Will Homosexuality die out in the West?

A Primal Nut · 12-02-2011 4:42pm #1

I have a feeling this is going to be seen as trolling or something else but its a genuine question. I'm certainly not homophobic or anything, this is just a purely rational question based on curiosity, nothing more.

Evolution and the laws of natural selection suggest that genes which express themselves through causing a person to be gay should be reasonably quickly removed from the gene pool in only a few generations. But its my belief that genes for being homosexuality survived due to cultural factors: throughout history gay people had religious and cultural pressure to get married and have children; wouldn't admit to being homosexual or engage in homosexual acts due to fear of punishment or orther social factors; and in addition may themselves have regularly felt shame for feeling a certain way, due to their upbringing as people throughout history were taught that homosexuality was evil. Also, as there were no openly gay people around them, they might not have completely understood their own sexuality and admitted it to themsevles. Many would have got married and had kids in spite of their sexuality, perhaps through arranged/forced marriages, and hence, passed on their genes almost as much as straight people.

So now that gay people have almost equal rights etc, with less confusion about sexuality, less religious pressure; and less pressure to get married and have kids, will there be a dramatic reduction in the percentage of gay people in countries where it has become accepted, in particular Europe and America, as less gay people pass on their genes? I would expect it to continue to be quite common in the Middle East, which seems to be the case based on rumours, but no strong evidence to go on.

Of course you would have to believe being gay is a genetic thing in the first place, personally I think there is enough evidence for this; but I'm hoping this thread won't go down the path of discussing whether its genetic or not, as there has been enough discussions about this elsewhere.

Also I'm aware that genes can have multiple phenotypes; however that doesn't stop traits from being taken out of the population. Afterall thats how natural selection works, right? Of course there will always be a tiny minority of gay people in any population - just like there are infertile people; natural selection is built on variation in a population.

Dave! · 12-02-2011 8:58pm

But isn't there evidence of homosexual behaviour observed in almost all animals? I'm not sure that that fits in well with your thesis regarding cultural factors as an explanation for homosexuality being preserved in the population.

I've no idea what evolutionary reason there would be for homosexuality to be around, though.

josey_whale · 13-02-2011 1:50am

Dave! wrote: »

But isn't there evidence of homosexual behaviour observed in almost all animals?

Amoung animals, homosexual behaviour is usually non-exclusive... that is they are bisexual.

A Primal Nut wrote: »

Evolution and the laws of natural selection suggest that genes which express themselves through causing a person to be gay should be reasonably quickly removed from the gene pool in only a few generations. But its my belief that genes for being homosexuality survived due to cultural factors

Yes, you are right... Any property that causes 100% reproductive failure will be weeded out of the population. The genes of individuals that exhibit exclusive homosexual behaviour will of course die out. Given that homosexual behaviour in humans has been around since the beginning of recorded history would suggest that there is some benefit. Also, culture changes... What is taboo in a culture today, may not necessarily have been taboo historically.

I don't belive that the cultural change that has lead to western society's acceptance of homosexuality will have a significant affect on the number of people exhibiting homosexual behaviour.

This is much more complex than simple natural selection. The desire to pass on genes to the next generation must be much greater than exhibiting exclusive homosexual behaviour.

You might be interested in reading the comments on this New Scientist article

Improbable · 14-02-2011 2:04am

You're assuming that any genetic mechanism through which homosexuality is transferred from one generation to the next is a simple process. In reality, if it is the result of genetic programming (I haven't read up on any of the literature with regards to this so I'm hesitant to say one way or another), it's more likely to be the interaction of several different gene's which cause a person to be homosexual versus heterosexual. If one or more of the gene variations is missing, it may be possible that heterosexual carriers may exist which are not selected against via natural selection. Not entirely sure but this would probably mean that the percentages of homosexual to heterosexual individuals would probably remain stable over the long term and I do think I remember hearing something about such a result.

ArtSmart · 14-02-2011 2:09am

as above.

pragmatic1 · 15-02-2011 8:21am

The little I have read on the subject suggests that if homosexuality is in some way genetic, it comes from the mother, not the father. If a gay man has kids, they have as much chance of being gay as a straight mans kids.

