The differences that they discovered in left-handed DNA (also in their brains)

But now, for the first time, a team of scientists from Oxford University (England) has discovered the genetic instructions of human DNA related to the southpaw.

These instructions, related to the organization of the internal skeleton of the cells, also seem to be very involved in the structure and functioning of the brain, especially in the domains related to language.

The researchers published their findings in the journal Brain Thursday, in which they suggest that left-handers have better verbal skills.

But there are still many mysteries to be solved around the link between brain development and the dominant side.

How did the study take place?

Studies on twins have already revealed that genetics play a role in the dominant side they use the most.

However, the details of how this dynamic works are just beginning to be known.

The research team has turned to the British Biobank project, a comprehensive database on the genetic code of about 400,000 people. Just over 38,000 were left-handed.

Scientists have been trying to detect the genetic differences between this group and others, in order to find the regions of DNA that influenced lefties.

The study revealed four critical mutations.

"This tells us for the first time that the use of one hand or another has a genetic component," Professor Gwenaëlle Douaud, one of the researchers, told BBC News. .

How do these mutations work?

The mutations have been found in the instructions for the complex "scaffolding" that organizes inside the body's cells, called the cytoskeleton.

Similar mutations that modify the cytoskeleton in snails have shown that molluscs have a shell that is anti-clockwise or "left-handed".

Do you remember looking for a partner for Jeremy, the "left-handed" garden snail "because in the world of snails, right-handed and left-handed people can not have bad since their bodies bads are in the wrong place for each other? They finally found him a "left-handed" conch and had 56 snails, although all turned out to be "right-handed".

The badyzes of the participants in the Biobank project showed that the cytoskeleton altered the structure of the white matter in the brain.

"For the first time in humans, we have been able to establish that these cytoskeletal differences badociated with the dominant hand are really visible in the brain," said Professor Douaud, southpaw.

In left-handed participants, the left and right hemispheres were better connected and better coordinated in the regions involved in the language.

Researchers speculate that left-handers may have better verbal skills, although this study does not provide the data to prove it.

Research has also shown a slightly higher risk of schizophrenia and a slightly lower risk of Parkinson's disease in left-handed people.

Does this change what it means to be left-handed?

Being left-handed has often been synonymous with unfair treatment.

"In many cultures, being left-handed is considered unfortunate or malicious and this is reflected in the language," said Professor Dominic Furniss, hand surgeon and one of the authors of the report.

In French, "left" means "left", but also "clumsy". In English, "right" is used in the expression "being right", which means "to be fair".

"What this study shows, is that being left-handed is only a consequence of the biology of brain development, it has nothing to do with luck or the malice, "explained Professor Furniss.

"This is motivated, at least in part, by the genetic variants we have discovered, which adds to the understanding of what makes us human beings," he added.

Is it the end of history?

The best guess is that the dominant side of a person depends on 25% of genetics and 75% of the environment.

However, this study found only the first 1% of this genetic component and only in a British population.

Therefore, much remains to be done to understand the genetic component of the dominant group around the world, regardless of the enormous environmental effects, and then to reconstruct how these elements determine whether individuals are left-handed or right-handed.

BBC