Shift workers are slightly more at risk of having a heart attack or stroke than day workers, research suggests. An analysis of studies involving more than 2m workers in the British Medical Journal said shift work can disrupt the body clock and have an adverse effect on lifestyle. It has previously been linked to an increased risk of high blood pressure and diabetes. Limiting night shifts would help workers cope, experts said. The team of researchers from Canada and Norway analysed 34 studies. In total, there were 17,359 coronary events of some kind, including cardiac arrests, 6,598 heart attacks and 1,854 strokes caused by lack of blood to the brain. These events were more common in shift workers than in other people. The BMJ study calculated that shift work was linked to a 23% increased risk of heart attack, 24% increased risk of coronary event and 5% increased risk of stroke. But they also said shift work was not linked to increased mortality rates from heart problems and that the relative risks associated with heart problems were "modest". The researchers took the socioeconomics status of the workers, their diet and general health into account in their findings. BBC © 2012

Keyword: Biological Rhythms; Stress
Link ID: 17103 - Posted: 07.30.2012

By RODNEY MUHUMUZA KITGUM, Uganda — Augustine Languna's eyes welled up and then his voice failed as he recalled the drowning death of his 16-year-old daughter. The women near him looked away, respectfully avoiding the kind of raw emotion that the head of the family rarely displayed. "What is traumatizing us," he said after regaining his composure, "is that the well where she died is where we still go for drinking water." Joyce Labol was found dead about three years ago. As she bent low to fetch water from a pond a half mile from Languna's compound of thatched huts, an uncontrollable spasm overcame her. The teen was one of more than 300 young Ugandans who have died as a result of the mysterious illness that is afflicting more and more children across northern Uganda and in pockets of South Sudan. The disease is called nodding syndrome, or nodding head disease, because those who have it nod their heads and sometimes go into epileptic-like fits. The disease stunts children's growth and destroys their cognition, rendering them unable to perform small tasks. Some victims don't recognize their own parents. Ugandan officials say some 3,000 children in the East African country suffer from the affliction. Some caregivers even tie nodding syndrome children up to trees so that they don't have to monitor them every minute of the day. Beginning Monday, Uganda hosts a four-day international conference on nodding syndrome that health officials believe will lead to a clearer understanding of the mysterious disease. © 2012 NBCNews.com

Keyword: Development of the Brain; Epilepsy
Link ID: 17102 - Posted: 07.30.2012

By Laura Sanders A baby’s brain is a thirsty sponge, slurping up words, figuring out faces and learning which foods are good and bad to eat. Information about the world flooding into a young brain begins to carve out traces, like rushing water over soft limestone. As the outside world sculpts the growing brain, important connections between nerve cells become strong rivers, while smaller unused tributaries quietly disappear. In time, these brain connections crystallize, forming indelible patterns etched into marble. Impressionable brain systems that allowed a child to easily learn a language, for instance, go away, abandoned for the speed and strength that come with rigidity. In a fully set brain, signals fly around effortlessly, making common­place tasks short work. A master of efficiency, the adult brain loses the exuberance of childhood. But the adult brain need not remain in this petrified state. In a feat of neural alchemy, the brain can morph from marble back to limestone. The potential for this metamorphosis has galvanized scientists, who now talk about a mind with the power to remake itself. In the last few years, researchers have found ways to soften the stone, recapturing some of the lost magic of a young brain. “There’s been a very, very significant change,” says Richard Davidson of the University of Wisconsin–Madison. “I don’t think the import of that basic fact has fully expressed itself.” © Society for Science & the Public 2000 - 2012

Keyword: Development of the Brain
Link ID: 17101 - Posted: 07.28.2012

by Michael Slezak Despite the fact that women live longer than men, their brains seems to age faster. The reason? Possibly a more stressful life. When people age, some genes become more active while others become less so. In the human brain, these changes can be observed through the "transcriptome" – a set of RNA molecules that indicate the activity of genes within a population of cells. When Mehmet Somel, a computational biologist at the University of California, Berkeley, and his colleagues compared the transcriptome of 55 male and female brains of different ages, they were surprised to find that the pattern of gene activation and deactivation that occurs with ageing appeared to progress faster in women than in men. This was particularly apparent in an area of the pre-frontal cortex. "This was just the opposite of what we'd originally expected," says Somel, who was at the Shanghai Institutes for Biological Sciences in China when he did the research. He says that given the fact that females have a longer lifespan, they had expected to see slower or later ageing-related changes in their brain. "But it fits everyday observations on ageing. Not all organs within an individual age at the same rate," he says. Somel's team compared the expression of more than 13,000 genes in four brain regions. In one region – the superior frontal gyrus – they found 667 genes that were expressed differently in men and women during ageing. Of those, 98 per cent were skewed towards faster ageing in women. Some of these gene changes have previously been linked to general cognitive decline and degenerative disease. © Copyright Reed Business Information Ltd