A Primal Nut · 18-02-2011 4:07pm

Improbable wrote: »

You're assuming that any genetic mechanism through which homosexuality is transferred from one generation to the next is a simple process. In reality, if it is the result of genetic programming (I haven't read up on any of the literature with regards to this so I'm hesitant to say one way or another), it's more likely to be the interaction of several different gene's which cause a person to be homosexual versus heterosexual. If one or more of the gene variations is missing, it may be possible that heterosexual carriers may exist which are not selected against via natural selection. Not entirely sure but this would probably mean that the percentages of homosexual to heterosexual individuals would probably remain stable over the long term and I do think I remember hearing something about such a result.

I agree thats its not a simple process. Nevertheless, many genetic traits which have complex processes and are the by-product of many genes, have been weeded out by natural selection in the past. Of course I am not talking about homosexuality being wiped out altogether, but a dramatic reduction.

I have even heard rumours that homosexuality is more widespread in some countries in the middle east which is what you would expect given that homosexuals are much more likely to pass on their genes in those countries due to arranged marriages, etc. Not very scientific evidence of course and gender ratios may also play a part.

josey_whale wrote: »

Amoung animals, homosexual behaviour is usually non-exclusive... that is they are bisexual.

Yes, you are right... Any property that causes 100% reproductive failure will be weeded out of the population. The genes of individuals that exhibit exclusive homosexual behaviour will of course die out. Given that homosexual behaviour in humans has been around since the beginning of recorded history would suggest that there is some benefit.

I don't agree that the fact homosexuality exists means there is some benefit. For example infertility, blindness and mental disabilty, due to genetics, have also being around since the beginning of recorded history but nobody would suggest there is a benefit to being infertile, blind or mentally disabled. In fact you would expect them to be weeded out by natural selection, which is what has nearly happened. Yes, homosexuality is more widespread than them, but I don't think that means there is a benefit, its simply cultural factors that caused it to be more widespread, but still a big minority in comparison with hetrosexuality (if you go with the 10:1 idea). Sorry if this paragraph seems harsh or offensive, but I am just trying to make a point!

To me homosexuality is a result of genetic variation, nothing more. In the same way as people's eyesight goes from blindness to average eyesight to perfect eyesight, and everything in between; people go from gay, to bisexual, to hetrosexual, and everything in between. In the hunter-gatherer society, you would expect blindness to die out pretty quickly but of course that it didn't happen as due to genetic variation it will always exist to some extent. This doesn't mean there is a benefit to being blind. There are many examples like this.

Also, culture changes... What is taboo in a culture today, may not necessarily have been taboo historically.

It has been taboo for much of human history in most regions, particularly in the last 2000 years.

I don't belive that the cultural change that has lead to western society's acceptance of homosexuality will have a significant affect on the number of people exhibiting homosexual behaviour.

This is much more complex than simple natural selection. The desire to pass on genes to the next generation must be much greater than exhibiting exclusive homosexual behaviour.

But do you really think that is the case? Are you suggesting that homosexuals will mate with members of the opposite sex because the desire to have children is stronger than the desire to have a mate of the same sex? I don't think this is the case among any homosexuals that I know. Maybe it changes as they grow older? I am not saying that homosexuals don't have a desire to have children; of course they do, but I don't think they would do what they need to do in order to make that happen. IVF gives them hope, but its still too rare to have an impact on this discussion.

You might be interested in reading the comments on this New Scientist article

Thanks I will read the comments when I get a chance. I read the article and he makes a similiar point to me:

A common assumption is that homosexuality means not having children, but this is not necessarily true, especially in cultures other than our own. Until it became acceptable for same-sex couples to live together in western countries, many homosexual people had partners of the opposite sex. In some traditional societies, various forms of non-exclusive homosexuality were common.

19-02-2011 7:54pm

A Primal Nut wrote: »

To me homosexuality is a result of genetic variation, nothing more.

