1 in 5 women will undergo pelvic surgery in her lifetime, study says

About 1 in 5 women now will undergo certain pelvic surgeries during her lifetime, nearly double the risk of having one of these surgeries in the 1990s, according to a recent study.

Researchers looked at women's likelihood of undergoing surgery before age 80 for either stress urinary incontinence (a condition that can cause urine to leak during sneezing or laughing), or pelvic organ prolapse (in which pelvic organs begin to droop within a woman's body).

"Surgeries for both of these conditions have increased substantially," said Dr. Jennifer M. Wu, associate professor at University of North Carolina at Chapel Hill's department of obstetrics and gynecology, an author of the study. "The 20 percent figure is nearly double that of earlier U.S. studies, which reported rates of 11.1 percent and 11.8 percent," for stress urinary incontinence surgery and pelvic organ prolapse surgery, respectively, she said.

Wu said she is not surprised by the results of this study, because stress incontinence and pelvic organ prolapse are very common conditions, which 1 in 3 women will experience in her lifetime. Many women, however, are embarrassed discussing symptoms such as involuntary urine leakage with their doctors, she said. [7 Embarrassing Health Problems (And How to Treat Them)]

"It's often not talked about until they are referred to a sub-specialist," Wu told Live Science. "Many women have suffered in silence for years with problems such as 'accidents' in public places. This can lead to social isolation for many of them."

Stress incontinence can be triggered by any sudden pressure increase within the abdomen. Pelvic organ prolapse occurs when a pelvic organ, such as the bladder, drops (prolapses) from its normal spot in the lower belly and pushes against the sides of the vagina, causing bulging, pressure or urine leakage during intercourse. This can happen when the muscles that hold the pelvic organs in place get weak or stretched from childbirth or surgery.

In the study, researchers used 10 years of data from a database of U.S. health plan claims and doctors' visits that included more than 10 million women from ages 18 to 89. Previous studies on this topic had small sample sizes, or were limited to one geographic region, Wu said.

The study appears today (May 7) in the journal Obstetrics & Gynecology.

"Many women believe these conditions are a normal part of the aging process," Wu said. "They're not."

However, surgery is not the only option. "With prolapse, one treatment option is no treatment at all," she said. "We just watch and wait if it's not affecting a woman's quality of life."

Other options, she said, include treatment with a pessary device, which is used to lift the bladder or apply compression to the urethra during activities certain activities, or pelvic floor physical therapy (Kegel exercises) designed to improve muscle tone.

For women with bladder incontinence, she said, nonsurgical treatments include lifestyle changes such as weight loss for those who are overweight or obese, dietary changes, anti-spasmodic medications, a pessary, Kegel exercises and nerve stimulation.

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Bat-Eating Spiders Are Everywhere, Study Finds

There's only one place in the world to escape bat-catching spiders: Antarctica. These arachnids ensnare and pounce on bats everywhere else in the world, researchers say.

Bats rank among the most successful groups of mammals, with the more than 1,200 species of bats comprising about one-fifth of all mammal species. Other than owls, hawks and snakes, bats have few natural enemies.

Still, invertebrates — creatures without backbones — have been known to dine on bats. For instance, giant centipedes in a cave in Venezuela were seen killing and eating bats, and the arachnids known as whip spiders were spotted feeding on dead bats in caves of the Caribbean. Cockroaches have been observed feeding on bat pups that have fallen to the floor of caves.

Spider-eat-bat world

Accidental deaths of bats in spiderwebs were known as well, but were thought to happen very rarely. Still, spiders are known to occasionally dine on a variety of vertebrates — creatures with backbones. For instance, fishing spiders capture and devour fish and frogs; some species of wolf spiders, huntsman spiders, tarantulas and related spiders have been seen killing and eating frogs and lizards; and tarantulas and comb-footed spiders have apparently fed on snakes and mice. There are also numerous reports of spiders killing other flying vertebrates, snagging birds with large orb webs. 

Recent studies of a web-building spider species (Argiope savignyi) and a tarantula species (Poecilotheria rufilata) both killing small bats led researchers to suggest that bat captures and kills due to spiders might be more frequent than previously thought. So they analyzed 100 years' worth of scientific reports, interviews of bat and spider researchers and the staff of bat hospitals, and scans of image and video sites. The search revealed 52 cases of bat-catching spiders worldwide. [See Photos of Bat-Eating Spiders in Action]

Giant webs

Approximately 90 percent of known bat-catching spiders live in the warmer areas of the globe, in the third of the Earth surrounding the equator. About 40 percent live in the neotropics — the whole of South America, and the tropical regions of North America — while nearly a third live in Asia and more than a sixth live in Australia and Papua New Guinea.

Eighty-eight percent of the reported cases of bat catches were due to web-building spiders, with giant tropical orb-weaving spiders with a leg-span of 4 to 6 inches (10 to 15 centimeters) seen catching bats in huge, strong orb-webs up to 5 feet (1.5 meters) wide. 

In instances seen in Costa Rica and Panama, the spiders had built their webs near buildings inhabited by bat colonies. Bat-catching via spiderwebs was also witnessed particularly often in the parks and forests of the greater Hong Kong area. Future research may investigate whether the huge webs that sometimes block the entrances of tropical bat caves in east and southeast Asia and the neotropics may occasionally snag any members of the giant swarms of bats that emerge from the caves at night. [Photos: Creepy, Crawly & Incredible Spiders]

The other 12 percent of cases of spider kills of bats were from spiders that hunt without webs. For instance, tarantulas were seen eating small bats in tropical rainforests in Peru and eastern Ecuador and on the forest floor in northeastern Brazil. A reddish parachute tarantula (Poecilotheria rufilata) was also seen predating on a small bat in Kerala, India, while a huntsman spider (Heteropoda venatoria) was observed capturing and killing a small bat in a shed near Kolkata, India. An attempt by a large fishing spider (Dolomedes triton) to kill a bat pup was also witnessed below a bridge in Indiana.

The victims

Most bat prey of spiders are small or juvenile insect-eating bats, and usually are among the most common bat species of their areas. Bats entangled in webs were usually 4 to 9.5 inches (10 to 24 cm) in wingspan, including some of the smallest species of bats in the world, and they sometimes died of exhaustion, starvation, dehydration or overheating — but there were many cases where spiders were seen actively attacking, killing and eating these victims.

Bats are likely capable of detecting spiderwebs via echolocation, their biological sonar. Even if bats do collide with spiderwebs, only the strongest traps are likely capable of withstanding the energy of such an impact without breaking. As such, bat captures are likely rare.

