Evolutionary Explanation for Homosexuality

[The Nihilist]

http://www.sciencedaily.com/releases/2008/06/080617204459.htm

 

[sbvera13]

I'd heard about the fertility/homosexuality link before, and it's good to see more progress in the study.

Of course, you realize that we're just giving the fundies more ammunition. "Evolution is evil and promotes sin! See! They're saying gay is good!" I can hardly wait.

 

[True_Blue]

The article is incomprehensible. It looks like they're on a fishing trip for an explanation. Over a long time horizon, any trait that reduces fertility will be eradicated by natural selection. If homosexuality reduces fertility by any assumed percentage, even if low (rather than 50-100%, as is more likely), then at each successive generation, the incidence of any mythical gay gene will assymptotically approach ZERO.

 

[True_Blue]

http://www.sciencedaily.com/releases/2008/06/080617204459.htm

As an encore, I would like to point out that the methodology used by the researchers is a process of elimination based on a faulty assumption. Check out this quote:

"To discover and clarify the dynamics of the genetic factors for homosexuality, the researchers had to screen a large set of models and exclude them one by one. They concluded that the only possible model was that of sexually antagonistic selection. The other models did not fit the empirical data, either implying that the alleles would become extinct too easily or invade the population, or failing to describe the distribution patterns of male homosexuality and female fecundity observed in the families of homosexuals. Only the model of sexually antagonistic selection involving at least two genes -- at least one of which must be on the X chromosome (inherited in males only through their mother) -- accounted for all the known data."

So the assumption of the researchers was that genes explain male gayness, and from that assumption, only one model could possibly work.

I happen to believe that homosexuality is an addiction, just like alcoholism, smoking, chewing fingernails, etc. People become addicted to pornography, and homosexuality is no different. In the last few months, some studies are showing that environmental parameters switch genes for certain behaviors in higher life forms (like caring for young) on and off. We may find that exogenous environmental factors cause genes that control human sexual behavior to be expressed or not expressed. In other words, the genetic component may be what makes addictions of all sorts so intractable and so difficult to overcome, but the genetic component itself is not the prime CAUSE of the behavior in the first place.

A close friend of mine disclosed to me that he tried quitting smoking a dozen times. When he finally quit smoking, he had the desire to smoke for almost a year. After one year, he had a sudden, overpowering urge to smoke. When he successfully resisted that urge, the desire dissipated completely and he was back to normal. I predict that a homosexual or a porn addict who successfully resists urges to gratify their desire for porn or the desire to have sex with members of the same sex can find restoration with patience. A year (perhaps more or perhaps less, depending on the individual) is a long time to fight the urge, but it's worth the effort.

 

[TeddyKGB]

The article is incomprehensible. It looks like they're on a fishing trip for an explanation. Over a long time horizon, any trait that reduces fertility will be eradicated by natural selection. If homosexuality reduces fertility by any assumed percentage, even if low (rather than 50-100%, as is more likely), then at each successive generation, the incidence of any mythical gay gene will assymptotically approach ZERO.

The confluence of factors is beyond your immediate grasp, and you can't simply dismiss the entire study by distilling it into a handwavable sound bite.

Please stop trying to portray yourself as an immediate expert on every single bit of evidence that arises.

 

[Bombila]

The article is incomprehensible. It looks like they're on a fishing trip for an explanation. Over a long time horizon, any trait that reduces fertility will be eradicated by natural selection. If homosexuality reduces fertility by any assumed percentage, even if low (rather than 50-100%, as is more likely), then at each successive generation, the incidence of any mythical gay gene will assymptotically approach ZERO.

I'll go out on a limb and suggest the article is incomprehensible to you.

From the article: This changed when previous work by Camperio Ciani and collaborators, published in 2004, showed that females in the maternal line of male homosexuals were more fertile than average.

The proposed reduction in fertility is in males. The thesis of the study is that fertility in females is increased by the same mechanism, therefore the decrease in male fertility as an effect of the same trait as expressed in males is of little consequence. Women who have the trait would bear more children than average, thereby increasing the number of descendents bearing their genes, and, since women ultimately bear the children, increasing the population overall. Increased fertility in some females is a positive reproductive strategy, both for the females whose DNA is propagated and for the growth rate of the general population.