I haven't posted here til now because you stated in your first post that you wanted to treat sexuality as a purely genetic trait. But you really cant just state that. It's like saying lets have an argument for or against smoking but without mentioning that it's bad for your health. You can't treat this subject seriously if you're going to ignore environmental influence and the way in which genes are expressed in different circumstances.

It has been taboo for much of human history in most regions, particularly in the last 2000 years.

Yes, christianity has had a large influence on this, along with other religions/cultures. But before that it wasn't. The Romans indulged in homosexual/heterosexual/bisexual acts, mixed sex orgies, same sex orgies. I'm sure the media has probably overplayed it for entertainment value but historically it is accurate to say that it happened, maybe not as openly/often as we're led to believe, but it certainly didn't have some big taboo wrapped around it.

I don't think this is the case among any homosexuals that I know.

Do you have enough homosexual friends to count as a scientifically sound sample size?

BTW I'm not saying your proposition is completely wrong, just wanted to try and poke a few holes in it for the sake of argument.

Improbable · 19-02-2011 8:01pm

true-or-false wrote: »

Do you have enough homosexual friends to count as a scientifically sound sample size?

Just as to this point, I wouldn't be surprised if the desire to pass on your genes (have children) is the reason why people who can't have biological children of their own adopt children. A little evolutionary misfiring perhaps.

aquarian_fire · 24-03-2011 7:48pm

As far as I know, homosexuality isn't strictly caused by your genes, more by developmental processes in utero, namely the way certain lobes in the brain develop and also the neurons. I don't think it could be weeded out by evolutionary processes if that's the case.

nozzferrahhtoo · 28-03-2011 9:20am

A Primal Nut wrote: »

Evolution and the laws of natural selection suggest that genes which express themselves through causing a person to be gay should be reasonably quickly removed from the gene pool in only a few generations.

josey_whale wrote: »

Yes, you are right... Any property that causes 100% reproductive failure will be weeded out of the population. The genes of individuals that exhibit exclusive homosexual behaviour will of course die out.

Actually it is not as safe an assumption as you think it is. Quite the opposite in fact.

The first thing to remember that one of the main things selected in natural selection is the gene, not the individual. That said it is worth thinking about what we are discussing here.

Homosexuality, in it’s pure form, is essentially something that causes individuals in our species to not reproduce (Exceptions exist of course through surrogacy, which is why I say pure form).

Can we assume therefore that it will be selected against and bred out? Very clearly not.

In fact looking around the entire animal kingdom we see not only species which carry genes preventing them from reproducing… but the species is made much stronger, not weaker, for carrying such elements.

This is most notable, though not exclusively, in “hive” species. Insects like ants and wasps, or mammals like the bald mole rat are good examples.

These species have very specific individuals that never reproduce. Ever. Drones, Soliders and more. The species as a whole benefits from their existence and the genes to ensure their existence are propagated despite the elements themselves never reproducing.

We can make sense of this, as I said in the opening, by realising that the gene is what is selected, not the individual. The reason the gene for non-reproduction is successfully propagated is that the existence of that gene in those in whom it is expressed… ensures the reproductive success of those who ALSO contain the gene, but do not express it.

If the theory that homosexuality will be “bred” out merely because gay people do not reproduce WERE correct, we should also long ago have seen non-reproductive elements bred out of hive species. We see the opposite however.

The fact is that as long as X having a gay sibling provides even a small benefit of any kind for X’s offspring, then any gene for homosexuality will continue to be selected for and propagate happily, because it is very likely X also contains said gene and it just has not been expressed.

Both diversity and having a species with non-reproductive elements are things that we know make species stronger and as such I neither expect homosexuality to go away… nor am I unhappy to have it as part of our species and culture.

All of this is written based on the assumption that being gay IS something there is a gene for. I do not believe it is as such. All males and females contain the same genes, they are just expressed differently in each. That means we all contain the genes for being attracted to males, and the genes for being attracted to females. Homosexuality is more likely to be some quirk in what causes those genes to be expressed… than it is to be an actual gene in and of itself…. an idea that has been backed up a lot recently by studies showing that the increase in certain hormones in the mother correlates with an increase in the likelihood of homosexual children.

