which aid the onset of sleep. In its natural context, which is in tea and coffee plants, caffeine can kill or paralyse insects and is thus an effective natural pesticide. The earliest recorded caffeine consumers were in China in the 10th century BC, when philosophers believed tea-drinking was "an indispensable ingredient to the elixir of life". Coffee-quaffing originated in Yemen in the 15th century. The exact amount of caffeine present in a drink depends on its growing conditions and preparation. While tea naturally has more caffeine gramme for gramme than coffee, there is less tea per cubic centimetre of cup, leading to its weaker stimulant properties. For the record, in a 5oz cup of filter coffee, there is between 100mg and 150mg of caffeine. The same sized serving of tea holds 35-45mg. Meanwhile, a 12oz serving of cola contains just 40mg. Doctors say at least 100mg is necessary to properly increase our alertness. (A study published by Bristol University last week argued that caffeine can't make irregular users more alert; a cup of coffee in the morning, the research suggested, only counteracts the effects of withdrawal that have built up overnight.) How does it work? Adenosine bonds to receptor cells in the brain to calm the activity of the central nervous system, thus triggering tiredness. There is also evidence to suggest that it decreases blood flow in the brain. Caffeine molecules bind to these receptor cells but have no active effect on the nervous system. However by doing so they take the place of adenosine molecules that could make a difference. This process is known as "competitive inhibition" and effectively delays the onset of fatigue, increases alertness and improves people's ability to sustain attention. ©independent.co.uk

Keyword: Attention; Drug Abuse
Link ID: 14155 - Posted: 06.24.2010

Amy Maxmen A leading antipsychotic drug temporarily reduces the size of a brain region that controls movement and coordination, causing distressing side effects such as shaking, drooling and restless leg syndrome. Just two hours after injection with haloperidol, an antipsychotic commonly prescribed to treat schizophrenia, healthy volunteers experienced impaired motor abilities that coincided with diminished grey-matter volume in the striatum — a brain region that mediates movement. "We've seen changes in the brain before, but to see significant remodelling of the striatum within a couple of hours is staggering," says Clare Parish at the Howard Florey Institute for brain research in Melbourne, Australia, who was not involved in the study. "Our viewpoint was that only chemical changes would happen in such a short time." In functional magnetic resolution imaging (fMRI) scans the authors observed the participants' striatal volume diminishing and changes to the structure of the motor circuitry in their brains. Further, their reaction times slowed in a computer test taken after the treatment, indicating the onset of lapses in motor control that affect many patients on antipsychotics. © 2010 Nature Publishing Group,

Keyword: Schizophrenia; Brain imaging
Link ID: 14154 - Posted: 06.24.2010

By MATT RICHTEL SAN FRANCISCO — When one of the most important e-mail messages of his life landed in his in-box a few years ago, Kord Campbell overlooked it. Not just for a day or two, but 12 days. He finally saw it while sifting through old messages: a big company wanted to buy his Internet start-up. “I stood up from my desk and said, ‘Oh my God, oh my God, oh my God,’ ” Mr. Campbell said. “It’s kind of hard to miss an e-mail like that, but I did.” The message had slipped by him amid an electronic flood: two computer screens alive with e-mail, instant messages, online chats, a Web browser and the computer code he was writing. While he managed to salvage the $1.3 million deal after apologizing to his suitor, Mr. Campbell continues to struggle with the effects of the deluge of data. Even after he unplugs, he craves the stimulation he gets from his electronic gadgets. He forgets things like dinner plans, and he has trouble focusing on his family. His wife, Brenda, complains, “It seems like he can no longer be fully in the moment.” This is your brain on computers. Scientists say juggling e-mail, phone calls and other incoming information can change how people think and behave. They say our ability to focus is being undermined by bursts of information. Copyright 2010 The New York Times Company

Keyword: Attention
Link ID: 14153 - Posted: 06.24.2010

By PAUL BLOOM It is one of the most famous psychological demos ever. Subjects are shown a video, about a minute long, of two teams, one in white shirts, the other in black shirts, moving around and passing basketballs to one another. They are asked to count the number of aerial and bounce passes made by the team wearing white, a seemingly simple task. Halfway through the video, a woman wearing a full-body gorilla suit walks slowly to the middle of the screen, pounds her chest, and then walks out of the frame. If you are just watching the video, it’s the most obvious thing in the world. But when asked to count the passes, about half the people miss it. This experiment, published in 1999 by Christopher Chabris and Daniel Simons, is a striking demonstration of the zero-sum nature of attention. When you direct your mental spotlight to the basketball passes, it leaves the rest of the world in darkness. Even when you are looking straight at the gorilla (and other experiments find that people who miss it often have their eyes fully on it) you frequently don’t see it, because it’s not what you’re looking for. In “The Invisible Gorilla,” Chabris and Simons begin by talking about their study and its implications for everyday life. It is a mistake, they argue, to see it as revealing a bug in our software, rather than an inherent limitation. Our brains are physical systems and hence have finite ­resources. The real problem here — what Chabris and Simons call “the illusion of attention” ­— is that we are often unaware of these limitations; we think that we see the world as it really is, but “our vivid visual experience belies a striking mental blindness.” They go on to explore a series of related illusions having to do with perception, memory, knowledge and ability, providing vivid examples of the real-world problems these illusions cause. Copyright 2010 The New York Times Company