While further studies may not uphold this theory, it makes perfect sense and is worth further investigation.

 

[Naraoia]

So the assumption of the researchers was that genes explain male gayness, and from that assumption, only one model could possibly work.

No, the assumption was that genes are involved. I don't think anyone assumed that they are the cause. And the question was why certain genes don't go extinct even though they can lead to such a detrimental phenotype. It's irrelevant if they do that in conjunction with environmental triggers - if the trait manifests at all, it is subject to natural selection.

I happen to believe that homosexuality is an addiction, just like alcoholism, smoking, chewing fingernails, etc.

And why should anyone care what you believe?

People become addicted to pornography, and homosexuality is no different. In the last few months, some studies are showing that environmental parameters switch genes for certain behaviors in higher life forms (like caring for young) on and off. We may find that exogenous environmental factors cause genes that control human sexual behavior to be expressed or not expressed. In other words, the genetic component may be what makes addictions of all sorts so intractable and so difficult to overcome, but the genetic component itself is not the prime CAUSE of the behavior in the first place.

What does "not the prime cause" mean in this context? If the person wouldn't have become homosexual without certain alleles then they are as indispensable (in fact, probably more so) than environmental triggers.

BTW, homosexuals' brains are more similar to the brain of the opposite sex in some respects (including overall shape and symmetry). See New Scientist on 21 June (or the study they report on in PNAS):

Most notably, they found that lesbian women and straight men had asymmetric brains, with the right hemisphere slightly larger than the left. Gay men, meanwhile, had symmetrical brains like those of straight women.

Secondly, they used scans based on positron emission tomography (PET) to measure blood flow to the amygdala [explanation of what the amygdala is]. The images revealed how the amygdalas are connected to other parts of the brain, giving clues to how this might influence behaviour. They found that the patterns of connectivity in gay men matched those of straight women, and vice versa.

Even though,

...as Savic herself acknowledges, the study can't say whether the brain differences are genetic, or result from unusually high or low exposure in the womb to sex hormones such as testosterone.

it doesn't seem like these people can do much about it. It would probably be like a straight person trying to fight their straightness.

I predict that a homosexual or a porn addict who successfully resists urges to gratify their desire for porn or the desire to have sex with members of the same sex can find restoration with patience. A year (perhaps more or perhaps less, depending on the individual) is a long time to fight the urge, but it's worth the effort.

What do you base your prediction on? Is there any evidence that homosexuality is like porn addiction?

 

[Naraoia]

I'll go out on a limb and suggest the article is incomprehensible to you.

From the article: This changed when previous work by Camperio Ciani and collaborators, published in 2004, showed that females in the maternal line of male homosexuals were more fertile than average.

The proposed reduction in fertility is in males. The thesis of the study is that fertility in females is increased by the same mechanism, therefore the decrease in male fertility as an effect of the same trait as expressed in males is of little consequence. Women who have the trait would bear more children than average, thereby increasing the number of descendents bearing their genes, and, since women ultimately bear the children, increasing the population overall. Increased fertility in some females is a positive reproductive strategy, both for the females whose DNA is propagated and for the growth rate of the general population.

While further studies may not uphold this theory, it makes perfect sense and is worth further investigation.

Exactly what I was about to say.

From the introduction of the PLoS paper:

Other fundamental empirical observations connected to male homosexuality indicate the existence of characteristic ‘pedigree asymmetries’ concerning (a) male sexual orientation, and (b) female fecundity. Specifically, male homosexuality is higher in the maternal line of homosexuals, relative to all other parental lines of either homo- and heterosexuals ([2], [4], [10]–[13], [24], but see [1]). Recent research has also associated a higher female fecundity to male homosexuality: indeed, it was found that homosexuals' mothers are more fecund than mothers of heterosexuals [2], [6], [31]–[33]. Further female fecundity asymmetries include a higher fecundity of maternal vs. paternal aunts of homosexuals [2], [32], [33] (see also below).

(emphasis mine) True_Blue, feel free to explore the references.