Still, as scarce as spider captures of bats likely are, they would prove well worth the effort. The catch of a 2-gram bat by the giant orb-weaving spider Nephila pilipes, a common killer of bats, would be a bonanza about 10 times the mass of the average daily catch of insect prey, researchers noted.

Martin Nyffeler and Mirjam Knörnschild detailed their findings online March 13 in the journal PLOS ONE.

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Big Bird Helps Scientists Study Brain Development

Children are not the only ones who can learn from Big Bird — brain scans of children and adults watching "Sesame Street" reveal how brains change as they learn reading and math, researchers say.

One goal of brain imaging is discovering more about how children learn. Such an understanding of the building blocks of learning might help diagnose and treat learning difficulties.

For instance, "when children fail to learn mathematics well, there could be a number of different reasons for that — it could be that they have weak concepts of numbers, that they have poor memory, that they have limited attention," researcher Jessica Cantlon, a cognitive neuroscientist at the University of Rochester in New York, told LiveScience. Brain tests could help determine the precise cause of a kid's math impairments, "because different patterns of brain activity likely accompany each of those different cognitive impairments."

Although scientists currently cannot see what goes on in the brains of children when they are learning in the classroom, Cantlon and her colleagues instead focused on analyzing what happens when kids watched educational television programs.

For the investigation, 27 children between the ages of 4 and 11 joined 20 adults in watching the same 20-minute "Sesame Street" recording as they had their brains scanned with functional magnetic resonance imaging (fMRI). The video featured a variety of short clips with Big Bird, the Count, Elmo and other stars of the show, and focused on numbers, words, shapes and other subjects. The children then took standardized IQ tests for math and verbal ability. [See Elmo Video]

"This took three years," Cantlon said. "Working with children can be challenging ... It also took time for us to get the analyses right."

Using statistical algorithms, the researchers created "neural maps" of the thought processes for the children and the adults and compared the groups. Children whose neural maps more closely resembled those of adults scored better on standardized math and verbal tests, showing that the brain's neural structure, like other parts of the body, apparently develops along predictable pathways as people mature. [Inside the Brain: A Photo Journey Through Time]

This research also confirmed where these developing abilities are located in the brain. For math, adultlike neural patterns in the intraparietal sulcus, a region of the brain involved with the processing of numbers, were linked to higher scores. For verbal tasks, more mature patterns in Broca's area, which is linked to speech and language, predicted better verbal test scores in children.

Normal activities such as TV watching may be a better way of learning about "neural maturity" than the short and simple tasks typical of fMRI studies. For instance, when the children matched simple pictures of faces, numbers, words or shapes, the neural responses of the children did not predict their test scores like watching "Sesame Street" did, the researchers said.

The researchers stress "that these results do not mean that there is anything special about 'Sesame Street' in particular," Cantlon said. "We chose 'Sesame Street' because it is mainstream. There are likely lots of stimuli that could yield the same result."

Still, while this research does not advocate watching television, it does show that "neural patterns during an everyday activity like watching television are related to a person's intellectual maturity," Cantlon said. "It's not the case that if you put a child in front of an educational TV program that nothing is happening — that the brain just sort of zones out. Instead, what we see is that the patterns of neural activity that children are showing are meaningful and related to their intellectual abilities."

Future studies can help pinpoint what areas might be linked with difficulties with learning math or verbal tasks. Research could also see if educational television shows are better than noneducational shows at eliciting math- and verbal-related brain activity, Cantlon said.

Cantlon and her colleague Rosa Li detailed their findings online Jan. 3 in the journal PLOS Biology.

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Crabs Really Do Feel Pain: Study

Scientists have long held that crabs are unable to feel pain because they lack the biology to do so, but behavioral evidence has recently shown otherwise. Now, new research further supports the hypothesis that crabs feel pain by showing that crabs given a mild shock will take steps to avoid getting shocked in the future.

From humans to fruit flies, numerous species come equipped with nociception, a type of reflex that helps avoid immediate tissue damage. On the other hand, pain, which results in a swift change of behavior to avoid future damage, isn't so widespread. (Research has also shown naked mole rats may be immune to pain.)

In the new study, researchers allowed shore crabs (Carcinus maenas) to choose between one of two dark shelters in a brightly lit tank. One shelter came with a mild shock. After just two trials, crabs that initially chose the shocking shelter began opting for the zapless shelter, suggesting they learned to discriminate between the two options and headed for the less painful one.

"It's almost impossible to prove an animal feels pain, but there are criteria you can look at," said lead researcher Robert Elwood, an animal behaviorist at Queen's University, Belfast, in the U.K. "Here we have another criteria satisfied — if the data are consistent, a body of evidence [showing crabs feel pain] can build up."

Building evidence

Elwood initially set out to see if crabs and other crustacean decapods feel pain after a chef posed him the question around eight years ago. If the invertebrates (animals without backbones) feel pain, he reasoned, their reactions to unpleasant stimuli would be more than the simple reflex of nociception — the experience would change their long-term behavior.

Elwood's first experiment showed that prawns whose antennae were doused with caustic soda vigorously groomed their antennae, as if trying to ameliorate pain. Importantly, this behavior didn't occur if Elwood treated the antennae with an anesthetic first.

Another experiment showed that hermit crabs would leave their shells if given a mild shock. "A naked crab is basically a dead crab — they were trading off avoiding the shock with getting out of the shell," Elwood told LiveScience, adding that many of the crabs moved into new shells if any were available. [The 10 Weirdest Animal Discoveries]

For his new study, Elwood tested 90 shore crabs, which naturally seek dark spaces, to see if they exhibited "avoidance learning" and would discriminate between a dangerous and a safe area. Half of the crabs were shocked upon entering the first chamber of their choice, while the other half were not. For each crab, the jolting chamber stayed the same throughout the 10 trials.

In the second trial, most of the crabs returned to their original shelter; whether they were shocked in the first trial had little effect on their second choice. However, crabs were more likely to change shelter in the third trial if they were shocked in the second trial. And as the trials wore on, crabs that chose incorrectly became more likely to exit the unpleasant chamber, brave the bright arena and hide in the alternate shelter. By the final test, the majority of the crabs chose the nonshock shelter at first go.

Time for change?

The research "provides evidence that supports the issue that crabs — and other crustacean decapods as well — feel pain," Francesca Gherardi, an evolutionary biologist at the University of Florence in Italy who wasn't involved in the study, told LiveScience in an email. "It is avoidance learning that makes the difference."