Keyword: Stress; Sexual Behavior
Link ID: 17100 - Posted: 07.28.2012

By Jason G. Goldman The baby, assailed by eyes, ears, nose, skin, and entrails at once, feels it all as one great blooming, buzzing confusion; and to the very end of life, our location of all things in one space is due to the fact that the original extents or bignesses of all the sensations which came to our notice at once, coalesced together into one and the same space. There is no other reason than this why “the hand I touch and see coincides spatially with the hand I immediately feel.” This passage, so often quoted in introductory psychology textbooks, was written by William James in his 1890 volume Principles of Psychology, and it encapsulates the dominant viewpoint of developmental psychology for most of the history of the field. James wasn’t the first one to articulate the idea that babies are born knowing essentially nothing of the world, of course. In 1689, John Locke wrote, in An Essay Concerning Human Understanding: Let us suppose the mind to be, as we say, white paper [tabula rasa] void of all characters, without any ideas. How comes it to be furnished? Whence comes it by that vast store which the busy and boundless fancy of man has painted on it with an almost endless variety? Whence has it all the materials of reason and knowledge? To this, I answer, in one word, from experience. John Locke (1632-1704) The argument proposed by philosophers like Locke and theorists like James is that babies are born as “blank slates,” ready to be inscribed upon – by experience, by learning, by culture. Infants, they argue, are equipped with basic sensory mechanisms, like vision and touch, and a powerful statistical brain that is highly skilled at detecting and learning associations between those sensory inputs. Throughout development, or so the argument goes, children learn more and more associations until their minds become more like adult minds. © 2012 Scientific American

Keyword: Development of the Brain
Link ID: 17099 - Posted: 07.28.2012

by Andy Coghlan Treating disease by stimulating brain cells with light is a step closer to reality following the first demonstration that the technique can improve mental performance in monkeys. Two monkeys performed better on simple computer tasks after light was used to boost the activity of brain cells necessary for the task. "For the first time, we were able to change behaviour in primates with our technique," says Wim Vanduffel of Massachusetts General Hospital in Charlestown, who is head of the group that performed the experiment. Known as optogenetics, the method has the potential to treat conditions such as epilepsy, where the light could temporarily deactivate the brain cells that cause seizures, or Parkinson's disease, where it can activate cells that make dopamine, the neurotransmitter vital for controlling mobility that those with Parkinson's lack. Previously, it has been used in nematode worms to trigger them to lay eggs, and mice to relieve depression and paralysis. Researchers have also used it in monkeys, but only on single, isolated neurons. Vanduffel and his colleagues wanted to see if they could extend this to entire networks of cells, boosting a monkey's ability to perform a simple computer-based task. Natural performance enhancers First, Vanduffel's team scanned the two monkeys' brains using functional magnetic resonance imaging while they followed a green dot on a computer screen. From the scans, the researchers could tell that the monkeys relied on an area of the brain called the arcuate sulcus to do the task. © Copyright Reed Business Information Ltd.

Keyword: Vision
Link ID: 17098 - Posted: 07.28.2012

Monya Baker Last week, the Sacramento Bee reported that two neurosurgeons at the University of California, Davis, had been banned from research on humans after deliberately infecting three terminally ill cancer patients with pathogenic bacteria in an attempt to treat them. All three died, two showing complications from the infection. Nature explores what happened and the science behind it. Who authorized the researchers to infect the patients? All three patients consented to infection. However, anyone testing experimental drugs in the United States requires approval from their university’s Institutional Review Board (IRB) and oversight by the country's Food and Drug Administration (FDA), both of which review evidence for safety and efficacy. Neurosurgeons Paul Muizelaar and Rudolph Schrot at the University of California (UC), Davis, did not obtain this approval; they say they did not think it was required. Harris Lewin, the vice-chancellor of research at UC Davis, wrote a letter to the FDA describing what had occurred as “serious and continuing noncompliance”. In 2008, working under instructions from Muizelaar, Schrot asked the FDA about the possibility of deliberately infecting a postoperative wound in a particular patient with glioblastoma with the bacterium Enterobacter aerogenes. He was told that animal studies were needed first. Muizelaar did not infect that patient, but arranged for a graduate student to begin tests in rats. Although bacteria were purchased as research materials not to be used in humans, they were eventually used in three other patients with glioblastoma. © 2012 Nature Publishing Group

