Why are we right-handed or left-handed?

The preference for one hand or the other comes, in particular, from certain genetic variants, according to work published in the journal “Nature communication”.

The preference for the right or left hand for writing and daily gestures has intrigued scientists for decades. This preference also exists for the feet while one of the eyes is also dominant. The numbers have been consistent throughout human history: approximately 90% of the population is right-handed and 10% left-handed, a constant proportion in all regions of the world. From work published on Tuesday, April 2, in the British journal, Nature of communication, reveal to us that this preference is visibly established very early in our brain. From our conception. The preference for one hand or the other would come, in particular, from certain genetic variants.

For this study, the team from the Max Planck Institute in the Netherlands looked for rare genetic variants associated with being left-handed. To do this, the researchers reviewed DNA sequencing data from a large British cohort, including more than 300,000 right-handers and more than 30,000 left-handers. They actually identified certain genetic variants present, 2.7 times more often in left-handed people. These are variants involved in the production of a family of proteins, tubulins. Proteins that influence the development of the brain and the establishment at the time of its formation, of the predominance of one or the other, of the two hemispheres.

These tubulins can then influence brain development and the predominance of one or the other of the two hemispheres. This certainly does not explain everything, but this study confirms a genetic lead, to at least partially explain the existence of left-handers and right-handers.

Advantages and disadvantages

From a brain function standpoint, left-handed or right-handed, there are advantages to both sides. The world is made for the 90% of right-handed people, so it is easier for a right-handed person to learn to read, write, drive and use certain tools. But previous studies have shown that many left-handers, in adapting to the world of right-handers, also develop certain particular kinesthetic skills. They can be more precise and dexterous in performing certain gestures. They also often seem to have better visualization in space, and to be more comfortable with mathematics and geometry. Perhaps being left-handed helped Leonardo da Vinci, Mozart, or Jimi Hendrix in their careers.