Animals in pain should quickly learn to avoid the unpleasant stimulus and show long-term changes in behavior, Gherardi noted. More research is needed on decapods' avoidance learning and "discrimination abilities between painful and nonpainful situations," he said.

Elwood said he thinks future research should go in a different direction. Stress often comes with pain, he said, so other experiments could look at changes in crustacean hormones or heart rates due to shock.

Whatever the case, Elwood feels it may be time to reconsider the treatment of decapods in the food industry. "If the evidence for pain in decapods continues to stack up with mammals and birds that already get some protection, then perhaps there should be some nod in that direction for these animals," he said.

The study was published today (Jan. 16) in the Journal of Experimental Biology.

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Loneliness Is Bad for Your Health, Study Suggests

NEW ORLEANS — Feeling lonely? New research suggests you might want to reach out. Not only is loneliness an unpleasant condition, it can harm the body's immune system.

The new study, presented Saturday (Jan. 19) here at the annual meeting of the Society for Personality and Social Psychology, reveals that people who are lonely experience more reactivation of latent viruses in their systems than the well-connected. Lonely people also are more likely than others to produce inflammatory compounds in response to stress, a factor implicated in heart disease and other chronic disorders.

"Both, in different ways, indicate that the immune system is a little out of whack," said study researcher Lisa Jaremka, a postdoctoral fellow at the Institute for Behavioral Medicine Research at Ohio State University College of Medicine.

The lonely body

Jaremka and her colleagues were interested in immune links to loneliness because feeling socially disconnected is associated with poor health and chronic disease. They recruited 200 female breast cancer survivors, average age 51, and 134 overweight, middle-age adults with no major health problems.

In the first study, the researchers analyzed the blood of the breast cancer survivors for antibodies against cytomegalovirus, a herpes virus. These common viruses can remain dormant and symptomless inside the body. Even when active, they may not cause symptoms, but they do trigger the immune system to produce antibodies, or protective proteins that help the immune system hunt down the rogue viruses. Higher antibody levels indicate higher levels of activated virus. The participants also filled out questionnaires about their loneliness and social connectedness. [7 Personality Traits That Are Bad For You]

The results revealed that the lonelier the participant, the higher the levels of cytomegalovirus antibodies in the blood.

"It's definitely indicating that the immune system is compromised in some way," Jaremka told LiveScience. "It's unable at that time, for whatever reason, in this case loneliness perhaps, to keep that virus under control."

In a second study, the researchers measured inflammatory proteins called cytokines in 144 of the breast cancer survivors as well as the healthy though overweight middle-age adults. The participants gave a blood sample and then were subjected to the stress of having to give an impromptu speech and do mental math in front of a panel of people in white lab coats. To up the anxiety, the panel gave the participants no encouragement.

"No matter what they say and no matter what jokes they crack, no matter how much they smile, the panel just stares at them, basically," Jaremka said.

The researchers also triggered the participants' immune systems with a harmless compound from bacterial cells before taking a second blood sample.

The lonelier the person, the higher the levels of cytokine interleukin-6 after the stressful speech. This cytokine is important for healing in the short term, because it promotes inflammation — think of the redness and swelling that accompanies a healing cut. However, when cytokines react too readily, inflammation can be harmful. Chronic inflammation has been linked to coronary heart disease, arthritis, Type 2 diabetes and even suicide attempts.

Loneliness and stress

Researchers have long known that chronic stress has a similar inflammation-producing, immune-disrupting effect on the body. Loneliness, in fact, may act as its own source of chronic stress, Jaremka said. Earlier research shows that close and connected relationships are necessary to help people thrive; without them, people are under a constant stressful cloud of missing this crucial social connection.

People who are lonely also tend to react more strongly to negative events in their lives, Jaremka said. If lonely people experience daily life as more stressful, it may cause chronic stress, which in turn disrupts the immune system.

Solving the problem is harder than telling lonely hearts to go out and seek more close friends, Jaremka said — it's easier said than done. But if researchers can figure out how loneliness results in poor health, they may be able to come up with treatments that disrupt the links, in essence making loneliness less of a burden, at least physically. 

The study shouldn't be seen as all doom and gloom, Jaremka said. The flip side is that those who feel close to friends and family can know that their health is likely getting a boost from those relationships.

"People who feel socially connected are experiencing positive outcomes," she said.

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'Universal' Personality Traits Are Not, Study Finds

Psychologists can get a pretty clear picture of someone's personality by evaluating to what degree they express traits known as the "Big Five" — openness, conscientiousness, extroversion, agreeableness and neuroticism. These factors are thought to be rooted in biology and to transcend cultural differences, but a new study of an indigenous Bolivian society shows the traits might not be universal after all.

Researchers spent two years studying more than 1,000 Tsimane forager-farmers, who live in isolated communities, each ranging from 30 to 500 people. Most are not formally educated, and they live in extended family clusters, sharing food and labor and limiting contact with outsiders.

The team first surveyed adults in the villages with a standard questionnaire (translated into the Tsimane language) that assesses the Big Five personality traits. Next the researchers asked Tsimane participants to evaluate their spouse's personality. This second part revealed that the subject's personality as reported by his or her spouse also did not fit with the Big Five traits. The researchers found that their results held true even when they controlled for education level, Spanish fluency, gender and age.

The team instead discovered evidence of a pair of broad traits that could be considered the Tsimane "Big Two." The researchers labeled one prosociality — socially beneficial behavior, which among the Tsimane, looks like a mix of items under the extroversion and agreeableness portions of the Big Five. The other trait is industriousness, which blends the efficiency, perseverance and thoroughness found in the conscientiousness portion of the Big Five, the researchers said.

The team says their results don't support the universality of the Big Five, and they speculated that the social structure of the Tsimane could have resulted in a trait structure different from the Big Five.

"Individuals in all human societies face similar goals of learning important productive skills, avoiding environmental dangers, cooperating and competing effectively in social encounters, and finding suitable mates. In small-scale societies, individuals have fewer choices for social or sexual partners and limited domains of opportunities for cultural success and proficiency. This may require abilities that link aspects of different traits, resulting in a trait structure other than the Big Five," the team wrote.

The research was detailed online in December in the Journal of Personality and Social Psychology.

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Women's Migraines Not Linked to Mental Decline: Study

Researchers have some reassuring news for women who suffer from migraines: There is no strong link between the intensely painful headaches and cognitive decline or dementia.

