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Old 03-25-2016, 03:38 AM
Sleel Sleel is offline
Join Date: Mar 2004
Location: Japan
Posts: 2,809
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My reply in that thread:

Handedness is one byproduct of brain lateralization. We still don't really know why lateralization became prevalent, but it seems to confer some advantages for separate processing. One reason why lefties are supposed to be more creative is that they tend to have less strongly lateralized brains, so they come up with connections between disparate ideas more easily. High intelligence also seems to be lightly correlated with left-handedness.

There's a pretty good chunk of The Language Instinct and How the Mind Works, both by Steven Pinker, that discuss lateralization, particularly the connection with language. Those are probably the most approachable, yet scientific books I've read on the subject.

Handedness is actually a continuum, with few people being totally right- or left-dominant. Some degree of mixed body dominance is common. You might have someone who is strongly right-handed, but strongly left-eyed and weakly left-footed, like a friend of mine I taught to shoot better. You should shoot based on eye dominance, not hand dominance; target acquisition and aiming are the most important things. It took some work to get him using his left hand, but his accuracy and speed went way up afterward.

While there is no single "left handed" gene, there are some genetic factors; handedness can run in families. But environment seems to be a stronger selector. Stressful conditions at conception and birth have an effect on the prevalence of left-handedness.

I would also imagine this effect would become more pronounced when it came to weapons, for combat, for hunting. People who were more proficient would kill off their opponents and have an easier time feeding themselves. Thus, if there was some social order for being trained to use them right-handed, and there's some genetic predisposition toward one or the other, those who would have had a bit more natural skill would start to win out and spread that genetic predisposition, even if it is slight.
Actually, violence selects for more lefties. In other words, the minority preference confers an advantage in combat. Either that, or left handed people are naturally more violent

(Full disclosure: I'm left handed. You got a problem with that?!)

From some of my anthropology reading I remember that the Yanomami have something like 20% incidence of left-handedness. "Fierce" men, who go on more raids and are more willing to undergo inter-tribal duels, have more wives than men who show less aggression, and these men are more likely to be left handed. (In duels they beat each other over the head with really long wooden poles, deliberately receiving head wounds to show how tough they are; this is not dissimilar to Heidelberg dueling).
On preview: NOT a reply to the left-handed pedophilia thread. I'm pretty sure I stayed away from that mess.