Humans are the only one among all animal species who exhibit a distinct right or left handedness. 90% of every human population that has ever lived appears to be right handed, where nine out of ten people are right handed and eight are right footed.
According to researchers, handedness is an inherited virtue, that predominantly depends upon Genetic constitution of an individual. For Instance:
- With both parents right handed, there is 6% possibility of getting the children with left handed.
- Among two left handed parents , perhaps 40% of the children will be right handed.
- When one parent is right & other one is left-handed,20% of the children Will be left-handed.
- Among teen, one in six pairs of Twins differ in their handedness.
- As cited above the main cause is Genetics, which contributes predominantly for left or right handedness.
- Moreover, as right side of brain controls left part of body and right part of body is controlled by left hemisphere of the brain. So psychologists now believe that due to left hemisphere of the brain which contributes toward 95% of right handed character or phenomenon.
One of the research conducted by Dr. Brinkman, a brain researcher at the Australian National University in Canberra, has suggested that evolution of speech went with right handed preference. She observed that if left handed person is brain damaged in the left hemisphere, the recovery of speech is quite often better and this is explained by the fact that left handers have a more bilateral speech function. In her studies of macaque Monkeys, Brinkman found that monkeys seem to learn a hand preference from their mother in the first year of their life. Areas that are involved with the production of speech are usually larger on the left hand side than on the right.
American Researchers, Geschwind and Galaburda studied the brains of human embryos and discovered that the left-right asymmetry exists before birth. Every brain is initially female in its organization and it only becomes a male brain when the male foetus begins to secrete hormones. Different parts of brain mature at different rates. The right hemisphere develops first then the left one. Moreover, a girl’s brain develops somewhat faster than that of a boy. So, if something happens to the brain’s development during pregnancy, it is more likely to be involved in the left. It is more interesting and surprisingly to note that among mathematicians and architects, left handers are more common and there are more left handed males than females.
According to Charles Moore, anything on the right can be trusted while anything on the left is dangerous or even sinister. According to Moore, it is interesting that if we force left handed children to use right hand, they develop stammer as they are robbed of their freedom of speech.
However, the attitude towards left handed people are gradually changing for better. When the champion tennis player Ivan Lendel was asked that what single thing he would choose in order to improve his game, He said he would like to become a Left-Hander.