Natural Selection and the Genetic Basis for Homosexuality

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posted on Oct, 19 2008 @ 01:55 PM
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This is not a moral or religious statement of any sort . It is a purely scientific question.

First let's define a couple terms:

From wiki on natural selection



Natural selection is the process by which favorable heritable traits become more common in successive generations of a population of reproducing organisms, and unfavorable heritable traits become less common, due to differential reproduction of genotypes. Natural selection acts on the phenotype, or the observable characteristics of an organism, such that individuals with favorable phenotypes are more likely to survive and reproduce than those with less favorable phenotypes.

en.wikipedia.org...

And on the wiki article on homosexuality, they Gay rights movement is attempting to assert that homosexuality has a genetic origin:



The genetic basis of animal homosexuality has been studied in the fly Drosophila melanogaster. Here, multiple genes have been identified that can cause homosexual courtship and mating.These genes are thought to control behavior through pheromones as well as altering the structure of the animal's brains. These studies have also investigated the influence of environment on the likelihood of flies displaying homosexual behavior.

en.wikipedia.org...


Natural selection works by favoring the organisms with traits that favor the ability to successfully reproduce. If the genetic basis for human homosexuality is real and man has truly evolved over a process of millions of years, why would we have any homosexuals today? Why wouldn't natural selection have eliminated those genes long long ago? They certainly work in direct opposition to each other. Over a period of millions of years of evolution the trait should have been eliminated.

I think it is a logically incoherent and unscientific position to believe in both human evolution by natural selection and the genetic basis for homosexuality. At least one of the two theories must be false. How can you be intellectually honest and reconcile these two contradictory beliefs?




posted on Oct, 19 2008 @ 02:02 PM
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One theory that's been presented is that homosexuality is a natural safeguard against overpopulation. When a sort of critical mass is reached, the "Gay gene" if we can call it that, is triggered, thereby encouraging the population level to become more managible.



posted on Oct, 19 2008 @ 02:07 PM
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Here ya go...




Genes handed down by one's mother and having a large number of older brothers may determine whether someone is a homosexual, according to a study published.
Put together, these two factors may account for perhaps 20 percent of the prevalence of homosexuality, although social and cultural influences probably make up most of the rest, it suggests.
Psychologists at the University of Padova asked 98 homosexual men and 100 heterosexual men in northern Italy to fill out a confidential questionnaire detailing their sexual orientation and that of their siblings, first cousins, parents, aunts, uncles and grandparents.
Among the homosexuals, 22 out of the 396 male relatives on the maternal line of their family were gay, as were 12 out of 593 on the paternal side.
Among the heterosexuals, none of the 370 male relatives on the maternal line was gay; on the paternal line, the number was eight out of 604.
Just as striking was the relationship between birth order and sexual orientation.
In large families, homosexuals were likelier to have been born second, third, fourth or later, and were far likelier to have older male siblings rather than older sisters.
The study, led by Francesca Corna, says this adds statistical support to hypotheses about possible genetic causes for homosexuality, although it did not investigate homosexuality in women.
Previous research, carried out among gay brothers, suggests a link between homosexuality and a genetic sequence called Xq28 on one of the arms of the X chromosome, one of the chromosomes that determines sex.
Men have an X chromosome, which comes from their mother, and a Y chromosome, from their father. Women have two X chromosomes, one from each parent.
Research published in the mid-1990s bred the theory, strongly contested by some, that the male foetus presents an antigen, a molecule that triggers a response from the woman's immune system.
With each successive male birth, the mother is successively immunized against this antigen and the subsequence chemical change in the uterus has an effect on the sexual differentiation of the fetus, according to this idea.
An architect of this hypothesis, Canadian scientist Ray Blanchard, has calculated that each additional older brother increases the odds of homosexuality in the next male by some 33 percent...
While acknowledging that the Nature versus Nurture debate about homosexuality will continue to rage, the authors believe they may have resolved one of the enigmas about homosexuality.


Keep reading!


This is the so-called Darwinian paradox: if homosexuality is conferred in part by genes, why haven't these genes been progressively eliminated over the millennia by natural selection -- the process that prefers genes which are useful for reproduction and survival?
The answer could lie in Xq28, for the mothers of homosexuals could be exceptionally fertile.
In other words, this particular genetic variation is a Darwinian tradeoff -- there is low or zero fecundity among men because they are homosexuals, but high fecundity among women.

The study appears in Proceedings of The Royal Society B, a journal published by the Royal Society, Britain's leading scientific association.



read more here



...taps...

[edit on 19-10-2008 by silo13]

Mod edit:Replaced quote tags with external tags.
Mod Edit: New External Source Tags – Please Review This Link.


