New Work, May 30 (TIWN): After a certain age, most adults settle into long-term partnerships that remain relatively stable for years, even a lifetime. But it’s not uncommon, either, for people to have briefer, less committed relationships: hookups, “friends with benefits,” extramarital affairs and the like.

This poses something of a problem for evolutionary psychologists, who seek to explain much of human behavior as inherited adaptations that have arisen over tens of thousands of years. It’s easy to find an adaptive reason why men might seek short-term sexual relationships. After all, a promiscuous man could potentially sire dozens, even hundreds of children, thus contributing more of his genes to the next generation — a win, in evolutionary terms. But the asymmetries of pregnancy and lactation mean a woman can’t have hundreds of children, so she gains little benefit, evolutionarily speaking, from sowing wild oats. Why, then, should women engage in short-term dalliances at all?

One possibility, of course, is that there is no evolutionary goal in play, that women are merely enjoying the benefits of our modern, relatively egalitarian, contraceptive-equipped society. There is likely to be some merit in that explanation. Simply talking about human behavior as evolutionary psychologists do — as though we were just another animal piloted by instinct — can draw ire from some social scientists and members of the general public, who counter that biology is not destiny, and that people control their own behavior. But evolutionary psychologists wonder whether there might be other forces operating as well, with women’s short-term mate choices representing an active strategy with specific evolutionary goals. Sorting this out has emerged as one of the hottest current research topics in the field of human mating behavior.

Fling theory
The standard evolutionary explanation for women’s short-term relationships, at least for those who already have a long-term partner, is that an affair on the side could be a good strategy because it provides an opportunity to mate with someone more physically attractive than her regular partner, that dependable, caring guy. “Those sexy men are likely to have more partners — and, historically, more children — than the good dads,” says Sarah Hill, an evolutionary psychologist at Texas Christian University in Fort Worth. A woman who acquires those sexy genes for her sons, then, should leave more grandchildren.