Sex has always been a mystery to me. Not in pertaining it — women flock to me like grizzled prospectors rushing to the latest river reported to have a shiny bounty. Nor is sexual practice a mystery — my skills at pleasuring women are legendary. Rather, sex is a mystery from a perspective of the evolutionary sciences. Why did we evolve to practice it?

Some might say that the sex act fulfills the most basic desire of any creature — to replicate its genes. And it does, sometimes, though months past the actual date of the event. The more correct answer is that our biology rewards sexual acts with pleasure. The resulting children are merely a side effect.

But what about oral sex? It makes sense that the person to whom oral sex is being applied would enjoy it since it’s pleasurable in a way similar to regular sex. But often the person performing the oral sex enjoys the act. Why would this be?

One theory might be that the person realizes that they are “warming up” his or her partner, and will receive some sexual payback eventually.

But here’s what I wonder about. Do the sex organs exude some kind of olfactory treasure, a smell that turns us on? If that were the case, then we would have a general interest in burying our noses in each other’s crotches. Of course, we live in a culture where burying your nose in another person’s crotch is considered unseemly (unlike dogs.) So how do we convince another person to let our nose near their crotch? We essentially say, “while I’m down here, I’ll use my mouth to stimulate your genitalia.”