[edit on 19-10-2008 by GAOTU789]



posted on Oct, 19 2008 @ 02:14 PM
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Cancer is said to sometimes have a genetic basis, along with a lot of other conditions which limit the capacity to reproduce, but those conditions are still around today. One theory I've heard, which I haven't looked into much, is the prenatal hormone thing, in which case there wouldn't be a genetic basis but a hormonal one, which would still mean the person wouldn't have control over it.

Just looking quickly I found that if one brother of an identical twin is gay, there's a 52% chance the other will be gay also. That sounds pretty genetic to me. Gay's brains are more similar to women than straights and same with lesbians, something genetic or hormonal is going on there.

worldpolicy.org...

[edit on 19-10-2008 by ghaleon12]



posted on Oct, 19 2008 @ 02:31 PM
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Genes handed down by one's mother and having a large number of older brothers may determine whether someone is a homosexual, according to a study published.


Having a large number of older brothers infers a lot of possibilities that are no genetic.



The answer could lie in Xq28,


Hmmmmm, a lot of "may determine" and "could haves" - too much tentative language there to be very convincing. It offers no explanation whatsoever for females that are gay. This appears to be largely speculation. It really reeks of philosophical beliefs driving the search for and interpretation of the data.



posted on Oct, 19 2008 @ 02:38 PM
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reply to post by ghaleon12
 



One theory I've heard, which I haven't looked into much, is the prenatal hormone thing, in which case there wouldn't be a genetic basis but a hormonal one, which would still mean the person wouldn't have control over it.


Hormonal basis makes much more sense than a genetic basis to me. They are called sex hormones for a reason. Male transvestites take estrogen to feminize themselves. When female body builders use anabolic steroids start to look and act like men. Yet if this is the case it seems like medical science would address homosexuality as a hormonal disorder and treat it with corrective hormone therapy.



posted on Oct, 19 2008 @ 02:40 PM
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Keep in mind that homosexuality isn't NEW. It goes back thousands of years. People are just now accepting it and trying to figure out why it happens. All I know is that it has to be something genetic, because I don't know if someone would choose to be treated as a second class citizen.

I don't see people mistreating homosexuals in Canada where I live, but I know in the US there's a lot of people who don't want to give them rights. I think its horrible. Why should anyone be denied rights because of who they love? One of my good friends is gay, and I don't think he should get anything less than I do because of who he chooses to spend his life with...and because he lives in Canada he doesn't. The US needs to get on this boat and needs to stop being afraid of silly things.



posted on Oct, 19 2008 @ 02:47 PM
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Originally posted by asmeone2
One theory that's been presented is that homosexuality is a natural safeguard against overpopulation. When a sort of critical mass is reached, the "Gay gene" if we can call it that, is triggered, thereby encouraging the population level to become more managible.


Now this is really interesting wild stuff... Doesn't sound very blind or purposeless to me.

If evolution by natural selection is a "blind watchmaker" driven by reproductive process, how did these externally triggered safe guards get installed? What triggers the "gay gene" ?

Most importantly, how is it aware that population has reached a critical mass and who (or what) sets the level that is critical?

I've always heard evolution described in natural terms. This is supernatural.



posted on Oct, 19 2008 @ 02:48 PM
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reply to post by Bigwhammy
 


hello there

if it is genetic then its either

A) A genetic defect. if it was evolution then to continue down that path would lead to the destruction of the species through non reproduction. A defect like any other requires treatment.

B) Homosexuality is part of the genetic make up that is or was of another species of humanoid. this species reproduces by cross fertilisation with and lives in some sort of evolved symbiotic/parasitic way with the general human species.

not having ago here but the genetics line seems way off.

we will be having genetic issues for all sorts of things leading to them being accepted without any credible scientific evidence whatsoever.

david

oh before anyone says i am a bigot, im disagreeing that is all



posted on Oct, 19 2008 @ 02:53 PM
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reply to post by Malzypants
 


Thanks for your comments. I agree that I do not think people would choose to have that disposition, that doesn't necessarily mean it is genetic. It could be a product of brain chemistry that is not genetic, hormonal or purely psychological.

I would prefer to keep this a scientific discussion. If we side track on to morality and rights etc. it will cease to be worthwhile.



posted on Oct, 19 2008 @ 02:55 PM
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reply to [url=http://www.abovetopsecret.com/forum/thread403143/pg1#

removed post as i saw bigwhammys request to keep it science based.

sorry big guy

[edit on 19-10-2008 by drevill]



posted on Oct, 19 2008 @ 03:01 PM
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reply to post by Bigwhammy
 


It's more the effect of the hormones on the developing brain in a fetus, which will cause an effect later on in life. You could mess all you want giving gay and straight males more or less estrogen/testosterone and it will have no effect on changing preference for one gender or the other. If the effect on the brain has already happened you can't go back and change it.



posted on Oct, 19 2008 @ 03:05 PM
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reply to post by drevill
 


I agree David, on a purely amoral and pragmatic basis any behavior that would result in the extinction of the species if adopted universally is completely in opposition to the evolutionary paradigm. Yet to refer to it as dysfunction is so politically incorrect, you are labeled a bigot for questioning it.



posted on Oct, 19 2008 @ 03:05 PM
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reply to post by drevill
 


If not genetic, then biological in nature. If it were a CHOICE then do you think we would even have homosexuality? Given the way they're treated, abused, and killed? It's obviously something that can't be changed by choice.

