WHY SOME PEOPLE ARE LEFT-HANDED?

Most of the people in the world are right-handed. Right-handed people are more skillful with their right hands when performing tasks. Studies suggest that 70-90% of the world populations are right-handed. Left-handedness is less common than right-handedness. Left-handed people are more skillful with their left hands when performing tasks. Studies suggest that approximately 10% of the world’s population is left-handed.

Each side of the Brain controls the muscles on opposite side of our body. In most people,the left side of brain is more dominant than right side. Thus we will be more likely right-handed and vice-versa.

Researchers, who study the human hand preference, agree that the side of the preferred hand is produced by biological and most likely genetic causes. The 2 most widely published genetic theories of human hand preference argue that evolutionary natural selection produced a majority of individuals with speech and language control in the left hemisphere of brain because the left hemisphere controls the movement of right hand.

The genetic proposal to explain hand preference states that there are 2 alleles or 2 manifestation of a gene at the same genetic location that are associated with handedness. One of these alleles is ‘D’ gene and other is the ‘c’ gene. The ‘D’ gene is more frequent in population and promotes right-handed preference in majority of humans. The ‘c’ gene is less likely to occur within gene pool. Individuals with ‘c’ gene will have 50% chance of being right-handed and 50% chance of being left-handed.