A trait doesn't have to give an advantage to every single carrier to be preserved. The sickle cell trait is the classic example, and it seems male homosexuality is another (I wonder if female homosexuality is similar).

 

[Bombila]

Thanks for the references, Naraoia.

I'm curious as well about whether a sex-linked trait can be found in female homosexuals. I think we are just beginning to understand some of the significance of family structure (sexual orientation being just one factor) and how it relates to reproductive success.

I remember a few years ago reading studies regarding the importance of maternal grandmothers to the survival rates of male children. (I just did a search for that study and unfortunately the papers that look like they may be relevant are behind walls.)

I don't know if any studies have been done regarding the influence of aunts on child survival, or the general fertility of lesbians, but it seems plausible that more childless aunts (and maybe childless uncles) might be a positive for children.

Anecdotally (as in, true in North America to my knowledge within the last hundred years), in agrarian populations where extended families remained out of necessity with the family land, unmarried childless aunts and uncles almost always remained with and contributed to the core family. That has to have been a largely positive factor, and it is certainly likely that a good proportion of these individuals were homosexual, whether expressed or acted upon or not.

 

[Naraoia]

I don't know if any studies have been done regarding the influence of aunts on child survival, or the general fertility of lesbians, but it seems plausible that more childless aunts (and maybe childless uncles) might be a positive for children.

Anecdotally (as in, true in North America to my knowledge within the last hundred years), in agrarian populations where extended families remained out of necessity with the family land, unmarried childless aunts and uncles almost always remained with and contributed to the core family. That has to have been a largely positive factor, and it is certainly likely that a good proportion of these individuals were homosexual, whether expressed or acted upon or not.

The paper in PLoS ONE mentions kin selection as a refuted hypothesis with regards to maintaining homosexuality. Though I didn't read the relevant references, so I can't really say just how refuted it is.

 

[True_Blue]

Exactly what I was about to say.

From the introduction of the PLoS paper: (emphasis mine) True_Blue, feel free to explore the references.

A trait doesn't have to give an advantage to every single carrier to be preserved. The sickle cell trait is the classic example, and it seems male homosexuality is another (I wonder if female homosexuality is similar).

I can't help but think that "fecundity" is a synonym for promiscuity. If so, then it makes sense that women who are promiscuous will find that their children are statistically more sexually unconstrained than the control group. We already know that children share many behavioral traits in common with their parents. It's scary watching how my daughters' behaviors resemble those of my wife and I. The best way to teach character, good manners, and good behavior to their children is to BE a person with good character, good manners, and good behavior.

Also, the relationship between genes expression and environmental parameters is just barely being explored isn't well known. Much research is needed. I would be unsurprised if homosexuality has a genetic component that is triggered by environmental factors, especially child-rearing and exposure to sexual activity. I would also be unsurprised if homosexuality were exclusively behavioral and not genetic at all. But I would be surprised if homosexuality were exclusively genetic and not at all behavioral. People have free will, and there isn't a gene that makes a person go out into the world and have anal sex. We are thinking, reasoning human beings, and we can control our behaviors, even if our internal thoughts are mostly intractable.

 

[Naraoia]

I can't help but think that "fecundity" is a synonym for promiscuity.

Sorry to disappoint you, "fecundity" in biology is simply the number of offspring.

If so, then it makes sense that women who are promiscuous will find that their children are statistically more sexually unconstrained than the control group.

How does it make sense? And, while I would understand if the children of such women were more likely to be promiscuous (with genetic components/role models/whatnot), what does that have to do with homosexuality? It's two completely different aspects of sexual behaviour.

We already know that children share many behavioral traits in common with their parents. It's scary watching how my daughters' behaviors resemble those of my wife and I. The best way to teach character, good manners, and good behavior to their children is to BE a person with good character, good manners, and good behavior.

All this assuming that promiscuity is not "good character" and "good behaviour". What, apart from a certain religious moral code, makes you conclude that?

Also, the relationship between genes expression and environmental parameters is just barely being explored isn't well known. Much research is needed. I would be unsurprised if homosexuality has a genetic component that is triggered by environmental factors, especially child-rearing and exposure to sexual activity. I would also be unsurprised if homosexuality were exclusively behavioral and not genetic at all.