Keyword: Attention
Link ID: 14152 - Posted: 06.24.2010

By William Saletan Elizabeth Loftus warmed to the idea of memory tampering for the best of reasons. She wanted to help people. In her official career, as she described it in books, she studied the art of mental manipulation only to dissect, expose, and defeat it. Occasionally, she lent her psychological expertise to lawyers or advertisers for their self-interested purposes. But these purposes weren't hers, so she never turned them into a career. To embrace memory tampering, she needed a purpose of her own. Something she could believe in and care about. Something that could put her skills to good use. The story of how Loftus found that purpose—the story of her shadow career—began 30 years ago with a metaphor. "Imagine a world in which people could go to a special kind of psychologist or psychiatrist—a memory doctor—and have their memories modified," she mused in her 1980 book, Memory. This was no fantasy, she argued. The doctor was memory itself. "Every day, we do this to ourselves and others," she explained. "Our memories of past events change in helpful ways, leading us to be happier than we might otherwise be." Indeed, this was nature's design: Why should we cling tightly to those memories that disturb us and spoil our lives? Life might become so much more pleasant if it is not marred by our memory of past ills, sufferings, and grievances. … We seem to have been purposely constructed with a mechanism for erasing the tape of our memory, or at least bending the memory tape, so that we can live and function without being haunted by the past. Accurate memory, in some instances, would simply get in the way. © Copyright 2010 Washington Post.Newsweek Interactive Co. LLC

Keyword: Learning & Memory; Depression
Link ID: 14151 - Posted: 06.24.2010

By Katherine Harmon When your stomach growls and you have the urge to reach for the nearest snack, it is, in a way, your tummy talking. Those signals are in part sparked by the gut-based hunger hormone ghrelin, which blocks certain receptors in the brain, telling your body when it is time to eat. But a team of researchers thinks this hormone might be doing more than just urging you to pile on some calories. It might also be helping to regulate the levels of cholesterol in your bloodstream. The new research was published online June 6 in Nature Neuroscience (Scientific American is part of Nature Publishing Group). Although so-called bad cholesterol (low-density lipoprotein, or LDL) can result in clogged arteries and cardiovascular disease, good cholesterol (high-density lipoprotein, or HDL) is thought to actually prevent plaque build-up in the arteries by helping to transport lipids more smoothly through the bloodstream. Cholesterol levels have long been thought to be mainly a factor of diet and liver function. But new research in mouse models shows that changes in ghrelin and in a ghrelin-inhibited receptor in the hypothalamus altered how much HDL went to the liver for processing and how much remained in the blood stream. "Our study shows for the first time that cholesterol is also under direct 'remote control' by specific neurocircuitry in the central nervous system," Matthias Tschöp, a professor of endocrinology at the University of Cincinnati and coauthor of the paper, said in a prepared statement. © 2010 Scientific American,

Keyword: Obesity
Link ID: 14150 - Posted: 06.24.2010

A biological factor may play an essential part in the development of eating disorders in girls during puberty, a new study finds. The research, led by Michigan State University (MSU) scientists, finds that the genes of girls who have higher levels of estradiol at puberty can act as a catalyst for the development of eating disorders. Estradiol is the primary form of estrogen in women's bodies. It plays a key role in the development of secondary sex characteristics and bone development. "The reason we see an increase in genetic influences during puberty is that the genes for disordered eating are essentially getting switched on during that time," said Kelly Klump, MSU associate professor of psychology, in a release. "What we found is that increases in estradiol apparently are activating genetic risk for eating disorders." The genes responsible for activating eating disorders have yet to be identified. The researchers also believe that environmental factors and a genetic link (having a family history of eating disorders) play a part in the development of the condition. The researchers measured the amount of estradiol in the bloodstreams of 200 sets of twin girls between the ages of 10 and 15. The study is published in the journal Psychological Medicine. © CBC 2010

Keyword: Anorexia & Bulimia; Hormones & Behavior
Link ID: 14149 - Posted: 06.24.2010

By OLIVIA JUDSON A few weeks ago, I was walking through a wood in the English countryside when I heard the unmistakable call of the cuckoo. For some reason, it caused me to fall into a reverie, and as I walked, I began to meditate on that iconic bird and what it represents. The European cuckoo (Cuculus canorus) is, famously, a “brood parasite”: the female lays her eggs in other birds’ nests. Typical victims are small birds like reed warblers and wagtails. When the young cuckoo hatches, its first act is to dispose of any other eggs: it heaves them out of the nest, leaving itself as the sole occupant. What happens next is peculiar. The foster parents don’t appear to notice they are rearing a monster. Instead, they work hard to satisfy the demands of the chick, even though it sometimes becomes so large that it no longer fits inside the nest, and has to sit on top. It’s one of the oddest sights in nature. The cuckoo habit has evolved several times. It’s found in species as diverse as cowbirds, indigobirds, honeyguides and even a species of South American duck. (Actually, brood parasitism can also occur within a species — geese sometimes slip an egg into a neighbor’s nest, as do coots and starlings. Nor is it restricted to birds — fish and insects sometimes foist the rearing of their offspring onto others. But for the rest of this article, I want to focus on the birds that are “professional” brood parasites — the ones that, like the cuckoo, never build nests, and always palm their offspring onto another species.) Copyright 2010 The New York Times Company

Keyword: Sexual Behavior; Vision
Link ID: 14148 - Posted: 06.24.2010