Researchers identified rare mutations in a gene that has a role in determining the shape of cells, and found that they are about 2.7 times more common in left-handed people, according to Reuters.
While these genetic mutations represent only a small portion, perhaps 0.1%, of the causes responsible for left-handedness, the researchers said that the study shows that this gene, called (TUBP4B), may play a role in the development of what is known as left-handedness. Brain symmetry, which is responsible for determining the dominant hand.
Brain asymmetry
In most humans, the two parts of the brain have a slightly different anatomical structure and are responsible for different functions.
Clyde Franks, a scientist specializing in neurobiology at the Max Planck Institute for Linguistic Psychology in the Netherlands, and one of the main authors of the study published last Tuesday in the journal Nature Communications, said: “For example, the left hemisphere of the brain dominates language in most humans, while the Right hemisphere tasks that require directing visual attention to a place.”
He added: “Also in most people, the left hemisphere of the brain controls the dominant right hand. The relevant nerve fibers cross from left to right in the lower part of the brain. In left-handed people, the right hemisphere controls the dominant hand.”
The question is: What causes brain asymmetry to develop differently in left-handed users?
The TUPB4B gene controls a protein that fuses into threads called microtubules, which provide the internal structure of cells.
Franks said the identification of rare mutations in this gene, which are more common in left-handers, suggests that microtubules are involved in the formation of normal brain asymmetry.
Rare genetic mutations
The two hemispheres of the brain begin to develop differently in embryos, but the mechanism of their development remains unclear.
“Rare genetic mutations in a small number of people can determine the genes involved in the development of brain asymmetry in all people,” Franks added. “The gene TUBPBP4 could be a good example of this.”
The results were based on genetic data covering more than 350,000 middle-aged and older people in Britain, 11% of whom were left-handed.
The determination of the dominant hand in most people may be the result of chance.
“We believe that most cases of left-handedness simply occur as a result of random variation during fetal brain development, without genetic influences or influence from the surrounding community,” Franks said. “For example, random fluctuations in the concentrations of certain molecules during key stages of brain formation.”
Cultures over the centuries have disparaged left-handedness and tried to force left-handers to use their right hands.
In English, the word “right” also means “right” or “suitable,” and the word “right” is derived from a Latin word meaning “on the left side.”
Cultural and psychological influences
Franks stated that the prevalence of left-handedness varies in different parts of the world, with lower rates in Africa, Asia and the Middle East compared to Europe and North America.
He added: “This likely reflects the suppression of left-handedness in some cultures; “This causes left-handed children to switch to right-handed children, which was also the case in Europe and North America.”
The new findings may have uses in the field of psychiatry.
“While the vast majority of left-handed people do not suffer from psychological problems, those with schizophrenia are about twice as likely to be left-handed or ambidextrous, and those with autism are nearly three times more likely,” Franks said.
Franks added: “Some genes that play a role in brain development during the early stages may have a role in its asymmetry and psychological traits.” “Our study found evidence to suggest this, and we have also seen this in previous studies, where we looked at the most common genetic mutations.”
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2024-04-09 14:25:38