Assume that there is a biological determinant that makes a large number of men and women homosexual, how would such a seemingly self-obliterating gene survive natural selection?
Obviously earlier genetic ancestors with this theoretical “mutation” (or whatever) may have reproduced despite their homosexuality, but still there seems to be something ironic about the concept of a homosexual gene reproducing itself for millions of years.
Also, some homosexual behavior seems to have a greater likelihood of being medically dangerous. Wouldn’t several million years of natural selection eventually kill off the animals that wanted to have anal sex with each other?
BTW, i dont have any problem with gays. You know, I’m just curious.
Getting the obvious out of the way: No one has found a “gay gene” and darned few people are looking for one.
However, speculation regarding an evolutionary benefit to homosexuality (of which there is also not really a lot out there) generally focuses on the idea that an individual who does not expend the energy to procreate himself or herself will have more energy to expend in the support of his/her nieces and nephews, providing them with a better opportunity to survive. Since they are carrying on genes that the non-reproducing individual shares with that individual’s sibs, the non-reproducing individual is promoting the continued existence of his or her genetic complement. (Remember that such activity would be supposed to have evolved in the small hunter/gatherer/scavenger extended families of the earliest prot-humans.)
Such speculations are generally of the armchair variety. We really do not yet have enough information regarding any of the aspects of this to draw serious conclusions.
The same way genes survive which generate sterile worker castes in many social insects: the trait to produce gametes which result in offspring which are sterile (or, in this case, homosexual) is the trait that would be affected by natural selection, not the sterility (or homosexuality) itself.
Although, in the case of humans, such a trait may well be selectively neutral (as opposed to the case in insects, where it is advantageous), which would also allow it to persist.
Will a lesbian who is impregnated through an arrangement with a sperm bank give birth to a homosexual child, if the sperm used is guaranteed to be from a homosexual man?
Sometimes.
If there is any gentical material that is devoted to determining a human’s homosexuality, it can be overridden due to social envionment. Thus, it cannot be considered an evolutionary trait on the same level as, say, opposable thumbs.
As I mentioned in another thread twin studies give pretty conclusive evidence that homosexuality is not purely genetic. Whatever genes that might contribute to “gayness” probably were continued through heterosexual bearers of it.
It’s fairly obvious that any genetic component of homosexuality is moderated by social and psychological development. If there were a single gene that was found in all gay people, and that accounted for their sexual preference, it would only do so in the context of the necessary stimuli (and lord knows what such stimuli might be).
For those in whom this gene does not “cause” homosexuality, it might be evolutionarily neutral, or even confer some reproductive advantage.
Well, there are worker bees and Queen bees…and you never wanna mess with the Queen.
Divas aside, there are a lot of theories…someone into reincarnation once told me gays are the end of the reincarnation path, and upon death they go directly to the “higher state”. I am not sure if he meant Nirvana or Colorado.
But calling it “a seemingly self-obliterating gene” is going a little far. Not all heterosexuals can conceive children, and a hell of a lot of homosexual people have. I don’t think there is an immedicate cause for concern about population growth.
I like to think of it as proof that there is a reason and purpose. No matter how hard cultures have tried, and continue to try, to stamp out, kill, imprison and do other harm to homosexuals, we just keep popping back into society, in every culture - throughout all of recorded history.
The Incas should be so lucky.
Assuming this genetic component to a very complex behavior, it could be recessive. We all carriers of recessive genes that we (potentially) pass to our offspring. Genetic coding is not as simple as a laundry list of on/off switches that determine all of our behaviors.
There’s a disease called Tay-Sachs, which is genetic, recessive, and almost entirely affects Eastern European Jews, and the decendants of Eastern European Jews. People with Tay-Sachs lack an enzyme that allows them to digest a certain kind of fat, and so it builds up in their brain. As far as I know, the oldest anyone with Tay-Sachs has lived has been 5. This is obviously a condition that is more detremental to producing offspring than homosexuality, because homosexuals can have children, while people with Tay-Sachs never can. In spite of this, Tay-Sachs still exists, and babies are still born with it.
I am going to have to second tomndebb’s point about all this being armchair speculation, but I heard an interesting theory once.
Homosexuality is not genetic. It is inborn, however, and is the result of elevated testoterone levels in the mother during fetal development. This slight hormonal imbalance can be caused by any number of things, but the researcher was attempting to correlate it to a statistical trend she found in groups of brothers. (Apparently, if a woman has given birth to several sons, her womb may become a higher testoterone environment, and the younger brothers are more likely to be gay. If she bears a daughter the increasing testoterone cycle stops, as it only holds when she bears a sucession of sons).
I am unsure if this is true, of course, but I think it illustrates the fact that biology is a lot more complicated than a simple gene or no gene thing.
Dean Hamer’s famous study suggested that the gene that influences male homosexuality is in region Xq28, on the X chromosome. A genetics student at McGill University once informed me that this region is given to frequent mutation, but since IANAG, I’ll leave it to dopers with more expertise in this field to confirm or deny this.
As a gay man, I like the theory that homosexuality does fulfill a useful role in nature – we could help the overall family unit while not reproducing ourselves. And if Dean Hamer is right, then women could carry the gene for male homosexuality without being lesbians, so it wouldn’t necessarily be selected against.
