I happened to read the first chapter of _The Dopaminergic Mind in Human Evolution and History_ today. The author, Fred Previc, thinks that handedness is an indirect effect of human bipedalism (and thus will not be found in the genome). Specifically, he thinks that due to the mother's sometimes upright, sometimes seated, etc. position, the fetus lies asymmetrically during the third trimester of gestation, leading to lateralization. Possibly his theory is contradicted because lateralization is more widespread among non-bipedal primates than he thinks?

My handedness is similarly strange. I'm ambidextrous when writing (but a little faster with my right hand), right-handed when I eat with a fork or spoon, right-handed with a pistol, and left-handed when it comes to most other activities involving projection: throwing a basketball, tossing a baseball, firing a rifle, etc.

I've heard the theory that the development of language lead to handedness, as the left and right parts of the brain handle very different functions in language processing. The tool making hypothesis sounds reasonable, too.

I was left handed as an infant, trained to be right handed by my parents. I suspect more people would be left handed if their parents had just let them be as babies.

Over 50 years ago I watched a guy (owner of an automotive electric store on Broadway near 238th in the Bronx) capable of engaging each hand in an entirely different operation (simultaneously) to such extent that "ambidexterous" seems a pale description of that dual manual/mental ability.

Coming late, but the opposable thumb and handedness correlate with advanced forms of masturbation. Chimp masturbation is crude and bestial.

That kind of thing can be learned, for example by pianists. Independence of the hands and developing the left hand are major goals in piano teaching. (One side of piano teaching is pure physical training, like athletic training, with no necessary aesthetic content at all. I have heard arguments about the degree to which the two parts should be separated; my hunch is that hand development by purely athletic mthods would speed up piano education and get people more quickly to the place where they could find out if they're really musicians.)

Don't most musicians do much the same thing? And organists engage both feet as well.

John:

Who knows, John--what they're tryin' to simulate may be pretty crude and bestial, too.