Sexual Evolution

I'm not exactly sure what Sumner is trying to convey. I think we can all agree that human and chimps are parallel creatures. Is he speculating about why we don't have the desire to cross breed? Dogs tend to hump things for fun. I've never seen a dog on a horse...does this mean that the dog doesn't mount the horse because it is physically impossible or because he has no desire to mount the horse? It doesn't take a genius to speculate about puzzle pieces fitting versus desire to make those pieces fit. The fact will always remain that species capable of propagating will continue and those that cannot will fail.

Maybe I can look at his piece in that he is speculating if creatures that are more prone to mounting anything possible have more success? I don't really see how people screwing horses, goats, and other barnyard animals helps the race to continue. In the same since I was always under the impression that a mule was the product of a donkey and horse which are more or less forced to breed. The mule isn't intended to exist as it is sterile, so one would think that a horse and donkey would not be inclined to copulate. The only thing that I picked up from this piece is that Bonobos are very horny, kind of like teenage males