Why most people are Right-handed:-

A simple experiment draws several straight lines at random on a sheet of paper. Without the help of any measuring scale, by eye estimation only put dots where you think, the midpoint of the lines are. Now take the scale and measure out the two halves. If you are right handed you will be surprised to find that in most cases you have placed the dots fractionally to the left of the true center. You have underestimated the length of the left half. Your brain seems to have a bias towards the right.

It is seen that almost all creatures on land, sea, or air are laterally symmetrical from the outside. One side seems to be the mirror image of the other. The same is true for man. Two pairs of identical limbs are attached to either side of the body. A pair of eyes and ears are equidistant from the nose which itself is situated in the mid-line of the face.

However on close observation it is found that there is a marked asymmetry on the outside of the human body and there is no point to point correspondence between the two sides. One eyebrow may be slightly higher than the other. One ear may be at a slightly lower level, one eye may be imperceptibly smaller than the other, and it is a well-known fact that the nasal septum, which is the dividing, line between the two nostrils, is bent either towards the right or towards the left. It is never at the true center. This means an unequal amount of air is passed through the nostrils. There is a distinct difference in the power of the two eyes. The same is true for the ears. We hear well with one of them than the other.

But the most marked asymmetry occurs in muscular power and dexterity of the hands and legs. More than 90 % of people are right handed and do most of the daily work, such as eating, writing, and picking up things or exerting force with their right hand. Only in some special cases is the left hand used and that too, in a subordinate roles. Similarly while playing football most people kick with their right legs are stronger, why this preference for right-handedness? Going by statically chance, there should be an equal number of right and left handed persons why is this not so?

Animals seldom show preference in the use of either paws or claws. The only exception is in the case of some species of parrots that use the same clawing every time for feeding. It is only in the case of human that we find more than 90 % of individuals to be right handed.                    

There are different opinions about our right-handedness. One opinion attributes this to heredity factors as the traits are transmitted to the genes from parents to children. One argument against this theory is that right-handed children may have left-handed parents and vice-versa.

The other theory supports environmental factors. A newborn baby does not show hard preference and can use both hands with same dexterity, during the first few weeks of its life. When the child is old enough to grasp objects, parents in most cases push toys and other objects nearer to its right hand, thus encouraging it to grasp with the right hands. In this way the child may develop right-handedness unconsciously during infancy. As the child grows-up, the right side of the body grows stronger due to greater use.