Why are there so many gay people?

[Uncertain]

@astro

I thought the latest research was that being gay had a lot less to do with genetic factors, and was, to a large extent, a random dice roll as a function of the inter-utero hormonal environment of the fetus at very specific time windows of development, with higher than normal concentrations of testosterone or estrogen (at those critical development points) tending to feminize or masculinize the mental development of the child.

If this is true gay people will continue to be produced regardless of their tendency to procreate.

Even if that’s true, it doesn’t resolve the issue. Why doesn’t natural selection eliminate the dice roll?

[Illuminatiprimus]

As a gay man who hasn’t been in a relationship for well over a year, I think the question should be changed to “why aren’t there enough gay people?”.

[yorick73]

@Illuminatiprimus

As a gay man who hasn’t been in a relationship for well over a year, I think the question should be changed to “why aren’t there enough gay people?”.

Location, location, location! San Fran, New Orleans, and DC might be good places to start.

[md2000]

@astro

I thought the latest research was that being gay had a lot less to do with genetic factors, and was, to a large extent, a random dice roll as a function of the inter-utero hormonal environment of the fetus at very specific time windows of development, with higher than normal concentrations of testosterone or estrogen (at those critical development points) tending to feminize or masculinize the mental development of the child.

If this is true gay people will continue to be produced regardless of their tendency to procreate.

@pancakes3

pancakes3 my bit of armchair psychobio here is that homosexuality deals with the arousal/attraction portions of the brain. certain biological predispositions can obviously affect which way the attraction swings, but also in development there are factors that mess with how arousal mechanisms are triggered.

thus, there isn’t a necessarily a “gay” gene, but probably a gene that makes people more susceptible to altered attraction/arousal mechanisms. so, people can certainly be a carrier of that gene but by sheer chance their arousals remain strictly hetero.

Hmmm… I know a pair of identical twins with one obvious lack of identicality. So, gay is not really hereditary.

My theory is similar - that there are attraction center “modules” in the brain that recognize things. Hence we like cute and cuddly, we recognize young as cute in kids (who are not screaming their lungsout), kittens and puppies, for example. We recognize beauty in adult human bodies; we hate slimy and dirty, we recognized “sick” or “not healthy”, another favourite perception brought up by evolutionary biologists.

I think the ability to percieve with our higher-level thought processes and recognition patterns is connected to that lower set of functions, the “arousal/attraction portions of the brain” or other motivations. The connection is likely such that misconnections are a normal part of development, not tied to genetics, but possibly influenced by in utero and early childhood. SO just as you might accidentally end up with cleft palate or downs or overactive thyroid, you may end up with “gay” or “bi” or “pedo” or sadist" or any number of other misconstructions of the brain.

I suppose the question is - is this strictly a physical development, or is it also something that evolves in neural pathways - i.e. learned from experiences? Or both?

And as to the previous paragraph - this is not to imply that gay=pedophiliac or anything else like that. First, I don’t care what people do with their equipment in their spare time. Also, as someone who has to wear glasses and take regular medication, I can’t criticize that sometimes nature does not follow the blueprint perfectly, and that’s no reason not to enjoy what you got.

[The_Great_Philosopher]

I’ve wondered this as well. Because - while I think gay people should be allowed to do whatever they want - from the perspective of the evolutionary drive, (strict) homosexuality is a mistake. From an evolutionary perspective the ‘purpose’ of living organisms is to foster the survival and propagation of our genes, and being strictly homosexual removes the possibility of propagation at a stroke. Yet there’s been significant numbers of gay people in every society and in every country, throughout history. How does a trait that contradicts evolution so directly become so common? I wonder the same thing about suicidal depression: it’s so horrible and so debilitating, it makes it so much harder to survive and propagate (committing suicide because of depression strikes me as basically the antithesis of the way organisms succeed through evolution), so why is it so common?

[The_Great_Philosopher]

Also, just to point out: it’s irrelevant whether homosexuality stems more from our genes or from our environment, ‘nature or nurture’. Either way, strict homosexuality is a characteristic which, in terms of evolution, seems like a singular mistake. So how is it that it’s managed to remain so common in human society? It’s one of those miraculous “against the odds” success stories when you think about it.

[Whack-a-Mole]

@Chronos

Another possible genetic explanation is that homosexuality might be an extreme manifestation of a trait that, in smaller doses, is beneficial for survival. For instance, there might be a gene which increases how much one is attracted to men. Such a gene would be associated with homosexuality in men, but with increased fecundity in women. Alternately, there might be a set of genes associated with male bonding. Get a small number of those genes, and you’re a pathetic loner. Get a moderate amount, and you can get along with other men well enough to do things like go on successful group hunts with them. Get a lot of those genes, and you end up gay.

Actually there is some compelling evidence out there for this.

