Sexual motivation

Sexual motivation finds it’s expression in behaviour.

In nature, a dog can smell when a bitch is in heat, it has olfactory cues. Although we are told pheromones play a part in human mating, usually by the perfume companies, humans tend to work on more visual cues.

A man sees a woman who is sexually alluring and this arouses him. He becomes physically ready for sex.

Which brings us to the cultural phenomenom that is pornography. Because media is a recent invention, a man may technically know that the image of the girl in front of him in the magazine or on the TV is not real, but his body still responds the way it has evolved to. Which leads us to masturbation, a ridiculous waste of energy and “seed”, but something we know everybody does.
Even if they don’t admit to it.

Masturbation, in particular for the male, is seen as something shameful. It is an insult to call a man a “wanker”. But this negative reinforcement does little, if nothing, to curb the practice.

Perhaps evolution is trying to eliminate masturbation as a behaviour by the social conditioning that it is shameful. Instead of sitting at home wasting your “efforts” on a fantasy, go out and find a real girl to have sex with.