Here's an interesting line of inquiry. One of my abiding interests is evolutionary biology. It's part and parcel of my prime directive: Figure Out Why. Evolutionary biologists procede in their work by a process of 'reverse engineering': They look at some aspect of physiognomy and ask, "Why would that make our ancestors more fit, and thus better able to pass on their genes?" For example, a mutation resulting in keen eyesight would benefit the creature who received that, and that creature would thus be able to get more to eat, and have more offspring who would outcompete those with less acute vision. Some adaptations are fairly obvious, and some avail themselves to no more than a best guess. Some are downright mysterious. Like this one... why would it be that men's assholes are the locus of more nerve endings than almost any place in our bodies, with the possible exception of the prostate gland, found just inside the asshole?

Now why would that be?

------------------------------------------