Basically a gene that may help women may make men gay. Thing is females dominate the genetic lottery compared to the male (which may partly explain the greater prevalence of homosexual men versus women).

[T]he Y-chromosome is tiny by comparison with the X and only produces 20-odd proteins, mostly concerned with highly male-specific functions like sperm-production. The X, by contrast, has almost 1200 genes, with at least 150 implicated in intelligence and cognition. Look at it this way: if all the genes for being male were on the Y, no woman could ever have a beard! But because hardly any genes related to maleness are on the male chromosome, the vast majority must be on autosomes (the 22 non-sex chromosomes) or the X, which are of course carried by females. Such masculinizing genes could easily be turned on accidentally, explaining—and indeed predicting—bearded ladies.

But this is just the start of it. Because X-chromosome genes spend twice as much of their evolutionary history riding in female bodies rather than male ones (because mammalian females have two Xs and males only one), X-chromosome genes are selected to benefit females twice as often as they are selected to benefit males. Indeed, if an X-gene conferred at least twice as much benefit to a woman’s reproductive success as it inflicted costs on a male carrier’s, natural selection could not fix it. For example, there is now good evidence for genes on the X that increase the fecundity of their female carriers but make their male carriers homosexual. To the extent that such homosexual males may be feminized, the evolutionary insight explains the apparent paradox: sex-chromosome genes can be in conflict, and what is good for one sex is not necessarily good for the other.

SOURCE: http://www.psychologytoday.com/blog/the-imprinted-brain/201001/what-determines-sex

[rivulus]

@Chronos

As I understand it, what’s known so far:
The orientations of identical twins are not completely correlated, indicating that it’s not purely genetic.
The orientations of identical twins are, however, better-correlated than those of fraternal twins, indicating that it’s at least partly genetic.
And the orientations of fraternal twins are better-correlated than those of non-twin siblings, indicating that it’s at least partly dependent on the uterine environment.

@astro

I thought the latest research was that being gay had a lot less to do with genetic factors, and was, to a large extent, a random dice roll as a function of the inter-utero hormonal environment of the fetus at very specific time windows of development, with higher than normal concentrations of testosterone or estrogen (at those critical development points) tending to feminize or masculinize the mental development of the child.

IMO the mixed results suggest the activity of epigenetic switches. That is, the gay phenotype is partly genetically determined, but not entirely so. Epigenetic switches are:

…a network of chemical switches that sit on our DNA, turning genes off and on. Called collectively the epigenome, the switches appear to play a major role in everything from how our cells keep their identity to whether we contract dread diseases. Epigenetic switches may even help mold our personalities…

Elements in the environment, including hormones in utero, have an effect on gene expression. Maybe a real scientist can come along and explain this better. There’s also a recent Time magazine article (January 18, 2010) that explains this concept.

[Smeghead]

@The_Great_Philosopher

So how is it that it’s managed to remain so common in human society? It’s one of those miraculous “against the odds” success stories when you think about it.

No, it really really isn’t. As I stated before, there are many possible explanations that are perfectly consistent with current evolutionary theory. We don’t have a definitive answer because there’s so much we still don’t understand, but it’s really not a big issue.

[Illuminatiprimus]

@yorick73

Location, location, location! San Fran, New Orleans, and DC might be good places to start.

I suspect it’s actually down to me not trying very hard - I do live in London after all (not exactly known as a gay desert).

@The_Great_Philosopher

I’ve wondered this as well. Because - while I think gay people should be allowed to do whatever they want - from the perspective of the evolutionary drive, (strict) homosexuality is a mistake. From an evolutionary perspective the ‘purpose’ of living organisms is to foster the survival and propagation of our genes, and being strictly homosexual removes the possibility of propagation at a stroke. Yet there’s been significant numbers of gay people in every society and in every country, throughout history. How does a trait that contradicts evolution so directly become so common?

Traits are not passed on solely on the actions of the carrier though, genes are passed through families. I was listening to a radio programme today with Richard Dawkins discussing the evolutionary benefit to cooperation (specifically within families) because genes are shared amongst them so doing something that benefits others actually helps your genes too.

If a trait for cooperating with others cropped up and survived better than the “screw you, I’m out for myself only” types (and it seems to otherwise how did we end up in the packs/societies that we did?) then having an individual within a gene pool that has something that stops them reproducing directly doesn’t stop their genes being carried on through nurturing the offspring of others. I’m pretty sure someone said something to this effect upthread.

I wonder the same thing about suicidal depression: it’s so horrible and so debilitating, it makes it so much harder to survive and propagate (committing suicide because of depression strikes me as basically the antithesis of the way organisms succeed through evolution), so why is it so common?

No cite but I would take an educated guess that the majority of those are due to people growing up and living in a society that is (or certainly was) profoundly unaffirming of homosexuality, for a variety of pretty obvious reasons.

