Feb 09 2010
A Narrow Perspective on Homosexuality
Homosexuality, where not repressed out of view, occurs in all cultures across the globe. Clearly there is a genetic component to it. From a strict evolutionary perspective, this doesn’t make sense. Like grandparents, homosexuals leave very few offspring and consume resources. There is a cost to a population, so where is the evolutionary benefit?
Similar to thinking about the group-level adaptiveness of grandparents, some evolutionary psychologists have advanced a “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. [article source]
While this is an intriguing idea, it remains an inert idea until supported by indirect evidence, at least. Or, better yet, until put to a direct test. And news of such a test has recently been released.
Paul Vasey and Doug VanderLaan of the University of Lethbridge, Canada 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 recognized 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 adult men as sexual partners. This clear demarcation makes it easier to identify a sample for study.
What were the results of the test? (I would call it a “weak” test due to the methods–questionnaires–and data generated–self-reported answers). It seems the Samoan homosexual males did indeed show helping/resource-allocation favoritism toward the offspring of their siblings. They doted on nieces and nephews.
Certainly, in this one case it could be that culture has fashioned a productive role for these men, and it has nothing to do with evolution. But we don’t know that.
This line of research, however, has left me with one important question: Must all gene combinations be adaptive? Assuming that homosexuality is at least partly genetic, it is highly unlikely that there is a single “gay” gene. Or lesbian gene.
Consider this hypothetical: homosexuality results when A, B, and C genes occur together. The combination is not strictly adaptive because homosexuals tend to leave fewer offspring, if any. But perhaps the combinations of A and B, A and C, and B and C are adaptive. Maybe even highly so. And so the genes have not been trimmed out of existence via natural selection.
Additionally, we must remember that “gay” and “lesbian” are intellectual categories. Human sexual orientation likely comes in many forms or degrees. Similar to the personality attribute of extroversion/introversion, there is not just fully “extroverted” and fully “introverted.” There are 101 degrees of this element of social orientation. I imagine the same is true for sexual orientation.
If extreme introverts don’t leave as many offspring, one could ask why introversion continues to persist? Which is silly. That’s a taking a narrow view of things. As usual, it is likely much more complicated than that.
