Homosexuality and Natural Selection

[Mise]

If homosexuality is not a choice and indeed caused by certain genetic factors, how come gay people haven't been wiped out yet by natural selection? Surely if genes are to blame, then men who have sex with other men (clearly) don't reproduce and therefore don't pass on the gay gene. If they don't pass on the gay gene, then the resulting population will be entirely free of the gene.

But I suppose lots of gay men still have hetero sex and pass on their gay genes because society demanded it of them. But now, we have come to accept gay people, and they don't have to have kids if they don't want to. Doesn't this pose a problem for homosexuals? What happens when all gay people stop having hetero sex? Surely, their genes will, as predicted by Darwin, be wiped from the face of the Earth, gone the way of the dodo?

So I say, for the sake of the homosexuals the world over, stop being gay!

 

[sysyphus]

Do you get all of your personality traits from your parents?

 

[Yom]

Homosexuality is not necessarily simply (or even at all) decided by genetics.

 

[Mise]

@sysyphus:
Well, no, I don't get all my personality traits from my parents. I get physical ones, though, like height. I can chose what parts of my personality to ignore. I can chose to be obnoxious, or I can chose to be intelligent, if I want. But I can't chose if I'm black or if I'm short.

@Yom: Well what is it decided by?

 

[Cuivienen]

Homosexuality is not necessarily simply (or even at all) decided by genetics.

Even if it was, it would be recessive and thus survive indefinitely. Aniridia, the condition of having no iris in your eyes (and thus being unable to see) is a genetic condition caused by a recessive allele. I doubt any early humans with aniridia survived long enough to breed, but it's still around.

@ Mise again

Conditions in the uterus.

 

[Mise]

If it was recessive, we'd have as many gay people as we have blue eye'd people.

conditions in the uterus

what kind of conditions?

 

[Cuivienen]

I would say that we probably do. Consider the estimate that 5% of the world's male population is gay. I think we can also say that about 5% of the world's male population has blue eyes (remember, the trait is nonexistant outside of peoples of European descent and at max 25% of Caucasians have blue eyes).

Also, recessive alleles have varying frequencies. Some are very rare, like aniridia, and some not-so-rare, like straight hair.

 

[Amenhotep7]

what kind of conditions?

I'm no expert on the subject, but I hear homosexuality/bisexuality is decided in the womb. It depends on the level of testosterone in the female... Dunno how true this is...

The way I see it, there are only three solutions to the question:

-Homosexuality is genetic
-Homosexuality is a choice
-Homosexuality is a learned behavior from early childhood.

 

[sysyphus]

@sysyphus:
Well, no, I don't get all my personality traits from my parents. I get physical ones, though, like height. I can chose what parts of my personality to ignore. I can chose to be obnoxious, or I can chose to be intelligent, if I want. But I can't chose if I'm black or if I'm short.

You really think you have that much control of your personality? I'd say not.

If it was recessive, we'd have as many gay people as we have blue eye'd people.

We probably do.

 

[Perfection]

Four things:

#1. Homosexuality's inheritability is low. It stems from a biochemical abnormality in the womb environment, so while the chances can be minimized by natural selection acting against genes that increase risks, natural selections impact is less than if it was directly genetic.

#2. Having homosexual members may increase the provider to children ratio, giving familial clans a greater chance for sucess. It may be beneficial for a tribe to have a few homosexuals.

#3. Homosexuals can and do reproduce

#4. Genes that increase risks for having homosexual children may be advantageous for other reasons that offset the occasional homosexual child.

 

[elfangor801]

So I say, for the sake of the homosexuals the world over, stop being gay!

That's awfully hard, you know?

If homosexuality is not a choice and indeed caused by certain genetic factors, how come gay people haven't been wiped out yet by natural selection?

It's not . And I personally think something happens to the baby while it's a fetus, or something in very early life, because I have distinct memories in early life that correspond with later life . If there was a gene, on the other hand, it would still be passed on, but it might be recessive or only carried by straight people (Like male pattern baldness). I'm pretty sure there aren't any other gays in my family, so I'd don't think it's genetic or hereditary.

 

[Cuivienen]

what kind of conditions?

There are various theories out there, I'm not so certain about the uterine-conditions theory, but I know it seems to hold water the best. I think it has to do with the acidity of uterine fluids during pregnancy.

 

[andrewgprv]

From what I've heard the gene is passed via the mother. Apparantly if a women has a gay brother then she has a 7% chance of having a gay son. The percentages are supposed to be different for lesbians but I'm not sure what they are.

Of course this is one hunch in a pile of hunches about what causes homosexuality.

Of all the hunches I've read about though I tend to think the idea of development in the womb seems the most realistic. Apparantaly studies have shown that the eldest born son is least likely to be gay while the more down the line the more likely to be gay. Something having to do with hormones the mom gives to the baby, I guess the more sons she has the less she gives off. If you think about it this would make some sense evolutionary wise. Gays tend to be less agressive and many agressive males in one family can cause instability. An agressive eldest and successovly less agressive younger brothers would lead to a more stable family structure.

 

[Perfection]

I'm no expert on the subject, but I hear homosexuality/bisexuality is decided in the womb. It depends on the level of testosterone in the female... Dunno how true this is...

The way I see it, there are only three solutions to the question:

-Homosexuality is genetic
-Homosexuality is a choice
-Homosexuality is a learned behavior from early childhood.

There is a fourth, it's due to womb environment.

 

[elfangor801]

There is a fourth, it's due to womb environment.

Is there a link or something you have for that?

 

[Mark1031]

You are using analogies in simple Mendelian genetics to explain something that is certainly a complex genetic trait. There is no single gay gene but the evidence suggests that there is a genetic component to this behavior. Sexual orientation will be determined by the interaction of multiple genes and the environment. It is possible that each of the genes involved provide a selective advantage in some circumstances and are thus selected for.

 

[andrewgprv]

Is there a link or something you have for that?

google it, there are tons of articles out there on the subject

 

[Mise]

I would say that we probably do. Consider the estimate that 5% of the world's male population is gay. I think we can also say that about 5% of the world's male population has blue eyes (remember, the trait is nonexistant outside of peoples of European descent and at max 25% of Caucasians have blue eyes).

Hmm.... well, that makes sense, I guess. But there are places in the world where there is a high proportion of Blue eyes vs Brown eyes, such as Europe. There are, presumably, no such places for homosexuals, because they've all died out. Does that mean I'm a little bit right?

 

[Cuivienen]

Is there a link or something you have for that?

http://archives.cnn.com/2000/HEALTH/03/29/gay.fingers/

 

[Mise]

You are using analogies in simple Mendelian genetics to explain something that is certainly a complex genetic trait. There is no single gay gene but the evidence suggests that there is a genetic component to this behavior. Sexual orientation will be determined by the interaction of multiple genes and the environment. It is possible that each of the genes involved provide a selective advantage in some circumstances and are thus selected for.

So homosexuality is a side-effect of other more advantageous genes?