[panache45]

@Illuminatiprimus

As a gay man who hasn’t been in a relationship for well over a year, I think the question should be changed to “why aren’t there enough gay people?”.

Many guys would narrow it even further: “Why aren’t there enough Tops?”

[born_too_late]

@The_Great_Philosopher

I’ve wondered this as well. Because - while I think gay people should be allowed to do whatever they want - from the perspective of the evolutionary drive, (strict) homosexuality is a mistake. From an evolutionary perspective the ‘purpose’ of living organisms is to foster the survival and propagation of our genes, and being strictly homosexual removes the possibility of propagation at a stroke. Yet there’s been significant numbers of gay people in every society and in every country, throughout history. How does a trait that contradicts evolution so directly become so common? I wonder the same thing about suicidal depression: it’s so horrible and so debilitating, it makes it so much harder to survive and propagate (committing suicide because of depression strikes me as basically the antithesis of the way organisms succeed through evolution), so why is it so common?

Maybe it’s not a mistake at all - maybe there’s an environmental trigger built into the genes that suppress the ‘go forth and multiply’ directive. Sort of like there’s a trigger that determines the sex of certain amphibians and reptiles, is it possible that there is some population threshold that’s been reached that would make it optimal to begin curbing the reproductive rate of the species? Unlikely, but not impossible.

[Illuminatiprimus]

@panache45

Many guys would narrow it even further: “Why aren’t there enough Tops?”

Yeah, sucks that so many of us have to take turns doesn’t it?

[Chronos]

Quoth Whack-a-Mole:

Actually there is some compelling evidence out there for this.

Basically a gene that may help women may make men gay. Thing is females dominate the genetic lottery compared to the male (which may partly explain the greater prevalence of homosexual men versus women).

Interesting, when I’d heard of it it was just speculation. I wasn’t aware that they’d actually found empirical evidence.

[Horatio_Hellpop]

@bizerta

It’s just that gay people, by their very nature, don’t have hetrosexual sex, and so fail to have offspring and pass-on that trait.

A surprising number of people discover/acknowledge their homosexuality later in life after a good run of heterosexual activity, or keep plugging away at heterosexual behavior in denial of their homosexuality. For that matter, there’s Anne Heche. These categories aren’t as ironclad as we’d like to believe.

My niece, a lesbian, has a partner who’s pregnant. I didn’t press for details, but there are plenty of circumstances where a gay person can become a parent. And plenty more where he or she would want to.

[Chronos]

But it wouldn’t need to be “gay people don’t reproduce at all” for evolution to work on it. Anything that changes the likelihood that someone will reproduce will be affected by evolution, and I don’t think it’s much of a stretch to say that gay people reproduce less than straight people.

[Whack-a-Mole]

@Chronos

Quoth Whack-a-Mole:Interesting, when I’d heard of it it was just speculation. I wasn’t aware that they’d actually found empirical evidence.

Here’s one such study…bet there have been more.

**Evidence for maternally inherited factors favouring male homosexuality and promoting female fecundity.
**

The Darwinian paradox of male homosexuality in humans is examined, i.e. if male homosexuality has a genetic component and homosexuals reproduce less than heterosexuals, then why is this trait maintained in the population? In a sample of 98 homosexual and 100 heterosexual men and their relatives (a total of over 4600 individuals), we found that female maternal relatives of homosexuals have higher fecundity than female maternal relatives of heterosexuals and that this difference is not found in female paternal relatives. The study confirms previous reports, in particular that homosexuals have more maternal than paternal male homosexual relatives, that homosexual males are more often later-born than first-born and that they have more older brothers than older sisters. We discuss the findings and their implications for current research on male homosexuality.

SOURCE: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1691850/

[Illuminatiprimus]

So maybe homosexuality is a “break” on females who produce too many offspring? Can’t think how that would turn out to be an advantage though.

[Uncertain]

@born_too_late

is it possible that there is some population threshold that’s been reached that would make it optimal to begin curbing the reproductive rate of the species? Unlikely, but not impossible.

An allele that says “sacrifice your own reproduction for the good of the species” will be disfavored.

[Uncertain]

@rivulus

IMO the mixed results suggest the activity of epigenetic switches. That is, the gay phenotype is partly genetically determined, but not entirely so. Epigenetic switches are:
Elements in the environment, including hormones in utero, have an effect on gene expression. Maybe a real scientist can come along and explain this better. There’s also a recent Time magazine article (January 18, 2010) that explains this concept.

“Epigenetic switches” are just one way that genes are regulated. And although the fact that I speak English rather than Albanian is not genetic, I’m not sure that it’s helpful to attribute it to gene regulation (even though gene regulation is involved in memory and such).