UNIVERSIDAD DE RUHR

24/07/2018

German researchers from the Ruhr University of Bochum (Germany) have revealed in an article published in 'eLife' what is the real reason we are born left-handed or right-handed. Currently, between 10% and 15% of the population is left-handed, 1% ambidextrous and the rest is right-handed.

Until recently it was believed that the differences between the activity of the left and right hemisphere determined the use of one side or the other. That is, it was thought that this inclination was determined by the brain. The study has revealed the moment in which the inclination to be left-handed or right-handed is made. Researchers have concluded that it occurs during pregnancy and in the spinal cord, not in the brain.

The scientists detected that the fetus begins to develop genetic differences according to their preferences of left or right at eight weeks of gestation. The expression of certain genes of the spinal cord that are responsible for controlling the movement of the legs and arms is different for each of these groups.

In addition, researchers have discovered that the preference for using one hand or another depends on environmental factors produced during pregnancy and that are yet to be determined. In this way scientists have found that this preference is not written from the beginning in the DNA, as they thought at first.

According to the experts, "environmental influences affect the left or right side of the spinal cord in different ways" and that would explain why people are right-handed or left-handed since the development of the fetus.