BLACK SPRINTERS' NAVEL ADVANTAGE

To size up a sprinters potential speed, start by examining his navel. That's the conclusion of researchers at Duke University, who dared to examine the historically verboten question: Why do African-Americans tend to run faster than whites? The answer, says Science Daily, lies with the bellybutton, which marks the body's center of gravity. An analysis of prior studies of human measurements revealed that, on average, people of West African origin have longer legs than people with European hertiage; the longer legs, and shorter torsos, place their center of gravity 3%, or roughly an inch, higher. Collating a century's worth of sprinting records revealed that this height difference translates into a 1.5% boost in speed-enough to make a big difference in the results of sprints, in which fractions of a second separate winners from losers. "Locomotion is essentially a continual falls from a higher altitude falls faster," says research leader Andre Bejan. The converse holds true for swimmers: Europeans have a 3% longer torso than West Africans, which equals a 1.5% speed advantage in the pool. The researchers were careful to note that they focused on the athletes' geographics origins and physical measurements, not race, which they deem a "social construct."