Although sex may have originated hundreds of millions of years ago as a purely reproductive act, for people (and for some other species) it has become more than that. There seems to have been a layering of different impulses that developed over time.

The most basic sexual impulse for a man appears to be to have sex with the most attractive woman or women available. A man can impregnate multiple women during a short time, and in this way he spreads his genes to the greatest extent. Very few men actually have sex with every woman that opportunity allows, but the impulse is there.