Looking for sex partners

Men, she says, already know that they need to appear fit and socially powerful to attract a mate. "Men are looking for youth and beauty in the short term -- women really do know this," Fisher says. It is remarkable how the makeup and clothing industry constantly plays on this.Makeup makes the face clearer, the eyes bigger, the lips more baby-like red, the hair the sweet light color of youth.

"I help people become conscious of their own desires," Williams tells Web MD.

Clothing, too: The belts and things that show off the waist-to-hip ratio, the tight blue jeans and shirts that mold the figure.

Both sexes always know these things." People built their hopes and dreams on relationships, not mating strategies.

We can use reason in our sex lives." Just because men and women are programmed for promiscuity doesn't make it impossible -- or unnatural -- to have faithful, monogamous, long-term relationships.

"I tell people to honor their values," Williams says.