Controversy between gay origins, a possible biological explanation

A team of scientists at the prestigious Swedish Karolinska Institute is changing the conception of human sexuality. Its latest contribution to this field promises to raise some controversy: the brains of homosexual people have some differences with respect to that of heterosexuals. Specifically, the symmetry of the hemispheres nerve connections from some of the subjects (gays in this case) differ from what would be expected based on their biological sex. The same applies to the brains of lesbians.

gay brain studies

After checking how gays and lesbians processed smells differently as they do to people attracted by the opposite sex, Ivanka Savic, one of the most prolific researchers in this field, and his colleague Per Lindström, from the department of neuroscience Institute Karolinsa, launched to explore directly the brain and some of its connections in 90 different subjects of sexual orientation.

Previous studies suggested that women and homosexual men had a brain structure atypical for their gender during the conduct of certain evidence. The activity of the two hemispheres was not the normal thing that could be explained by changes in their volumes. That was precisely what Savic and Lindström measured using magnetic resonance in the participants.

Feminization and masculinization

In the cerebellum, a structure located on the back and lower their heads around the brain stem, which integrates a wealth of information- they didn’t found striking differences. However, the brains of homosexuals, rather than the typical sex shows a similar to the opposite. In gays of it is feminized and in lesbians masculinized.

In ‘hetero’ women the right hemisphere is usually larger than the left. This feature can be seen, paradoxically, in gay men. “Lesbians, by contrast, have a more symmetric brains, more similar to heterosexual men. The finding” fits well with previous observations, ” the authors note.

They have also detected, thanks to PET (positron emission tomography), functional differences in a region called the amygdala. This structure, which is bilateral (there is one on each side of the brain) is part of the limbic system and is involved in processing and storage of emotions.

Genetics or environment

For Francisco Mora, professor of human physiology of the medical faculty of the Universidad Complutense de Madrid, these differences can be explained by social influences, psychological and cultural.

“The amygdala is the gateway to the limbic system. It comes across sensory information, which is emotionally neutral, and it gives it a category (good, bad, etc..)”, Explained Mora. “Although this structure possesses circuits that are preprogrammed, it is necessary to learn to make this classification,” he adds.

From this standpoint, “the cultural patterns are capable of physically and chemically alter the brain” so that the comments of Lindström Savic and can be explained from the environment and would not innate but learned.

Controversial field study

If a homosexual is born or made is an old question and its response, feared by many. The possibility that sexual orientation is something innate, for example, having a biological substrate, could reopen the door to search, which has caused so much harm, a cure for this condition which ceased to be regarded as a disease by the World Health Organization 18 years ago.

On the other hand, the idea that sexual orientation comes ‘from the factory’ would reverse to the ugly argument of ‘unnatural’, because, if it is determined by genes, the homosexual would remain exactly what it is was intended. “The best of the work of Lindström Savic is perhaps the end of the old idea that the bad influences and experiences are behind the attraction for same-sex”.

Since the controversial Simon Levay make public its conclusions about the differences between the brains of homosexual and heterosexual, many studies have detected some differences between them. Work with twin brothers suggest a role of DNA fingerprinting on sexual orientation, which undoubtedly will have its influence.

The Swedes authors seem inclined toward the multi factorial theory. On the issue of sexual dimorphism of the brain, “we must take into account three factors: the environment, genetics and hormones.”