The psychological and cerebral differences between left-handed and right-handed
Great historical figures such as Napoleon, Albert Einstein, Leonardo Da Vinci, Charlot or Mozart had a common characteristic (obviously, of course, their popularity): they were all left-handed .
At present, we also coincide with several celebrities and illustrious people who used the left hand to write, such as the late Hugo Chávez, or four of the last seven presidents of the United States, including Barack Obama.
Science investigates the peculiarities of left-handed and right-handed
They were all left-handed . Judging by this introduction, one might think that history has left us great left-handed personalities. Maybe more able to govern countries? With better artistic and creative gifts? Science, for decades, investigates about the incidence of this particularity.
Approximately, it is often said that 90% of the population is right-handed , that is, use the right hand and the right foot first. A much smaller percentage, 10%, are left-handed. The research on this issue is somewhat confusing, but in this article I will try to explain what are the main differences in the health, brain and psyche of individuals according to whether they are left-handed or right-handed.
Left-handed or right-handed: what is the cause of this characteristic?
According to experts in neurosciences, there is no definitive evidence or any contrasted neurobiological marker that causes a person to be left-handed or right-handed. But nevertheless, yes they coincide in pointing out that, in the fetal stage, humans have already begun to develop a preference over one hand or the other . Other theories point out that, during the ultrasounds performed on pregnant women, it can be distinguished if a baby will be right-handed or left-handed observing which hand is closest to the mouth most of the time.
10% of the world population preferably uses the left hand
Although science still does not know exactly many questions about left-handed and right-handed people, it has been able to shed several interesting data. As I said before, it is estimated that the percentage of left-handed people in the world is around 10%, although it is also true that there are individuals who would not be "natural right-handers", but would have been born left-handed but would have been corrected to use their right hand .
And it is that, in fact, Until a few decades ago many people were forced, with all kinds of methods, to use the right hand instead of the left to write . It was a habitual practice during the beginning of the Spanish Francoism.
The historical disgrace of left-handed people
It is not the only historical abuse suffered by left-handers. People with this peculiarity they have been especially repudiated at different times, under the stigma of being possessed by the devil , or by false stereotypes that labeled them as criminals and thugs.
It is not surprising, then, that this persecution of left-handers culminated in certain methods - say - "pedagogical" to correct this supposed deviation. Many left-handed elderly in Spain remember with regret how they were pressured and forced to write with their right hand in their school years, converted right-handed even against their nature.
Scientific studies
Several investigations have tried to explain why some people are left-handed and others are right-handed , and their brain, biological and psychological differences.
The right-handers are "more skilful"
Going into the scientific field, it should be noted that, according to a study conducted at the University of Ontario, "right-handers are more skilled compared to left-handed people, who tend more to be ambidextrous; to execute with more skill both hands ". In other words, the researchers say that people who use the left hand are much more skilled with the right than right-handed people with respect to the left hand.
This could be explained because left-handed people have been forced, from a young age, to handle utensils and tools designed for right-handers , with which they end up developing a greater capacity to control their "bad hand".
Lefties live less years, on average
One of the aspects on which more science has deepened is about the longevity of left-handed and right-handed people. And, as has been shown, left-handers tend to live about nine years less than average right-handers . But why does this happen? There are several hypotheses that try to explain this difference.
One of the most widespread says that it is possible that lefties are more likely to suffer some minor alterations during their development, which would make them more prone to suffer certain diseases.
Genetics come into play
Yes, it seems that there are already data that suggest that the preference for one or the other hand could have a genetic origin. Specifically, this is what a group of researchers from the University of Oxford discovered, when they isolated a genetic variable that is related to the fact that they prefer to use the left hand. This variant, named LRRTM1, is also a predictor of schizophrenia. That is, people who have this genetic variable are more at risk of suffering from this neurological disease.
In any case, the relationship between possessing this genetic variation and having schizophrenia has only been correlated in a slight way; Exactly what role this gene plays in the multitude of characteristics and propensities that the individual will develop during his life is unknown. In fact, the degree of correlation between the left and the possession of this gene is still being studied.
Crossed laterality and brain differences
The differences between the brain of left-handed and right-handed contribute to deepen the few answers and many unknowns about the laterality of human beings. As we have already explained in previous articles of Psychology and Mind, our brain consists of two hemispheres, right and left, and although the brain operates globally, each of these hemispheres is specialized in certain functions.
It is often said, although it is a somewhat unscientific simplification, that the left side of the brain is responsible for processing the numerical and logical information, while the right hemisphere is more linked to creativity and the way we feel and get excited. And to all this, what happens with writing? In more than 80% of the population, writing is more linked to activity in the left hemisphere , which in turn governs our right side (yes, although it sounds counterintuitive). These people, therefore, are right-handed. In the case of lefties, things get a little more complicated, since the activity related to writing is more evenly distributed between both hemispheres.
It will be necessary to continue investigating around this question to continue contributing interesting data about the causes of laterality and the differences between left-handed and right-handed. For now, we are left with more questions than certainties .
