Evolution and homosexuality? (minority, creation, mission, disease)

[Flappycat]

Oh, I'm do happy and excited because this just occurred to me! Remember, this isn't a political or social forum, so let's keep to scientific thought. This is really exciting because it could explain a number of things.

Okay, to begin, a genetic "defect" can apparently survive as long as there is an environment in which it offers any increase in chances of survival, including in holocaust scenarioes. For example, Sickle Cell Anemia, the hybrid form of which offers some resistance against Malaria, seems to flourish in environments in which there is a high call for its helpful hybrid manifestation. Since the pure form of it reduces reproductive chances in a harsh environment to close to nil, it would always have an off switch which would allow a population to shed the gene almost entirely within a relatively few Malaria-free generations, leaving a minority of carriers in reserve. As long as a "harmful" gene can possibly show itself helpful periodically, there is a chance for it to become a part of the species' heritage. Really, you have to think of it as a genetic game of chess; sometimes a few men are sacrificed to improve the chances of eventual victory.

What I think might have contributed to homosexuality remaining for so long in our heritage could be a role played genetic pruning. Primitive humans would have HAD to keep a healthy breeding stock, or they were screwed when a disease came flashing through the region; it happens to primates all the time, killing off often most of a colony. From what I've heard, men are more likely to be monosexual, and homosexual men seem to be a result of the way their mothers deactivate part of the X-chromosome. If it is true that it's a quirk of the female reproductive process and it's rooted in genetics, it would cut the woman's reproductive chances significantly less than in half, making it more likely than direct transmission to survive.

Basically, my little speculation here is that a few entirely homosexual males would force tribal females to compete more for the remaining men. With this creation of genetic competition even in a culture that practices monogamy, ESPECIALLY in a culture that practices monogamy, it would be easier for the population to shed unwanted stock, which would be very helpful in the event of a sickness. Though the pruning factor might not be strong enough all on its own to allow its survival in such a high proportion of the current population, this could still be part of the puzzle.

Also possible is a carrier's advantage, as in Sickle Cell Anemia. Could it be possible that another side effect of this biological behavior of some women is an improved chance of health in other offspring? Could it be possible that this is a side-effect of another genetic quirk that offers some sort of edge in the ongoing genetic olympics?

It's certainly a very interesting puzzle.

[Sunstone]

Male homosexuals can and often do father children. Female homosexuals can and often do bear children. In primitive societies, the social pressure on someone to have children might very well have been much greater than it is in today's advanced societies. Thus, any genetic basis for homosexuality would not have been weeded out by a failure of homosexuals to pass those genetics on. Just a thought.

[Flappycat]

Originally Posted by Sunstone

Male homosexuals can and often do father children. Female homosexuals can and often do bear children. In primitive societies, the social pressure on someone to have children might very well have been much greater than it is in today's advanced societies. Thus, any genetic basis for homosexuality would not have been weeded out by a failure of homosexuals to pass those genetics on. Just a thought.

Well, this could also be true, but I tend to think that there is usually a reason for the existence of any widespread genetic oddity. We just need to find out what it is. However, yes, it is most probable that this is nothing more than a quirk that has survived the ages.

Something else that I would like to point to is that male homosexuality might be passed matrilineally. The significance of this is that the female offspring of women who produced homosexual boys would in no way be inhibited from reproducing and, in fact, would have anyone else's odds of doing so. Unless male homosexuality became dominant in a tribe, there would never be a shortage of males with whom they could produce offspring. Take offspring Xg and Yg of Mg. Only X carries the gene that might produce homosexual males. Yg is stricken off the genetic map, leaving Xg. Now, you would think that this might make M the less successful reproducer, but the trick of it is that X would not have any unusual difficulty in reproducing, so, between Xg and X, there are equal odds of producing offspring. It wouldn't matter that Yg doesn't reproduce because it isn't Yg that carries the gene; only Xg is required to reproduce for g to be carried on to the next generation. The tribe would not suffer from a high Xg population unless they became so dominant as to cause their numbers to dwindle due to a shortage of reproductive males.

This leaves a question to be asked: then whence cometh lesbians? Well, apparently, it would seem that lesbians are not strictly lesbians at all. A fairly recent study was done showing that women seem to naturally find both sexes attractive, making it perfectly possible for even those whose interests are mainly with other women to reproduce in polygamous cultures, perhaps even increasing their chances of drawing the attention of a male through sexual play with one another.

[Victor]

Are you saying that homosexuality is our edge on the next phase of evolution? Do I have that right?

[standing_on_one_foot]

Or, perhaps (assuming it is genetic), it's just a quirk of the species. And since liking a certain sex is beneficial in some situations (if, say, you're the opposite sex), that inclination sticks around in humanity and every now and then some wires get crossed. We also have had infertility for a long time, but I don't think it's really "intentional" (in as much as evolution can have intent).

Heck, not every trait that shows up does so because it's beneficial. And I don't think you'd ever get enough homosexual males (what's the percentage, generally? three?) to make a significant difference in competition, and if there were that much shortage in a small enough group, I kinda suspect that the pressure would be great enough to make those men reproduce.

[jamaesi]

Basically, my little speculation here is that a few entirely homosexual males would force tribal females to compete more for the remaining men. With this creation of genetic competition even in a culture that practices monogamy, ESPECIALLY in a culture that practices monogamy, it would be easier for the population to shed unwanted stock, which would be very helpful in the event of a sickness. Though the pruning factor might not be strong enough all on its own to allow its survival in such a high proportion of the current population, this could still be part of the puzzle.

You're completely ignoring homosexual females and the fact females are more open to homosexual relationships in this.

[Booko]

A biological study of puppies mapped them in utero and tracked behaviour when they reached maturity. There was a relationship between homosexual behaviour in the male dogs and their proximity to females in utero. (My source, regrettably, is not the paper itself, but a friend who was working on his Ph.D. and had run across it in his studies.)

We know that sex hormones in utero are a factor in the development of gender in humans.

I think we have a great deal more study to do concerning human sexuality. Genetics and environmental factors may both be involved, and I'd be very interested to find why we are the way we are.