Scientists have for some time speculated as to the evolutionary value of male homosexuality. Because gay men are much less likely to reproduce than heterosexual men, researchers have wondered why the genes for homosexuality have not disappeared over time.
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.
Two evolutionary psychologists, Associate Professor Dr. Paul Vasey and Ph.D candidate Doug VanderLaan of the University of Lethbridge, located in Alberta, Canada have tested this idea for the past several years on the Pacific island of Samoa.
They chose Samoa because males who prefer men as sexual partners are widely recognised and accepted there as a distinct gender category—called fa’afafine; neither man nor woman.
The fa’afafine tend to be effeminate, and exclusively attracted to men as sexual partners. This clear demarcation makes it easier to identify a sample for study, said the researchers. 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 and education and so forth. In their study, the scientists set out see if their altruism is targeted specifically at related children rather than kids in general.
They recruited a large sample of fa’afafine, and comparable samples of women and heterosexual men. They gave them all a series of questionnaires, measuring their willingness to help their nieces and nephews in various ways—caretaking, gifts, teaching—and also their willingness to do these things for other, unrelated kids.
The findings, reported on-line last 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 less interest in children in general and instead tended to allocate their energies and efforts towards children that they were related to.
Do these findings have any meaning outside of Samoa? Yes and no. Samoan culture is vastly different from most Western cultures, said the scientists. Samoan culture is very localised, and centred on tight-knit extended families, whereas Western societies tend to be highly individualistic and homophobic.
Families are also much more geographically dispersed in Western cultures, diminishing the role that bachelor uncles can play in the extended family, even if they choose to. But in this sense, the researchers say, Samoa’s communitarian culture may be more—not less—representative of the environment in which male same-sex sexuality evolved eons ago.
In that sense, it’s not the bachelor uncle who is poorly adapted to the world, but rather the modern Western world that has evolved into an unwelcoming place, they suggested.