OBSTY CRSS

Obesity 'controlled by the brain'
BBC News - 5 hours ago
Seven new gene variants discovered by scientists suggest strongly that obesity is largely a mind problem. The findings suggest the brain plays the dominant role in controlling appetite, and that obesity cannot easily be blamed on metabolic flaws.


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Talking therapy has 'lasting impact' on those with eating disorders
Daily Mail - 48 minutes ago

By Daily Mail Reporter People with eating disorders could benefit from a special form of cognitive behavioural therapy, which works on their obsessive feelings researchers said.



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2, 4, 8, 16 ... how can you always have MORE ancestors as you go back in time?
August 21, 1987

Dear Cecil:

Have you ever considered the puzzle of doubling ancestors? Everybody has two parents, four grandparents, eight great grandparents, and so on back through time, with the number of ancestors doubling in each generation. Go back 30 generations and the number of ancestors tops one billion. Eventually we arrive at a time when we have more ancestors than there could have been people in the world. How can this be? Common sense, not to mention the book of Genesis, suggests the human race started off with a handful of individuals whose numbers steadily increased. What are the implications of these two surging numerical tides, ancestors and descendants, butting head to head? Enclosed is a $10 check for the trouble of a personal reply.

— George M., Monrovia, California

Dear George:

You ask a question as cosmic as this one and you think a lousy sawbuck is going to cover it? Keep your money until you can fork over some real cash. The ancestor puzzle has its explanation in what one genealogist has called "pedigree collapse." This occurs when relatives, usually cousins, marry, in effect narrowing the family tree. (Fortunately for the gene pool, most of the cousins are only distantly related.) When this happens you find that many of the "slots" in a given generation of your family tree are filled by duplicates.

Consider an extreme case. Mr. and Mrs. Nosepicker have two children, a girl and a boy. These two develop an unnatural yen for one another and marry. Six months later the girl gives birth to an eight-pound horseradish with a lisp. In theory, the horseradish has four grandparents. In reality, its maternal and paternal grandparents are identical. Two of the four grandparent slots are thus filled by duplicates--pedigree collapse with a vengeance. Only slightly less extreme is the case of Alfonso XIII of Spain (1886-1941). Because of inbreeding in the royal family, he had only ten great-great-grandparents instead of the expected 16.

If you go back far enough, however, pedigree collapse happens to everybody. Think of your personal family tree as a diamond-shaped array imposed on the ever-spreading fan of human generations. (I told you this was cosmic.) As you trace your pedigree back, the number of ancestors in each generation increases steadily up to a point, then slows, stops, and finally collapses. Go back far enough and no doubt you would find that you and all your ancestors were descended from the first human tribe in some remote Mesopotamian village. Or, if you like, from Adam and Eve in the Garden of Eden.



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The fossil record tells us that the oldest member of our own species lived 195,000 years ago in what is now Ethiopia. From there it spread out across the globe. By 10,000 years ago modern humans had successfully colonized each of the continents save Antarctica, and adaptations to these many locales (among other evolutionary forces) led to what we loosely call races. Groups living in different places evidently retained just enough connections with one another to avoid evolving into separate species. With the globe fairly well covered, one might expect that the time for evolving was pretty much finished.

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////////////////////////////////////////But that turns out not to be the case. In a study published a year ago Henry C. Harpending of the University of Utah, John Hawks of the University of Wisconsin–Madison and their colleagues analyzed data from the international haplotype map of the human genome [see “Traces of a Distant Past,” by Gary Stix; Scientific American, July 2008]. They focused on genetic markers in 270 people from four groups: Han Chinese, Japanese, Yoruba and northern Europeans. They found that at least 7 percent of human genes underwent evolution as recently as 5,000 years ago. Much of the change involved adaptations to particular environments, both natural and human-shaped. For example, few people in China and Africa can digest fresh milk into adulthood, whereas almost everyone in Sweden and Denmark can. This ability presumably arose as an adaptation to dairy farming.



////////////////////////////////////////Even if intelligence is not at risk, some scientists speculate that other, more heritable traits could be accumulating in the human species and that these traits are anything but good for us. For instance, behavior disorders such as Tourette’s syndrome and attention-deficit hyperactivity disorder (ADHD) may, unlike intelligence, be encoded by but a few genes, in which case their heritability could be very high. If these disorders increase one’s chance of having children, they could become ever more prevalent with each generation. David Comings, a specialist in these two diseases, has argued in scientific papers and a 1996 book that these conditions are more common than they used to be and that evolution might be one reason: women with these syndromes are less likely to attend college and thus tend to have more children than those who do not. But other researchers have brought forward serious concerns about Comings’s methodology. It is not clear whether the incidence of Tourette’s and ADHD is, in fact, increasing at all. Research into these areas is also made more difficult because of the perceived social stigma that many of these afflictions attach to their carriers.



