Quick update from the world of science.

A new scientific study by a research team from Sweden offers the strongest evidence that homosexuality is caused by biological, not environmental factor. The researchers reports that,

the brains of heterosexual men and homosexual women are slightly asymmetric—the right hemisphere is larger than the left—and the brains of gay men and straight women are not. (source: Science Daily)

The male homosexual brain shares strikingly similar characteristics with female heterosexual,

most notably in the size of their brains and the activity of the amygdala—an area of the brain tied to emotion, anxiety and aggression. (source: Scientific American)

The following scan of the brain shows the electrical activities present in amygdala seed region of heterosexual man (HeM), heterosexual woman (HeW), homosexual man (HoM) and homosexual woman (HoW).

Credit: National Academy of Sciences, PNAS

Further quote:

Dr Qazi Rahman, a lecturer in cognitive biology at Queen Mary, University of London, said that he believed that these brain differences were laid down early in foetal development.

“As far as I’m concerned there is no argument any more - if you are gay, you are born gay,” he said.

The amygdala, he said, was important because of its role in “orientating”, or directing, the rest of the brain in response to an emotional stimulus - be it during the “fight or flight” response, or the presence of a potential mate.

“In other words, the brain network which determines what sexual orientation actually ‘orients’ towards is similar between gay men and straight women, and between gay women and straight men.

“This makes sense given that gay men have a sexual preference which is like that of women in general, that is, preferring men, and vice versa for lesbian women.” (source: BBC News)

Despite the similarity of some part of the brain, Dr. Eric Vilain, professor of human genetics at University of California Los Angeles, says,

“The big question has always been, if the brains of gay men are different, or feminized, as earlier research suggests, then is it just limited to sexual 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 sexuality that seem to be feminized in gay males.”

He further 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 sexuality. “We know from studies that men, regardless of their sexual orientation, retain masculine characteristics when it comes to their sexual 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 sex, and to be aroused by visual stimuli. “So I expect that some regions of the brain will remain masculine even in gay men.” (source: Time)

Exciting time ahead. Let’s hope more scientific research will shed more light on homosexuality.