Why is Jamaica, with a population smaller than that of Los Angeles, home to so many of the world's elite sprinters -- runners who compete in the 100, 200, 400 and 800-meter races? Robert Trivers, an evolutionary biologist and professor of anthropology and biology in the School of Arts and Sciences, set out with his colleagues to find out if there was something about the symmetry of their knees that might partly explain this phenomenon. They already knew from their earlier research that the symmetry of children's knees at age 8 predicts how fast a person runs 14 years later in life.

"We then asked, "Is the degree of symmetry positively associated with sprinting ability among the very best sprinters?'" Trivers says. The answer to that question is yes.

Within all sprinters, those with the most symmetrical knees have the best times and this was particularly true of the 100-meter sprinters.

"You can easily imagine why," Trivers says. "If you watch someone running a 100-meter race, you can see his or her knees continually churning up and down, propelling the sprinter forward. Symmetry is very efficient."

Trivers and his co-authors -- Bernhard Fink of the University of Gottingen in Germany; Kristofor McCarty and Mark Russell of Northumbria University in England; Brian Palaestis of Wagner College in Staten Island, New York; and Bruce James of the MVP Track and Field Club in Kingston, Jamaica -- have published their work in the journal PLOS ONE.