Given the reasons why people choose their mates, maybe men and women are from the same planet, says an evolutionary anthropologist from UC Davis.

In fact, when men and women are out shopping in the mate market, they are actually looking for people with traits that they rank highly within themselves, says Monique Borgerhoff Mulder.

"We already know that men and women's preferences are relative: Individuals not only assess their own quality as a mate relative to that of their companions but also form a mate preference based on their self perception," she says.

In a review of several studies, Borgerhoff Mulder found that people want mates that reflect their own values. For instance, in a study of people advertising in singles columns, the women who claim to be attractive and men who claim to be wealthy and have high status make higher overall demands of prospective partners than do column advertisers without such credentials.

Perhaps the move toward choosing a mate more like oneself has to do with the evolution of society away from the traditional labor division between hunters and gatherers and toward a 21st century unisex work force, Borgerhoff Mulder surmises.

"By marrying someone similar to you, it might be easier to coordinate over childcare, shopping and cleaning the house, or simply be the best way of ensuring your partner doesn't walk out on you," she concludes.

Borgerhoff Mulder's journal article was published in the January issue of Trends in Ecology and Evolution.