Why are people either left- or right-handed?
It is not surprising that the two halves of the brain specialize because certain abilities require specific areas of the brain to organize to support the skills. There is an advantage in assigning roles to the left and right hands. For example a righty holds a nail with the left hand (the right brain controls the left hand and is good at judging space) and hammers with the right hand (the left brain controls the right hand and is good at logic). Where to hold the nail and what to do with the hammer are important considerations for the survival of thumbs! Lefties use the reversed procedure with equal skills. Ambidexterity (literally two right hands!) works great on a piano where the thumbs are not at risk. Switch hitters have a huge advantage in baseball and boxing. Cold water faucets are always on the right because in the early days there was only cold water and the right-handed majority found it more convenient to hold an item being washed (or soap?) with the left hand while turning o