I would be very surprised at the latter.

But I would be surprised if homosexuality were exclusively genetic and not at all behavioral.

I don't know if I would be surprised. It all depends on what the genes that influence its likelihood do.

People have free will,

Your "free will" can do nothing against Huntington's or a whole number of other genetic conditions involving the brain. It's a very real possibility that it can do just as little against some more complex and less devastating traits.

and there isn't a gene that makes a person go out into the world and have anal sex.

Which heterosexuals engage in just like homosexuals do.

We are thinking, reasoning human beings, and we can control our behaviors, even if our internal thoughts are mostly intractable.

I think you have an overly idealistic view of mankind.

 

[True_Blue]

All this assuming that promiscuity is not "good character" and "good behaviour". What, apart from a certain religious moral code, makes you conclude that?

If you're not convinced that promiscuity is bad behavior, then we don't share a common enough perspective on life to talk about homosexuality. I've written extensively and done a lot of analysis on why I believe homosexuality is wrong, independent of the Bible, but such analysis isn't going to persuasive. For us to have a conversation on this topic, I need to know whether you place any limits whatsoever on voluntary human sexual conduct, or if you place any limits on your own sexual behavior. If so, then I may reconsider and send you my thoughts.

 

[Psudopod]

If you're not convinced that promiscuity is bad behavior, then we don't share a common enough perspective on life to talk about homosexuality. I've written extensively and done a lot of analysis on why I believe homosexuality is wrong, independent of the Bible, but such analysis isn't going to persuasive.

Why not? if you have evidence, it should stand on its own merits.

For us to have a conversation on this topic, I need to know whether you place any limits whatsoever on voluntary human sexual conduct, or if you place any limits on your own sexual behavior. If so, then I may reconsider and send you my thoughts.

You've described pretty much every human alive. Everyone has things they will do, and things that they feel uncomfortable with. That someone personally chooses not to do something doesn't necessarily make it wrong.

 

[Naraoia]

If you're not convinced that promiscuity is bad behavior, then we don't share a common enough perspective on life to talk about homosexuality.

Really? Maybe you could help me understand your point of view. If you try to convince me with arguments and I still don't agree with you - maybe then you can give up. But I don't see why you would walk away without even trying.

I've written extensively and done a lot of analysis on why I believe homosexuality is wrong, independent of the Bible, but such analysis isn't going to persuasive.

How do you know that in advance?

For us to have a conversation on this topic, I need to know whether you place any limits whatsoever on voluntary human sexual conduct, or if you place any limits on your own sexual behavior. If so, then I may reconsider and send you my thoughts.

Well, I'm definitely against abusive sexual conduct. Other than that, I think it's people's own lives. As long as they don't cause harm in the process (and as long as they don't do it in front of me ) they can be as promiscuous and as naughty and as extreme as they like. Which doesn't mean I personally like some of the things people do - but I don't label something Wrong just because it's against my personal taste. As for my own private life, forgive me if I don't detail that to any random stranger. Suffice it to say I place stricter limits on myself than I do on other people.

 

[Bombila]

If you're not convinced that promiscuity is bad behavior, then we don't share a common enough perspective on life to talk about homosexuality. I've written extensively and done a lot of analysis on why I believe homosexuality is wrong, independent of the Bible, but such analysis isn't going to persuasive. For us to have a conversation on this topic, I need to know whether you place any limits whatsoever on voluntary human sexual conduct, or if you place any limits on your own sexual behavior. If so, then I may reconsider and send you my thoughts.

Good grief, TrueBlue: you've just demonstrated that you thought 'fecund' means 'promiscuous', which couldn't be much further from the actual meaning, and you expect people to think you capable of analysis of the rights and wrongs of reproductive/sexual behaviour? How many more words relevant to such a discussion are you cloudy on the meaning of?

I think even those of us most at ease with a wide range of sexual behaviours are able to recognize that some behaviours are harmful, and some of those harmful behaviours can be labelled promiscuous, others just unsafe. Any 'analysis' from you would likely be peculiar and punitive from the start - you're the person that advocates rape victims be forced into a sham marriage with their rapists, with family vigilantism as their only hope for a normal life thereafter.

