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.Dante embraced unrequited love. Fine. But the miserable Sydney Carton died for it. I find his experience more typical. Still, what can you do? Not much, apparently. Read Seneca, I suppose.
It seems, quite literally, that each day a new bit of information increases Nature's advantage in its epic struggle against Nurture. The conventional wisdom usually takes initial refuge in Nurture's camp before being forced by the sheer weight of empirical evidence to defect to the other side. But homosexuality is an exception, at least in women:
Presumably the masculinization of the brain shapes some neural circuit that makes women desirable. If so, this circuitry is wired differently in gay men. In experiments in which subjects are shown photographs of desirable men or women, straight men are aroused by women, gay men by men.This strikes me as circumstantial evidence for the gay germ hypothesis on male homosexuality. From an evolutionary perspective, male homosexuality carries too much baggage and too little of an advantage to have stuck around. Homosexual men procreate at a rate about one-fifth that of heterosexual men. As most of human history has involved male dominance in mate-making decisions, female-to-female attraction is less detrimental. What harm is there in Jen and Beth fooling around, as long as the Jim the Patriarch has access to both of them whenever he wants it? If the top dog, Jim, happens to be gay, however, the clan has some real problems.
Such experiments do not show the same clear divide with women. Whether women describe themselves as straight or lesbian, “Their sexual arousal seems to be relatively indiscriminate — they get aroused by both male and female images,” Dr. Bailey said. “I’m not even sure females have a sexual orientation. But they have sexual preferences. Women are very picky, and most choose to have sex with men.”
Even castration does not affect male sexual orientation. The sex drive of a eunuch may decrease, but it is still directed towards the same sex that it was pre-gonad loss. Female sexuality, in contrast, is at least somewhat malleable even without the removal of reproductive organs.
Female sexual ambiguity is intuitively sensible enough:
In the womb, the body of a developing fetus is female by default and becomes male if the male-determining gene known as SRY is present. This dominant gene, the Y chromosome’s proudest and almost only possession, sidetracks the reproductive tissue from its ovarian fate and switches it into becoming testes. Hormones from the testes, chiefly testosterone, mold the body into male form.Testosterone produces a powerful sexual drive. This drive is usually directed towards females, but 5% or so of the time it is directed toward males. A vigorous inbetween is uncommon (stateside, woman are between two and three times as likely as men to report having engaged in bisexual activity yet there are slightly more gay couples than lesbian couples--608,000 to 594,000 in 2000, respectively).
As Dr. Bailey alludes to, women have more control over their sexual impulses and how those are satisfied, which allows them to be more thoughtful. With more latitude in what provides satisfaction, they are less driven by uncontrollable biological urges. Not surprisingly, the explosive 'success' of gay bathhouses for men (both parties are very driven) has proven utterly incapable of being recreated for women-seeking-women (neither party is especially driven).
As the Western media continues to increasingly lionize same-sex intimacy, especially among women, (Ellen DeGeneres, Ally McBeal, Sex and the City, etc), I expect their to be a marked increase in the number of women who self-identify as lesbian or bisexual. I doubt male growth will keep up.
Lawrence Summers could've used this:
It is a misconception that the differences between men’s and women’s brains are small or erratic or found only in a few extreme cases, Dr. Larry Cahill of the University of California, Irvine, wrote last year in Nature Reviews Neuroscience. Widespread regions of the cortex, the brain’s outer layer that performs much of its higher-level processing, are thicker in women. The hippocampus, where initial memories are formed, occupies a larger fraction of the female brain.Fancifully looking to the future through a utopian lens, this paragraph is intriguing:
Techniques for imaging the brain have begun to show that men and women use their brains in different ways even when doing the same thing. In the case of the amygdala, a pair of organs that helps prioritize memories according to their emotional strength, women use the left amygdala for this purpose but men tend to use the right.
Sexual behavior includes a lot more than sex. Helen Fisher, an anthropologist at Rutgers University, argues that three primary brain systems have evolved to directImagine if genetic sequencing and manipulation eventually allows people to alter these three brain systems. Imagine Gwyneth Paltrow being madly in love with you--and not a single man other than yourself interested in her. Imagine if you were able to systematically enhance the way you viewed your significant other without her having to do a thing, if you were able to keep that initial rush alive indefinitely, even enhancing it as time wore on. The imagined consequential increase in human happiness and social stability is almost incomprehensible. Solipsism may provide larger society a palpable benefit yet!
reproductive behavior. One is the sex drive that motivates people to seek partners. A second is a program for romantic attraction that makes people fixate on specific partners. Third is a mechanism for long-term attachment that induces people to stay together long enough to complete their parental duties.