Kenneth Silva asked:
Why are people either right-handed or left-handed? What possible benefit does that have over being ambidextrous? I find I am right-handed, right-footed, and even right-eyed! When I wore single-muff headsets on my job, though, I preferred them on my left ear and not my right, so that's a bit of a question.
And, do animals also display handedness?
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I believe it could be possible due to the genes in one's body where one is more dominant than the other. In humans probably the right one is more dominant than the left one which leads to most people being right handed.
the left side of the brain is known to control the right side of the body, but it's also known as the side to control logic and "smartness", while the right side is known to be "artistic". Because of this more right handed people are known to be smarter because when they use that hand (or side of body) they activate the movement functions in the left side of your brain. Focused_science, Tue, 11th Feb 2014
IIRC the number of lefties in the UK has been increasing since the 1950s, when primary schools stopped insisting on rigththanded writing, sinistral tools (particularly scissors) became more generally available, and the Royal and Ancient allowed golfers to use lefthanded clubs.
One theory is that the degree of left or right domination in a species has to do with the whether a species is more cooperative or competitive, or has a kind of mixed strategy. Essentially, there is often an advantage to being different handed than your enemy, but same handed as your friend, and the researchers use professional sports like baseball as an example of this.