Scientists have suggested how the people are divided into left and right handers
Scientists from Ruhr University in Germany put forward the hypothesis that left-handedness and right-are formed through the spinal cord, before its connection with the head. The results were published in the journal eLife.
The observation of the embryos in the womb have revealed that even at 13 weeks they prefer to suck the left or right thumb. Hand movements occur thanks to the work of the motor cortex of the brain, which sends signals to the spinal cord. But at this stage of development the link between cortex and spinal cord has not formed yet.
This leads scientists to believe that the predominance of one of the arms does not depend on the brain and spinal cord.
In addition, the researchers observed the gene expression of five fruits on 8-12 week of development. They found a difference in the number of genes that is expressed on the right and left parts of the spinal cord. This difference was notable in those areas responsible for movement of the arms and legs. The reason for this asymmetry, scientists have described the influence of environment in their opinion, it leads to greater activity either side of the spinal cord.