According to Yolanda del Ro Portilla, an academic at the UNAM's Faculty of Psychology (FP), eight to thirteen percent of the population is left-handed, a condition that affects greater motor skills; it is more common in men than women.
Scholar in subjects such as cerebral laterality with electroencephalography considers that, in contrast to right-handed people, they are a mixed group whose neuropsychology and brain functioning are little known. It's not because they are smarter, but because they find it easier to use both hands for everyday tasks.
According to the book El mundo del zurdo (The World of The Left-Handed), by the Colombian psychiatrist Osvaldo Castilla Contreras, "being left-handed is not a disadvantage in itself. However, because they are a minority, they must face a world designed for right-handed people, such as the use of cutlery, western writing from left to right, sink keys, door handles, school desks, etc."
"Left-handed people are sometimes considered to be the objects of ridicule, prejudice, misunderstanding, and corrective mistreatment. However, this condition has some advantages, such as the greater speed with precision (unscrewing), better reflexes, or fewer sequels in cases of cerebrovascular accidents, "states the specialist in his work."
It is a question of genetics since there is no specific pattern that shows why people have this condition or ability, although it has been observed that there is a recessive gene (LRRMT1 and PCSK6) that later manifests itself as dominant, and when combined, this predominance is expressed.
"There is a lack of a clear genetic model to explain how this trait is transmitted. Previously, it was believed that being left-handed was a condition that was mainly observed in Anglo-Saxon races; today it is known that it is generalized in mankind, "she explains.
At the end of the 20th century, some left-handed children still had their hands tied so that they could write mainly with their right hand. This may have caused some disorders, such as stuttering. It was also thought that left laterality was caused by some injury in the brain region at birth, due to the use of forceps; nowadays it is known that it is not due to that.
According to some studies, they have advantages in sports such as soccer, basketball, table tennis, and baseball, among others, perhaps because right-handers are not used to facing them, but also because they have more development in the behavioral area. At the electroencephalographic level, we have found some changes. For example, their brains are less specialized than those of right-handers.
When an athlete hits more with the left hand or has a better kick with the left foot, he or she decontrols right-handers, because they have greater strength or certainty on the opposite side. The left-handed athlete can change his defense or position more easily.
Left-handed in a right-handed world
People who use their left hand to write or manipulate instruments use the right brain hemisphere instead of the left, as right-handers do. In the world, implements are generally designed for right-handers, which represents an obstacle for left-handers who have had to adapt to use them. "In reality, life is made for right-handers; left-handers (synonymous with left-handed) must develop the ability to use their right hand as well, to adapt to the right-handed world, which is easier for them".
When, for some reason, a right-handed person fractures their right hand, they may be forced to develop the use of the left limb, which is difficult for them, while left-handed people could adapt to using both hands more easily.
Del Río Portilla indicates that as part of the studies carried out in the laboratory on brain laterality and sex differences, "we have analyzed a small part of that ability to determine if left-handers are more intelligent or if they have greater abilities for some sports or to thread a needle and throw an object."
It has been described that the right hemisphere develops more spatial ability (perceiving reality by appreciating sizes, directions, and spatial relationships), while the left hemisphere develops language.
In the presentation of visuospatial stimuli (group of cognitive functions that allow us to analyze, understand, and manage the space in which we live), we observed the brain electrical activity of people who performed more than 80 percent of their activities with their dominant hand (right or left), both men and women.
"Differences were found when they were at rest; however, when they executed spatial skills, the brain activity was diluted, which allowed us to determine that there are almost no differences about laterality in both left-handed and right-handed people."
As for the participation of brain regions or brain connections, "we have observed that in the case of left-handers, more brain regions participate and right-handers have more brain specificity, that is, the latter have a more specialized brain region, and left-handers use a larger brain region."
Stigmatization of left-handers
According to historical studies, at the time of the Inquisition, they were a favorite prey of the inquisitors because they were considered to have witchcraft or demonic background; several were burned during the Middle Ages. Throughout time, they have been considered inferior. For generations, the Catholic Church declared them servants of the devil; those who attended Catholic schools were forced to be dexterous.
Today, the situation of social stigmatization has changed. However, rectification towards this population persists. Given this, some "guidance and support" is required at the educational and family level so that parents and teachers can contribute so that children with this ability can handle themselves with the left side of their body in a natural way, telling them: "use the pencil with the hand you prefer" (that they take it with the tweezers in an appropriate way, leaning on the middle finger), then help them place the notebook at 45 degrees to write. With this, there will be more attention to the child and their inclusion is encouraged, for example."
Several famous people in science, art, sports, and culture are or were left-handed. These include scientists Leonardo da Vinci, Marie Curie, Isaac Newton, Neil Armstrong, Buzz Aldrin, Charles Duke, Jim Lovell, and Edgar Mitchell, and artists Michelangelo, Rubens, Maurits Cornelis Escher, and Van Gogh.
In music: Jimi Hendrix, Paul McCartney, David Bowie, Kurt Cobain, Sting, Ringo Starr, and Bob Dylan. In the field of sports, John McEnroe, Rafael Nadal, Lionel Messi, LeBron Raymone James, and Mexican baseball player Fernando "El Toro" Valenzuela, among others, stand out.
This event is a worldwide day promoted by Lefthanders International. It is commemorated on August 13 every year, since 1976, and seeks to raise awareness and help reduce the difficulties encountered by people with this ability in a predominantly right-handed society, such as having to use tools designed for right-handed people and various situations of discrimination, including harassment.
This sector has a Left-Handers Club, formed in 1990 to keep its members in touch with developments; to make their views known to manufacturers and producers, and to provide a helpline and advice to promote research into left-handedness and the development of new items.