It could be a combination of genetics and environmental factors.


Genes + Brain Wiring + Prenatal Hormonal Environment = Temperament

Parents + Peers + Experiences = Environment

Temperament + Environment = Homosexual Orientation


Source



posted on Oct, 19 2008 @ 03:10 PM
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Originally posted by ghaleon12
reply to post by Bigwhammy
 


It's more the effect of the hormones on the developing brain in a fetus, which will cause an effect later on in life. You could mess all you want giving gay and straight males more or less estrogen/testosterone and it will have no effect on changing preference for one gender or the other. If the effect on the brain has already happened you can't go back and change it.


So let me get this straight, you are effectively theorizing it is brain damage resulting from improper levels in the fetus then?

It does seem more plausible than it being favored by natural selection.



posted on Oct, 19 2008 @ 03:13 PM
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reply to post by drevill
 


There is so much evidence that genes or other natural factors outside of a gays choice are playing out. People would have to have their head buried in the sand to not realize it. Off the top of my head, I'll list some examples. In gays, the ring finger is in proportion to other fingers more similar to women. Lesbians have finger lengths resembling more similarly men. In a double blind survey, gays respond more to male sweat (pheromones) than female sweat and similarly with lesbians. Like I mentioned above, if you are an identical twin and your brother is gay, there's more than a 50% chance that you will be gay also. The brains of gays and lesbians resembles more closely the opposite sex. In tests where they "scare" the test subjects, gay males react with much more surprise than straight men, and again, more closely resemble the reactions of women. Lesbians respond more similarly to men, in that the stimulus doesn't provoke a strong reaction. And on and on it goes, the ones that don't think there is a genetic or natural basis shouldn't even talk, because they won't even take the time to look at the research.

And being gay isn't a defect any more than being straight is. Liking one sex over the other isn't a huge deal in life. Gays proportionaly own more private businesses than straight people, they're doing something right.


[edit on 19-10-2008 by ghaleon12]

[edit on 19-10-2008 by ghaleon12]



posted on Oct, 19 2008 @ 03:14 PM
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sorry

"could"?????

homosexuals were not treated badly in Ancient Greece and they are not treated badly today Generally speaking

people grow up to be either violent and non violent when they come from a violent family.

society is what tells the world what is acceptable and what is not and this just goes around in circles.

go from one culture to another and see this for all different things. what is openly embraced in one culture can be a disgrace in another.



posted on Oct, 19 2008 @ 03:17 PM
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reply to post by ghaleon12
 


can i have the links then?

sorry but studies on sweat also show people attracted to animal sweat

so what does that prove?


reactions? sorry are these tests taking over a very long time period from childhood to adulthood? Means nothing, environment springs to mind here.

the finger thing is interesting, could you let me have a link for this

david

[edit on 19-10-2008 by drevill]



posted on Oct, 19 2008 @ 03:25 PM
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reply to post by ghaleon12
 



And being gay isn't a defect any more than being straight is. Liking one sex over the other isn't a huge deal in life.


In a purely practical and scientific view this statement is absurd. This a characteristic behavior that would wipe out the human race if it were universally adopted. How can you say it is not a defect?

Your statement is purely one of sentiment.



Gays proportionaly own more private businesses than straight people, they're doing something right.


Wait a minute, owning private business has absolutely nothing to do with this discussion. One could easily argue they own private businesses because they have a hard time being hired due to being gay.



posted on Oct, 19 2008 @ 03:27 PM
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Personally not being intereste in females, i beleive that the way i am is a spiritual thing. I think being gay or staright depends more on the spiritual part of humasn than genetics.

I think anyone could be gay, in theory. Spiritual self, can be a powerful force, and personally i am glad of the way i am, caused me alot of bother in my life, but heck looking back i am glad, i never wanted to be straight, or pretend i was straight, lol.

I have also heard all the theories about overpopulation etc... but there have always been gays. I think you are born for some reason, with a different type of spiritual feelings(not sure how to put that into words). But nowadays, it is alot easier to admit your not straight.

But i say it is spiritual not genetic, although i understand alot wanting to believe for what ever reason it is genetic.





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