Swedish
researchers are reporting in the current edition of
Proceedings of the National Academy of Sciences
that they've determined lesbians' brains react
differently to sex hormones than do the brains of
heterosexual women. This puts the brains of lesbians
more in line with the way the brains of heterosexual men
react to the pheromones, the Associated Press reports.
Previous studies have shown that gay men's
brains responded to pheromones similarly to the way
heterosexual women's brains responded.
Researchers say
the findings of all the studies give much more weight to
the theory that sexual orientation is innate and not a
response to environmental factors.
"It shows sexual
orientation may very well have a different basis
between men and women...this is not just a mirror image
situation," Sandra Witelson, a Canadian expert on
brain anatomy and sexual orientation, told the
Associated Press. "The important thing is to be open
to the likely situation that there are biological factors
that contribute to sexual orientation."
The Swedish study
had male and female study subjects sniff both male and
female pheromones, which can trigger sexual responses. The
researchers found that heterosexual men and lesbian
women preferred the female pheromones to male
pheromones. Heterosexual men and lesbian women also
found the male hormone to be more irritating than the female
one.
Brain scans also
showed that female pheromones stimulated a response in
the hypothalamus region of the brains of the male study
subjects, a part of the brain linked with sexual
response. Among heterosexual women, it was the male
pheromones that created the sexual response. Brain scans of
lesbians, however, showed that neither male nor female
pheromones produced a response in the hypothalamus
portion of the brain.
Gay men were not
included in the study. However, the same research team
reported last year that gay men's brains responded
more positively to male pheromones than female sex
chemicals. (The Advocate)