Monday, March 12, 2012

A Fascinating Tidbit:

Here’s a fascinating little bit of information I’ve just come across. At least it’s fascinating to me. I discovered it in the Evolutionary Psychology Textbook I’m reading for my class this year. The book is by David Buss, and is Evolutionary Psychology, 4th edition, 2012.

For evolutionary psychologists, homosexuality, particularly male homosexuality, has been difficult to explain. Although you will sometimes hear the argument that male homosexuals don’t reproduce and thus couldn’t pass on any genetic characteristics that lead to homosexuality, that is clearly not the case. Many homosexuals do reproduce and have reproduced down through time. However, there are differential reproduction rates. On average, male homosexuals produce about a fifth the offspring that male heterosexuals do. So why does this orientation continue to occur?

The traditional theory to explain this has been “Kin Altruism Theory.” Basically, it says that if male homosexuals channel more of their resources to their biological relatives than heterosexuals do, then the increased survival rate of those relatives will also carry along the genetic components involved in homosexuality. This is an example of something called “Indirect fitness” (how many copies of your genes get passed on by being carried by relatives) rather than “direct fitness” (How many children you have who directly carry your genes).”

The Kin Altruism Theory has garnered some support, but there are also plenty of studies that don’t support it. For example, in the US, male homosexuals often report greater estrangement from their relatives than heterosexual males do. I’ve talked about this theory, though, in most classes where I’ve discussed the potential basis for homosexuality.

Now we come to something I’ve only recently learned, which may be a much bigger influence on the issue. It’s called the “Female Fertility Hypothesis.” It turns out that the female relatives of male homosexuals, particularly their mothers and their aunts, have significantly higher reproduction rates than the same female relatives for male heterosexuals. In other words, the genetic aspects of male homosexuality could be carried down through the maternal rather than the paternal lines. I would also guess that this apparently greater fertility is hormone related, and hormone variations, especially in the fetal period, may explain many aspects of homosexuality.

Now ain’t that kind of cool?
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32 comments:

Ron Scheer said...

I'm glad to know that science continues to find a place for homosexuality in human evolution. I worry, though, when there's talk of a genetic basis. If a gay gene is found, it seems a likely target for genetic engineers invested in eradicating it.

Deka Black said...

Serious and above all, delicate matter. i share the fears of Ron.The search for a "gay gene" is worrying. I can hear many people saying "Eradicate it!"

Charles Gramlich said...

Ron, I don't imagine they'll ever find a gay gene. It would just be too complicated an issue to be controlled by any one gene. What they are likely to find is a combination of genes that leads to certain hormonal effects.

Deka, to continue my response from Ron, I think there are often people who would misuse science for their own ends but we can't let that stop us from investigating questions. Also, a clear, or clearer, understanding of genetics will generally show that the concept of "eradication" itself is based on a misunderstanding of how genes work and how they interact with the environment. For example, say we were to try and eradicate the "aggressive" genes in humans. The result would be something that we wouldn't even recognize as humans and the remaining "race" would not likely survive. To eradicate any "homosexual" genetic elements from the human race would not likely be possible, and if it were it would be like pulling fibers out of a tapestry. The result would unravel.

Deka Black said...

Touché. Very big point. I think maybe is because most of everyday people is driven by emotions rather than facts.

Merisi said...

Truly fascinating theory. It seems quite logical, and I am surprised it has been brought up only recently.

The Golden Eagle said...

It is!

eric1313 said...

From what you were saying about hormone levels during certain periods of fetal growth, it is not in and of itself a gay gene, but a combination of many things that make up the basic biological development of all human beings. If it is eradicated, then we all are eradicated as well, I'd bet.

Sad thing is some people have proven to be more or less that crazy, historically speaking.

eric1313 said...
This comment has been removed by the author.
Charles Gramlich said...

Deka, it is a sensitive subject. I do try to teach the complexity of the topic to my students, most of whom aren't really clear on it.

Merisi, I'm not sure how old the idea is. I only heard of it recently. I don't think it's very old though.

Golden Eagle, science is kinda cool.

Eric1313, definitely not a gay gene. an interaction between certain combinations of genes, and hormone levels during specific periods. And the one thing it shows, to me, is that all human beings are a complex byproduct of biology and environment, and all of them are "natural," though not all the same.

JR's Thumbprints said...

This is definitely a heavy, thought-provoking theory ... I'm sure it'll generate all kinds of opinions too.

Angie said...

I remember seeing a TV show (with John Barrowman doing that episode, although I can't find it on his IMDB listing now) where they were investigating homosexuality. One of the things they discussed is that in men, a guy's more likely to be gay if he has older brothers. They said that a woman's body responds to a male fetus as an intruder, in a way; similar to how the immune system responds to a virus or something. It "attacks" hormonally, trying to make the thing more like itself. (I'm probably remembering badly, but hopefully you get the idea.)