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Boy or girl? It's in the father's genes
Published: Thursday, December 11, 2008 - 11:58 in Psychology & Sociology
Learn more about: evolutionary biology genes newcastle university prospective parents x chromosome y chromosomes

A Newcastle University study involving thousands of families is helping prospective parents work out whether they are likely to have sons or daughters. The work by Corry Gellatly, a research scientist at the university, has shown that men inherit a tendency to have more sons or more daughters from their parents. This means that a man with many brothers is more likely to have sons, while a man with many sisters is more likely to have daughters.

The research, published online today by the journal Evolutionary Biology, involved a study of 927 family trees containing information on 556,387 people from North America and Europe going back to 1600.

"The family tree study showed that whether you're likely to have a boy or a girl is inherited. We now know that men are more likely to have sons if they have more brothers but are more likely to have daughters if they have more sisters. However, in women, you just can't predict it," Mr Gellatly explains.

Men determine the sex of a baby depending on whether their sperm is carrying an X or Y chromosome. An X chromosome combines with the mother's X chromosome to make a baby girl (XX) and a Y chromosome will combine with the mother's to make a boy (XY).

The Newcastle University study suggests that an as-yet undiscovered gene controls whether a man's sperm contains more X or more Y chromosomes, which affects the sex of his children. On a larger scale, the number of men with more X sperm compared to the number of men with more Y sperm affects the sex ratio of children born each year.

Sons or daughters?

A gene consists of two parts, known as alleles, one inherited from each parent. In his paper, Mr Gellatly demonstrates that it is likely men carry two different types of allele, which results in three possible combinations in a gene that controls the ratio of X and Y sperm;

* Men with the first combination, known as mm, produce more Y sperm and have more sons.
* The second, known as mf, produce a roughly equal number of X and Y sperm and have an approximately equal number of sons and daughters.
* The third, known as ff produce more X sperm and have more daughters.

"The gene that is passed on from both parents, which causes some men to have more sons and some to have more daughters, may explain why we see the number of men and women roughly balanced in a population. If there are too many males in the population, for example, females will more easily find a mate, so men who have more daughters will pass on more of their genes, causing more females to be born in later generations," says Newcastle University researcher Mr Gellatly.

More boys born after the wars

In many of the countries that fought in the World Wars, there was a sudden increase in the number of boys born afterwards. The year after World War I ended, an extra two boys were born for every 100 girls in the UK, compared to the year before the war started. The gene, which Mr Gellatly has described in his research, could explain why this happened.

As the odds were in favour of men with more sons seeing a son return from the war, those sons were more likely to father boys themselves because they inherited that tendency from their fathers. In contrast, men with more daughters may have lost their only sons in the war and those sons would have been more likely to father girls. This would explain why the men that survived the war were more likely to have male children, which resulted in the boy-baby boom.

In most countries, for as long as records have been kept, more boys than girls have been born. In the UK and US, for example, there are currently about 105 males born for every 100 females.

It is well-documented that more males die in childhood and before they are old enough to have children. So in the same way that the gene may cause more boys to be born after wars, it may also cause more boys to be born each year.

How does the gene work?

The trees (below) illustrate how the gene works. It is a simplified example, in which men either have only sons, only daughters, or equal numbers of each, though in reality it is less clear cut. It shows that although the gene has no effect in females, they also carry the gene and pass it to their children.

In the first family tree (A) the grandfather is mm, so all his children are male. He only passes on the m allele, so his children are more likely to have the mm combination of alleles themselves. As a result, those sons may also have only sons (as shown). The grandsons have the mf combination of alleles, because they inherited an m from their father and an f from their mother. As a result, they have an equal number of sons and daughters (the great grandchildren).

