Health & Science

Programming yourself to be fat

Eating lots of cheeseburgers, fries, and sugary snacks makes people gain weight—but not, new research shows, just because these foods are so high in calories. A high-fat, high-sugar diet, say Washington University scientists, changes the balance of bacteria in the gut, and effectively “programs’’ people’s digestive systems to make them fat. The human intestinal tract has two main types of bacteria that help us digest food: Firmicutes and Bacteroidetes. Research has shown that people—and mice—with a high percentage of Firmicutes in their intestines tend to be fat, because these bacteria are very efficient at converting food into calories that the body then absorbs. Those with a preponderance of the less-efficient Bacteroidetes remain relatively lean. Researchers found that when they transferred intestinal bacteria from obese mice into the guts of previously microbe-free mice, the mice rapidly gained weight. When both types of bacteria were inserted into skinny mice, they stayed lean—until they began eating a diet high in fat and sugars. Then the count of “lean’’ bacteria dwindled, while the “fat’’ bacteria proliferated and took over the gut. As a result, the once-skinny mice bulked up. The results, researcher Jeffrey Gordon tells the Los Angeles Times, suggest that our resident microbes

play a major role in determining whether we’re lean or fat; further research may provide new treatments for obesity.

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Chimps who talk with their hands

Chimps and humans have yet one more trait in common: We both gesture mainly with our right hands, says National Geographic—a finding that could shed light on the origins of spoken language. For nearly a year, scientists at the Yerkes National Primate Research Center in Atlanta studied the variety of communicative gestures that several dozen captive chimps shared among themselves, from hand slaps and threatening arm motions to gentle invitations to groom or play. The results showed a pronounced bias toward right-hand gestures. In humans, spoken language is mediated mostly by the left hemisphere of the brain, which also controls the movements of the right hand. The tendency of chimps to gesture with the right hand thus provides further support for the notion that human speech evolved from the gestural communication of our primate ancestors.

Is empathy genetic?

If you’re not the empathetic type, don’t feel too bad, says the London Daily Telegraph; it could be genetic. Empathy is thought to be mediated in part by oxytocin, the so-called “cuddle hormone” in the brain; numerous studies have shown that people with elevated oxytocin levels are more generous and trusting. In a new study, subjects were shown a series of photos of facial expressions and then asked to characterize the emotions they saw—a classic “empathy test.” The scientists found that subjects with a gene that made them more receptive to oxytocin were significantly more accurate in their assessments of other people’s feelings. The results, says Oregon State University neuropsychologist Sarina Rodrigues, suggest that “some of us have a natural capacity to be more empathic than others and that some people are more closed-off and detached.”

What’s wrong with mummy

Heart disease is considered a modern ailment, a consequence of too many French fries and too little exercise. But in fact it’s as old as ancient Egypt, new research shows. A team of American and Egyptian scientists conducted medical scans on 22 ancient mummies, some up to 3,500 years old, for signs of atherosclerosis, or hardening of the arteries. Of the 16 mummies with identifiable hearts or arteries, nine—including seven of eight over age 45—showed a buildup of calcium plaque, an indicator of heart disease. “It throws out a lot of old myths about how we’re going to pot because of our modern lifestyle,” anthropologist Sandra Olsen tells ScienceNow. Then again, only members of ancient society’s upper crust were mummified, and they were known to engage in “some of these lifestyle factors that we think of as linked with atherosclerosis,” including diets rich in salt, meat, and fat, says co-author Michael Miyamoto. Heart disease, he says, “might be part of our genetic makeup,” waiting to be triggered by affluence.

Long toes, faster running

It’s often said that great sprinters are born, not made. Now there’s more biological evidence that this is true. Scientists have long known sprinters tend to have a higher percentage of fast-twitch muscle fibers in their legs. Now it turns out that sprinters possess another physical edge: longer toes. When researchers measured the feet and ankles of a group of university runners, the sprinters were found to have toes at least a third of an inch longer than non-sprinters. That likely converts into a more effective push-off and more ground contact while getting up to speed. “Early in the race is where it’s won or lost,” Penn State biome­chanist Stephen Piazza tells Discovery News. “If you can maintain contact with the ground longer, you can get more speed earlier.’’