On top of every bull's head are two pedicles -- bones shaped like cups and covered with skin. Antlers grow out of these pedicles. Once testosterone hardens the bond, the antlers are locked into the pedicles so tightly that a bull could hang 10 bowling balls from each antler and the antlers wouldn't budge.

Testosterone is also the hormone that rages through a bull in September. He bugles, fights with other bulls, and tries to mate with the cows. But by October, the amount of testosterone slowly begins dropping, and will continue to fall until early spring when the antlers snap off and startle the bull. The pedicles bleed a little right after the antlers fall off, but they soon heal. And the cycle begins again as a new set of antlers sprouts from the pedicles.