What do Lady Gaga, Barack Obama, Bill Gates, Paul McCartney, and Justin Bieber have in common with Ronald Reagan, Jimi Hendrix, Judy Garland, Fidel Castro, and David Bowie? All are left-handed, a trait shared by about 10% of the population.
But why are some people left-handed when most people are right-handed? This is an area of active research, and new research shows that the genetics of left-handedness in some people elements have been revealed. Researchers have identified rare variants in genes involved in controlling cell shape and found they are 2.7 times more common in left-handed people.
Although these genetic variations account for only a small fraction of left-handedness (perhaps 0.1%), researchers believe that this gene, called TUBB4B, plays a role in the development of brain asymmetries that underlie left-handedness decisions. He said this study shows that it is possible. dominant hand.
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In most people, the two halves, or hemispheres, of the brain have slightly different anatomy and are responsible for different functions.
There is a rare genetic mutation that plays a role in cell shape and is thought to be associated with left-handedness. (Reuters/Carlos Jasso/File photo)
“For example, in most people, the left hemisphere is dominant when it comes to language, and the right hemisphere is dominant when it comes to tasks that require directing visual attention to a specific location in space.” Dutch Max Planck Psycholinguistics said Clyde Franks, a neurobiologist at the institute. The findings were published Tuesday in the journal Nature Communications.
“In most people, the left hemisphere controls the dominant hand. Associated nerve fibers cross from left to right in the lower part of the brain. For left-handed people, the right hemisphere controls the dominant hand.” The question is: What causes brain asymmetry to develop differently in left-handed people?”
TUBB4B controls proteins that are assembled into filaments called microtubules, which provide the internal structure of cells. The identification of a rare mutation in this gene, which is common in left-handed people, suggests that microtubules are involved in setting up normal asymmetry in the brain, Franks said.
The two cerebral hemispheres begin to develop differently in the human fetus, but the mechanisms remain unclear.
“Rare genetic mutations found in just a handful of people can identify genes that provide clues to the developmental mechanisms of brain asymmetry in all people. TUBB4B may be a good example of this,” Franks added.
The discovery was based on genetic data from more than 350,000 middle-aged and older people in the UK, included in a dataset called the UK Biobank. Approximately 11% were left-handed.
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For most people, which hand is dominant may be determined by chance.
“We believe that most cases of left-handedness occur simply due to random fluctuations during fetal brain development, with no specific genetic or environmental influences. For example, certain things like random fluctuations in the concentration of molecules,” Franks said. He said.
For centuries, many cultures looked down on left-handedness and tried to force left-handed people to become right-handed. In English, the word “right” can also mean “correct” or “appropriate.” The word “sinister” comes from the Latin word meaning “left side.” And by “left-handed compliment” I mean an insult disguised as a compliment.
The prevalence of left-handedness varies by region of the world, with lower rates in Africa, Asia and the Middle East than in Europe and North America, Franks said.
“This probably reflects the oppression of left-handedness in some cultures. Switching left-handed children to right-handedness used to occur in Europe and North America as well,” Franks said. added.
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The new findings may be relevant to the field of psychiatry. Although the vast majority of left-handed people do not have these symptoms, people with schizophrenia are about twice as likely to be left-handed or ambidextrous, and people with autism are about three times as likely to be left-handed or ambidextrous, Franks said. Stated.
“Some of the genes that function in the developing brain during early childhood may be involved in both brain asymmetry and psychiatric traits. Our study shows evidence to suggest this. “We also saw it in previous studies that looked at genetic variations that are more common in the population,” Franks added.
