Societal Norms Rather Than Sexual Orientation Influence Kin Altruism and Avuncularity in Tribal Urak-Lawoi, Italian, and Spanish Adult Males

摘要

Homosexual males could balance their low fitness by increasing benefits to relatives either through kin-directed altruism or by avuncularity (altruistic behavior toward the children of siblings). Evidence in support of kin selection and avuncularity includes the fact that homosexuals seem to be more empathic and altruistic than heterosexuals. Other studies have not confirmed behaviors that increase kin altruism in homosexuals. We explored altruistic behavior and avuncularity in a sample of 278 subjects, either homosexual or heterosexual, from three populations: Italian, Spanish, and Urak-Lawoi, a Southeast Asian tribal population. Among the Urak-Lawoi, the kathoeys, androphilic men who dress and behave as women, were compared with heterosexuals. All populations were rated for societal norms on the expression of affiliative behavior. No greater kin altruism or avuncularity among the kathoeys or in homosexuals in either Mediterranean population was found. Greater avuncularity and kin-directed altruism, independent of sexual orientation, were found among the Urak-Lawoi, and these traits were the least prevalent among the Italians, corresponding to different societal norms. The increase in kin altruism and avuncularity was associated in all males with societal differences and norms on general altruism toward nonkin children, suggesting it is not an adaptive design to maintain homosexuality in humans.