This post first appeared at the Scientific American Guest Blog and is republished with permission.
With a single bad step as he ran untouched across a field this September, one of the best cornerbacks in the National Football League removed himself from the game for a whole season. New York Jets fans who saw Darrelle Revis’s left knee buckle under him that day may have pled with their televisions: not the ACL. But it was too late for Revis and his anterior cruciate ligament, which will undergo surgery this week.
Football fans are all too familiar with the ways in which a knee or ankle can fail a person. But athletes, like other humans, are simply doing the best that an ape running around on two legs can.
Before we lived and walked on the ground, our ancestors inhabited the tree branches. They didn’t look quite like chimpanzees or any ...