As with other immune responses, once a body's been exposed to that particular type of invader, the next response will be stronger. So a second son is more likely to succumb to the hormonal attacks, as it were, and a third even more, etc. There's probably a genetic component in how the woman's system responds, and how strongly? [ponder]

Anyway, John's an only son, but they talked to his mom on the show and found out that she'd had a miscarriage before he was born, and that it would've been an older brother. Clearly not all second sons are gay, but it was interesting that it did work out in John's case, and he didn't know before the show. (Or I assume, before they started setting up for the show; they likely mentioned the birth-order thing and talked to his mom, then set up the filmed conversation to repeat it, since it was relevant in his case.)

But if this is one of the mechanisms for producing a gay man, then it might be a case of the cause and effect being reversed -- rather than gay men having female relatives who are more fertile, maybe more fertile women are more likely to have homosexual sons, and other male relatives, because their body's hormonal response gets a bit stronger each time they're pregnant with a boy.

Angie

Charles Gramlich said...

JR., indeed I would imagine.

Angie, I knew about the birth order effect, but hadn't thought about the "intruder" effect essentially. I'd have to give that some thought. Fascinating idea. Age of pregnancy might have something to do with it as well.

Ron Scheer said...

Thanks for generating the discussion, Charles. It's an important one.

Charles Gramlich said...

Ron, I think, although I know it won't be true for everyone, that if we begin to look at homosexuality as a "natural" behavior that is as biologically based as heterosexuality, then we will start to see an acceptance of the differences without looking for some simple "choice" that such an individual might have made.

Chris Benjamin said...

Fascinating actually. And reminds us again what we miss when we forget the female half of humanity...Just finished reading, along these lines, Mothers and Others - which I think you might like: http://www.goodreads.com/review/show/269017991

Charles Gramlich said...

Chris, hey, man, long time no see. I'll check it out. But you're right.

Richard Prosch said...

Interesting topic, indeed. I appreciate your scholarship as much as your fiction. You're a renaissance man, my friend.

Charles Gramlich said...

Richard, thanks, man.

ivan said...

This kind of jogs me, as a journeyman neurotic.

I know two and two is four, but I don't like it.

Sidebar:... "in the US, male homosexuals often report greater estrangement from their relative."

Hm. Old Calypso song: "I wonder why nobody don't like me."

Prashant C. Trikannad said...

Charles, a very fascinating theory! "The genetic aspects of male homosexuality could be carried down through the maternal rather than the paternal lines..." I hadn't thought of this aspect of homosexuality. Thanks for the scholarly post and comments.

Charles Gramlich said...

Ivan, I wonder if the estrangement is partially religiously based. Seems kind of odd.

Prashant, it's very interesting to me, but then I'm a biology fellow at heart.

the walking man said...

I would have to go with the gene or trait or whatever it is being passed from the female line. simply because there are other trait, like male pattern baldness that are passed from the mother to the son.


I have always though that homosexuality was an inborn trait not a nurtured phenomena.

As for exterminating the gay gene from the human genome then we would ALL regardless of orientation no longer be able to be quantified as truly human but some genus of of what used to be human.

Charles Gramlich said...

Mark, yes there are various traits, including personality traits that are passed through the female side. I agree absolutely with you last statement. Such beings wouldn't be humans as we understand them.

laughingwolf said...

not at all surprising to me, charles, since it was determined some years back the 'family line' is carried on through the female, ie. mother and her daughters, not the sons as was previously thought

that would partly explain why so many tribes were matriarchal; the women as 'chiefs' and other lead positions, including 'medicine women'...

often the gay son was seen as one with 'special spiritual powers', if mostly shunned

dunno if it's true, but somewhere i heard: of four sons, one will almost certainly be gay - not heard if it's the same with daughters

a friend has four sons, one is bi - maybe that counts?

then there's the finding - many birds/animals are queer... others, hermaphroditic... not heard the same about plants/insects; none are something i've researched

i suspect you're correct on the 'hormonal effects'

laughingwolf said...

hah... posted before i read mark's comment....

David Cranmer said...

Very intriguing, Charles.

Charles Gramlich said...

Laughingwolf, a woman's hormonal responses to pregnancy changes across pregnancies, which could be why younger sons are somewhat more likely to be gay than older sons. At least so the thinking goes.

David Cranmer, I'm coming upon lots of cool tidbits in this book.

Travis Cody said...

Sciences is pretty dang cool.

Steve Malley said...

That is indeed kind of cool... :p

Charles Gramlich said...

Travis cody, amen, brother.

Steve malley, yep indeed.

G said...

Wow, that's pretty interesting stuff. Shows how much I know... I majored in psychology, and I didn't even know there was a field called "evolutionary psychology."

Charles Gramlich said...

G, it's pretty new. Some aspects of it used to be called sociobiology.