In fact any evolutionary prediction based on the idea that X’s offspring will benefit from X’s homosexual siblings would suggest that such a benefit would be higher if X’s sibling was younger and fitter than X. The prediction therefore would be that the likelihood of gay offspring should go UP with each successive child. This is in fact what we found as the hormones that have been correlated with gay children have also been shown to have a higher presence in fetal development with each progressive child the woman has.

Squashie · 31-03-2011 2:46am

I've always believed people are thinking about this in the wrong way. Clearly there is no "homosexual gene," it would have already been removed by natural selection. If perhaps not for whatever reason in humans, it would have been in other animals.

The genes that I think the geneticists need to be focusing on are those associated with brain development. Functional MRI scans in recent years have shown that homosexual male brains are developing more like females, and lesbians like males. It seems much more logical to reason therefore that homosexuals are, for whatever reason, merely inheriting some particular wrong-sex genes associated with their brain development, or are inheriting genes which are causing particular sensitivities to certain male or female hormones associated with development.

Genes associated with male / female / associated hormone sensitivities and brain development would and will never be removed by natural selection.

nozzferrahhtoo · 31-03-2011 8:16am

Squashie wrote: »

I've always believed people are thinking about this in the wrong way. Clearly there is no "homosexual gene," it would have already been removed by natural selection.

Again, no, I do not think it would for the reasons I laid out above.

Essentially there are many species on this planet who have individual elements within them that prevent them from reproducing. We can see that these elements do not weaken the species but in fact strengthen it.

How such non-reproduction is achieved varies from species to species. In some they simply develop without the capability to reproduce. In some they develop without the motivation to reproduce... they can reproduce... they simply do not. Homosexuality essentially has the same effect by not preventing the ability to reproduce, or the desire, but by re-directing it into avenues that will not result in reproduction. The capabilities and desires are still there, they just are just directed where they can have no effect.

Yet if the genes that cause that are not bred out by natural selection, despite the fact that they do not reproduce and hand on their genes.... then there is simply no basis for thinking that homosexuality would be bred out if it was a gene either. None at all.

However as you said, and I agree, there is little reason to think that homosexuality is a gene in and of itself, but more likely the expression of genes, which we all carry, from the other sex. If you are a man, you carry all the same genes as a woman, from the genes to make breasts to the genes that cause women to be attracted to men. Homosexuality is likely just those genes being expressed... rather than some new and magical gene of it's own.

skregs · 21-04-2011 1:51pm

nozzferrahhtoo wrote: »

These species have very specific individuals that never reproduce. Ever. Drones, Soliders and more. The species as a whole benefits from their existence and the genes to ensure their existence are propagated despite the elements themselves never reproducing.

You've completely misunderstood the concept of kin selection to be honest.
There is nothing that reproduces for the good of the species. Eusocial insects gain inclusive fitness from allowing the queen to reproduce, because of some strange genetics meaning that the sterile workers actually have more genes in common with the queen than they would with their offspring, if they were capable of reproducing.
The mole rat is a freak species, and not a great way for a mammal to reproduce

The only way there would be eusocial benefits to homosexuality is if your gay brother spent all his free time finding you girlfriends.

gbee · 21-04-2011 1:54pm

Dave! wrote: »

But isn't there evidence of homosexual behaviour observed in almost all animals?.

No, actually what is observed as homosexual behaviour is a dominant behavioural practice. Female animals can be seen exerting mating behaviour on other males, this is not for sex, it's a weapon or a threat.

gbee · 21-04-2011 2:07pm

A Primal Nut wrote: »

Evolution and the laws of natural selection suggest that genes which express themselves .

Since homosexuality has been around for as long as mankind has, there seems to be a permanent portion of genes to make the homosexual.

There were obvious uses for them in the past, they are usually more intelligent, creative, problem solving and safe around your womenfolk as you go off to slay that day's dinner, Oh and BTW they make great chefs too.

