The Kin Selection Hypothesis

Male androphilia has a genetic component, yet male androphiles reproduce at a fraction of the rate of gynephilic males. One would expect genes for male gynephilia to have long replaced those for male androphilia given the reproductive benefits associated with the former. Nevertheless, prehistoric cave art and pottery suggests that male same-sex sexual activity has existed for millennia. Given this, how do genes for male androphilia persist over evolutionary time?

One potential explanation is that genes for male androphilia could be maintained in a population if enhancing one’s indirect fitness offset the cost of not reproducing directly. Indirect fitness is a measure of an individual’s impact on the fitness of kin (who share some identical genes by virtue of descent) weighted by the degree of relatedness. Androphilic males could increase their indirect fitness by directing altruistic behaviour toward close kin, which, in principle, would allow kin to increase their reproductive success. No support for this Kin Selection Hypothesis has been garnered from studies conducted in industrialized cultures such as the USA, Canada, the UK and Japan. However, cultural factors like individualism and homophobia may mitigate the expression of elevated kin altruism by male androphiles living in industrialized cultures.  Thus, tests of this hypothesis are needed in non-industrialized, collectivistic cultures such as Samoa where androphilic males are relatively accepted.

In keeping with the predictions of the Kin Selection Hypothesis, we have demonstrated repeatedly that fa’afafine exhibit significantly higher altruistic tendencies toward nieces/nephews (i.e., avuncularity) compared to childless women, mothers, childless gynephilic men and fathers. In terms of one behavioural assay, we have shown that the fa’afafine’s elevated avuncularity is manifested in terms of more money given to nieces, compared to women and gynephilic men.

On the basis of this body of work, we have concluded that elevated avuncularity on the part of the fa’afafine cannot be explained in terms of their childlessness; their increased femininity; a generalized interest in all children; a desire to respond to questions in a socially desirable manner; a failure to form or invest in intimate relationships; social expectations on the part of Samoans for fa’afafine to behave in an extremely avuncular manner; or expectations on the part of the fa’afafine themselves to behave in such a way.

In addition, we have conducted a number of studies which indicate that the avuncular cognition of fa’afafine appears to be adaptively designed. For example, compared to women and gynephilic men, fa’afafine appear to be more focused on maximizing resources directed to nieces/nephews while minimizing resources directed to non-kin children.

So, the bottom line is that our research in Samoa has furnished consistent support for the Kin Selection Hypothesis.  That being said, more research needs to be done before any strong statements can be made regarding the adaptive basis of male androphilia or elevated avuncularity among fa’afafine.

The Sexually Antagonistic Gene Hypothesis

An alternative explanation for the evolution of male androphilia (but not a mutually exclusive one) is that the reproductive costs associated with genes for male androphilia are offset by the reproductive benefits that accrue if the same genetic factors result in increased reproductive success among the female kin of male androphiles. Empirical support for this Sexually Antagonistic Gene Hypothesis (otherwise known at the Female Fecundity Hypothesis) comes from various low fertility Western populations in which the female relatives of androphilic males exhibit higher reproductive success compared to those of gynephilic males. These findings are intriguing, but require replication in non-Western populations in which individuals are reproducing at, or near, their maximum capacities.

Our work in a higher fertility population, Samoa, has shown repeatedly that the mothers of fa'afafine are, on average, produce significantly more offspring than the mothers of gynephilic men. We have also shown that the maternal grandmothers of fa’afafine produce more offspring, on average, compared to those of gynephilic men. However, we have been unable to replicate a paternal grandmother effect, and we have found no evidence that the aunts of fa’afafine produce more children. Taken together, the results of our research provides some support for the Sexually Antagonistic Gene Hypothesis. 

The Ancestral Form of Male Androphilia

The manner in which male androphilia manifests varies cross-culturally. Sex-gender congruent male androphiles occupy the gender role typical of their sex and identify as “men.” In contrast, transgendered androphilic males often occupy alternative gender role categories distinct from the categories of “men” and “women,” and exhibit gender role presentation that is markedly similar to that of members of the opposite sex within their given cultural context.

Societies in which transgendered male androphilia predominates are characterized by a significantly greater presence of socio-cultural conditions that are thought to have characterized the ancestral past. This suggests that the transgendered form of male androphilia was likely the ancestral form.  The outcome of evolutionary process may be obscured when using more derived forms of male androphilia as models

Further Reading:

Kin Selection and the Evolution of Male Androphila

Playà, E. Vinicius, L., & Vasey, P.L. (2017. Need for alloparental care and attitudes toward homosexuals in 58 countries: Implications for the Kin Selection Hypothesis. Evolutionary Psychological Science, 3: 345-352.

VanderLaan, D.P., Petterson, L.J., & Vasey, P.L. (2017). Elevated kin-directed altruism emerges in childhood and is linked to feminine gender expression in Samoan fa’afafine: A retrospective study.  Archives of Sexual Behavior, 46: 95-108.

