The reason for some people being left-handed cannot be explained with
certainty. Some authorities declare that people are born with strongly-developed tendencies towards either right- or left-handedness. Others assert that either
tendency is merely
acquired. Neither party, however, has beeen able to prove its
case. The former state that the left side of the
brain, which controls the right hand, is more highly developed than the right side, which controls the left hand. This, though, has not been proved and no
explanation as to why one side of the brain should be
superior to the other is available.
It is often surmised that the reason for the right hand being the superior is that our distant ancestors acquired the habit of using the right hand to wield
weapons while protecting their
hearts with the left and in the course of time, therefore, children began to be born with a tendency towards right-handedness.
It is estimated that fewer than 10% of people are left-handed.