BEHAVIOR Human mating driven by rivalry, researcher says

The evolutionary drives behind human mating are similar to fruit flies'.
By ALEXANDRA WITZE
KNIGHT RIDDER NEWSPAPERS
KNOXVILLE, Tenn. -- Every pas de deux is really a m & eacute;nage & agrave; trois -- at least from the evolutionary point of view.
In their never-ending dance to seduce each other, men and women step into biological roles shaped over the eons by outside competition, says David Buss of the University of Texas at Austin. Every step we take may reflect the influence of a third participant.
From this new perspective, promulgated by Buss and other evolutionary psychologists, human mating can be viewed as an extension of the competitive copulation among, for instance, fruit flies and termites.
A wandering male termite may palpate a neighboring female with his antennae only to find his female partner biting them off in a fit of termite rage. To counter competition, male fruit flies make their sperm toxic to other males' sperm -- a killer move that unfortunately has the side effect of shortening the female's life span.
Jealousy and competition drive human mating, too, Buss said last week at a symposium in Knoxville, Tenn., sponsored by the Council for the Advancement of Science Writing. People often have sex because of -- or perhaps in spite of -- a third party.
It may seem obvious, but this insight took psychologists 130 years to formulate.
Darwin's theory
Charles Darwin, the father of evolutionary theory, dispensed with sex quickly and elegantly. His theory of sexual selection, published in 1871, argued two basic points: same-sex competition and between-sexes selection. For example, two males might compete to win the sexual favors of a female; females take the winners as their mates, thus ensuring that the characteristics associated with winning would be passed from generation to generation.
Although Darwin's theory of sexual selection was "absolutely brilliant," says Buss, some modern psychologists think it could use a new twist. The traditional Darwinian view assumes that evolution is "dyadic," or driven by two participants.
But in mating, most interactions are at least triadic, or driven by three participants, says Buss. Examples include the jealous termites and the toxic fruit flies.
The same is true of humans, he argues. People have a wide range of mating strategies, from one-night stands to lifelong commitments and everything in between. But many seemingly bizarre human behaviors can be explained by three-way interactions, Buss argues.
For example
Among such behaviors are bidding wars -- where two men try to out-boast each other to attract a particular woman -- and infidelity, in which a woman might try to seduce another man to get her partner to pay more attention to her.
Another strategy is mate poaching, in which a man might pretend to be friends with another man in order to get close to his wife. Related approaches are mate-guarding or stalking, in which a woman might try to safeguard her relationship by making sure her partner never has the chance to interact with other women.
Both sexes are equally guilty of such strategies but with some notable differences, says Buss.
Men, for instance, have a natural inclination to see opportunities for sex even where they don't exist. A man might assume that a woman who is smiling at him wants to go to bed with him; evolutionarily, he isn't a lout but is just trying to ensure that he doesn't miss a chance to pass along his genes.
"Males evolve a bias so as not to miss out on potential sexual opportunities," explains Buss, author of "The Evolution of Desire."
What gets us upset
Perhaps in response, women have evolved to be more upset than men by sexual aggression. Studies by Buss and others have shown that men routinely underestimate the effect of their aggressive actions toward women.
Men, on the other hand, become more upset than women if they feel they are being misled or subjected to a "bait-and-switch" strategy of mating, Buss says. Evolutionarily speaking, that's because they are at risk of becoming a genetic cuckold -- "mama's baby, papa's maybe," as the saying goes.
And yet there are still some ways in which men and women always agree, says Buss, who has also studied how relationships end. When asked who instigated the breakup of their most recent romance, 70 percent of men said they did the dumping.
So did 70 percent of the women.