Pas de Deux of Sexuality Is Written in the Genes

Beginning of an intriguing article in The New York Times:

When it comes to the matter of desire, evolution leaves little to chance. Human sexual behavior is not a free-form performance, biologists are finding, but is guided at every turn by genetic programs.

Desire between the sexes is not a matter of choice. Straight men, it seems, have neural circuits that prompt them to seek out women; gay men have those prompting them to seek other men. Women’s brains may be organized to select men who seem likely to provide for them and their children. The deal is sealed with other neural programs that induce a burst of romantic love, followed by long-term attachment.

So much fuss, so intricate a dance, all to achieve success on the simple scale that is all evolution cares about, that of raising the greatest number of children to adulthood. Desire may seem the core of human sexual behavior, but it is just the central act in a long drama whose script is written quite substantially in the genes.

Money quote: “Several advances in the last decade have underlined the bizarre fact that the brain is a full-fledged sexual organ, in that the two sexes have profoundly different versions of it. This is the handiwork of testosterone, which masculinizes the brain as thoroughly as it does the rest of the body.”

And this: “. . . although average IQ is identical in men and women, there are fewer average men and more at both extremes.”