An adaptive cognitive dissociation between willingness to help kin and nonkin in Samoan Fa'afafine.

Androphilia refers to sexual attraction and arousal to adult males, whereas gynephilia refers to sexual attraction and arousal to adult females. Previous research has demonstrated that Samoan male androphiles (known locally as fa'afafine) exhibit significantly higher altruistic tendencies toward nieces and nephews than do Samoan women and gynephilic men. The present study examined whether adaptive design features characterize the psychological mechanisms underlying fa'afafine's elevated avuncular tendencies. The association between altruistic tendencies toward nieces and nephews and altruistic tendencies toward nonkin children was significantly weaker among fa'afafine than among Samoan women and gynephilic men. We argue that this cognitive dissociation would allow fa'afafine to allocate resources to nieces and nephews in a more economical, efficient, reliable, and precise manner. These findings are consistent with the kin selection hypothesis, which suggests that androphilic males have been selected over evolutionary time to act as "helpers-in-the-nest," caring for nieces and nephews and thereby increasing their own indirect fitness.