05/10/2005: Distinct Differences
Differing brain response found in homosexual, heterosexual men by Randolph E. Schmid (The Associated Press):
”Scientists trying to sniff out biological differences between gay and straight men have found new evidence — in scent.
It turns out that sniffing a chemical from testosterone, the male sex hormone, causes a response in the sexual area of gay men's brains, just as it does in the brains of straight women, but not in the brains of straight men.
"It is one more piece of evidence ... that is showing that sexual orientation is not all learned," said Sandra Witelson, an expert on brain anatomy and sexual orientation at the Michael G. DeGroote School of Medicine at McMaster University in Ontario, Canada.
When they sniffed smells like cedar or lavender, all of the subjects' brains reacted only in the olfactory region that handles smells.
But when confronted by a chemical from testosterone, the male hormone, portions of the brains active in sexual activity were activated in straight women and in gay men, but not in straight men, the researchers found.
The response in gay men and straight women was concentrated in the hypothalamus with a maximum in the preoptic area that is active in hormonal and sensory responses necessary for sexual behavior, the researchers said.
And when estrogen, the female hormone was used, there was only a response in the olfactory portion of the brains of straight women. Homosexual men had their primary response also in the olfactory area, with a very small reaction in the hypothalamus, while heterosexual men responded strongly in the reproductive region of the brain.
Savic said the group also is doing a study involving homosexual women, but those results are not yet complete.
In a separate study looking at people's response to the body odors of others, researchers in Philadelphia found sharp differences between gay and straight men and women.
"Our findings support the contention that gender preference has a biological component that is reflected in both the production of different body odors and in the perception of and response to body odors," said neuroscientist Charles Wysocki, who led the study.
In particular, he said, finding differences in body odors between gay and straight individuals indicates a physical difference....”
Other links for information:
Proceedings of the National Academy of Science: www.pnas.org
Karolinska Institute: http://info.ki.se/index_en.html
Monell Center: www.monell.org/
Karen on 05.10.05 @ 03:47 PM CST