If you slip in the bath and bang your head, you might end up in the hospital; but bighorn sheep regularly bang heads without giving it a second thought. How do they do it?
Male big horn sheep actually butt horns, not heads, during mating season. Some biologists estimate that this activity generates forces sixty times greater than that needed to crack our own skulls. The bighorn’s thick, curled horns can weigh as much as thirty pounds and have a spread of up to thirty-three inches. Most male bighorns don’t mate until they are about seven years old and have a well-developed set of horns.
How do sheep manage this impressive display? The answer is all in their heads. Bighorn sheep take advantage of the fact that the skull is made of many bones: it is not just one solid bone. For example, most of us know that human babies have soft heads because the human skull is not solid at birth. It is made up of separate plates of bones that slowly fuse together and become solid later in life. The lines where the separate plates meet are called sutures.
Bighorn sheep sutures are much more jagged than human sutures, and they do not entirely fuse as the sheep grow. Some scientists believe that when the bighorn sheep bang their horns, the force is distributed along the sutures, and since the sutures are flexible, the skull actually gives a little. The bones can shift slightly and absorb the force of the blow while our own solid skulls would simply crack under that kind of force. Rather ironically, it’s the flexibility of the bighorns’ skull that is responsible for their apparent hard-headedness.