Wednesday, June 18, 2008

Sexual Preference and Brain Makeup


There's an interesting piece from Time about physical differences between the heterosexual and homosexual brain. It seems that those after women-- heterosexual males and homosexual women-- had brains that were mildly asymmetrical. Those after men-- homosexual males and heterosexual females-- had brains that were more symmetrical. The impact here, though the biology types here may have something more of substance to say, is that it's not just regions of the brain devoted to reproduction and sexuality that seem to play a role.

Taken at face value, this study strikes me as something that could then be a predictor of sexual preference, possibly before birth. Again, I'm not a biology expert, but I'd suspect brain asymmetries would exist from a very young age. Insofar that people have preferences about these things-- and I think it's a fair assumption to say that some people do-- then this could well lead further down the path of gene selection and choosing for yourself a child with characteristics you prefer. Without starting a holy war, I'm tentatively for gene selection, though could well be swayed with a convincing argument. I think you'd make the same arguments for gene selection of children that you'd make for coercing them to eat their vegetables, though part of your gene selection decision helps form the preference set by which you are supposed to be acting on their behalf. Yikes. Would you then have to play by some overarching set of preferences above both you and your child? This gets messy very quickly.

Interesting, too, was the part at the end concerning tendencies of men for younger partners, regardless of sexual orientation, and the opposite in women, again regardless of sexual preference. Once more, taken at face value, doesn't this lend towards a stable (unstable) equilibrium for heterosexual (homosexual) relationships?

1 comment:

Bryce said...

Just a couple of points.

Keep in mind causation vs. correlation. The environment can clearly have a massive effect on brain physiology. The brain asymmetries may not "exist from a very young age" as you suspect. The stress from being homosexual could in theory have similar effects.

However brain differences between homo and heterosexuals clearly exist. This has been shown repeatedly. There is also some intriguing research on the genetics and evolutionary stability of homosexuality here:
http://sciencenow.sciencemag.org/cgi/content/full/2008/618/1
In brief, the genes that might make men more likely to be homosexual may also make women more fertile. So a poor evolutionary trait (homosexuality) is balanced by a good evolutionary trait (increased fertility).

I'm not going to touch genetic screening here. It does already occur, however. IVF parents at some clinics can choose the sex of their child.

Your last point has been covered by evolutionary types. The key here is that humans are biologically polygamous. In an evolutionary perspective, men want young women because they are better able to care for young, thus increasing the chance of passing on their genes. Men who are older have shown their fitness and good genes by being able to survive for so long. Women want those good genes. Age doesn't matter cause men don't help raise the child.