The research out of Brigham and Women's Hospital in Boston is based on data from 6,349 women ages 45 and older who participated in a health survey. The participants were classified into four groups: no history of migraine, past history of migraine, and continued history of migraine with and without aura. (Auras can cause a person to see flashes of light or feel pins-and-needles sensations before a migraine kicks in.)

After this baseline information was collection, the participants were tested for cognitive function in two-year intervals up to three times. The results, which were published online Aug. 8 in the British Medical Journal, showed no strong relationship between migraines and long-term consequences on cognition, according to the researchers.

"Compared with women with no history of migraine, those who experienced migraine with or without aura did not have significantly different rates of cognitive decline," Pamela Rist, who led the study, explained in a statement from Brigham and Women's Hospital.

"Previous studies on migraines and cognitive decline were small and unable to identify a link between the two," Rist added. "Our study was large enough to draw the conclusion that migraines, while painful, are not strongly linked to cognitive decline."

About 30 million Americans suffer from migraines, but women are three times more likely than men to be impacted by them. The debilitating headaches have been linked to an increased risk of depression and even stroke. Much is still unknown about the chronic condition, but researchers recently found the first genetic link to migraines — a gene variant also found to change the activity of other genes, including one previously linked to disorders such as epilepsy.

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New Study Throws Dark Matter Finding Into Question (SPACE.com)

A new study of dark matter, the mysterious hidden stuff thought to pervade the universe, casts doubt on a previous finding that offered hope that dark matter had finally been seen.

In 2008, a European-Russian satellite called Payload for Antimatter Matter Exploration and Light nuclei Astrophysics (PAMELA) discovered a strange overabundance of particles called positrons, which are the antimatter counterpart to electrons. Matter and antimatter, which have the same mass but opposite charges, destroy one another when they meet.

According to theory, when a particle of dark matter collides with its antiparticle, they annihilate, unleashing a burst of energy and exotic particles. Dark matter is thought to make up 98 percent of all matter in the universe and 23 percent of its total mass and energy. Scientists have yet to directly detect invisible dark matter, but its existence is inferred based its gravitational pull on regular matter.

The positrons found by PAMELA were thought to be the products of dark matter annihilation with antimatter, and scientists were hopeful that the tantalizing discovery could prove the existence of the elusive dark matter.

But a new study has raised more questions about PAMELA's discovery. Researchers at the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC) at Stanford University in California confirmed the overabundance of positrons, but when they did not see a sudden drop-off of this excess beyond a certain energy level, they knew something was wrong.

"If the antimatter we measure is coming from the annihilation of dark matter particles, then the positron excess should drop off fairly suddenly at an energy level that corresponds with the mass of the dark matter particle," study co-author Stefan Funk, an assistant professor of physics at Stanford University, said in a statement.

Rather, Funk and his colleague, Justin Vandenbroucke, found that the number of positrons continued to increase in line with the level of energy. [7 Surprising Things About the Universe]

"Some have concluded that this altogether rules out dark matter as a source of the antimatter we're measuring," Funk said. "At the very least this means that if the positrons are coming from dark matter annihilation, then dark matter particles must have a higher mass than allowed by the PAMELA measurement."

But the results are not necessarily a definitive strike against the finding, the researchers said.

"We're taking an observational point of view and simply reporting the data that we observe," Vandenbroucke said. "However, I know that articles are already appearing that say our result likely rules out the dark matter interpretation. Personally, I think that is too strong of an interpretation."

Additional observations will be needed to settle the debate, the researchers said. One instrument in particular, the antimatter-hunting Alpha Magnetic Spectrometer (AMS), is expected to yield helpful results.

NASA's space shuttle Endeavour carried the AMS experiment to the International Space Station in May, where it was installed on the exterior of the complex. It has been operating ever since. This detector should be able to collect more precise data at higher energies, Vandenbroucke said.

"AMS has a very large magnet in its detector and so can naturally and very easily distinguish between electrons and positrons," Funk said. "That experiment will most likely be able to make a final statement on this. It's something we are all eagerly awaiting."

Funk and Vandenbroucke used NASA's Fermi Gamma-ray Space Telescope, which studies the highest energy forms of light. Since the telescope is designed to detect neutral light particles, called photons, it does not have a magnet to separate negatively charged electrons and positively charged positrons.

The researchers were forced to improvise, but luckily a natural magnet exists close to home: Earth. The planet's magnetic field naturally bends the paths of charged particles that almost continuously rain from space, they explained.

The scientists then studied geophysical maps of Earth and calculated how the planet filters out charged particles seen by the telescope, in a novel approach at the intersection of astrophysics and geophysics.

"The big takeaway here is how valuable it is to measure and understand the world around us in as many ways as possible," Vandenbroucke said. "Once you have this basic scientific knowledge, it's often surprising how that knowledge can be useful."

The researchers detailed their results in a paper submitted to the journal Physical Review Letters.

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Gender inequality persists in multitasking: study

A woman pushes her pram towards an ice cream vendor on Portstewart Strand beach, Northern Ireland, May 10, 2009.

Credit: Reuters/Cathal McNaughton

By Patricia Reaney

NEW YORK | Fri Dec 2, 2011 8:07am EST

NEW YORK (Reuters) - Men may be helping more in the home but working women still do more multitasking in U.S. families than their partners and are finding it stressful, according to a new study.

Whether it is housework, cooking or childcare, women do about 10 hours more multitasking in the home each week -- 48.3 hours compared to 38.9 -- which researchers say constitutes an important source of gender inequality.

"When you look at men and women in similar kinds of work situations they look very similar," Barbara Schneider, a professor of sociology at Michigan State University and a co-author of the study, said in an interview.

"But when they come home it is very clear that women are shouldering much more of the responsibilities of housework and childcare."

Schneider and Shira Offer, an assistant professor at Bar-Ilan University in Israel, used data from the 500 Family Study, which looked at how families in eight U.S. urban and suburban communities balance work and family life.

Their research, which is published in the American Sociological Review journal, is based on responses from a subset of 368 mothers and 241 fathers in dual-income families, which they said reflects the most time-pressured segment of the population.

"This (the findings) suggests that working mothers are doing two activities at once more than two-fifths of the time they are awake, while working fathers are multitasking more than a third of their waking hours," Schneider said.

In addition to doing more, the jobs women perform at the same time in the home are more labor intensive, such as housework and childcare, than what men tackle.

