Why economic theory is useful in understanding sex

I came across an old post in the Freakonomics blog today, about the economics of "desire" (read: sex). The authors discuss applying economic theory to sex, which is just about the least sexy thing imaginable to most people--and just about the sexiest thing to me.

In my own theories about the porn industry, I use economics to describe the dynamics on porn sets--for instance, why porn is one of the few industries where the wage differential favors women, even though the job is ostensibly harder (so to speak) for men. (It all has to do with both the supply side and end-user preferences; men are willing to work cheaply, money does little to enhance male physical performance, and consumers of porn dish money depending on the actress, not the actor.)

Economics is an excellent tool, even applied to porn/sex, because it cleanly explains rational behavior; the irrational behavior of passionate, aroused, emotional people does surprisingly little damage to the basic rational principles.

Here is one example from the Freakonomics blog post:

The reported prevalence of oral sex among affluent American teenagers would also seem to illustrate price theory: because of the possibility of disease or pregnancy, intercourse is expensive - and it has come to be seen by some teenagers as an unwanted and costly pledge of commitment. In this light, oral sex may be viewed as a cheaper alternative.

This sort of economic understanding, thoroughly harnessed, is deeply empowering in helping people navigate dating and courtship. I'm still waiting for an intelligent book to come out exploring the economics of sex (sorry to say, Mathematics and Sex, despite its promising title, was deeply disappointing). In the meantime, check out the Freakonomics post.