That seems to be the whole purpose of our existence. As one friend put it, nearly everything a man does is to increase his chances of getting laid or just to be desirable to the opposite sex. I think this is akin to asking the question, "Do bears shit in the woods?"
Its unnatural not to. The whole concept of one-woman-for-the-rest-of-your-life simply degrades what has been naturally hardwired into our bodies and minds through evolution...the need to breed.