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DSM4Life
"Sexy" Smells Different for Gay, Straight Men, and Women, Study Says:
Article From: National Geographic News
Another control clinical scientific study that adds validity the body of evidence that homosexuality is hard-wired at the genetic level, and that odors from gay men were the least preferred by straight men.
A new study shows that gay men respond differently from straight men when exposed to a suspected sexual stimulus found in male sweat. When homosexual men smelled a specific odor from a chemical in male sweat; male hormone testosterone, their brains responded similarly to those of women. The findings suggest that brain activity and sexual orientation are both linked. It also supports an opinion held by most scientists that people are born gay, and not bred.
"This is in line with the body of evidence that support there's a biological substring for sexual orientation," said Dean Hamer, a geneticist at the National Institutes of Health in Bethesda, Maryland. Hamer is the author of The Science of Desire: The Gay Gene and the Biology of Behavior. He was not involved in the research, which was conducted by scientists at Karolinska Institutet in Stockholm, Sweden. The study was published in the research journal Proceedings of the National Academy of Sciences:
Reproductive Behavior:
The scientists exposed heterosexual men and women and homosexual men to chemicals found in male and female sex hormones. One chemical is a testosterone derivative produced in men's sweat. The other chemical is an estrogen-like compound in women's urine. These chemicals have long been suspected of being pheromones, molecules emitted by one individual that evoke some behavior in another of the same species. Pheromones trigger basic responses, such as sexual attraction, in many animals. The researchers found that the testosterone compound activated the hypothalamus in homosexual men and heterosexual women, but not heterosexual men. Conversely, the estrogen compound activated the hypothalamus only in heterosexual men. "It shows a different physiological response to the same external stimulus," said Ivanka Savic, a neuroscientist at the Karolinska Institute and the study's lead researcher. "This response [occurred] in the brain region involved in reproductive behavior." When the study subjects sniffed scents such as cedar or lavender, all of their brains reacted only in the region that handles smells—not sexual behavior.
Biological Explanation:
The results show that the human brain reacts differently to potential pheromones compared with common odors. "It directly shows a link between brain activity and sexual orientation," said Hamer, the NIH geneticist. Hamer cautions that the gay men's different brain activity could be either a cause of their sexual orientation or an effect of it. But, he said, "It certainly seems unlikely that somehow being interested in men would cause the brain to rewire itself in such a dramatic way."
Other studies have also found that gay and straight men respond differently to the body odors of others. This study discredits unsupported hypothesis that homosexuality is a learned behavior, or that straight men can be sexually attracted to gay men, when in fact is the opposite. Scientists at the Monell Chemical Senses Center in Philadelphia, Pennsylvania, found that gay men preferred odors from other gay men, while odors from gay men were the least preferred by straight men and women.
There are many ongoing studies in the field, and I think that we soon will have better clarification," said Savic, the Karolinska Institute neuroscientist. "At the moment, there are no definite proofs." However, the new studies boost the hypothesis that homosexuality has a genetic basis and is not simply the result of learned behavior. "This, incidentally, is not in any way controversial for biologists," Hamer said. "It's completely expected from the basic tenets of biology. It's only controversial because of the religious, social, and political ramifications controversy over homosexuality."
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