Homosexuality

[angus]

Who cares? Live and let live.

when you were young and your heart was an open book...

[Torie]

I think, as others have noted that sexual preference could be shaped by environmental forces and it might be congenital, a trait you are born with, but not a genetic one.

One very strong argument against it being genetic is that, if it were, it would not lead to generational survival.  With some level of involvement of the opposite sex, humans cannot reproduce.  Throughout most of human history, that involved a heterosexual act.

Actually, a tribe having some gay men in it helped survival of the clan group, because they increased the survival rate of the young of the tribe by being sort of a social safety net as it were.  That is the theory anyway, and one I find persuasive.  It is very obvious to me that sexual preference along a continuum has a strong genetic component.

[ilikeverin]

I think, as others have noted that sexual preference could be shaped by environmental forces and it might be congenital, a trait you are born with, but not a genetic one.

One very strong argument against it being genetic is that, if it were, it would not lead to generational survival.  With some level of involvement of the opposite sex, humans cannot reproduce.  Throughout most of human history, that involved a heterosexual act.

Actually, a tribe having some gay men in it helped survival of the clan group, because they increased the survival rate of the young of the tribe by being sort of a social safety net as it were.

That's a hypothesis, yes, but group selection is junk science   Rather, you want to say something along the lines of "gay men helped the survival of gay genes, because they increased the survival rate of the young of the tribe who also had those gay genes (perhaps latent/recessive/what have you) by being a sort of social safety net".

[J. J.]

I think, as others have noted that sexual preference could be shaped by environmental forces and it might be congenital, a trait you are born with, but not a genetic one.

One very strong argument against it being genetic is that, if it were, it would not lead to generational survival.  With some level of involvement of the opposite sex, humans cannot reproduce.  Throughout most of human history, that involved a heterosexual act.

Actually, a tribe having some gay men in it helped survival of the clan group, because they increased the survival rate of the young of the tribe by being sort of a social safety net as it were.  That is the theory anyway, and one I find persuasive.  It is very obvious to me that sexual preference along a continuum has a strong genetic component.

How so?

[Verily]

I think, as others have noted that sexual preference could be shaped by environmental forces and it might be congenital, a trait you are born with, but not a genetic one.

One very strong argument against it being genetic is that, if it were, it would not lead to generational survival.  With some level of involvement of the opposite sex, humans cannot reproduce.  Throughout most of human history, that involved a heterosexual act.

Actually, a tribe having some gay men in it helped survival of the clan group, because they increased the survival rate of the young of the tribe by being sort of a social safety net as it were.  That is the theory anyway, and one I find persuasive.  It is very obvious to me that sexual preference along a continuum has a strong genetic component.

How so?

Having "spare" adults to assist in raising the children improves survivability. It fits with the idea that humans and other mammals have adopted the genetic survival strategy of having a low child-adult ratio and investing a lot in each child (compare, say, sea turtles or salmon, which instead having many offspring and invest very little in each child, relying on sheer numbers to continue the genetic line). Actually, it would be interesting to know if homosexuality has ever been documented in such a strength-in-numbers species.

An alternative possibility is that carriers for some genetic causes of homosexuality may be more fertile or have some other evolutionary advantage. (Similar to how carriers for sickle-cell anemia are immune to malaria, and female carriers of red-green colorblindness have greater ability to distinguish colors and better night-vision.) This is particularly strong for the theory that individuals themselves are not genetically homosexual, but their mothers have genes that make them predisposed to have gay children (through unusual womb conditions, etc.).

[J. J.]

That is interesting, but the high infant mortality rates should take care of that.

[Fmr President & Senator Polnut]

Who cares? Live and let live.

when you were young and your heart was an open book...

Damn it!!! It's going to be in my head all day now!!!

[Verily]

That is interesting, but the high infant mortality rates should take care of that.

"Take care of"? Who is to say what the ideal child-to-adult ratio is for survival of genes? The point is not simply to have a replacement for the inevitable early parents deaths--it might be better to have twelve adults raising twenty children than ten adults raising those same children.

(Ten adults might result in ten of the children surviving and having offspring, but the addition of two more childless adults might result in fifteen of the children surviving and having offspring--an enormous genetic advantage.)

[J. J.]