In the second tree (B) the grandfather is ff, so all his children are female, they have the ff combination of alleles because their father and mother were both ff. One of the female children has her own children with a male who has the mm combination of alleles. That male determines the sex of the children, so the grandchildren are all male. The grandsons have the mf combination of alleles, because they inherited an m from their father and f from their mother. As a result, they have an equal number of sons and daughters (the great-grandchildren).

http://www.ncl.ac.uk/press.office/press.release/photos/516diagram_06.1.jpg



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Research team explores causes of death on Mount Everest
Published: Tuesday, December 9, 2008 - 19:43 in Health & Medicine
Learn more about: british medical journal high altitude cerebral edema high altitude pulmonary edema leading causes of death massachusetts general hospital mount everest

An international research team led by Massachusetts General Hospital (MGH) investigators has conducted the first detailed analysis of deaths during expeditions to the summit of Mt. Everest. They found that most deaths occur during descents from the summit in the so-called "death zone" above 8,000 meters and also identified factors that appear to be associated with a greater risk of death, particularly symptoms of high-altitude cerebral edema. The report, which will appear the December 20/27 issue of the British Medical Journal has been released online. "We know that climbing Everest is dangerous, but exactly how and why people have died had not been studied," says Paul Firth, MB, ChB, of the MGH Department of Anesthesia, who led the study "It had been assumed that avalanches and falling ice – particularly in the Khumbu Icefall on the Nepal route – were the leading causes of death and that high-altitude pulmonary edema would be a common problem at such extreme altitude. But our results do not support either assumption."

Thousands of climbers have attempted to reach the summit of 8,850-meter (29,000-foot) Mount Everest since the 1920s. In order to examine the circumstances surrounding all deaths on Everest expeditions, the research team – which included investigators from three British hospitals and the University of Toronto – reviewed available expedition records including the Himalayan Database, a compilation of information from all expeditions to 300 major peaks in the world's highest range. Of a total of reported 212 deaths on Everest from 1921 to 2006, 192 occurred above Base Camp, the last encampment before technical (roped) climbing begins.



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Mayo researchers find potential links between breast density and breast cancer risk
Published: Saturday, December 13, 2008 - 08:22 in Health & Medicine
Learn more about: breast cancer risk breast density core needle biopsies dense breast tissue dr ghosh mayo clinic researchers

Having dense breasts - areas that show up light on a mammogram - is strongly associated with increased breast cancer risk, but "why" remains to be answered. Now, by examining dense and non-dense tissue taken from the breasts of healthy volunteers, researchers from Mayo Clinic have found several potential links. In two studies being presented simultaneously in poster form at the Cancer Therapy & Research Center-American Association for Cancer Research (CTRC-AACR) San Antonio Breast Cancer Symposium, the researchers report that dense breast tissue contains more cells believed to give rise to breast cancer, compared to non-dense tissue. "We found a dramatic difference in tissue composition between dense and non-dense tissue in the breast," says Karthik Ghosh, M.D., a Mayo Clinic breast cancer researcher and physician who led one study.

In a second study, researchers also found that dense breast tissue has more aromatase enzyme than non-dense tissue. This is significant because aromatase helps convert androgen hormones into estrogen, and estrogen is important in breast cancer development, says that study's lead investigator, Celine Vachon, Ph.D.



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Inside the consumer mind: brain scans reveal choice mechanism (12/15/2008)
Tags:
advertising, decisions

That gorgeous sweater has your name written on it. But, those red suede pumps are calling your name too. What goes through your mind as you consider these choices? During normal economic times, you might indulge in a whole new wardrobe. But now, with considerably tighter budgets, consumers don't have the luxury of saying "It's the holidays -- I'll just buy both!" What happens in buyers' brains as they consider difficult choices? What can retailers do to make the choice process easier for consumers?

Akshay Rao, a marketing professor at the University of Minnesota's Carlson School of Management, has conducted research that shows that decision making is simplified when a consumer considers a third, less attractive option. For example, when a second, less desirable sweater is also considered in the situation above, the shopper could solve their conundrum by choosing the more attractive sweater. The less appealing sweater plays the role of a "decoy" that makes the other sweater appear more pleasing than before. "In some ways, it is quite straightforward," said Rao. "When a consumer is faced with a choice, the presence of a relatively unattractive option improves the choice share of the most similar, better item."

In their forthcoming Journal of Marketing Research article "Trade-off Aversion as an Explanation for the Attraction Effect: A functional Magnetic Resonance Imaging Study," Rao and co-author William Hedgcock (University of Iowa) explain the reasons for this decoy effect. Volunteers had their brains scanned while they made choices between several sets of equally appealing options as well as choice sets that included a third, somewhat less attractive option. Overall, the presence of the extra, "just okay" possibility systematically increased preference for the better options. The fMRI scans showed that when making a choice between only two, equally preferred options; subjects tended to display irritation because of the difficulty of the choice process. The presence of the third option made the choice process easier and relatively more pleasurable.

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The little things? The little moments? They aren’t little.

Jon Kabat-Zinn
Author and stress expert