Homosexuality and Natural Selection.

nemesis_juggernaut asks astutely 'Why does homosexuality exist at all'? "Why would nature subvert itself?" is a good question. One would think that natural selection would be quite unfriendly to homosexuality. This begs for clarity in the definition of NS. After a long debate following Message 1 the functional definition of natural selection per E.O. Wilson (Sociobiology, 2000, p. 589) still stands firm:

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Natural selection: The differential contribution of offspring to the next generation by individuals of different genetic types but belonging to the same population. This is the basic mechanism proposed by Charles Darwin and is generally regarded today as the main guiding force in evolution.

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At least one conclusion about natural selection and homosexuality seems obvious: gay/lesbian sex must contribute to the differential reproductive success amongst the individuals of a population. Certainly, if all individuals of a population practiced only gay/lesbian sex, then that population would be wiped out by natural selection in its first generation.Therefore, a population’s evenness of reproductive success seems necessarily altered by homosexuality. And yet homosexuality manages to evade natural selection. It would seem to me that if natural selection is “the basic mechanism proposed by Charles Darwin . as the main guiding force in evolution” then homosexuality would not survive in any population. But it does, either by way of personal choice or genetic predisposition. How does it evade natural selection?”HM

Good point, which scores for the side that says homosexuality is not genetic. But it would seem to associate with natural selection nevertheless, given the accepted definition of it.”HM

Also a good point. Genetic altruism is not unknown. Homosexuality also may be a passive trait, in and of itself, and yet it may actually help other genes in a genome to survive. Over-population control has been mentioned up-thread as another service possibly provided by homosexuality.One thing I have not yet seen adressed, though, is whether or not STDs from same-sex contact ever move through non-human populations. I know of no such epidemics occurring amongst bonobos or baboons, for example.”HM

I went back to that thread but I could not find that post of Mod's you mention. Do you remember where it was? Maybe he's looking in and will explain "intragenomic conflict" for us.On the other hand, regarding my "viewpoint problem," it remains entirely possible that gays are gay by choice, not by "nature," let us say. If that's true then any scientist will have a "viewoint problem"...unless their choice is genetically predisposed.”HM

Why couldn't nurture instead of nature explain that? Certain configurations of influential female sibling personalities might expain how the otherwise straight boy turns gay. Matt Ridley writes in Genome (1999, p. 217) about nature v. nurture in sexual role playing:

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"[W]e are beginning to glimpse an end to the somewhat ridiculous argument over gender differences that has continued throughout the late twentieth century and has pitted nature against nurture. Those in favor of nurture have tried to deny any role for nature, while those who favor nature have rarely denied a role for nurture. The question is not whether nurture has a role to play, because nobody of any sense has ever gone on record as denying that it does, but whether nature has a role to play at all.

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”HM

I tend to agree. But in the absence of a genetic explanation for homosexuality, the role of person choice seems to become more important. Is it, then, mostly a psychological issue? No genes involved at all? Are there any good biological principles, other than genetic ones, that can explain such a choice favoring homosexuality? The "epiphenomenon" approach might do the job, but I don't yet know the principles it relies on. I'm not sure I trust the psychologists with this one.”HM

Believe me, Nosy, I want to see a genetic explanation for everything. That's my bias. But there were ambiguities in those pubs. I was reponding more specifically to WK's line: It was the "actual bearer" part that interested me. Not even a clue to a suggestion, because, dispite the ambiguities I see in the studies mention by WP, I don't know how an "uterine environment connection" can NOT be a genetically managed phenomenon. Yes, WK can go to epiphenomena is he want to, but I don't want to go there until I understand just the phenomenon part, if there realy is any.”HM

Oh, sure, I remember that. How could I forget it? I would have to agree with you. And I suppose, then, that you would have to agree with this: When they invent a "cure" for homosexuality in humans, being homosexual certainly will be a matter of choice.”HM