In the record books, the swiftest sprinters tend to be of West-African ancestry and the faster swimmers tend to be white. A study of the winning times by elite athletes over the past 100 years reveals two distinct trends: not only are these athletes getting faster over time, but there is a clear divide between racers in terms of body type and race. Researchers now argue that the answer lies in athletes' centers of gravity. That center tends to be located higher on the body of blacks than whites. The researchers believe that these differences are not racial, but rather biological.