The horse's major contribution to mankind has been shit. Such was the level of horse shit production late last century that measures were taken to centralise its disposal. Human The human being either evolved from the biologically very similar ape, or was created along with the rest of the world in a six-day creative spurt by an anonymous god. The human body is a wonderful thing. Well, most of them are.
Humans have one mouth and a limited number of genitals, which is probably just as well.