That is interesting, but the high infant mortality rates should take care of that.

"Take care of"? Who is to say what the ideal child-to-adult ratio is for survival of genes? The point is not simply to have a replacement for the inevitable early parents deaths--it might be better to have twelve adults raising twenty children than ten adults raising those same children.

(Ten adults might result in ten of the children surviving and having offspring, but the addition of two more childless adults might result in fifteen of the children surviving and having offspring--an enormous genetic advantage.)

I would think throughout most of human history, you'd have adults with fewer children because of infant mortality, though I can your point.

Also, I'm see that as helping survivability, but it wouldn't be passed on genetically. 

[Verily]

That is interesting, but the high infant mortality rates should take care of that.

"Take care of"? Who is to say what the ideal child-to-adult ratio is for survival of genes? The point is not simply to have a replacement for the inevitable early parents deaths--it might be better to have twelve adults raising twenty children than ten adults raising those same children.

(Ten adults might result in ten of the children surviving and having offspring, but the addition of two more childless adults might result in fifteen of the children surviving and having offspring--an enormous genetic advantage.)

I would think throughout most of human history, you'd have adults with fewer children because of infant mortality, though I can your point.

Not true at all. Families had a lot more children in the evolutionary past (pre-agriculture). Most did not survive to reproductive age, but that did not mean they weren't being raised.

You must be logged in to read this quote.

Yes, it would. We're talking small clan groups--everyone shares a lot of the same genes, some of which would be the genes related to homosexuality (which undoubtedly would be found, recessively carried or otherwise, in the heterosexual as well as homosexual members of the population).

[I spent the winter writing songs about getting better]

Democrat: genetic

Meaning it comes from God, so trying to suppress it is in the sin, not acting on it.

[J. J.]

That is interesting, but the high infant mortality rates should take care of that.

"Take care of"? Who is to say what the ideal child-to-adult ratio is for survival of genes? The point is not simply to have a replacement for the inevitable early parents deaths--it might be better to have twelve adults raising twenty children than ten adults raising those same children.

(Ten adults might result in ten of the children surviving and having offspring, but the addition of two more childless adults might result in fifteen of the children surviving and having offspring--an enormous genetic advantage.)

I would think throughout most of human history, you'd have adults with fewer children because of infant mortality, though I can your point.

Not true at all. Families had a lot more children in the evolutionary past (pre-agriculture). Most did not survive to reproductive age, but that did not mean they weren't being raised.

You must be logged in to read this quote.

Yes, it would. We're talking small clan groups--everyone shares a lot of the same genes, some of which would be the genes related to homosexuality (which undoubtedly would be found, recessively carried or otherwise, in the heterosexual as well as homosexual members of the population).

First, large families did occur in agricultural environments as well.  The ratio would be important; if a genetic homosexual preference accounted for 10% of the clan, how much of a difference would that make?

Second, even if recessive (and assuming an gay sexual preference doesn't switch on later in life), it still should be bred out. Some things, like sickle cell trait, actually help people survive to adulthood and procreate.

[Verily]

That is interesting, but the high infant mortality rates should take care of that.

"Take care of"? Who is to say what the ideal child-to-adult ratio is for survival of genes? The point is not simply to have a replacement for the inevitable early parents deaths--it might be better to have twelve adults raising twenty children than ten adults raising those same children.

(Ten adults might result in ten of the children surviving and having offspring, but the addition of two more childless adults might result in fifteen of the children surviving and having offspring--an enormous genetic advantage.)

I would think throughout most of human history, you'd have adults with fewer children because of infant mortality, though I can your point.

Not true at all. Families had a lot more children in the evolutionary past (pre-agriculture). Most did not survive to reproductive age, but that did not mean they weren't being raised.

You must be logged in to read this quote.

Yes, it would. We're talking small clan groups--everyone shares a lot of the same genes, some of which would be the genes related to homosexuality (which undoubtedly would be found, recessively carried or otherwise, in the heterosexual as well as homosexual members of the population).

First, large families did occur in agricultural environments as well.  The ratio would be important; if a genetic homosexual preference accounted for 10% of the clan, how much of a difference would that make?

I'm ignoring the agricultural period because it is too short to have had much impact on human evolution.