Keyword: Neuroimmunology; Glia
Link ID: 17097 - Posted: 07.28.2012

By Laura Sanders Light use of the club drug Ecstasy may cause subtle memory deficits. People who popped just three Ecstasy tablets a month over the course of a year saw their memory slip on a laboratory test, scientists report online July 25 in Addiction. The new results offer some of the best evidence yet that the drug can change the brain, says psychiatric neuroscientist Ronald Cowan of Vanderbilt University Medical Center in Nashville. “It’s been very, very difficult to convince people that there’s a causative effect of the drug,” he says. “This adds strong evidence to that.” Scientists debate whether Ecstasy, a drug that brings euphoria, boundless energy and heightened sensory experiences, can actually harm the brain in part by screwing with cells that produce the chemical messenger serotonin. Past studies have been notoriously hard to interpret because brain differences seen between Ecstasy users and nonusers could have existed long before the drug use began. And people who use Ecstasy frequently tend to use other drugs too, making it hard to tease out Ecstasy’s effect. For the study, Daniel Wagner of the University of Cologne in Germany and his colleagues wanted to catch people as they started using Ecstasy. The team recruited 149 people who had used Ecstasy five or fewer times and ran the subjects through a battery of brain tests looking for signs of mental deficits. One year later, the team retested 43 people who had not used Ecstasy since being recruited, and 23 who had used 10 or more Ecstasy pills in that time. These people reported using an average of 33.6 tablets. © Society for Science & the Public 2000 - 2012

Keyword: Drug Abuse; Learning & Memory
Link ID: 17096 - Posted: 07.28.2012

by Andy Coghlan, Cambridge, UK IT'S early evening, and I'm facing a dilemma of some delicacy - whether or not to break wind. Let me explain... I'm poised to be voluntarily trapped in a room for the night as part of research to find new treatments for obesity at the Wellcome Trust Clinical Research Facility at Addenbrooke's Hospital in Cambridge, UK. The aim of the experiment is to see if brown fat, a special type of fat tissue that turns energy obtained from food into heat, can be coaxed into burning more unwanted white fat than usual. They intend to do this using a simple food supplement - a daily capsule of spicy ingredients such as chilli pepper or cinnamon - aimed at mimicking the effects of being in the cold. Recruited as a control, I've spent the afternoon undergoing a battery of tests to serve as reference data for how people in reasonably good health burn energy. Investigator Andy Whittle at the University of Cambridge explains that comparisons with this data will help establish whether people burn more energy than normal when kept in the cold (at 18 °C for 2 hours) or when given the spicy food capsules. I will be confined to a special room for the night, which serves as a human-scale calorimeter. "We'll treat you as if you're a fire, measuring how much oxygen you take in and how much carbon dioxide you breathe out," says Peter Murgatroyd, who designed the calorimeter. In other words, they will be capturing everything that goes in and out of my body. © Copyright Reed Business Information Ltd.

Keyword: Obesity
Link ID: 17095 - Posted: 07.28.2012

By Helen Briggs BBC News The idea that exercise is more important than diet in the fight against obesity has been contradicted by new research. A study of the Hadza tribe, who still exist as hunter gatherers, suggests the amount of calories we need is a fixed human characteristic. This suggests Westerners are growing obese through over-eating rather than having inactive lifestyles, say scientists. One in 10 people will be obese by 2015. And, nearly one in three of the worldwide population is expected to be overweight, according to figures from the World Health Organization. The Western lifestyle is thought to be largely to blame for the obesity "epidemic". Various factors are involved, including processed foods high in sugar and fat, large portion sizes, and a sedentary lifestyle where cars and machines do most of the daily physical work. BBC © 2012

