Evolutionary Perspectives on Male Homosexuality: A Literature Review

Abstract

This review provides a comprehensive coverage of the leading evolutionary hypotheses to date on male homosexuality (namely the sexual antagonism model, the tipping-point model, and the kin selection hypothesis). It does so by first (1), surveying prominent findings on the nature and biological causes of male homosexuality; second (2), discussing the effects of male homosexuality on individual fitness; and third (3), outlining the contending evolutionary theories on male homosexuality and critically evaluating each against current pertinent empirical evidence. This review reveals that male homosexuality is a complex, multifaceted phenomenon influenced by an interplay of genomic and environmental factors that may have had unique evolutionary trajectories. Thus, there is likely more than one evolutionary mechanism at play responsible for the maintenance of gay alleles in the human population. Current research largely supports the notion that gay alleles bestow fitness benefits on heterosexual carriers. The tipping-point model and sexual antagonism model, but not the kin selection hypothesis, are in line with current empirical evidence. Future research into the genomic underpinnings of sexual orientation in homosexual males and its genetic equivalents in heterosexual males and females may allow for further evaluation of these hypotheses.

            Keywords: human evolution, evolutionary psychology, mating preferences, sexual orientation, homosexuality