Why are people divided into left-handers and right-handers?
Over the last 100 years scientists have studied very well the problem of why people predominantly use one hand and why it is more often the right hand. However, there is no standard empirical testing of right-handers or left-handers, as scientists cannot fully understand what mechanisms are involved in this process.
Scientists disagree on what percentage of humanity is right-handed and what is left-handed. In general, it is believed that the majority (from 70% to 95%) are right-handed, a minority (from 5% to 30%) are left-handed, and there is also an indefinite number of people with observed complete symmetry.
It has been proven that left-handedness and right-handedness are influenced by genes, but the exact “left-handed gene” has not yet been identified. There is evidence that social and cultural mechanisms may influence the propensity to use the right or left hand. The most characteristic example of this is how teachers retrained children, forcing them to switch from their left hand to their right hand when writing. At the same time, at the moment, more totalitarian societies have fewer left-handers than more liberal societies.
Some researchers talk about "pathological" left-handedness associated with brain injuries during childbirth. In the 1860s, the French surgeon Paul Broca noted the relationship between the activity of the hands and the cerebral hemispheres. According to his theory, the halves of the brain are connected to the halves of the body crosswise. But at the moment it is known that these connections are not as simple as Broca described them.
Studies conducted in the 1970s showed that most left-handed people have the same left hemisphere activity, which is typical for all people. At the same time, only a part of left-handers have various deviations from the norm.
Studying the problems of left-handedness and right-handedness of primates, scientists have found that the majority of animals in a particular population are either left-handed or right-handed. In doing so, individual monkeys often develop their individual preferences.
As a result, we still have only a general idea of the causes of right-handedness, and researchers have yet to understand in detail all the mechanisms of their formation.