Keyword: Obesity
Link ID: 17094 - Posted: 07.28.2012

By JOHN MONTEROSSO and BARRY SCHWARTZ ARE you responsible for your behavior if your brain “made you do it”? Often we think not. For example, research now suggests that the brain’s frontal lobes, which are crucial for self-control, are not yet mature in adolescents. This finding has helped shape attitudes about whether young people are fully responsible for their actions. In 2005, when the Supreme Court ruled that the death penalty for juveniles was unconstitutional, its decision explicitly took into consideration that “parts of the brain involved in behavior control continue to mature through late adolescence.” Similar reasoning is often applied to behavior arising from chemical imbalances in the brain. It is possible, when the facts emerge, that the case of James E. Holmes, the suspect in the Colorado shootings, will spark debate about neurotransmitters and culpability. Whatever the merit of such cases, it’s worth stressing an important point: as a general matter, it is always true that our brains “made us do it.” Each of our behaviors is always associated with a brain state. If we view every new scientific finding about brain involvement in human behavior as a sign that the behavior was not under the individual’s control, the very notion of responsibility will be threatened. So it is imperative that we think clearly about when brain science frees someone from blame — and when it doesn’t. © 2012 The New York Times Company

Keyword: Consciousness; Attention
Link ID: 17093 - Posted: 07.28.2012

by Michael Balter Many children (and adults) have heard Aesop's fable about the crow and the pitcher. A thirsty crow comes across a pitcher partly filled with water but can't reach the water with his beak. So he keeps dropping pebbles into the pitcher until the water level rises high enough. A new study finds that both young children and members of the crow family are good at solving this problem, but children appear to learn it in a very different ways from birds. Recent studies, particularly ones conducted by Nicola Clayton's experimental psychology group at the University of Cambridge in the United Kingdom have shown that members of the crow family are no birdbrains when it comes to cognitive abilities. They can make and use tools, plan for the future, and possibly even figure out what other birds are thinking, although that last claim is currently being debated. A few years ago, two members of Clayton's group showed that rooks can learn to drop stones into a water-filled tube to get at a worm floating on the surface. And last year, a team led by Clayton's graduate student Lucy Cheke reported similar experiments with Eurasian jays: Using three different experimental setups, Cheke and her colleagues found that the jays could solve the puzzle as long as the basic mechanism responsible for raising the water level was clear to the birds. To explore how learning in children might differ from rooks, jays, and other members of the highly intelligent crow family, Cheke teamed up with a fellow Clayton lab member, psychologist Elsa Loissel, to try the same three experiments on local schoolchildren aged 4 to 10 years. Eighty children were recruited for the experiments, which took place at their school with the permission of their parents. © 2010 American Association for the Advancement of Science

Keyword: Intelligence; Evolution
Link ID: 17092 - Posted: 07.26.2012

By Stephanie Pappas women, men, processing image, social psychology People focus on the parts of a woman's body when processing her image, according to research published in June in the European Journal of Social Psychology Image: Yuri Arcurs, Shutterstock A glimpse at the magazine rack in any supermarket checkout line will tell you that women are frequently the focus of sexual objectification. Now, new research finds that the brain actually processes images of women differently than those of men, contributing to this trend. Women are more likely to be picked apart by the brain and seen as parts rather than a whole, according to research published online June 29 in the European Journal of Social Psychology. Men, on the other hand, are processed as a whole rather than the sum of their parts. "Everyday, ordinary women are being reduced to their sexual body parts," said study author Sarah Gervais, a psychologist at the University of Nebraska, Lincoln. "This isn't just something that supermodels or porn stars have to deal with." Numerous studies have found that feeling objectified is bad for women. Being ogled can make women do worse on math tests, and self-sexualization, or scrutiny of one's own shape, is linked to body shame, eating disorders and poor mood. But those findings have all focused on the perception of being sexualized or objectified, Gervais told LiveScience. She and her colleagues wondered about the eye of the beholder: Are people really objectifying women more than men? © 2012 Scientific American

Keyword: Sexual Behavior; Attention
Link ID: 17091 - Posted: 07.26.2012

By PAULA SPAN Anna Hill’s mother-in-law had suffered from depression for years, it was clear in hindsight, and had denied it for years, too. Only 73, she’d lost interest in doing much of anything. In chronic pain after an earlier accident, she was taking high doses of methadone. Last November, she stunned her family by declining, at the eleventh hour, to come to Thanksgiving dinner. “I’d only seen her in a nightgown for a year straight,” said Ms. Hill, 42, an accountant in Atlanta. “She was just rotting away in bed, watching TV and taking methadone.” Depression in the elderly is a mixed picture these days. For years, mental health specialists lamented that depression was seriously underdiagnosed and undertreated in the elderly. Laypeople saw it not as a disease but as an inevitable part of aging. Doctors missed it because depression didn’t always look the way it did in younger patients — less sadness and weepiness, more physical symptoms and disengagement. Older people themselves often rejected help because mental illness carried a stigma. In primary care practices, Dr. Jürgen Unützer and colleagues found in a large study published in 2000, only 12 to 25 percent of older people with probable depression were getting a diagnosis and being treated. Not anymore. Over the past decade, “we’ve seen a really big increase in the recognition of depression and the initiation of treatment,” said Dr. Unützer, a geriatric psychiatrist now at the University of Washington. © 2012 The New York Times Company