Vasey, P.L., VanderLaan, D.P., Hames, R. & Jaidee, A. (2016). A problematic test of the kin selection hypothesis among the Urak-Lawoi of Ko Lipe, Thailand: Commentary on Camperio Ciani, Battaglia, & Liotta (2015). Journal of Sex Research, 53: 149-152.

VanderLaan, D.P., Petterson, L.J., Mallard, R. & Vasey, P.L. (2015). (Trans)gender role expectations and childcare in Samoa. Journal of Sex Research, 52: 710-720.

VanderLaan, D.P. & Vasey, P. L. (2014). Evidence of enhanced cognitive biases for maximizing indirect fitness in Samoan fa’afafine, Archives of Sexual Behavior, 43: 1009-1022.

Vasey, P.L., Parker, J.L, & VanderLaan, D.P. (2014). Comparative reproductive output of androphilic and gynephilic males in Samoa.  Archives of Sexual Behavior, 43: 363-367.

Abild, M.L., VanderLaan, D.P. & Vasey, P.L. (2014). Does proximity influence the expression of avuncular tendencies in Canadian androphilic males? Journal of Cognition and Culture,14: 40-62.

Abild, M., VanderLaan, D.P. & Vasey, P.L. (2013). No evidence for treating friends’ children like kin in Canadian androphilic men. Journal of Sex Research, 50: 697-703.

VanderLaan, D.P. & Vasey, P. L. (2013). Birth order and avuncular tendencies in Samoan men and fa’afafine. Archives of Sexual Behavior, 42: 371-379.

VanderLaan, D. P. & Vasey, P. L. (2012). Relationship status and elevated avuncularity in Samoan fa’afafine. Personal Relationships, 19: 326-339.

Vasey, P.L. & VanderLaan, D.P. (2012). Male sexual orientation and avuncularity in Japan: Implications for the Kin Selection Hypothesis. Archives of Sexual Behavior, 41: 209-215.

Forrester, D.L., VanderLaan, D.P., Parker, J.L. & Vasey, P.L. (2011). Male sexual orientation and avuncularity in Canada: Implications for the Kin Selection Hypothesis. Journal of Culture and Cognition, 11: 339-352.

Vasey, P.L. & VanderLaan, D.P. (2010a). Monetary exchanges with nieces and nephews: A comparison of Samoan men, women, and fa’afafine.  Evolution and Human Behavior, 31: 373-380.

Vasey, P.L. & VanderLaan, D.P. (2010b). Avuncular tendencies in Samoan fa’afafine and the evolution of male androphila. Archives of Sexual Behavior, 39, 821-830. (Selected as a “Editor’s choice” recommended reading by the journal Editor).

Vasey, P.L. & VanderLaan, D.P. (2010c) An adaptive cognitive dissociation between willingness to help kin and non-kin in Samoan  fa’afafine. Psychological Science, 21: 292-297.

Vasey, P.L. & VanderLaan, D.P. (2009). Materteral and avuncular tendencies in Samoa: A comparative study of women, men and  fa’afafine. Human Nature, 20: 269–281.

Vasey, P.L. & VanderLaan, D.P. (2009). Kin selection and the evolution of male androphilia [Letter to the Editor]. Archives of Sexual Behavior. 38: 170-171.

Vasey, P.L. (2008). Samoan research is consistent with the kin selection hypothesis for male androphilia. PLoS ONE, 3(6): e2282, note 1.

Vasey, P.L., Pocock, D.S., & VanderLaan, D.P. (2007). Kin selection and male androphilia in Samoan fa’afafine.  Evolution & Human Behavior,  28: 159-167.

The Sexually Antagonistic Gene Hypothesis and the Evolution of Male Androphilia

Semenyna, S., Petterson, L.J., VanderLaan, D.P. & Vasey, P.L. (2017). A comparison of the reproductive output among the relatives of Samoan androphilic fa’afafine and gynephilic men. Archives of Sexual Behavior, 46: 87-93.

VanderLaan, D.P., Forrester, D.L., Petterson, L.J, & Vasey, P. L. (2012). Offspring production among the extended relatives of Samoan men and fa’afafine. PLoS ONE 7(4): e36088. doi: 101371/journal.pone.0036088.

VanderLaan, D.P. & Vasey, P.L. (2011). Male sexual orientation in Independent Samoa: Evidence for fraternal birth order and maternal fecundity effects. Archives of Sexual Behavior, 40: 495-503.

Vasey, P.L. & VanderLaan, D.P. (2007). Birth order and male androphilia in Samoan fa’afafine. Proceedings of the Royal Society of London, Series B, 274: 1437-1442.

The Ancestral Form of Male Androphilia

VanderLaan, D.P., Ren, Z. & Vasey, P.L. (2013). Male androphilia in the ancestral environment: An ethnological analysis. Human Nature, 24:275-301.

VanderLaan, D.P., Garfield, Z.H., Garfield, M.J, Leca, J-B., Vasey, P.L., Leca, J-B., & Hames R.B. (2014). The “Female Fertility-Social Stratification-Hypergyny” Hypothesis of Male Homosexual Preference: Factual, Conceptual and Methodological Errors in Barthes et al. Evolution and Human Behavior, 35: 445-447.