As for the latter question, that's basically impossible to know. It's a hypothesis (and one that's not easy to test). It does not seem an unreasonable proposition that there is an "ideal" adult-child ratio, however.

You must be logged in to read this quote.

You seem to have an extremely poor grasp of genetics. One does not need to be phenotypically expressive of a trait to pass down the genes related to that trait.

Sickle cell provides no advantages whatsoever to the person afflicted. In fact, before modern medicine, nearly every person with sickle cell died before reaching sexual maturity and thus had no descendants. The advantages of the sickle cell genes accrue, not to those afflicted, but to the carriers of the sickle cell genes who do not express the trait (because it is recessive). Thus, the genes survive among the carrier-relatives of the sickle cell-afflicted even though those who express the sickle cell phenotype generally do not have direct descendants.

There are two ways this could be true of homosexuality. (1) The genes related to homosexuality could provide direct genetic benefits to the carriers, like sickle cell does. (They might increase fertility, for example.) (2) Alternatively, the genes related to homosexuality could provide indirect benefits to the carriers. (Having homosexual relatives to increase the adult-child ratio might be a biological advantage.)

[Torie]

Verily, your body of posts above are most helpful and impressive in saying so well what would have taken me some time to think through and pound out on the keyboard. I just did the Reader's Digest version myself.  Thanks!

[ilikeverin]

Yeah, Verily's doing a better job than I ever could at explaining

[J. J.]

I'm ignoring the agricultural period because it is too short to have had much impact on human evolution.

As for the latter question, that's basically impossible to know. It's a hypothesis (and one that's not easy to test). It does not seem an unreasonable proposition that there is an "ideal" adult-child ratio, however.

We're still talking about 40-75 generations; I can see your argument even extending to that period.  I can see the extension of the child-adult ratio extending well into historical times.

You must be logged in to read this quote.

You seem to have an extremely poor grasp of genetics. One does not need to be phenotypically expressive of a trait to pass down the genes related to that trait.

Sickle cell provides no advantages whatsoever to the person afflicted. In fact, before modern medicine, nearly every person with sickle cell died before reaching sexual maturity and thus had no descendants. The advantages of the sickle cell genes accrue, not to those afflicted, but to the carriers of the sickle cell genes who do not express the trait (because it is recessive). Thus, the genes survive among the carrier-relatives of the sickle cell-afflicted even though those who express the sickle cell phenotype generally do not have direct descendants.
[/quote]

CS trait does; it weakens the effects of malaria.  There is an advantage to having the trait as you pointed out.  That advantage is that you survive long enough to breed and possibly pass the trait to your children.  It keeps the species alive in malaria prone areas, and it keeps the trait around to be passed on to future members of the species.  It might even permit someone with CCA to live long enough to pass the trait, but not the disease, to the next generation.

You must be logged in to read this quote.

The second argument is compelling, and could be broader than you suggest, but it doesn't really answer the first one.

If you have a trait that might be very advantageous, but it renders you unable to reproduce, it won't stay around after you die.  It it would be triggered later in life, "turned on" as it where, it would make sense.

Assume that the "gay gene" is g and the "straight gene" is s; the gay gene is recessive.

Parents:

gs and gs

Offspring:

gg (no children)
gs (children)
gs (children)
ss (children)

You are basically breeding out the gene, unless there is a substantial advantage of the gs over the ss.  I'm not seeing that evolutionary advantage.

[angus]

gg (no children)
gs (children)
gs (children)
ss (children)

you're assuming that all straight folks have children.  And that gay folks never do.  Both are demonstrably false.  For example, in my department there are 15 of us, all over 35 and, as far as I can tell, all straight.  Only 11 of us have any children.  Also, of the three closer personal friends I have who are definitely gay, one has had two biological children with his wife of nearly 20 years.  I don't know if these are "average" stats, but it's enough to disprove your assumption.  

[J. J.]

gg (no children)
gs (children)
gs (children)
ss (children)

you're assuming that all straight folks have children.  And that gay folks never do.  Both are demonstrably false.  For example, in my department there are 15 of us, all over 35 and, as far as I can tell, all straight.  Only 11 of us have any children.  Also, of the three closer personal friends I have who are definitely gay, one has had two biological children with his wife of nearly 20 years.  I don't know if these are "average" stats, but it's enough to disprove your assumption.  

