What the Gay Brain Looks Like
Tuesday, Jun. 17, 2008 By ALICE PARK Michael Prince
What makes people gay? Biologists may never get a complete answer to that
question, but researchers in Sweden have found one more sign that the
answer
lies in the structure of the brain.
Scientists at the Karolinska Institute studied brain scans of 90 gay and
straight men and women, and found that the size of the two symmetrical
halves of the brains of gay men more closely resembled those of straight
women than they did straight men. In hetero***ual women, the two halves of
the brain are more or less the same size. In hetero***ual men, the right
hemisphere is slightly larger. Scans of the brains of gay men in the
study,
however, showed that their hemispheres were relatively symmetrical, like
those of straight women, while the brains of homo***ual women were
asymmetrical like those of straight men. The number of nerves connecting
the
two sides of the brains of gay men were also more like the number in
hetero***ual women than in straight men.
Just what these brain differences mean is still not clear. Ever since
1991,
when Simon LeVay first do***ented differences in the hypothalamus of gay
and
straight men, researchers have been struggling to understand what causes
these differences to occur. Until now, the brain regions that scientists
have come to believe play a role in ***ual orientation have been related
to
either reproduction or ***uality. The Swedish study, however, is the first
to find differences in parts of the brain not normally involved in
reproduction - the denser network of nerve connections, for example, was
found in the amygdala, known as the emotional center of the brain. "The
big
question has always been, if the brains of gay men are different, or
feminized, as earlier research suggests," says Dr. Eric Vilain, professor
of
human genetics at University of California Los Angeles, "then is it just
limited to ***ual preference or are there other regions that are gender
atypical in gay males? For the first time, in this study it looks like
there
are regions of the brain not directly involved in ***uality that seem to
be
feminized in gay males."
Vilain, who studies the genetic factors behind ***uality and ***ual
orientation, notes that it may turn out that the brains of gay men possess
only some 'feminized' structures, while retaining some masculine ones, and
this is reflected in how they act on their ***uality. "We know from
studies
that men, regardless of their ***ual orientation, retain masculine
characteristics when it comes to their ***ual behavior," he says. Both gay
and straight men, for example, tend to prefer younger partners, in
contrast
to women, who gravitate toward older partners. Most men are also more
likely
than women to engage in casual ***, and to be aroused by visual stimuli.
"So
I expect that some regions of the brain will remain masculine even in gay
men," says Vilain. For something as complex as ***ual orientation, it's no
surprise that everything from genes to gender to environment may play a
role
in ultimately determining your perfect partner.
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