In the scheme of things its unlikely we, as in mankind would have evolved much beyond the caveman as we entered the first prosperous period without them. They have been the driving force of thought, ideas and invention.

Throughout history they have been revered and shunned in probably equal proportions. We are living in an enlightened West and it's probably only religious groups who openly preach against them.

In another thousand years there will almost certainly still be the same proportion as there is today, as religion will have died off completely by then, it may seem more, but let's say there is 30/70% mix, as mankind evolves, this mix will probably remain the same.

nozzferrahhtoo · 21-04-2011 2:53pm

skregs wrote: »

You've completely misunderstood the concept of kin selection to be honest.

There is nothing that reproduces for the good of the species. Eusocial insects gain inclusive fitness from allowing the queen to reproduce

I doubt it. Especially given what you just said is exactly what I am saying, just said a different way. That individuals in a species gain advantage from allowing others to do the reproduction is essentially exactly what I am saying.

Those who think that homosexuality should be bred out of our species therefore, simply because they are non-reproducing individuals, is missing the point that many species have vast numbers of non-reproducing elements and yet those elements are not bred out. Clearly what they are missing is that this "gene" for not reproducing is being passed from generation to generation by a different pathway. The gene is still being selected for, even if it is not being selected from the hosts in which it is "expressed".

That fact alone is the entire point I am making. The fact that having such non-reproducing elements in the species is more often than not also an advantage for the entire species is a parallel, but noteworthy point which is why I included it.

AtomicHorror · 21-05-2011 6:07pm

gbee wrote: »

No, actually what is observed as homosexual behaviour is a dominant behavioural practice. Female animals can be seen exerting mating behaviour on other males, this is not for sex, it's a weapon or a threat.

Citation needed. This may well be true for some cases, but you seem to be extrapolating it to dismiss all homosexual behavior in animals. A colossal overstretch unless you got some evidence that this is broadly true rather than specific for some animals. I mean, bonobos seem to do it for pleasure, to cement relationships and reconcile differences- homosexual behavior forms an integral part of their social structure and dominance does not appear to be a major player.

dissed doc · 15-06-2011 8:19pm

A Primal Nut wrote: »

Evolution and the laws of natural selection suggest that genes which express themselves through causing a person to be gay should be reasonably quickly removed from the gene pool in only a few generations.

You could also consider that homosexuality like autism is simply a developmental disorder. In this sense, a sexual development disorder. It has a repeated chance of occurring to different degrees (sexuality being a spectrum) every generation.

JamJamJamJam · 22-06-2011 9:52pm

dissed doc wrote: »

You could also consider that homosexuality like autism is simply a developmental disorder. In this sense, a sexual development disorder. It has a repeated chance of occurring to different degrees (sexuality being a spectrum) every generation.

I agree. I haven't read much about it, and other than sitting Leaving Cert Biology (last week!

), I'm pretty ignorant on the whole subject of genetics. However, I can't quite understand how a gene will tell a man to be attracted to a woman or vice versa (Ignoring our responses to pheremones and the like).

Rather, I can understand that a gene will result in the desire for pleasure; that the genotype estabishes a libido. This is the biological 'tool' employed by our sexuality. Environmental influences alone - at least as far as I can see it - can then develop the phenotype which causes a person to become attracted to a particular sex. People have a certain propensity to appreciate what is perceived to be beautiful - art, music, poetry, etc. Is the sexuality of an individual not also some deep-seated psychological association between a sex (the same or opposite) and what we are 'taught' is attractive?

That would explain the "spectrum" of sexualities in a way which makes more sense to me than to say that a certain combination of genes leads to heterosexuality, homosexuality or bisexuality.

Now, I may be wrong, but I just can't understand the genetic mechanism driving a person to be attracted to the body (and emotional tendencies???) of the opposite (or same) sex.

So in response the OP's origional proposition, I don't think homosexuality will die out in any culture because the environmental influences that (I think) cause it are unlikely to be eliminated.

Will Homosexuality die out in the West?

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