Posted on 10/06/2003 9:11:12 PM PDT by El Conservador
MONDAY, Oct. 6 (HealthDayNews) -- The origins of sexual orientation may be evident in the blink of an eye.
In what is the first study to show an apparent link between a non-learned trait and sexual orientation, British researchers have discovered the way peoples' eyes respond to sudden loud noises may signal differences between heterosexual and homosexual men and women that were developed before birth.
The authors, whose study appears in the October issue of Behavioral Neuroscience, say about 4 percent of men and 3 percent of women are gay. Scientists have long sought to determine whether sexuality is learned or biological.
"We have several decades of research which suggests rather strongly that human sexual orientation is to some degree biologically determined," says study author Qazi Rahman, a lecturer in the School of Psychology at the University of East London. "The problem with those types of studies is that we can't disentangle the effects of learning."
The question then became, "What kind of task could be used that is not influenced by learning or socialization?" The answer came in human startle responses, which are involuntary and instinctual.
Specifically, Rahman and his colleagues decided to use pre-pulse inhibition (PPI (news - web sites)). When humans hear a sudden noise, they respond by blinking. If that loud noise is preceded by a quieter noise (the pre-pulse), the response to the second, loud noise is weaker. In other words, it is inhibited.
The researchers compared responses to a loud noise both alone and after a quieter noise to see what the degree of inhibition was. Participants were 59 gay and straight men and women.
In the heterosexual women, the PPI averaged 13 percent and, in heterosexual men, 40 percent.
Lesbians, however, had a PPI of 33 percent, closer to the straight-man end of the spectrum, while gay men averaged 32 percent, slightly lower than that of straight men but not statistically significant.
The findings are consistent with other studies, which have found that certain traits in lesbians are highly "masculinized," while the same traits in gay men are almost the same as in straight men.
While it's difficult to make generalizations about gay behavior on the basis of these findings (for example, "all gay male thinking is like that of women"), it is possible to build a case for the origins of sexuality, the authors say.
"On the basis of these results and in conjunction with the bulk of the literature in the last three decades or so, the evidence points to some prenatal factor or factors [in determining sexual preference]," Rahman says.
The findings could have implications for a number of social issues.
"Actual sexual orientation and sex-related research is now being accepted as a legitimate national investment in terms of research," Rahman says. "We have problems with STDs [sexually transmitted diseases]. Understanding sexual behavior is clearly important to that."
The findings may also help illuminate sex differences in mental health issues. "Although homosexuality per se is not related to psychiatric problems, on those occasions that gays and lesbians do present with psychiatric problems, they often show disorders that are typical of the opposite sex," Rahman says. Gay men, for example, may be more likely to suffer depression, anxiety and eating disorders than their straight counterparts, while lesbians may be more vulnerable to substance abuse than heterosexual women.
"Maybe having an understanding of brain basis of sexual orientation in healthy individuals may give us some clues in what is going wrong in the brain circuitry underlying certain psychiatric problems," Rahman says. "In the future, we may be able to tailor treatments more specifically."
It's important not to draw too many generalizations. "It's not that the gay brain is like the heterosexual brain of the opposite sex. It seems to be a mosaic of male and female typical traits," Rahman says. "Because we're looking at humans, thing are always more complicated that you would expect."
More information
The University of California, Davis has more on research related to sexual orientation, as does the American Psychological Association.
Maybe. But wouldn't the females who bear this chromosome not reproduce by definition? Wouldn't the homosexuality gene, being part of their genes makeup, effect them also? I've never heard of a genetic trait that dominates when the Y chromosome is present but takes back seat with the X.
Or are there male and female homosexuality genes??
Bottom line, until science can prove different, I believe homosexually is an aberrant behavior by choice. If any trait is inherited or nurtured, it's narcissism. That seems to be their strength.
As for the genetic's case we may be speaking of a case of both recessive and dominant characteristics, similar to what one finds in the case of eye color, whereby if both parents have brown eyes but have the recessive gene for blue eyes there is a .25% probability they will have a blue eyed child. My only point about it showing up on the X chromosome was that no principle of natural selection would remove it from the gene pool.
I wish folks would get beyond the myth that because one might be "born that way" that should be accepted as an argument for the acceptability of their behavior, let alone its normalcy.
Just out of curiosity, what would be the darwinian/evolutionary reason for homosexuality?
Ultimately, the argument was that it didn't matter one iota. Animal's may eat their young or starve them to death and that's perfectly acceptable, natural and no one's going to take them to court or indict them for it. Humans fall under moral law and that makes a vast difference.
Are you postulating this or claiming evidence of it? Why would homosexual behavior, which (almost by definition) does nothing to promote perpetuation of itself, be more helpful than any number of other traits which do.
I can imagine that there might be random instances of homosexuality helping in such a situation, but it seems to be too, uh, counter productive.
Along those lines, I have not read this book, but Unto Others is supposed to be an argument for something similiar.
Hmm. How about this? Please read this link for additional information on this issue.
You're making the point exactly.
Homosexual's have been fond of making the argument that homosexuality exist in nature, so how can it be considered as "un-natural."
The actual observation in nature was that those species of animals who were described as being homosexual in their mating habits were practicing a survival strategy. This strategy was a response to the environmental stresses on their ecological niches due to overpopulation. This particular strategy results in a reduction of population, and so promotes their survival; because they will not overtax the system and end up all starving themselves to death. Other species have similar survival strategies such as eating or starving their young.
Once the environmental stresses are removed these species revert to their previous mating habits. And those that practice the other survival strategies no longer eat their young or starve them.
Using the same logic that homosexuals employ, there ought to be nothing considered un-natural in either eating one's children or starving them to death. Especially, when there're too many mouths to feed!
I don't understand that. If X recessive, it would lead to a higher percentage of males affected but why wouldn't any trait that leads to not reproducing (and clearly by definition, that is something they usually don't do) continue? It would die out no matter the genetic linkages.
All in all, "the genes made me do it" argument, doesn't pan out. It's absurd.
Maybe. But wouldn't the females who bear this chromosome not reproduce by definition? Wouldn't the homosexuality gene, being part of their genes makeup, effect them also?
No! Why who anybody assume that its presence on the Y chromosome in a female would predispose her to lesbianism? This would indicate that what ever function or role it plays in the female is the exact opposite of how it operates in a male. Sorry even genetic defects don't work in this fashion.
Or are there male and female homosexuality genes??
No, I don't believe there exist a genetic predisposition for lesbianism, nor a mechanism for it that wouldn't violate the laws of natural selection.
And from your last post:
All in all, "the genes made me do it" argument, doesn't pan out. It's absurd.
Ah! Something we might agree on. It was the final conclusion I made in my original post, though I don't think your reasoning was even similar to mine or that you even read the arguments I made.
Dear one, females can't have a Y. They are always XX. XXs are the definition of a girl, XYs are guys.
(except in Klinefelter's Syndrome which is XXY and they're pretty much "femalish" but don't reproduce.) (And then there is Turner's syndrome which is an XO female and they don't even have ovaries.) But I might be missing something but I can't remember any female syndrome with a Y.
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