Of course, it could just simply be one of nature’s mistakes. I have no problem with that – some of the best things out there were invented by accident
One final note – most gay men and lesbians feel that homosexuality is “inborn” – but as Beeblebrox pointed out, “inborn” does not necessarily mean “genetic.” I suspect it’s a combination of genetics and prenatal hormones, myself.
I’m glad to see that people have pointed out that there is no proof of a “gay gene” – and very few traits are governed by a single gene, anyway, meaning that a genetic component to homosexuality might be in the nature of a gene complex, as are many other genetically conditioned or influenced personality components.
However, putting all that to one side and assuming for the sake of argument a single “gay gene,” one very logical explanation would be the “sickle-cell” effect: heterozygosity produces a biologically beneficial effect, while homozygosity produces the (putatively undesirable) other effect. For example, if two alleles S and G exist at a given gene site, SS might conduce to loner status while SG fostered the male-bonding characteristic that enabled early man to conduct successful hunts and men to work together on major projects, GG resulting in a gay orientation. Clearly a group of SG men is going to be more successful than an equal number of SS loners – and the “reproductive penalty” of having a number of GG individuals who will not reproduce may be more than outweighed by the benefits of a largely SG population.
The responses above adequately address the point that nobody really knows. But I just want to address a major misconception in the OP –
Both gay men and lesbian women are just as capable of producing offspring as heterosexuals are, as, so far as we know, in societies in which homosexual activity was less astigmatised than in modern Anglo-American culture (such as Spartan Greece and in some Native American culture), there is no indication that those who engaged in homosexual behaviour weren’t just as likely to produce offspring as straight heterosexuals.
In fact, the idea that someone is either homosexual or heterosexual, or bi-sexual is a characteristic of our culture that is not necessariliy a characteristic of all cultures and that is probably why homosexuals today are less likely to produce offspring.
Sperm Wars author Robin Baker speculated that an individual who engaged in sex with both sexes might possibly have a better chance of hiding extracurricular sexual activities from a partner and therefore might have a slight advantage in producing offspring. The range of bi-sexuality would include, as a side effect, some individuals who were a lot more interested in sex with their own sex than with the opposite sex.
If we assume the existence of a “gay gene”, there are a number of possible explanations for its continued existence. For one, it may be that this is a particularly common mutation or class of mutations, so as one “gay gene” fades away, another ends up taking its place. For another, it’s possible that the same gene carries some other advantages, possibly completely unrelated to sexuality. It’s possible that hosexuality itself is advantageous, via the “gay uncle” effect tomndebb cited. It’s also possible that such a gene would ordinarily evolve away, but that historical treatment of homosexuals has resulted in many homosexuals bearing children anyway, despite their inclinations, to avoid persecution, and that the gene is therefore (in those societies) not an evolutionary disadvantage.
The question of what “point” homosexuality might have played in the past is a rather dicey area IMHO. It is an area with a lot of interesting theories, but I rekon they are all guesswork. There is also a risk of “revisionist history” from the gay community, reading much too much into things and the risk of almost inventing a key-status for gay people. I think the comment above of “gay people are one step from nirvana” is a good example.
However, I have heard an interesting one (and I consider this to be most likely crap, but this thread is all IMHO area anyhow so I will let it fly). This is that in days gone by (way by), gay men played the roll of ‘homestead-protector’ or something similar. In other words, when the majority of the men in their prime were out hunting food or at war or whatever, the gay guys stayed to protect the village, since they could safely be left amongst the women without the rest of the lads coming home to a bunch of preggie wives. I have never heard any good proof for this theory, but I think its a fun one
Bringing young into same sex unions may give the offspring (of the mother/father bringing the kids in) a better chance of survival if the alliance offers a competitive benefit to food resources and/or protection from enemies. Penguins, Geese and Dolphins have been observed bringing kids into such unions.
Among Bonobos homosexual mating among young males, (this is controversial) MAY be a way to dominance. If true, the dominant males with many offspring would be the ones that through intimidation and alliance (in this case using homosexual sexual activity) were able to use their homosexual gene to great effect. Just a theory and a speculative one at that, brought on by a lot of male bonobo homosexual activity.
This is an area about which I know second to nothing so please excuse the tangential ignorance in this question. I know testosterone is a major steroid produced by both the testes and (to a lesser extent) the adrenal gland but after that I’m lost…
" The immediate precursor of gonadal steroids is cholesterol. LH promotes the conversion of cholesterol to pregnenolone. The mechanism by which LH stimulates this conversion is via the formation of the second messenger cAMP via a G-protein linked LH receptor. cAMP then activates protein kinase A, which activates enzymes within the pathway. The subsequent conversion of pregnenolone to testosterone requires the action of 5 enzymes located in the microsomal fraction within the progesterone pathway. Pregnenolone can also be converted to testosterone via the dehydroepiandrosterone pathway."
I’m sure this has been addressed in threads I haven’t read but…is it possible that ‘gayness’ is a product of a differently composed or comprised testosterone ?
“I’m sure this has been addressed in threads I haven’t read but…is it possible that ‘gayness’ is a product of a differently composed or comprised testosterone ?”
IANAD but I don’t think it would be called testosterone as that is a specific chemical. If it was shaped differently it would not effect the same chemical gates.
Also while testosterone is linked to sex drive it is only in strength not direction. I don’t have a cite but IIRC one of the earliest modern attempts at a “medical cure” for homosexuality was testosterone injection. This produced very horny yet still quite homosexual men.
