Physiology

In 1998, two sisters with chronic ear, sinus and lung infections were examined at a North Carolina hospital. The sisters were twins, but not quite identical. They looked exactly the same on the outside, but inside, one twin's organs were reversed, making the girls mirror images of each other. As anyone who has pledged allegiance knows, the human heart lies slightly left of center. This internal asymmetry extends to other organs too.

THAT leggy friend who looks better than you in shorts also burns fuel more efficiently while walking or running, a researcher has found. Herman Pontzer, a biological anthropologist at Washington University in St. Louis, made this discovery while testing a mathematical model for calculating energy costs for locomotion. He found that a tall person walking the same distance as a short person of identical weight and gait burns fewer calories, because longer legs are more efficient.

The human body has been tested in recent weeks in a heat wave that has killed more than 100 people in California, many of them elderly or homeless. The human body has complex strategies for beating the heat -- but when the system is overwhelmed, it can fail on many fronts. -- Mary Beckman The body keeps tabs on its internal temperature via a thermoregulator in a part of the brain called the hypothalamus.

FOR $235 (and up!) you can buy a funny looking pair of shoes to make you stand up straight, work your "core," elevate and shape your buttocks and, perhaps ladies, burn some extra calories to eliminate those dimpled saddlebags. Using technology named after the Masai warriors of East Africa, who have long, lean bodies and superb posture, the shoes are meant to re-create the feel of walking barefoot for miles in desert sand. Introduced in the U.S.

Many doctors and others have dismissed people with chronic fatigue syndrome as depressed, lazy or just plain whiny. Now a slew of research -- more than 2,000 scientific papers by some counts -- is suggesting that chronic fatigue is not a psychiatric illness, but a nasty mix of immunological, neurological and hormonal abnormalities.

SHAM medicines can sometimes bring real pain relief. Now scientists say they know why. New research shows that the "placebo effect" has a real physiological basis: It triggers the brain's pain-fighting chemicals. The findings could boost the search for drug-free ways to treat pain. "Just the expectation of pain relief is enough to activate anti-pain mechanisms," says lead scientist Jon-Kar Zubieta, a neuroscientist at the University of Michigan in Ann Arbor.

Able to carry a fifth of their body weight with virtually no effort, porters in the mountains of Nepal are the most efficient human haulers ever described, a study published in the current issue of the journal Science has found. Guillaume Bastien and colleagues at Belgium's Universite catholique de Louvain analyzed the porters' efficiency by measuring their oxygen consumption and carbon dioxide production, both of which reflected how much energy was used.

Larger male genitalia in some fish are more attractive to females, but they make the males more susceptible to predation, Yale researchers reported Friday in the Proceedings of the National Academy of Sciences. Studying western and Bahamas mosquitofish -- species in which the males cannot retract their gonopodia -- the team found that females preferred to watch videos of males with digitally enhanced genitalia.

Scientists have discovered a trove of life-forms lurking in the human gut -- 395 different bacteria, 60% of which had never been described, according to a report published Thursday in the online edition of the journal Science. The study analyzed samples of stool and mucous from six parts of people's colons. The results were surprising and "a bit sobering," said the paper's lead author, Stanford University researcher Dr. Paul Eckburg.

Pictures of products danced in his head. There was an Apple iPod, then a black Aeron chair. A coffeepot by Capresso and a washing machine by Dyson. Christian Dior followed by Versace, Oakley, Honda, Evian and Louis Vuitton. Each icon of commercial design -- 140 in all -- was projected onto goggles covering the eyes of a 54-year-old, college-educated, middle-class white male.