Homosexuality and natural selection

[Fly]

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As that changes, will homosexuality be naturally selected out?


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Homosexuality may very well be a side effect of a gene (or combination of genes) that confers some more significant advantage. If thats the case, it won't be selected out.

[furyshade]

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i don't see how it's flawed based on your reasoning. the gene could be recessive or the trait could need an environmental trigger. how does that make the idea flawed?

(i personally think it's unlikely that "gayness" is adaptive, but the idea isn't flawed because straight parents have gay kids)

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its flawed in that if what you say there is true, doesn't that invalidate your OP?

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huh? wasn't that my original post?
the gene being recessive or the trait needing an environmental trigger invalidates...the idea that being a "gay uncle" could be adaptive? no.
i guess i don't follow.

maybe you mean that it means that the answer to the orignal poster's question "will natural selection eliminate the trait" is no. sure, if the "gay uncle" hypothesis is right, the answer to that question would be no. still not sure that that's what you meant.

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you are right, i confused you for OP, sorry bout that

[MidGe]

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If homosexuality is genetic (trendy view nowadays and one I actually agree with), now that it is increasingly ok to come out of the closet, won't homosexuality be naturally selected out? (i.e the gay gene won't be passed on). In past generations homosexuality was repressed and so gay people were forced into child-producing hetrosexual relationships. As that changes, will homosexuality be naturally selected out?

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Obviously it has not been naturally selected out, as a matter of fact. That says it all! Your question rest on incorrect premises.

Homosexuality was not/is not repressed in all cultures at all times either, by the way.

[foal]

What I can't figure out is how sexual pleasure derived from being on the receiving end of anal sex evolved. Is there an evolutionary benefit to taking it up the bum (applies to both men and women)? And how could something like that evolve from a simple mutation?

[foal]

Maybe it's so we'd enjoy pooping and not hold it in.

[ChrisV]

this thread has more drivel in it than any thread I have read on SMP in the last six months.

[Tweety]

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From Wiki:

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Some scholars have suggested that homosexuality is adaptive in a non-obvious way. By way of analogy, the allele (a particular version of a gene) which causes sickle-cell anemia when two copies are present may also confer resistance to malaria with no anemia when one copy is present.[citation needed]

The so-called "gay uncle" theory posits that people who themselves do not have children may nonetheless increase the prevalence of their family genes in future generations by providing resources (food, supervision, defense, shelter, etc.) to the offspring of close relatives. This "gay relative" hypothesis is an extension of the theory of kin selection. Kin selection was originally developed to explain apparent altruistic acts which seemed to be maladaptive. The initial concept was suggested by J.B.S. Haldane in 1932 and later elaborated by many others including John Maynard Smith and West Eberhard.[3] This concept also was used to explain certain social insects where most of the members are non-reproductive.

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Genetic but environmental? I wonder what Darwin would think of that.

Sounds like crap to me.

[tame_deuces]

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What I can't figure out is how sexual pleasure derived from being on the receiving end of anal sex evolved. Is there an evolutionary benefit to taking it up the bum (applies to both men and women)? And how could something like that evolve from a simple mutation?

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For men its just about stimulating the prostate gland, which gives a much more powerful orgasm. You don't anal sex for that, but I guess it is one way. So obv pleasure seeking.

And I as I was browsing through wikipedia to check out my facts (I wisely decided not to use google for this one), I came across cited surveys that tell far from all gay men have anal intercourse. So there.

[hmkpoker]

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What I can't figure out is how sexual pleasure derived from being on the receiving end of anal sex evolved. Is there an evolutionary benefit to taking it up the bum (applies to both men and women)? And how could something like that evolve from a simple mutation?

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For men its just about stimulating the prostate gland, which gives a much more powerful orgasm. You don't anal sex for that, but I guess it is one way. So obv pleasure seeking.

And I as I was browsing through wikipedia to check out my facts (I wisely decided not to use google for this one), I came across cited surveys that tell far from all gay men have anal intercourse. So there.

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As the resident 2+2 expert on anal sex, there is more to anal sex than the stimulation of the prostate. I love anal sex, but I'm fairly apathetic to prostate stimulation (it is NOT a "male g-spot")

Anal sex shouldn't surprise people that much. Everyone here knows the intense physical pleasure of a good bowel movement. Anal sex pleasure is in many ways like that, although my use of that metaphor is probably not going to help promote sodomy here :P

[CORed]

Another possibility is that a recessive "gay gene" confers some sort of survival advantage in heterozygous individuals. What that might be I have no idea (better fashion sense gives males with one copy of gay gene a better chance of getting laid? :-) ).

This would be analogous to sickle cell anemia and cystic fibrosis, both lethal recessives. However, people with just one copy of the sickle cell gene have increased resistance to malaria, and people with one copy of the cystic fibrosis gene have better resistance to water-borne diarrheal diseases (leading cause of infant and child mortality where sanitation is bad, which was just about everywhere until 100 years or so ago).

Actually, I suspect that the reality is much more complex. There is probably a gene, or more likely several genes, that create a pre-disposition to homosexuality, but there are probably psychological factors that trigger it, as previous poster suggested. There still may be some sort of survival advantage to the gene or genes. Non-genetic developmental effects could be a factor, too, such as hormone levels in the mother. It seems to me that I have read of studies of identical twins, and there was something like a 50% concordance rate. If it was purely genetic, it should be 100%. Of course, the true number may well be higher, due to one twin being in the closet and one openly gay. Also, twin studies don't control for psychological factors, since ususally both twins grew up in the same home. Finding enough gay identical twins separated at birth to make a significant sample could be difficult, though.

And of course, it is correct that gay vs. straight is not a black-and-white matter. Many straight people have gay sex at some time in their lives, and vice versa. Sometimes the heterosexual encounters by "gay" people produce children. Also, quite a few lesbian women have children with donor sperm, sometimes using gay men as the donors, so I don't think homosexuality is going to be completely selected out any time soon.