Keyword: Depression
Link ID: 17090 - Posted: 07.26.2012

By Janet Raloff Psychiatrists sometimes prescribe light therapy to treat a form of depression in people who get too little morning sun. But too much light at other times may actually trigger such mood disorders. Chronic exposure to light at night unleashes depression, a new study finds — at least in animals. The new data confirm observations from studies of people who work night shifts, says Richard Stevens of the University of Connecticut Health Center in Farmington. Mood disorders join a growing list of problems — including cancer, obesity and diabetes — that can occur when light throws life out of balance by disrupting the biological clock and its timing of daily rhythms. In the new study, appearing online July 24 in Molecular Psychiatry, Tracy Bedrosian, Zachary Weil and Randy Nelson of Ohio State University exposed Siberian hamsters to normal light and dark cycles for four weeks. For the next four weeks, half of the animals remained on this schedule, and the rest received chronic dim light throughout their night. Compared with animals exposed to normal nighttime darkness, those getting dim light at night lost their intense preference for sweet drinks, “a sign they no longer get pleasure out of activities they once enjoyed,” Bedrosian says. In a second test, animals were clocked on how long they actively tried to escape a pool of water. Hamsters exposed to night lights stopped struggling and just floated in the water — a sign of “behavioral despair” — 10 times as long as animals that had experienced normal nighttime darkness, Bedrosian reports. © Society for Science & the Public 2000 - 2012

Keyword: Depression; Biological Rhythms
Link ID: 17089 - Posted: 07.25.2012

By Sandra Upson All elite athletes train hard, possess great skills and stay mentally sharp during competition. But what separates a gold medalist from an equally dedicated athlete who comes in 10th place? A small structure deep in the brain may give winners an extra edge. Recent studies indicate that the brain's insular cortex may help a sprinter drive his body forward just a little more efficiently than his competitors. This region may prepare a boxer to better fend off a punch his opponent is beginning to throw as well as assist a diver as she calculates her spinning body's position so she hits the water with barely a splash. The insula, as it is commonly called, may help a marksman retain a sharp focus on the bull's-eye as his finger pulls back on the trigger and help a basketball player at the free-throw line block out the distracting screams and arm-waving of fans seated behind the backboard. The insula does all this by anticipating an athlete's future feelings, according to a new theory. Researchers at the OptiBrain Center, a consortium based at the University of California, San Diego, and the Naval Health Research Center, suggest that an athlete possesses a hyper-attuned insula that can generate strikingly accurate predictions of how the body will feel in the next moment. That model of the body's future condition instructs other brain areas to initiate actions that are more tailored to coming demands than those of also-rans and couch potatoes. This heightened awareness could allow Olympians to activate their muscles more resourcefully to swim faster, run farther and leap higher than mere mortals. In experiments published in 2012, brain scans of elite athletes appeared to differ most dramatically from ordinary subjects in the functioning of their insulas. © 2012 Scientific American

Keyword: Brain imaging
Link ID: 17088 - Posted: 07.25.2012

by Douglas Heaven Watch where you look – it can be used to predict what you'll say. A new study shows that it is possible to guess what sentences people will use to describe a scene by tracking their eye movements. Moreno Coco and Frank Keller at the University of Edinburgh, UK, presented 24 volunteers with a series of photo-realistic images depicting indoor scenes such as a hotel reception. They then tracked the sequence of objects that each volunteer looked at after being asked to describe what they saw. Other than being prompted with a keyword, such as "man" or "suitcase", participants were free to describe the scene however they liked. Some typical sentences included "the man is standing in the reception of a hotel" or "the suitcase is on the floor". The order in which a participant's gaze settled on objects in each scene tended to mirror the order of nouns in the sentence used to describe it. "We were surprised there was such a close correlation," says Keller. Given that multiple cognitive processes are involved in sentence formation, Coco says "it is remarkable to find evidence of similarity between speech and visual attention". Word prediction The team used the discovery to see if they could predict what sentences would be used to describe a scene based on eye movement alone. They developed an algorithm that was able to use the eye gazes recorded from the previous experiment to predict the correct sentence from a choice of 576 descriptions. © Copyright Reed Business Information Ltd.