The study showed that 52.7 percent of all multitasking for working mothers involved housework, compared to 42.2 percent for fathers, and 35.5 percent was taken up with childcare, as opposed to 27.9 percent for men.

"Fathers, by contrast, tend to engage in other types of activities when they multitask at home, such as talking to a third person or engaging in self-care. These are less burdensome experiences," Schneider explained.

The researchers said the study showed multitasking is also more stressful for women. Only women reported negative emotions when they multitasked at home or in public, while men found it a positive experience.

"We should not be under any false assumptions that things have dramatically changed," said Schneider when asked about the role of women at home and at work.

"I think there are still many issues, both in the workplace and certainly in the home, that suggest there are and continue to be gender inequalities."

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Twin NASA craft launched to study insides of moon (AP)

CAPE CANAVERAL, Fla. – A pair of spacecraft rocketed toward the moon Saturday on the first mission dedicated to measuring lunar gravity and determining what's inside Earth's orbiting companion — all the way down to the core.

"I could hardly be happier," said the lead scientist, Maria Zuber. After two days of delays and almost another, "I was trying to be as calm as I could be."

NASA launched the near identical probes — named Grail-A and Grail-B — aboard a relatively small Delta II rocket to save money. It will take close to four months for the spacecraft to reach the moon, a long, roundabout journey compared with the zippy three-day trip of the Apollo astronauts four decades ago.

Grail-A popped off the upper stage of the rocket exactly as planned 1 1/2 hours after liftoff, followed eight minutes later by Grail-B. Both releases were seen live on NASA TV thanks to an on-board rocket camera, and generated loud applause in Launch Control.

The spacecraft are traveling independently to the moon, with A arriving on New Year's Eve and B on New Year's Day.

Once they were safely on their way, Zuber announced a contest for schoolchildren to replace the "working-class names" of Grail-A and Grail-B.

"Grail, simply put, is a journey to the center of the moon," said Ed Weiler, head of NASA's science mission directorate, borrowing from the title of the Jules Verne science fiction classic, "Journey to the Center of the Earth."

The world has launched more than 100 missions to the moon since the Soviet Union's Luna probes in 1959. That includes NASA's six Apollo moon landings that put 12 men on the lunar surface.

NASA's Grail twins — each the size of a washing machine — won't land on the moon but will conduct their science survey from a polar lunar orbit.

Beginning in March, once the spacecraft are orbiting just 34 miles above the moon's surface, scientists will monitor the slight variations in distance between the two to map the moon's entire gravitational field. The measurements will continue through May.

"It will probe the interior of the moon and map its gravity field 100 to 1,000 times better than ever before. We will learn more about the interior of the moon with Grail than all previous lunar missions combined," Weiler said.

At the same time, four cameras on each spacecraft will offer schoolchildren the opportunity to order up whatever pictures of the moon they want. The educational effort, called MoonKAM, is spearheaded by Sally Ride, America's first spacewoman. As of Saturday, more than 1,100 schools had signed up.

The entire Grail mission costs $496 million.

Zuber, the mission's principal investigator and a planetary scientist at the Massachusetts Institute of Technology, said the precise lunar gravity measurements will help her and other planetary scientists better understand how the moon evolved over the past 4 billion years. The findings also should help identify the composition of the moon's core: whether it's made of solid iron or possibly titanium oxide.

Another puzzle that Grail may help solve, Zuber said, is whether Earth indeed had a smaller second moon. Last month, astronomers suggested the two moons collided and the little one glommed onto the big one, a possible explanation for how the lunar highlands came to be.

Knowing where the moon's gravity is stronger will enable the United States and other countries to better pinpoint landing locations for future explorers, whether robot or human. The gravity on the moon is uneven and about one-sixth Earth's pull.

"If you want to land right next to a particular outcrop (of rock), you're going to be able to do it," Zuber said. "There will be no reason to do another gravity experiment of the moon in any of our lifetimes."

Zuber said the Grail findings should eliminate cliffhangers like the Apollo 11 landing in 1969 by Neil Armstrong and Buzz Aldrin. They overshot their touchdown site in part because of the subtle gravity changes in the moon's surface below; they almost ran out of fuel before safely touching down on the Sea of Tranquility.

"It will be easier next time," Zuber promised.

For now, NASA has no plans to return astronauts to the moon, Earth's closest neighbor at approximately 240,000 miles away. That program, called Constellation, was canceled last year by President Barack Obama, who favors asteroids and Mars as potential destinations in America's future without the shuttle.

This is the second planetary mission for NASA since the space shuttle program ended in July, and attracted a large crowd to Cape Canaveral. NASA counted nearly 1,000 guests at Kennedy Space Center on Saturday, nowhere near the 12,000 on hand for the Juno launch to Jupiter at the beginning of August.

Grail was supposed to soar Thursday, but high wind interfered. Then NASA needed an extra day to check the rocket after engine heaters stayed on too long. High wind almost stopped NASA again Saturday; the launch team had to skip the morning's first opportunity, but the wind dissipated just in time for the second.

The year's grand finale will be the launch of the biggest Mars rover ever the day after Thanksgiving.

"NASA is still doing business even though the shuttles stopped flying," Weiler told reporters earlier in the week.

Grail is the 110th mission to target the moon, according to NASA records. Missions have been launched by the United States, Soviet Union, Japan, China and India.

The previous moonshot was two years ago: NASA's Lunar Reconnaissance Orbiter. Just last month, the moon-circling probe beamed back the sharpest pictures yet of some of the Apollo artifacts left on the moon from 1969 through 1972 — and even moonwalkers' tracks. NASA released the photos earlier in the week.

Ride and Zuber will help pick the winning names for the Grail twins later this year, well before the spacecraft reach the moon.

Zuber said she has her own pet names, "but I think I'll keep those to myself because I don't want to influence the contestants." Some of the names used by members of her team over the four-year life of the project: Fred and Ginger, Castor and Pollux, and Tom and Jerry.

___

Online:

NASA: http://www.nasa.gov/mission_pages/grail/main/index.html

Sally Ride Science: http://moonkam.ucsd.edu/

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Weight Watchers works, scientific study finds

By Kate Kelland

LONDON | Thu Sep 8, 2011 10:29am EDT

LONDON (Reuters) - Overweight patients told by their doctors to go to Weight Watchers lose around twice as much weight as people receiving standard weight loss care over 12 months, according to the findings of a study published on Thursday.

