Not to be crude, but gays and lesbians may function in humans as akin to the large clitorises in bonobos.
In the bonobo female, the clitoris is unusually large, and it’s used to bond socially with other females. They rub their large clitorises on each other. Sexual bonding gives the females an enhanced solidarity with one another against the males. By displaying this behavioral preference, it has put selective pressure on the bonobo clitoris to enlarge over time–and so it must be conferring a benefit to the species as a whole (for females to gather collective power against the males).
But to what evolutionary benefit, exactly?
Perhaps females that are tightly bonded and share greater power with males constitute a successful evolutionary group strategy in primates (or at least an alternative strategy to the male dominated sort).
Now apply this to humans. Have you noticed the coalition of gays and lesbians with feminists and liberals in our species? What if homosexuality lingers in the human population as a function of equalizing, to some degree, group dynamics between males and females?
Perhaps liberal vs. authoritarian in our politics reflects our evolution: the tensions between bonobo vs. chimp in terms of evolutionary strategy (in their social relations, bonobos being a more hippie-like species, chimps being more male dominated).
Of course, to consider this idea of women’s bodies producing at least some gays and lesbians in the population so as to nudge the species’ gender relations in a gentler direction, one would also have to accept the controversial proposal of group selection in evolution.
In any case, I’ve never heard or read of what I’m proposing before, but it occurred to me, and so I’m putting it out here. Maybe a biologist will notice the post, and set me straight–or find it intriguing (or point to where it has already been proposed somewhere else before).
UPDATE. I’d also like to put forward something a bit provocative in this context. What if religion functions in part as a patriarchal counter-balance to the evolution of homosexuality in our species? Traditionally, who ends up in large numbers (per capita) among the clergy? And what do patriarchal religions tend to promote surrounding sex and the naturalness of male rule?
You can see where I’m going here. Perhaps male-dominated religion functions in part as a way to defang the coalitional strength of heterosexual women aligned with gays and lesbians. By diverting gay men into the clergy, an alliance of males against females is forged, and the evolutionary nudge toward bonobo-like behavior that homosexuality represents in the ongoing evolution of our species is hijacked.
But perhaps with the ongoing decline of religion in the 21st century, it will prove ever more difficult for authoritarian males to counter the evolution-generated alliance of females with gays and lesbians. Maybe, in place of religion, they’ll come up with a different strategy?