U of L psychologists examine sexual orientation through Samoan study

Male homosexuality doesn't make complete sense from an evolutionary point of view, prompting a pair of evolutionary psychologists from the University of Lethbridge to venture to the Pacific island of Samoa to try and discover why.

Associate professor Dr. Paul Vasey (Psychology/Behaviour and Evolution Research Group) and PhD candidate Doug VanderLaan of the University of Lethbridge chose Samoa because males who prefer men as sexual partners are widely recognized and accepted there as a distinct gender category – called fa'afafine, neither man nor woman.

It appears that the trait of homosexuality is heritable, but because homosexual men are much less likely to produce offspring than heterosexual men, shouldn't the genes for this trait have been extinguished long ago?

What value could this sexual orientation have, that it has persisted for eons even without any discernible reproductive advantage?

One possible explanation is what evolutionary psychologists call the "kin selection hypothesis."

What that means is that homosexuality may convey an indirect benefit by enhancing the survival prospects of close relatives. Specifically, the theory holds that homosexual men might enhance their own genetic prospects by being helpers in the nest.

By acting altruistically toward nieces and nephews, homosexual men would perpetuate the family genes, including some of their own.

The fa'afafine of Samoa tend to be effeminate, and exclusively attracted to adult men as sexual partners. This clear demarcation makes it easier to identify a sample for study.

Past research has shown that the fa'afafine are much more altruistically inclined toward their nieces and nephews than either Samoan women or heterosexual men.

They babysit a lot, tutor the kids in art and music, and help out financially – paying for medical care, education and so forth.

In a new study, Vasey and VanderLaan set out to unravel the psychology of the fa'afafine, to see if their altruism is targeted specifically at kin rather than kids in general.

The findings, reported on-line this week in the journal Psychological Science, lend strong support to the kin selection idea.

Compared to Samoan women and heterosexual men, the fa'afafine showed a much weaker link between their avuncular, or uncle-like behavior, and their altruism toward kids generally.

This cognitive dissociation, the scientists argue, allows the fa'afafine to allocate their resources more efficiently and precisely to their kin – and thus enhance their own evolutionary prospects.

For more information about this study, contact Paul Vasey at, or follow this Notice Board link for a deeper examination of the issue. As well, check out the programs offered by the U of L's Department of Psychology.