In the first randomized controlled trial -- considered the gold standard of scientific analysis -- to directly compare a commercial weight-loss program with standard care by family doctors, Weight Watchers was found to be more than twice as effective.

More people stuck to the Weight Watchers diet, they lost more weight and fat mass, and also shaved more off their waist measurements than those assigned to standard care.

Susan Jebb of Britain's Medical Research Council (MRC) Human Nutrition Research Unit, who led the study, said the results showed Weight Watchers is "a robust intervention that is generalisable to other economically developed countries."

"This kind of research is important so that we can identify clinically effective interventions to treat obesity," she said.

The study, published in the Lancet medical journal, comes in the wake of research last month which said obesity is a global epidemic that is fast replacing tobacco as the single most important preventable cause of costly chronic diseases like heart disease, diabetes and cancer.

Worldwide, around 1.5 billion adults are overweight and another 0.5 billion are obese, with 170 million children classified as overweight or obese. Obesity takes up between 2 to 6 percent of healthcare costs in many countries.

In the weight loss study, which was funded by Weight Watchers International but run as an investigator-led trial with all data collection and analysis conducted by the independent research team, researchers assessed 772 overweight and obese adults in Australia, Germany and Britain.

Patients were randomly assigned to receive either 12 months of standard care as usually offered by the primary care team, or referred to and given a 12-month free membership for a Weight Watchers group in their neighborhood.

As well as losing twice as much weight as those in the standard care group, patients referred to Weight Watchers were also more than three times as likely to lose 10 percent or more of their initial body weight. Some 61 percent of patients in the Weight Watchers group lost at least 5 percent of their body weight, compared with 32 percent in the standard care group.

The average weight loss at 12 months was 5.1 kg (11.2 lbs) for those using Weight Watchers versus 2.2 kg for those on standard care. For those who completed the full 12 months, average weight loss was 6.7 kg on Weight Watchers versus 3.3 kg on standard care.

"These important findings show that obesity treatment is effective and structured commercial programs can enhance outcomes," said Nick Finer a consultant endocrinologist and bariatric physician at University College London Hospitals, who was not involved in the research.

In a commentary on the study, Kate Jolly and Paul Aveyard of the school of health and population sciences at Britain's Birmingham University said cost-effectiveness was a key factor in determining whether commercial programs like Weight Watchers become part of publicly funded health care.

They added that "the low cost of these programs -- at present about 50 to 60 pounds ($80 to $95) for 12 weeks -- makes the case for incorporation intuitively appealing."

David Kirchhoff, CEO of Weight Watchers International said the Lancet study "proves that Weight Watchers is part of the solution to help transform the health of nations."

"There is a clear need for practical treatment solutions that are proven effective, affordable and scalable to have a population-wide impact," he said in a statement.

(Reporting by Kate Kelland, editing by Paul Casciato)

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Battle against lice may be aided by new genome study

By Randolph E. Schmid, Associated PressWASHINGTON — Sometimes scientific research can be a lousy job. Literally.In their quest to understand how life works, researchers reported Monday they have sequenced the genome of the human body louse.

That's right, those annoying little suckers that live on human blood and place their eggs in clothing.

From a practical standpoint, the findings could lead to better ways to eliminate this parasite, which can carry diseases to people, according to the researchers who were led by Ewen F. Kirkness of the J. Craig Venter Institute in Rockville, Md. and Barry R. Pittendrigh of the University of Illinois, Urbana.

For its digestion, the human body louse relies on a specific type of bacteria, which is not resistant to antibiotics. So finding a way to get drugs to the bacteria might kill the lice too. Knowing more about lice may also lead to new types of repellent.

The louse genome is small and contains relatively few genes related to light reception or reacting to odors and tastes, the study found.

The researchers said it appears that the human body louse evolved from the human head louse about the time people started wearing clothes, offering lice another place to hide.

In addition, they noted that the human louse and the Chimpanzee louse evolved from a common ancestor between 5 million and 7 million years ago.

It's been more than an annoyance ever since, potentially carrying typhus, relapsing fever and trench fever.

"Beyond its importance in the context of human health, the body louse genome is of considerable importance to understanding insect evolution," said May R. Berenbaum, head of the entomology department at the University of Illinois, in a statement.

The genome sequencing effort involved researchers at 28 institutions in the U.S., Europe, Australia and South Korea.

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Ocean life on the brink of mass extinctions: study

A scuba diver swims near a school of swirling jacks on the Indonesian resort island of Bali, May 14, 2011.

Credit: Reuters/David Loh

OSLO | Tue Jun 21, 2011 1:41pm EDT

OSLO (Reuters) - Life in the oceans is at imminent risk of the worst spate of extinctions in millions of years due to threats such as climate change and over-fishing, a study showed on Tuesday.

Time was running short to counter hazards such as a collapse of coral reefs or a spread of low-oxygen "dead zones," according to the study led by the International Programme on the State of the Ocean (IPSO).

"We now face losing marine species and entire marine ecosystems, such as coral reefs, within a single generation," according to the study by 27 experts to be presented to the United Nations.

"Unless action is taken now, the consequences of our activities are at a high risk of causing, through the combined effects of climate change, over-exploitation, pollution and habitat loss, the next globally significant extinction event in the ocean," it said.

Scientists list five mass extinctions over 600 million years -- most recently when the dinosaurs vanished 65 million years ago, apparently after an asteroid struck. Among others, the Permian period abruptly ended 250 million years ago.

"The findings are shocking," Alex Rogers, scientific director of IPSO, wrote of the conclusions from a 2011 workshop of ocean experts staged by IPSO and the International Union for Conservation of Nature (IUCN) at Oxford University.

Fish are the main source of protein for a fifth of the world's population and the seas cycle oxygen and help absorb carbon dioxide, the main greenhouse gas from human activities.

OXYGEN

Jelle Bijma, of the Alfred Wegener Institute, said the seas faced a "deadly trio" of threats of higher temperatures, acidification and lack of oxygen, known as anoxia, that had featured in several past mass extinctions.

A build-up of carbon dioxide, blamed by the U.N. panel of climate scientists on human use of fossil fuels, is heating the planet. Absorbed into the oceans, it causes acidification, while run-off of fertilizers and pollution stokes anoxia.

"From a geological point of view, mass extinctions happen overnight, but on human timescales we may not realize that we are in the middle of such an event," Bijma wrote.

The study said that over-fishing is the easiest for governments to reverse -- countering global warming means a shift from fossil fuels, for instance, toward cleaner energies such as wind and solar power.

