to rasor: You would agree, though, I think, that when you're dealing with something as sensitive as this, where "against nature" arguments have been used as a basis to criminalize behavior, it is best to think carefully before using value-laden terms.
Of course, it is hard to discuss anything without them, but still, I do think you could be more careful in your word choices.
O.K., having officially been begged, here it is, and yes, it is long and complicated.
With evolutionary biology, you think in terms of the ancestral environment, which is basically hunter-gatherer.
It is easy to find a male to have sex with, and harder to find one to marry. Most men have a capacity for promiscuous sex, and a single male can impregnate many females.
Men die younger than women.
Many societies are polygamous.
So, in all, you have more women than men. It is quite likely that a woman would find herself pregnant, or with young children, and no husband, or in a polygamous situation.
Children have a better chance of survival if they have two parents than one.
Female sexuality is more fluid and responsive than male. Many women have a capacity to form homosexual or heterosexual attachments. This capacity may or may not ever be activated or even discovered. What I mean is, I have know many women who lived as a lesbian or as a heterosexual at different times in their lives. Female homosexuality seems to be less often determined purely internally and early in life, but often emerges later and in the context of a specific relationship.
In this situation, if a woman with children has the capacity to form a homosexual bond, she will get more help and support for raising her children than if she is restricted to heterosexual bonds. (Remember, there is a shortage of adult males.) This help, in the form of female-female pair bonding, would contribute to her children living long enough to reproduce. Thus the capacity to form a homosexual bond could have an evolutionary advantage.
Women who have only a homosexual capacity are quite rare. I posit that they are an extreme, probably heterozygous remnant of this homosexual capacity that many women have.
That's the hypothesis!
