Poaching, promiscuity, and deceit: Combatting mating rivalry in same-sex friendships

If humans faced recurrently over evolutionary history the adaptive problem of competition with same-sex friends for mates, they may have evolved psych ological mechanisms designed to prevent and combat mating rivalry with same -sex friends. Four studies were conducted to test hypotheses about the desi gn of these mechanisms. In Studies 1 and 2 (N = 406 and N = 342, respective ly) we found that, as predicted, people experience more upset in response t o imagined rivalry from a friend than from a stranger. In Study 3 (N = 455) . in which a between-subjects design was utilized, we found that women's, b ut not men's, willingness to become friends with a member of the same sex i s lower when the person is described as sexually promiscuous. In Study 4 (N = 169) we found that people report being deceived by friends about mating rivalry more often than they themselves report engaging in deceit about riv alry, and women more than men deceive each other about how sexually experie nced and promiscuous they are. Discussion addresses implications of the fin dings and the use of an evolutionary approach for understanding conflict in same-sex friendship.