For the first time, a new study identified regions of the human genome associated with left-handedness in wider human society and linked them to a site in the deeper brain. A study conducted by researchers at Oxford University under the auspices of UK Research and Innovation found a link between this genetic difference and synapses between the areas of the brain responsible for speech and language. Genes have long been known to play a role in determining laterality - twin studies have estimated that 25% of differences in right or left preferences can be attributed to genes - but it was still unclear which genes specifically caused the phenomenon.

New left-handed study

New study, published in the magazine Brain, noted some genetic variations associated with left - handedness in the genome study of some 400 UK citizens from national biobanks, including 000 left - handers. Of the four genetic regions thus identified, three had to do with proteins that ensure the development and proper structuring of the brain. In particular, these proteins have been associated with microtubules, fibers that serve the cell as a "scaffold," collectively called the cytoskeleton. This, among other things, controls the construction of new cells and their commissioning. Using detailed brain imagery by a total of 38 participants, the researchers found that these genetic effects are associated with differences in the tracts of a part of the brain called white matter, containing a wider cytoskeleton of the brain connecting the centers responsible for language processing and speech production.

Dr. Akira Wiberg, a member of the Oxford University Medical Research Council and author of these analyzes, says:

"About 90% of all people on earth are left-handed, and this has been the case for at least 10 years. Many researchers have dealt with the biological origin of laterality, but the use of biobanks and the amount of samples obtained to reveal the structure of the processes leading to left-handedness helped us. We found that in left-handed participants, the speech centers on the left and right sides of the brain were able to communicate better and in a more coordinated manner. This opens up an interesting opportunity for future research to favor left-handers in performing speech-oriented tasks, but it should be borne in mind that these differences have only been noted as averages in research on many people and not all left-handers will show the same, if any , benefits. "

Professor Gwenaelle Douaud, co-author of the Center for Integrative Neuroimaging at Oxford University, adds:

"Many animals show signs of lateral prominence, such as snails and their shells always turned to one side. This is caused by genes for the cell "scaffold" or cytoskeleton. For the first time, we were also able to establish in humans that these cytoskeletal differences are indeed visible in the brain. In snails and frogs, these processes are caused by early genetics-driven events, so we have a reasonable suspicion that signs of lateral prominence will be visible in the womb. "

Left-handed - less chance of developing Parkinson's disease

The researchers also found correlations between left-handedness, a slight decrease in the chances of developing Parkinson's disease and a slight increase in the chances of developing schizophrenia. However, they emphasize that these are only minor variations in the actual number of people and can only correlate without proven causality. In any case, by studying these links, scientists could better understand the evolution of these diseases.

Professor Dominic Furniss, another co-author of the Nuffield Department of Orthopedics, Rheumatology and Musculoskeletal Research at Oxford University, says: In Czech, for example, authenticity is used, in addition to the authoritative determination, as a confirmation of validity or authenticity, while leftness or leftness, on the other hand, means unfairness and bad intent. Of course, we will not be able to change established idioms, but this research has largely verified that left-handedness has a biologically traceable origin in the human body as a by-product of the complex processes of genetic ontogenesis and is part of a rich register of what makes us human. "