"Unlike climate change, it can be directly, immediately and effectively tackled by policy change," said William Cheung of the University of East Anglia.

"Over-fishing is now estimated to account for over 60 percent of the known local and global extinction of marine fishes," he wrote.

Among examples of over-fishing are the Chinese bahaba that can grow 2 meters long. Prices per kilo (2.2 lbs) for its swim bladder -- meant to have medicinal properties -- have risen from a few dollars in the 1930s to $20,000-$70,000.

(Editing by Jan Harvey)

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Solar Storms Sparked By Giant 'Magnetic Rope,' Study Finds (SPACE.com)

A giant "magnetic rope" made up of twisting magnetic field lines could produce the strong electric currents that trigger solar storms, a new study finds.

Researchers at George Mason University sifted through data from NASA's Solar Dynamics Observatory (SDO) to study the magnetic rope phenomenon. Scientists have predicted that this rope is the cause of violent eruptions on the sun, but have previously struggled to prove its existence because of how quickly it moves.

Confirming the magnetic rope's existence would not only help astronomers understand the formation of solar storms, but would also be a key first step toward mitigating the adverse effects these eruptions can have on satellite communications on Earth. [Amazing New Sun Photos from Space]

Jie Zhang, an associate professor in the department of physics and astronomy at George Mason University, and graduate student Xin Cheng closely examined images taken by SDO's Atmospheric Imaging Assembly (AIA) telescope.

The researchers were able to pinpoint an area on the sun where a magnetic rope was forming. The AIA telescope captures images of the sun every 10 seconds, 24 hours a day.

"The magnetic rope triggers a solar eruption," Zhang said in a statement. "Scientists have been debating whether or not this magnetic rope exists before a solar eruption. I believe that the result of this excellent observation helps finally solve this controversial issue."

Powering solar storms

It is widely believed that magnetic fields in the sun play an essential role in storing energy and powering solar storms. Yet, the exact form that magnetic field lines take prior to eruptions is not well understood. Most field lines are semicircular loops with their foot-points rooted on the surface of the sun. As a result, they cannot erupt easily, and in fact, they often can prevent eruptions.

Scientists suspected that the magnetic rope, if it indeed exists, is the phenomenon that powers eruptions. A magnetic rope contains many magnetic field lines wrapping around a center axis and possibly twisting around each other.

Because of the twisting, a strong electric current can be carried by the magnetic rope. Theoretically, the electric current could produce enough electromagnetic force to overcome the overlying constraining force from other field lines and power the magnetic rope to move outward. [Photos: Sunspots on Earth's Star]

Images from the AIA telescope now reveal that, prior to eruption, there is a long and low-lying channel running through the entire active region, which heats to a scorching-hot temperature and slowly rises. When it reaches a critical point, it starts to erupt quickly.

This feature is distinctly different from the surrounding magnetic field lines, and the intensely hot channel is now believed to be the magnetic rope that scientists have been looking for.

More than just a pretty picture

Solar storms are violent eruptions on the sun that send a wave of charged particles, called plasma, into space at the speed of more than one million miles per hour. The cloud of plasma carries with it a strong magnetic field.

Sometimes these plasma clouds are directed at Earth, and can deposit a large amount of energy into the planet's magnetosphere.

Normally, the Earth's magnetosphere acts as a shield from these harmful particles and protects the environment. But a solar storm has the potential to disrupt the shielding effect, and severe space weather can have harmful effects on a wide array of technological systems, including satellite operations, communications, navigation and electric power grids.

Studies of space weather aid in the development of early warning systems for solar storms and help to minimize the damage from turbulent solar activity, researchers said.

"Understanding the eruption process of these storms will definitely help us better predict them," Zhang said. "We cannot prevent solar storms, just like we cannot prevent earthquakes or volcanoes. But the development of prediction capacity can help mitigate adverse effects. For instance, satellite operators can power-down key systems to prevent the possible damage to the systems."

The results of the study were reported at the American Astronomical Society Solar Physics Division Meeting, which is being held from June 12 to 16 at New Mexico State University in Las Cruces.

Follow SPACE.com for the latest in space science and exploration news on Twitter @Spacedotcom and on Facebook.

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Satellite study helps thirsty Sahel (AFP)

PARIS (AFP) – Embattled farmers in the Sahel countries of West Africa can take heart from a new study that should boost the accuracy of rainfall prediction in one of the world's most fragile regions.

Sharp differences in moisture in small patches of land can trigger precious rain, says the paper, published online on Sunday in the journal Nature Geoscience.

Researchers from Britain, France and Australia looked at satellite data that located nearly 4,000 rainstorms which occurred in the Sahel between 2006-2010.

Between 80 and 90 percent of rainfall in the Sahel comes from this kind of storm, which can brew suddenly when moisture-laden air lifts from heated earth.

The scientists then overlaid this data with satellite information on soil moisture.

They found that an area where there are large differences in soil moisture plays a big role in making rain.

A moist area just 10 to 40 kilometres (six to 25 miles) across can trigger rain provided it is next to a far drier patch.

This small-is-beautiful finding contrasts with conventional weather models.

These tend to calculate the probability of rainfall on the basis of huge swathes of moist land and on the presence of rain-making features like mountain ranges.

"Rainfall is difficult to predict, particularly in regions such as the Sahel where huge storms can grow from nothing in a matter of hours," said lead author Chris Taylor of Britain's Centre for Ecology and Hydrology.

"We found that areas with contrasting soil moisture can play an important role in the creation of new storms, a factor not accounted for in current climate models.

"(...) This effect is important for typically one in eight storms, in a region particularly prone to droughts and associated crop failures."

In areas where there are these sharp differences in soil moisture, rainstorms are twice as likely compared to regions where the moisture level is uniform.

The rain often falls around 10 kilometres (six miles) upwind of the moist patch, not downwind, Taylor explained to AFP.

This occurs when the moist air is driven against weak prevailing winds by a strong local breeze coming from the opposite direction.

The study could help fine-tune knowledge about how climate change could affect the Sahel, he said.

Semi-arid, tropical west Africa is one of the most demanding regions in the world for agriculture, given its fragile soils and a short growing season that is crucially dependent on when and where rain will land.

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Study: Water vapor may help 'flatten global warming trend'

Why the Earth's surface temperature hasn't warmed as expected over the past decade continues to be a puzzle for scientists. One study out earlier this month theorized that the Earth's climate may be less sensitive to greenhouse gases than currently assumed.Another surprising factor could be the amount of water vapor way up in the stratosphere, according to a new study out Thursday in the journal Science.

