Is human sexuality determined by testosterone’s effect on the brain?


[Early experiments have shown] that the Y chromosome is essential for the formation of a testis, and it is the testosterone from this testis that acts on the brain…Amazingly, giving testosterone to little new-born females resulted in their sexual behavior being much more like that of males when they grew up.  And the opposite was also true: Removing the testes of new-born males resulted in female-like patterns of behavior.

Human sexuality, of course, is made up of several components, though they overlap.

But does testosterone play a role in the development of human sexuality? Testosterone acts on the brain (and other organs) by activating a complex protein, the androgen receptor. If a mutation in the latter occurs, the brain may not respond to testosterone: It’s as if it didn’t exist.

Recent experimental evidence also points to real differences in male and female rodent brains…The hypothalamus of female rodents has greater levels of methylation than males: that is, more genes are suppressed. Giving such females testosterone post-natally reduces this: in other words, some of the methylation markers are removed, releasing those genes to become active. Such females behave more like males. Furthermore, giving a drug to little males that prevents de-methylation results in them behaving more like females.

[Read the full study here]

The GLP aggregated and excerpted this blog/article to reflect the diversity of news, opinion, and analysis. Read full, original post: How the Brain Determines Sexuality