Keyword: Language
Link ID: 17087 - Posted: 07.25.2012

By Travis Riddle In the final hand of the 2011 World Series of Poker, Pius Heinz, a 22-year-old German who had honed his poker chops online was matched up against 35-year-old Martin Staszko – a former Hyundai automobile plant foreman. Staszko was in bad shape, having only about a quarter of the chips his younger opponent had, and had been dealt a relatively mediocre hand. Despite this, he decided to risk it all in an attempt to wage a comeback. In effect, he was lying, and Heinz, fortunately blessed with a relatively good hand, called him on his lie. Heinz, having successfully detected his opponents attempt at deceit, won the hand, the tournament, and $8.7 million while Staszko, the failed deceiver, took runner up and had to console himself with just $5.4 million. Although humans are the only species that plays poker, we are far from the only species that uses deception. And though several million dollars may seem like a high stakes game to us, the stakes for animals which use deception are even higher – often life or death. A frog which successfully fakes its croak to make itself seem bigger will be more likely to succeed in life than a similarly sized one which unsuccessfully fakes its croak. However, the ability to detect deception is just as important as the ability to deceive. A female frog with a talent for detecting deception will be more likely to mate with the actual biggest frog in the pond, rather than the one which only sounds the biggest, ensuring a greater likelihood of success for her genes. And so the evolutionary arms race continues, with liars and lie detectors successively attempting to one-up each other in reproductive fitness. © 2012 Scientific American,

Keyword: Emotions; Language
Link ID: 17086 - Posted: 07.25.2012

by Nicholas St. Fleur A house fly couple settles down on the ceiling of a manure-filled cowshed for a romantic night of courtship and copulation. Unbeknownst to the infatuated insects, their antics have attracted the acute ears of a lurking Natterer's bat. But this eavesdropper is no pervert—he's a predator set on a two-for-one dinner special. As a new study reveals, the hungry bat swoops in on the unsuspecting flies, guided by the sound of their precoital "clicks." Previous studies of freshwater amphipods, water striders, and locusts have shown that mating can make animals more vulnerable to predators, but these studies did not determine why. A team from the Max Planck Institute for Ornithology in Germany, led by the late Björn Siemers, found that the bat-fly interactions in the cowshed provided clues for understanding what tips off a predator to a mating couple. The researchers observed a teenage horror film-like scene as Natterer's bats (Myotis nattereri)preyed on mating house flies (Musca domestica). Bats find prey primarily through two methods: echolocation and passive acoustics. For most bats, echolocation is the go-to tracking tool. They send out a series of high frequency calls and listen for the echoes produced when the waves hit something. The researchers found that by using echolocation, bats could easily find and catch house flies midflight, yet they had difficulty hunting stationary house flies. © 2010 American Association for the Advancement of Science

Keyword: Hearing; Sexual Behavior
Link ID: 17085 - Posted: 07.24.2012

by Michael Marshall If you believe the Manic Street Preachers, there is no true love – just a finely-tuned jealousy. Once we've decided that another person is our special someone, we can become dangerously possessive and murderously unwilling to share them with others. Such all-consuming jealousy has a major downside: it's just so much effort. What if you can't be bothered? That seems to be how Hoffmann's two-toed sloths treat their sexual partners. Males do defend territories from rivals, but their slothful natures mean they aren't much good at holding onto females. Slow, so slow All sloths have a reputation for being lazy. This is sometimes exaggerated – they don't sleep much more than humans do – but basically correct. Sloths have unusually low metabolic rates and spend hours each day doing nothing. Hoffmann's two-toed sloth is a case in point. It spends the day hanging upside-down from branches high in trees, often hidden away within tangles of vines. During the night the sloths move around and feed, often for 7 or even 11 hours. But they're not exactly athletes, moving along branches at just 14 centimetres per second. They are also completely and utterly antisocial. Unless they're mating or caring for a youngster, you hardly ever see more than one sloth in a tree. © Copyright Reed Business Information Ltd.

Keyword: Sexual Behavior; Evolution
Link ID: 17084 - Posted: 07.24.2012