Partner Poaching

Evolution at Work?

The usual story goes something like this: Boy meets Girl. Boy meets Girl's parents. Boy and Girl live happily ever after.

But more often than you might realize, there's another step in the story, another character in the drama: Boy meets Girl, Boy leaves Current Girlfriend for Girl, Boy and Girl live happily ever after.

Research by the International Sexuality Description Project (ISDP) suggests that up to 20 percent of long-term relationships start when one partner (or both) is dating, even married to, someone else. (Sixteen thousand people in 53 countries were polled for the study, which is based at Bradley University in Peoria, Illinois, and designed to explore the relationship between personality and sexuality and sex differences in mating preferences.) Evolutionary psychologists call this "mate poaching."

Who poaches and why? What happens to relationships when it does? Are you likely to fall prey to a poacher -- or become one yourself?

According to ISDP lead researcher David P. Schmitt, PhD, a psychology professor at Bradley University, approximately 60 percent of U.S. men and 40 percent of women admit they've tried to lure someone else's squeeze into a short-term fling. "When you look at the long term, the numbers become much more similar," adds Schmitt: 63 percent of men and 52 percent of women cop to trying to purloin a partner for a long-term relationship.

Seems that both men and women have a grass-is-greener gene. From an evolutionary standpoint -- which basically posits that everything we do stems from the drive to propagate our species with lots of big healthy babies -- it makes sense that at some level we'd always, instinctively, be on the lookout. Especially considering that, according to Schmitt, women seek particularly virile men when most fertile, a few days before ovulation.