Evolution and Genetic Homosexuality

[dknightx]

This is an honest question and something that I was thinking about last night. How can evolution and genetic homosexuality coincide? It would seem to me (and my very basic understanding of both items), that if we supported evolution, and homosexuality was genetic, we would see a natural "weeding out" of people born homosexual ... I mean, you can't really continue a species without procreating (or being attracted to) the opposite sex. So if we follow the idea of "survival of the fittest", wouldn't we be seeing a lot less homosexuality? (instead of more?).

Also, if homosexuality is genetic, then would other types of fetishes be genetic as well? Like, what if you only liked people of a certain race, or what if you were only turned on by animals? Where do we draw the line between what is a choice and what is genetic?

thanks in advance for your time and thought out responses.

[Sykes]

If homosexuality is purely genetic, it is still possible for it to have survived humann history since in the beginning, sexuality was open, so there was no way to tell who was purely gay or not. In the middle ages, when sexuality was closeted, you had people who were gay but forced into heterosexuality and "bred" their homosexuality into future generations. The way things are now, if everyone can be truly open on who they are, and if you're correct on homosexuality being 100% genetics, then yes, the number of homosexuals on Earth would go down.

[madnak]

It's not that black-and-white. Sexual attraction is extremely complex and certain combinations of traits could result in homosexuality as a "side effect."

It's the genome that's relevant, not the individual. Meaning, if a certain trait reduces the ability of the specific organism to reproduce, but helps preserve the relevant social group, that trait may be selected for. Generally the trait will occur with a frequency related to an equilibrium point in terms of the propagation of the genome.

Evolution is sloppy and slow. It can result in many nonsensical traits (particularly sexually selective traits that are basically arbitrary) and as the environment changes selective mechanisms as they previously existed can fall apart. Genetic traits may also manifest in different ways. There's a lot of room for "slip-ups."

The difference between the genders rests in a single chromosome. Much of the male "programming" exists in the female, and vice versa. Unfortunately attraction isn't well-understood at a biological level, but in many ways gender is a strange concept. Some people see it as a male-female "switch," and in a sense it is (XY or XX), but physiologically gender is really weird. That's to say nothing of people born with an extra chromosome, etc.

Finally, the dichotomy between "genetics" and "choice" is false. Many, many environmental factors have nothing to do with choice. These include everything from the biological factors relevant in the womb to developmental psychology to brain damage. For example, different hormone levels in the womb can have measurable effects on later personality. And if a young child is abused or neglected, his psychology will develop in such a way that he will never be able to have a normal psychological profile. I know of at least one famous case where a construction worker had an accident and pierced his skull, destroying a large portion of his brain. He survived but later exhibited some strange and interesting behavior patterns. These have nothing to do with choices made at a conscious or unconscious level. The division between "nature" and "nurture" isn't as clear as some make it out to be.

[MrMon]

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This is an honest question and something that I was thinking about last night. How can evolution and genetic homosexuality coincide? It would seem to me (and my very basic understanding of both items), that if we supported evolution, and homosexuality was genetic, we would see a natural "weeding out" of people born homosexual ... I mean, you can't really continue a species without procreating (or being attracted to) the opposite sex. So if we follow the idea of "survival of the fittest", wouldn't we be seeing a lot less homosexuality? (instead of more?).


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There are many conditions where if an individual has one copy of a gene, they are afforded a certain advantage, but if they hold two copies of the gene (get it from both parents), then the condition results. I believe sickle cell disease is an example, where if you have one copy, you have a resistance to malaria, two copies result in sickle cell. The chances of producing a child with the trait but not the disease are 2:1.

This is not to say that homosexuality fits this mold, just that if it did, there's no reason that failure to reproduce by the affected individual would weed it out.

[evolvedForm]

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I know of at least one famous case where a construction worker had an accident and pierced his skull, destroying a large portion of his brain. He survived but later exhibited some strange and interesting behavior patterns.



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I think you're referring to the poor fella who got a piece of steel lodged in his brain from a construction accident. It knocked out a certain portion of his brain, and (I think) resulted in him having terrible short term memory. Worse yet, they were afraid to remove the piece of steel, so it remained visibly sticking out of his head. One good thing to come out of this, at least, is that it inspired the "lightning bolt-in-the-head" toy, which never gets old.

Okay, just looked it up and found I was pretty wrong. He didn't lose his memory, but became a self-obsessed, shrewd guy with childish inclinations. url=http://http://en.wikipedia.org/wiki/Phineas_Gage]link[/url]

[kurto]

[ QUOTE ]
This is an honest question and something that I was thinking about last night. How can evolution and genetic homosexuality coincide? It would seem to me (and my very basic understanding of both items), that if we supported evolution, and homosexuality was genetic, we would see a natural "weeding out" of people born homosexual ... I mean, you can't really continue a species without procreating (or being attracted to) the opposite sex. So if we follow the idea of "survival of the fittest", wouldn't we be seeing a lot less homosexuality? (instead of more?).

Also, if homosexuality is genetic, then would other types of fetishes be genetic as well? Like, what if you only liked people of a certain race, or what if you were only turned on by animals? Where do we draw the line between what is a choice and what is genetic?

thanks in advance for your time and thought out responses.

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For a species to survive, every member does not have to procreate. Matter of fact, if a species grows too quickly, having members who don't procreate could aid in the species survival.

Regarding your second part... I wouldn't describe homosexuality as a 'fetish' any more then heterosexuality.

[Rduke55]

Done a few times here recently.
Here's one thread.

Linky

And a previous response of mine:

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Because selection happens at the gene, not the individual.

For example, some studies have shown that sisters of homosexual men may be hyperfertile. This suggests that the "gene for homosexuality" has different effects depending on gender.
Examples similar to this idea are rampant. A more extreme example is saying "Why hasn't the gene that predisposes worker behavior in ants been selected out?"

In all actuality, we're most likely talking about a bunch of genes which makes blanket statements like "If queerness is genetic it would have been selected out by now." ridiculous since different combinations of alleles may have wildly different influences in fitness leading those pesky gay genes to not only avoid being selected out but actually selected for.

For example, lets take that most feminine of neuropeptides - oxytocin.
Let's say certain combinations of alleles make men with high oxytocin levels and this causes them to be gay. Why hasn't that damn oxytocin gene been selected out?
Well it's responsible for bonding between mother and child, between woman and mate, lactation, labor, and recently implicated, along with its macho partner vasopressin, in general social behaviors. Pretty important, right?
In this example you should be able to imagine why it would still be retained.
Stupid gay oxytocin gene.

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[bdypdx]

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How can evolution and genetic homosexuality coincide?

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Namely, enough homosexuals reproduce in order to continue the trait. Also, homosexuality may be more related to a mother's hormonal balance than to genetics, so it may just naturally and continuously occur in any human population.


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So if we follow the idea of "survival of the fittest"...

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"Survival of the fittest" in biological terms refers more to populations, not so much to individuals. Homosexuality may very well be a population survival function. For example, in hunter gatherer times, the non-breeding homosexual males may have made a population more "fit" by making significant contributions to the overall group. Contributions such as hunting, gathering, toolmaking, defense, etc....

[FredBoots]

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I mean, you can't really continue a species without procreating (or being attracted to) the opposite sex. So if we follow the idea of "survival of the fittest", wouldn't we be seeing a lot less homosexuality? (instead of more?).

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If you had a bunch of brothers that were not gay, they could be out procreating (i.e., spreading your genes) while you could afford to be gay. A recent study found exactly this. In evolution, individuals don’t matter, but genes do.


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Where do we draw the line between what is a choice and what is genetic?

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We draw the line when someone is hurt by the actions.