The mystery of the left hand: for the first time, genetics finds clues to manual dominance in humans

Nine out of ten people have been right-handed for no less than 10,000 years. We know this from prehistoric tools, from cave paintings and from cross-cultural studies. Lefties are, even if it doesn't seem like it, a puzzle that has been intriguing to experts for decades.

Above all, because it is something that does not happen in the animal kingdom where the traits of this type are distributed more uniformly. Now a team of researchers from the University of Oxford has identified a series of genetic variants that may be behind the mystery of the left hand.

The left hand of ... humanity

Pablo Garcia Saldana

The researchers analyzed the genetic data, medical reports, and brain images of 721 left-handed and 6,685 right-handed. As a result, they identified four specific places in the genome associated with the dominant left hand. Three of them, in addition, have a very important role in the development of brain areas related to language.

And indeed, when studying those areas in detail they found that they seemed to behave more coordinated in left-handed than right-handed. These differences, as much as they were expected (the studies with twins told us that there was something), had not been found yet.

Another very interesting thing about the study is that these genetic variants can explain "moderately" part of the propensity that left-handers seem to develop in the face of schizophrenia and anorexia nervosa, or their lower Parkinson's rate. These are very small figures, but they allow us to unravel a mystery that until now we did not know how to solve.

And it is that this work, beyond its concrete results, represents the first significant association between specific genetic mutations, the brain structure and the left-handed population. As Ryan F. Mandelbaum says, we have not found the "left-handed gene", but it is not necessary. We are facing a very exciting study because it is very possible that it will open one of the ways that will help us understand how all this works in the dominant hand.

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