 

[True_Blue]

Good grief, TrueBlue: you've just demonstrated that you thought 'fecund' means 'promiscuous', which couldn't be much further from the actual meaning, and you expect people to think you capable of analysis of the rights and wrongs of reproductive/sexual behaviour? How many more words relevant to such a discussion are you cloudy on the meaning of?

I think even those of us most at ease with a wide range of sexual behaviours are able to recognize that some behaviours are harmful, and some of those harmful behaviours can be labelled promiscuous, others just unsafe. Any 'analysis' from you would likely be peculiar and punitive from the start - you're the person that advocates rape victims be forced into a sham marriage with their rapists, with family vigilantism as their only hope for a normal life thereafter.

Fecunity and promiscuity clearly mean different things. I was attempting (and apparently failed) to make a subtle point to a subtle article that gene-linked homosexuality is related to increased female fecundity. This begs the question as to whether increased fecundity is itself related to genes, or related to behavior. A promiscuous mother is certain to have higher fecundity than the average population (provided abortions are included in the fecundity metric). It is a fact that children, just like animals, learn behavioral traits from parents. My theory, which I'm certain is backed up with amble documentation, is that if their mother is promiscuous, children are more likely to be promiscuous as well, whether that promiscuity is manifested as promiscuous heterosexual conduct, or homosexual conduct, whether or not promiscuous. If true, then the article's central point that homosexuality is gene-linked may not be true. Of course, the underlying reason to print an article on gene-related homosexuality is to argue that homosexuality is involuntary. It may be that a person's sexual acts or thoughts cause otherwise dormant genes to be expressed, meaning that even though genes are involved, the genes are not the true cause. And even if the genes are the true cause, mere genes cannot turn a person into an involuntary slave to homosexual sex. Our conscious mind controls where our feet go, even if our desires tempt us to engage in a particular type of sex.

I've laid out a multifaceted rebuttal against this article. To prove involuntariness, all of the rebuttals must collectively be disproved, and I don't believe such a thing is possible. Homosexuals are not slaves, they are not robots, and they are not insane.

 

[Bombila]

Fecunity and promiscuity clearly mean different things. I was attempting (and apparently failed) to make a subtle point to a subtle article that gene-linked homosexuality is related to increased female fecundity. This begs the question as to whether increased fecundity is itself related to genes, or related to behavior. A promiscuous mother is certain to have higher fecundity than the average population (provided abortions are included in the fecundity metric). It is a fact that children, just like animals, learn behavioral traits from parents. My theory, which I'm certain is backed up with amble documentation, is that if their mother is promiscuous, children are more likely to be promiscuous as well, whether that promiscuity is manifested as promiscuous heterosexual conduct, or homosexual conduct, whether or not promiscuous. If true, then the article's central point that homosexuality is gene-linked may not be true. Of course, the underlying reason to print an article on gene-related homosexuality is to argue that homosexuality is involuntary. It may be that a person's sexual acts or thoughts cause otherwise dormant genes to be expressed, meaning that even though genes are involved, the genes are not the true cause. And even if the genes are the true cause, mere genes cannot turn a person into an involuntary slave to homosexual sex. Our conscious mind controls where our feet go, even if our desires tempt us to engage in a particular type of sex.

I've laid out a multifaceted rebuttal against this article. To prove involuntariness, all of the rebuttals must collectively be disproved, and I don't believe such a thing is possible. Homosexuals are not slaves, they are not robots, and they are not insane.

My bolding in above quote - B

Clearly you are pulling this out of your hat. It is a fact that until the last two generations in any part of Francophone Canada, the most fecund population of women were devout Catholic farmers' wives. It was not uncommon for them to bear fifteen or more living children. I had friends whose siblings numbered twenty-one, sixteen, twelve, and six or seven was a common number.

Presently, the most fecund women appear to be the very Christian 'quiverfull' families. In fact, any population which refuses to use conventional birth control and is generally in good health will prove to be fecund, to greater or lesser degree influenced by genetic pre-disposition to be fecund.

