Why do lizards do push ups?

Lizards work out for the same reason a guy at the gym might: as a display of strength. And with lizards, as can be the case with men, the push-ups also mean "get out of my territory."

And a new study finds some lizards make a morning and evening routine out of the displays.

Four species of male Jamaican lizards called anoles greet each dawn with vigorous push-ups, head bobs and a threatening extension of a colorful flap of skin on the neck. They repeat the ritual at dusk.