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Old 03-14-2016, 04:32 PM
md2000 md2000 is offline
Join Date: Feb 2009
Posts: 13,451
Originally Posted by Chronos View Post
Why have a dominant hand at all? Because it's more useful to have one hand that you're really good at than two hands that you're sort of good at, which you'd have if you practiced with both equally.

Why do most humans have the same dominant hand? At a guess, it's because we're tool-users, and it's advantageous for everyone to be able to use the same tools.

Why is it not all of us? Being the opposite handedness from normal can be an advantage in direct physical competition, because you'll react differently than your opponent expects. This used to be an advantage in swordfighting, and is still an advantage in baseball pitching. Apparently, a ratio of about 9 to 1 is the sweet spot where these two benefits balance out.

Why is the common dominant hand specifically the right one? That's just happenstance. With a slightly different evolutionary path, it could have been the left just as easily.
That's probably the likely explanation. We learn a lot of tasks (motor skills) by repetitive training until it becomes instinctive. By using the same hand every time, we learn the task faster and get better at it, until it just "feels right".

One explanation I recall reading (obviously someone being somewhat sarcastic) was that left-handedness was the brain development compensating for oxygen starvation and brain damage during birth.