The Love That Dares Not Speak Its Evolutionary Basis

Science is our best way of getting to know the realities of the natural world—indeed, I am prepared to argue that it is our only reliable way.  (If there are still any retro, postmodernist ideologues out there, claiming that the natural world lacks reality independent of our subjective “cultural narratives” and the particular world-view that we happen to “valorize,” I’m prepared to argue with you, too!)

Most of us look to science for answers, if only because to a remarkable degree, it provides them.  And so, not surprisingly, nearly every book or course dealing with science talks about what we know … which is something of a shame, because the greatest delight of science, and what keeps me coming back to it, is what we don’t know.

As for identifying (and ultimately, solving) scientific mysteries, one of the richest arenas is evolutionary biology—that of human beings in particular. I have been thinking a lot recently about such mysteries; in the future, as the spirit moves me, I’ll nip about the ankles of some of these mysteries—at least until I get it/them out of my system.

One of the most intriguing scientific unknowns is homosexuality.  Indeed, when Winston Churchill described the Soviet Union in 1939 as “a riddle wrapped in a mystery inside an enigma,” he could as well have been talking about homo-erotic preference.

Dean Hamer is an enterprising geneticist who raised quite a fuss some years ago when he announced the discovery of a “homosexuality gene,” and who subsequently claimed yet another one, this time for belief in God.  (His next finding might well be that God is really homosexual, or perhaps the existence of a gene for discovering genes.)  Although Hamer’s homosexuality gene hasn’t proven to be the slam-dunk that was originally hyped, there is growing conviction that the genetic underpinning for same-sex preference is real.  Why?  Among other things, not only does homoerotic preference run in families, but monozygotic (identical) twins have a higher “concordance rate” for homosexuality than do dizygotic (“fraternal”) twins, which in turn, are more likely to share homosexuality than are half-sibs, followed by unrelated individuals chosen at random.

Hence, the mystery.  Insofar as there is some genetic basis for homosexuality, then—as with another favorite evolutionary conundrum, altruism—natural selection should operate against such a tendency.  After all, there are strong data that homosexuals on balance produce fewer offspring than do heterosexuals.

And so, evolutionary biologists eagerly looked for evidence that homosexuality—like much animal and human altruism—is underwritten by kin selection: the process whereby genes prosper by benefiting identical copies of themselves in other bodies.

It didn’t pan out.

For starters, compared to heteros, homosexuals did not appear to spend an especially large amount of time helping, or even interacting with, their relatives. Also, it is noteworthy that—specifically in modern, Western societies—parents do not generally react with delight when they learn that a child is gay or lesbian, whereas if homosexual children were analogous to, say, the “helpers at the nest” phenomenon among birds (whereby non-reproducing older sibs help their parents rear a subsequent brood), we might expect tolerant acceptance if not outright enthusiasm on the part of those expecting help.

But it is now beginning to look like the death of kin selection as an evolutionary explanation for homosexuality—as Mark Twain famously responded to the announcement of his own demise—has been greatly exaggerated.  Thus, the unremarkable levels of intra-family benevolence earlier reported for homosexuals were based on technologized, 20^th-century populations, which might not reflect the long period of small-scale, nontechnological hunter-gatherer living during which such tendencies would presumably have evolved.  And in fact, some interesting and suggestive research has recently emerged, focusing upon male homosexuals among a traditional population on the island of Samoa.

Known as fa’afafine, these individuals do not reproduce.   They are, however, fully accepted into Samoan society in general, and into their kin-based families in particular.  Of particular note is that fa’afafine are significantly more prone to behave in a positive avuncular manner than are heterosexual uncles.  Thus, they are more likely to purchase toys for their nieces and nephews, to babysit, contribute money for the children’s education, and generally provide high levels of indulgence and emotional support, in addition to their material assistance.  This supportive role of fa’afafine also exceeds the contributions of heterosexual women as supportive aunts.

One effect of modernization worldwide has been a reduction in infant mortality and a parallel decrease in average family size, the so-called “demographic transition.”  A consequence of this, in turn, might well be that with fewer children per family, the industrialized world offers less opportunity for homosexual offspring to convey benefits to their heterosexual siblings, simply because there are fewer of the latter.  Add to this the fact that with enhanced mobility, it is increasingly common for individuals to leave their nuclear family to attend school and eventually start their own, separate domestic lives.

Hence, it is possible that kin selection was involved in the initial evolution of human homosexuality, although little or no fitness payoff is currently detectable, except in traditional societies.   It may also be significant, therefore, that unlike the experience of gays and lesbians in much of the industrialized world,  fa’afafine are fully integrated into Samoan society and are definitely not discriminated against.

The implications are potentially large, and not only for a deeper scientific understanding of how and why homosexuality may have evolved.  Thus, if—as could well be the case—homosexuals are only able to employ their kin-selected inclinations to benefit their straight relatives under conditions in which homosexuality is tolerated, even encouraged, then what is maladaptive these days is discrimination against homosexuals rather than homosexuality itself. (Sorry this post is so long!  I promise: Future ones will be more succinct.)