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Left-handed brains and bodies work differently than right-handed or left-handed and right-handed people with the same precision, or who use each hand separately to perform different tasks, according to CNN.
Being left-handed is determined very early in the development process as a fetus in the mother’s womb, says Professor Ronald Yu, professor of psychology at the University of Texas-Austin, and it has many health implications.
25% genetics
Yu says scientists aren’t sure why some people are left-handed, but they do know that genetics are only responsible for 25% of left-handed people tend to be left-handed, which is significantly less than other hereditary traits. such as like size or intelligence. He adds that in some cases of identical twins who share the same genes, sometimes the dominant hands are different. There are many theories about other things that could determine which hand a person writes with, but many experts believe this to be somewhat random.
stress during pregnancy
In a 2008 Swedish study of mothers and their 5-year-olds, women who were depressed or stressed during pregnancy were more likely to have mixed or dyslexic children. In other studies, a low birth weight baby or an older mother was also more likely to be left-handed.
common myth
A non-left-handed person uses the left hemisphere to process language, but that doesn’t mean most left-handed people use their right hemisphere, says Professor Gina Grimshaw, director of the Cognitive and Affective Neuroscience Laboratory at the University of Wellington in New Zealand It’s just a common myth.
She adds that around 98% of right-handed users are also left-handed, while the percentage does not exceed around 70% among left-handed users, noting that only around 30% are right-brained or dual-brained, that is, they have the same ability both halves of the brain. “It seems that most left-handed people have similar language treatment to right-handed people,” says Professor Grimshaw. For other one-sided brain functions, such as attention, emotions, music, and facial perception, there is less data.
school performance
Left handedness can affect academic performance. A 2009 Australian study of children aged 11 and under found that left-handed children performed worse on many criteria, such as vocabulary, reading and writing, social development and motor skills. overall. who used mixed hands worse than left-handed performance. Researchers suggest that mixed, left-handed children use both halves of their brains in unusual ways.
Professor Yu explains that the reason may be that, for example, some mixed-race children do not know which hand to write with, but he points out that in both cases most children catch up with their peers as they get older, so if a the pupil is left-handed or mixed is not an indicator.
mental health problems
Left-handed people may be more likely to develop psychotic disorders such as schizophrenia than right-handed or both-handed people, according to a 2013 Yale University study. When researchers interviewed patients at a mental health clinic, 40 % of people with schizophrenia or schizophrenia said they were left-handed, while left-handed people were more likely to develop psychotic disorders such as schizophrenia.Other studies found a link between lack of right-handedness, dyslexia , ADHD and certain other mood disorders.
Sports function
Most experts agree that the left-handed athlete stands out above the rest, especially in individual sports such as tennis, boxing, and baseball. In a French study conducted in 2005, researchers concluded that a left-handed person has a physical advantage over a right-handed or right-handed person and is based on the element of sudden or unexpected movement.
Risk of breast cancer
Use by left-handers appears to be associated with certain physical health problems. In a 2007 study published in the British Journal of Cancer, researchers reported that left-handed women have a higher risk of breast cancer than right-handed women, especially for postmenopausal cancers.
autoimmune disease
Scientists have long suspected that left-handed use is somehow related to immune function and may be a risk factor for autoimmune disease. Professor Grimshaw says scientific research has not been able to support most of these claims, and this theory has been widely refuted.
Some sleep problems
In a 2011 survey by the University of Toledo of 100 patients in a sleep clinic, researchers found that 69% of right-handed users experienced lateral limb movements while sleeping, while the percentage rose to 94% in left-handed patients, meaning that left-handed people are significantly more likely to develop PLMD related to bilateral limb movements.
negative feelings
The results of a 2007 Scottish study indicated that left-handed people were more likely to show symptoms of PTSD after watching clips from a horror movie, and that they experienced more negative emotions. Both findings could be due to the fact that left-handers are more likely to have their brains process fear and anger differently.
American presidents
“I hope we will have a better understanding,” says Professor Grimshaw [للعٌسر] Soon. One thing is for sure, said Professor Yu, is that “we shouldn’t assume much about the character or the health of people just because they write with their right or left hand. And we certainly shouldn’t worry about a southpaw’s odds of success, because for example, until 2015, five of the last seven U.S. presidents were left-handed or co-ed.
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