27 June, 2004
Why is Sex Fun? The Evolution of Human Sexuality, Jared Diamond (165 pp, TPB, 1997)
Well, this book sure has an eye-catching title, doesn't it? Why, indeed, is sex fun? Since it's by the author of the most excellent Guns, Germs, and Steel, I decided to buy the book and find out. In actuality, the subtitle describes the book better; Professor Diamond discusses the evolutionary logic behind various aspects of human sexuality, only one of which is why it's fun. Topics covered are: the genuine oddness of human sexual behavior in comparison to the rest of the animal world, gender-based behavior in humans and other animals, why men don't lactate, why humans engage in and enjoy sex all the tine, instead of only when females are fertile, the evolution of men's familial roles and female menopause, and "body signals."
The book isn't one long treatise like Guns, Germs, and Steel. Each chapter is pretty much self-contained. It's interesting, although some parts of it are on the dry side. It's written for a general audience, so non-specialists will be able to follow it easily.
Needless to say, this book isn't recommended for religious fundamentalists.
Why is sex fun? Well, to sum up a long answer: First, the question really is, "Why is sex fun, even when there is no chance of conception?" The answer is that it's one of many things which contribute to a strategy of "concealed ovulation." That is, neither the man or the woman knows when she is fertile. So, what's the reason for that? Well, there are two evolutionary pressures, both of which have played a role in producing concealed ovulation. Both are connected to the fact that our ape ancestors lived in "packs."
...concealed ovulation let the ancestral ape-woman distribute her sexual favors to many males, none of which could swear that he was the father of her child, but each of which knew that he might be. As a result, none of those potentially murderous males wanted to harm the ape-woman's baby, and some may actually have protected or helped feed it. One the ape-woman had evolved concealed ovulation for that purpose, she then used it to pick a good caveman, to entice or force him to stay at home with her, and to get him to provide lots of protection or help for her baby--secure in the knowledge that it was his baby too.