I'm assuming most gay people don't pass on their genetics (at least in the clan environment Verily suggested).  We could assume a certain percentage of straight people don't procreate, and take that into account.  The the number of people that can procreate within the same gender, however, will be zero.

Now, something could change that zero.  If the g gene would either be triggered later or if it were not an exclusively "gay gene," it could explain it. 

[Joe Republic]

Harking back to the excerpt from a Psych textbook I posted back on Page 4, one of the emerging causation theories concerns hormonal disruption in the womb.  As we know, fetal development is an incredibly delicate process, dependent on perfectly coordinated timing.  If just one tiny thing happens differently, or not at all, it could very well have massive psychological and/or physiological repercussions throughout the person's eventual life.

The fetal disruption theory therefore posits that the delicate process of hormonal masculinization of male fetuses (since every fetus starts out as female) can sometimes take a different course, therefore leading to a differently sized medial anterior hypothalamus.  (Hetero men usually have more tissue here than homosexual men, who have roughly the same amount as females.)

So the jury is still out on whether fetal hormonal disruption is genetic in origin, or if there's a 'gay gene' at all.  Rather, it seems likely that male homosexuality is more of a biological 'accident' that took place in the womb.  A lot like cleft palates, if you'll pardon the comparison.

[angus]

I'm assuming most gay people don't pass on their genetics (at least in the clan environment Verily suggested).  We could assume a certain percentage of straight people don't procreate, and take that into account.  The the number of people that can procreate within the same gender, however, will be zero.

yes, I understand.  I came into this argument mid-way, and I don't necessarily buy into the pretext of this poll, but I'm checking up on it occasionally, and I just wanted to point out that not only don't straight people always achieve biological success, but also that gay people actually do. Sometimes.  Like I said, one-third of the close personal friends I have that are gay--not that I have many--have procreated in the usual way.  I mean, as long as we're pursuing this Mendel's Pea experiment, we need to keep that in mind.  So your simple model, which assumes zero biological success for homosexuals, must be modified if you're going to realistically carry on with this line of argument.

[Fmr President & Senator Polnut]

I recently read a very interesting book recommended by a friend on the studies related to sexuality over the past 40 years.

His hypothesis is this - there is no actual single gay-gene - so in reality no trait to be passed on - but what does seem to happen is a flood of hormones at a key stage in the foetus' development that triggers an effect in a key part of the hyper-thalamus which control the more primal sexual attraction - which gives a gay man all of the testosterone of a man, and the same physical and sexual development of a man - but with a similar portion of the hyper-thalamus to that of a woman. So they end up finding those traits about men sexually arousing as well as triggered to 'nest' with a man rather than a woman.

Honestly, it's the most reasonable option out there I've heard.

[ilikeverin]

Sigh.  Just because there is no one gay gene does not mean there are none, or that homosexuality is not heritable.  That's like saying height isn't heritable, because there is no one height gene.  In fact, we hardly have any specific genes we can point to, at all, and call a "height gene", and the one we do know, with a certainty, influences height appears to change it by about a centimeter.

And differences in gross brain size are just correlational.  We don't know if fetal environment changes brain size, or if brain size influences fetal development, or if both brain size and fetal development are affected by some third factor (genetics?).

[Fmr President & Senator Polnut]

Lol... I said the in-utero hormonal theory makes the most sense... to me.

It's quite plausible that there is a heredity element - even if there isn't a clear genetic connection that doesn't mean that homosexuality isn't naturally occurring and inate to someone from the time they're born - and a non-changeable part of who a person is.

[Joe Republic]

Funny, Polnut and I posted much the same thing within three hours of each other.

[J. J.]

Lol... I said the in-utero hormonal theory makes the most sense... to me.

It's quite plausible that there is a heredity element - even if there isn't a clear genetic connection that doesn't mean that homosexuality isn't naturally occurring and inate to someone from the time they're born - and a non-changeable part of who a person is.

I think that might be the more logical conclusion, congenital factor.  It is not inheritable (but there may be a genetic predisposition), but there are some prenatal factors.  I would not rule out a learned trait, like first language, either.

I do doubt that sexual preference is a choice, though (excluding rape) sexual activity is.