Modern promiscuous women (I am applying your likely standards of 'having many sexual partners') are likely to use birth control and limit the numbers of their children. You may be able to find poverty-stricken and crime-ridden neighbourhoods in some US cities where promiscuous women may have five or six children, but those areas are exceptional.

There is no evidence that I've ever seen that homosexuality can be paired with a promiscuous mother, or with wealth or poverty, or with any specific groups. Homosexuality occurs at much the same rate throughout the population.

I think you will also find that figures for promiscuity among homosexual men are exaggerated, the statistics were generated from contact with a young urban population within the gay community known to be promiscuous, and not likely representative of homosexuals in the greater population, and certainly not true of homosexual women.

Of course homosexuals are not slaves or insane, but they are human. Try to imagine convincing yourself that you are sexually attracted to men, and that women are not in the least desireable. Do you think you could do that? Maintain it for the rest of your life? Marry and convince your partner that you find him desireable, even while you are inwardly repulsed by this intimacy? Your only other choice is a life without a family, celibate and lonely.

 

[True_Blue]

My bolding in above quote - B

Clearly you are pulling this out of your hat. It is a fact that until the last two generations in any part of Francophone Canada, the most fecund population of women were devout Catholic farmers' wives. It was not uncommon for them to bear fifteen or more living children. I had friends whose siblings numbered twenty-one, sixteen, twelve, and six or seven was a common number.

Presently, the most fecund women appear to be the very Christian 'quiverfull' families. In fact, any population which refuses to use conventional birth control and is generally in good health will prove to be fecund, to greater or lesser degree influenced by genetic pre-disposition to be fecund.

Modern promiscuous women (I am applying your likely standards of 'having many sexual partners') are likely to use birth control and limit the numbers of their children. You may be able to find poverty-stricken and crime-ridden neighbourhoods in some US cities where promiscuous women may have five or six children, but those areas are exceptional.

There is no evidence that I've ever seen that homosexuality can be paired with a promiscuous mother, or with wealth or poverty, or with any specific groups. Homosexuality occurs at much the same rate throughout the population.

I think you will also find that figures for promiscuity among homosexual men are exaggerated, the statistics were generated from contact with a young urban population within the gay community known to be promiscuous, and not likely representative of homosexuals in the greater population, and certainly not true of homosexual women.

Of course homosexuals are not slaves or insane, but they are human. Try to imagine convincing yourself that you are sexually attracted to men, and that women are not in the least desireable. Do you think you could do that? Maintain it for the rest of your life? Marry and convince your partner that you find him desireable, even while you are inwardly repulsed by this intimacy? Your only other choice is a life without a family, celibate and lonely.

You know, Bombila, I actually do agree with what you've written above, and it certainly partially refutes a couple of my points. Hats off! My own mom, a devout Christian and by no means promiscuous, had five kids. You're also correct that studies on homosexuality and family circumstances seem generally to point to absent or inadequate fathers, and/or doting or domineering mothers, not to the woman's sexual behavior.

However, one cannot be a Christian and enjoy fellowship with God without denying self. I have certain intractible evil habits that I'm presently having great difficulty overcoming. I don't think homosexuals can exempt themselves from life's struggles and from struggling with sin. There's is simply a different type of sin. All of us have internal wiring that virtually compels us to sin to a certain extent. That powerful compulsion, however strong it is, does not override our free will. We have a duty as humans to resist our unhealthy urges, whether for drugs, food, sex, lying, cheating, money, whatever, and do the right thing. The desire to resist is what defines a person's character, not the thing they personally have trouble with.

 

[True_Blue]

Of course homosexuals are not slaves or insane, but they are human. Try to imagine convincing yourself that you are sexually attracted to men, and that women are not in the least desireable. Do you think you could do that? Maintain it for the rest of your life? Marry and convince your partner that you find him desireable, even while you are inwardly repulsed by this intimacy? Your only other choice is a life without a family, celibate and lonely.

Tragically, I myself no longer find my wife very sexually attractive. Same is true for a lot of other husbands. That doesn't give me a license to go out and have affairs with younger, more beautiful women. Homosexual married men ought not to pretend that they have special status or special privileges because they find themselves attracted to other men. We all have a duty of sexual and marital faithfulness, regardless of our particular reasons for desiring otherwise.