How does evolution explain homosexuality? (Kingdom, celibacy, blood, experience)

[Seyorni]

Originally Posted by Jaiket

I don't agree. I think that a genetic basis to homosexuality is plausible.

Not only plausable, homosexuality can be identified with certain brain scans. There are identifiable, morphological differences.
I'm not saying all homosexuality is innate, as attractiveness clearly has a strong cultural component.

In re: the OP, I supect innate homosexuality to be the product of small variations in brain structure, easily within the range of normal prenatal development. Inasmuch as the resulting trait does not seriously handicap the species, it is no pressure to select it out.

[Francine]

Originally Posted by Seyorni

Not only plausable, homosexuality can be identified with certain brain scans.

You should tell the Army, so they can scan people before they sign up.

[9-10ths_Penguin]

Originally Posted by tomspug

It seems to me that homosexuality has simply ALWAYS existed and is not genetic. I think this was the point I was trying to make. Everyone's arguments seem to agree with this too.

Not mine, IMO. I tried to make the point that it's quite plausible that homosexuality is genetic, and that there's a very well-defined mechanism that would allow this to occur.

On top of this (though not mentioned by me in this thread) is the strong evidence that points to sexual orientation being set by birth, which would only leave two possible causes: genetics and prenatal environment.

[Autodidact]

I think that tomspug raises a valid and puzzling question. (Although I think he should have the integrity and humility to admit he was wrong elsewhere before he has the temerity to challenge anyone else.)

The problem is puzzling because homosexuality is obviously counter-reproductive. It is not that homosexuals don't reproduce--I myself have 3 children--but that the more homosexual one is, the less likely to reproduce. Therefore it is puzzling how this trait has survived, if you accept evolutionary psychology.

I think the answer requires a more sophisticated evolutionary approach. One possibility that has been looked at is "group selection", that is, that having homosexuals in a tribe or family benefits offspring in that group, but for complicated reasons I don't think that works.

First, you start from the premise that the answer is likely to be completely different for men than for women. Why? Because the difference between men and women is sex. There is no reason to assume that the answer would be the same for both.

Let's take men first. One strong possibility is that homosexuality is in effect vestigial in men, like nipples. What? Well, one study indicates that the mothers and sisters of homosexual men have more offspring than than those that don't. So this raises the possibility of a gene that benefits women. If this gene happened to be on the X chromosome, then a male could inherit it, and turn out gay. In this way the gene would persist, through the female relatives of gay men. Since homosexuality is relatively rare, occurring in only around 4% of the male population, I think this is an intriguing direction to look.

As for women, I have a long but I think correct explanation, but alas no time for it right now. If you're interested I'll lay it out.

[logician]

Originally Posted by Autodidact

I think that tomspug raises a valid and puzzling question. (Although I think he should have the integrity and humility to admit he was wrong elsewhere before he has the temerity to challenge anyone else.)

The problem is puzzling because homosexuality is obviously counter-reproductive. It is not that homosexuals don't reproduce--I myself have 3 children--but that the more homosexual one is, the less likely to reproduce. Therefore it is puzzling how this trait has survived, if you accept evolutionary psychology.

I think the answer requires a more sophisticated evolutionary approach. One possibility that has been looked at is "group selection", that is, that having homosexuals in a tribe or family benefits offspring in that group, but for complicated reasons I don't think that works.

First, you start from the premise that the answer is likely to be completely different for men than for women. Why? Because the difference between men and women is sex. There is no reason to assume that the answer would be the same for both.

Let's take men first. One strong possibility is that homosexuality is in effect vestigial in men, like nipples. What? Well, one study indicates that the mothers and sisters of homosexual men have more offspring than than those that don't. So this raises the possibility of a gene that benefits women. If this gene happened to be on the X chromosome, then a male could inherit it, and turn out gay. In this way the gene would persist, through the female relatives of gay men. Since homosexuality is relatively rare, occurring in only around 4% of the male population, I think this is an intriguing direction to look.

As for women, I have a long but I think correct explanation, but alas no time for it right now. If you're interested I'll lay it out.

With the population explosion, there is no pressure to reproduce, so the incidence of homosexuality on that basis at least would tend to rise.

[Autodidact]

Originally Posted by logician

With the population explosion, there is no pressure to reproduce, so the incidence of homosexuality on that basis at least would tend to rise.

No, I don't think this is right. It's not about pressure to reproduce, it's just axiomatic that traits that don't get reproduced die out.

[Seyorni]

Originally Posted by Autodidact

I think that tomspug raises a valid and puzzling question. (Although I think he should have the integrity and humility to admit he was wrong elsewhere before he has the temerity to challenge anyone else.)

The problem is puzzling because homosexuality is obviously counter-reproductive. It is not that homosexuals don't reproduce--I myself have 3 children--but that the more homosexual one is, the less likely to reproduce. Therefore it is puzzling how this trait has survived, if you accept evolutionary psychology.

Lots of "counter reproductive" traits exist in many species. Animals are not that finely honed. Good enough frequently works fine.
Keep in mind that homosexuality has been observed throughout the animal kingdom.

I think the answer requires a more sophisticated evolutionary approach. One possibility that has been looked at is "group selection", that is, that having homosexuals in a tribe or family benefits offspring in that group, but for complicated reasons I don't think that works.

I don't think the answer is "evolutionary" at all. It is a simple genetic anomaly, like albinism, red hair or left handednes. It doe not seriously detract from the reproductive succes of the species, so is not selected out.

First, you start from the premise that the answer is likely to be completely different for men than for women. Why? Because the difference between men and women is sex. There is no reason to assume that the answer would be the same for both.

I don't follow your reasoning here...Let's take men first. One strong possibility is that homosexuality is in effect vestigial in men, like nipples. What? Well, one study indicates that the mothers and sisters of homosexual men have more offspring than than those that don't. So this raises the possibility of a gene that benefits women. If this gene happened to be on the X chromosome, then a male could inherit it, and turn out gay. In this way the gene would persist, through the female relatives of gay men. Since homosexuality is relatively rare, occurring in only around 4% of the male population, I think this is an intriguing direction to look.

As for women, I have a long but I think correct explanation, but alas no time for it right now. If you're interested I'll lay it out.[/quote]

[crystalonyx]

Originally Posted by Autodidact

No, I don't think this is right. It's not about pressure to reproduce, it's just axiomatic that traits that don't get reproduced die out.

Then the increasing incidence of it in our socienty indicates it is not particularly a genetic trait, but more a choice.