My deskmate was being retrained from left-handed to right-handed. It was at the beginning of the harsh nineties. And then they did not stand on ceremony with us. They could slap the “wrong” palm, urged all the children to look after Lena. Well, at least they didn’t tie their hand to the thigh, I know there were such precedents.
More than 20 years have passed. Now many left-handers are proud of their peculiarity, studies are being carried out that are designed to prove: this is not a mistake of nature, but an indicator of outstanding ability. Scientists are struggling with only one riddle: why a child, in principle, becomes left-handed.
In fact, they do not become left-handed. Lefties are born. And this has been known for a long time. Until now, it was believed that the leading hand depends on the activity of the cerebral hemispheres. Scientists understood that this is inherent in nature, that it is formed even before the birth of a baby. But there was no clear evidence of this.
– Back in the 1980s, on ultrasound, starting from the eighth week of pregnancy, it was possible to understand which hand the baby prefers to use, – scientists say. – From the 13th week, they prefer to suck the thumb of either the right or left hand.
A number of studies were carried out by a group of specialists from the Ruhr University of Bohom in Germany, together with colleagues from the Netherlands and South Africa. The results are published on the university website. And they really managed to confirm: right- or left-handedness is laid at the genetic level. Only it is not the brain that participates in this, but the spinal cord.
– The kid sucks his finger, but at the same time the connection between the spine and the brain has not yet been formed, – biologists and psychologists explain. “This means that the head is unlikely to play a role in such an important matter as the choice of the thumb for sucking.
That is, they were looking for asymmetry not where it really was.
– We have fixed the asymmetric activity of genes in the neurons of the spinal cord, – the scientists cite the results of the research.
Another very important question: why does this asymmetry arise? In other words, is there anything that can be done at conception to “program” the birth of a right-hander or a left-hander? So far, this is a mystery. Although … Is it necessary to program it? ..