Water vapor, a potent, natural greenhouse gas that absorbs sunlight and re-emits heat, is "a wild card" of global warming, says the paper's lead author, senior scientist Susan Solomon of the National Oceanic and Atmospheric Administration in Boulder, Colo. Solomon was also a co-chair of one of the groups within the Intergovernmental Panel on Climate Change that put out the definitive forecast of global warming in 2007.

In the Science paper, Solomon and her colleagues found that a drop in the concentration of water vapor in the stratosphere "very likely made substantial contributions to the flattening of the global warming trend since about 2000."

While climate warming is continuing — the decade of 2000 to 2009 was the hottest on record worldwide — the increase in temperatures was not as rapid as in the 1990s.

The stratosphere is the layer of the atmosphere just above the troposphere, which is the layer of air here at the planet's surface. (The troposphere goes from the surface up to about 8 miles, and the stratosphere is from about 8 to 30 miles above the surface.)

The decline in water vapor in the stratosphere slowed the rate of surface warming by about 25%, compared to that which would have occurred due to carbon dioxide and other greenhouse gases, notes the study. Specifically, the planet should have warmed 0.25 degree F during the 2000s, but because of the influence of the water vapor, it rose just 0.18 degree F.

"We call this the 10/10/10 paper," says Solomon. "10 miles above your head, there is 10% less water vapor than there was 10 years ago."

Why did the water vapor decrease? "We really don't know," says Solomon, "We don't have enough information yet."

The findings are "surprising," says Bill Randel, an atmospheric chemist at the National Center for Atmospheric Research, who was not part of the study. He said it was surprising how big an effect such a very little change in stratospheric water vapor has had on the surface climate.

These fluctuations in water vapor could be part of a feedback loop. Although it's known that water vapor in the troposphere increases as the climate warms — and is a major climate feedback that is well simulated in global climate models — in sharp contrast, models do a poor job of simulating water vapor in the stratosphere, according to the paper.

But Solomon points out this isn't an indication that predictions on global warming are overstated: "This doesn't mean there isn't global warming," notes Solomon. "There's no significant debate that it is warmer now than it was 100 years ago, due to anthropogenic (man-made) greenhouse gases."

And how will this water vapor affect future global warming? "We really don't know the answer to this," says Solomon. "If the water changes are due to the specific way the sea-surface temperature pattern looks right now, then it may well not be linked to the overall warming. It could just be a source of variability from one decade to another as the ocean pattern slowly changes. Or it could be linked to the overall warming of the tropics, in which case it could continue to 'put the brakes on.' Only time will tell, and more data."

Contributing: Associated Press

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Battle against lice may be aided by new genome study

By Randolph E. Schmid, Associated PressWASHINGTON — Sometimes scientific research can be a lousy job. Literally.In their quest to understand how life works, researchers reported Monday they have sequenced the genome of the human body louse.

That's right, those annoying little suckers that live on human blood and place their eggs in clothing.

From a practical standpoint, the findings could lead to better ways to eliminate this parasite, which can carry diseases to people, according to the researchers who were led by Ewen F. Kirkness of the J. Craig Venter Institute in Rockville, Md. and Barry R. Pittendrigh of the University of Illinois, Urbana.

For its digestion, the human body louse relies on a specific type of bacteria, which is not resistant to antibiotics. So finding a way to get drugs to the bacteria might kill the lice too. Knowing more about lice may also lead to new types of repellent.

The louse genome is small and contains relatively few genes related to light reception or reacting to odors and tastes, the study found.

The researchers said it appears that the human body louse evolved from the human head louse about the time people started wearing clothes, offering lice another place to hide.

In addition, they noted that the human louse and the Chimpanzee louse evolved from a common ancestor between 5 million and 7 million years ago.

It's been more than an annoyance ever since, potentially carrying typhus, relapsing fever and trench fever.

"Beyond its importance in the context of human health, the body louse genome is of considerable importance to understanding insect evolution," said May R. Berenbaum, head of the entomology department at the University of Illinois, in a statement.

The genome sequencing effort involved researchers at 28 institutions in the U.S., Europe, Australia and South Korea.

Copyright 2010 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed. Guidelines: You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. Read more.

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Hominid females roamed while males waited: study

By Julie Steenhuysen

CHICAGO | Thu Jun 2, 2011 10:33am EDT

CHICAGO (Reuters) - Females from two hominid species that roamed the South African savannah more than a million years ago left their families and struck out on their own, while their male counterparts tended the home fires, an international team of researchers said on Wednesday.

The findings, published in the journal Nature, came from an analysis of traces of the isotope strontium that had built up in adult teeth from two extinct groups -- Australopithecus africanus and Paranthropus robustus.

Both Paranthropus robustus and Australopithecus africanus were part of a line of close human relatives known as australopithecines that included the Ethiopian fossil, Lucy, estimated to be some 3.2 million years old and regarded by many as the matriarch of modern humans.

To understand how these hominids used the landscape and formed social groups, the team, led by Sandi Copeland of Colorado University Boulder, turned to the ancient dental record.

Using a high-tech analysis known as laser ablation, the team zapped the hominid teeth with lasers to measure ratios of strontium, a naturally occurring element found in rocks and soils that is absorbed by plants and animals.

The team tested 19 teeth dating from roughly 2.7 to 1.7 million years ago from both Australopithecus africanus and Paranthropus robustus individuals from the Sterkfontein and Swartkans cave systems in South Africa.

The team found more than half of the smaller, female teeth came from outside the local area, but only about 10 percent of the male hominid teeth were from elsewhere.

That suggests that males likely grew up and died in the same area, Copeland said.

Copeland said the pattern in which the females left home in search of a mate is similar to chimpanzees and some groups of modern humans, in which a woman leaves her family to join her husband's household.

But it is different from most other primates -- including gorillas -- where the females stay with the group they are born into and the males move elsewhere.

"In any mammal group, including primates, where individuals live in groups, either the females or males must eventually leave their birth community. One of the important reasons for this is to prevent inbreeding," Copeland said.

"In most mammals, it is usually the males that leave their home community," she told a news briefing.

She said the findings were a bit of a surprise.

"We assumed more of the hominids would be from non-local areas since it is generally thought the evolution of bipedalism was due in part to allow individuals to range longer distances," Copeland said.

Such small home ranges suggest that bipedalism evolved for other reasons, she said.

(Editing by Cynthia Osterman)

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