Psychological and brain differences between left-handed and right-handed

Great historical figures such as Napoleon, Albert Einstein, Leonardo Da Vinci, Charlot or Mozart had one characteristic in common (in addition, obviously, to their popularity): they were all left handed.

Today, we also meet several celebrities and famous people who used the left hand to write, like the late Hugo Chávez, or four of the last seven presidents of the United States, including Barack Obama

Science investigates the peculiarities of left and right handed

They were all left handed. Judging from this introduction, you might think that history has left us with great left-handed personalities. Perhaps better able to rule countries? With better artistic and creative gifts? Science, for decades, has been investigating the incidence of this particularity.

Roughly, it is often said that 90% of the population is right-handed, that is, use the right hand and the right foot primarily. A much smaller percentage, 10%, are left-handed. Research on this issue is somewhat confusing, but in this article I am going to try to explain what the main differences are in health,

brain and the 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?

As recognized by experts in neurosciences, there is no definitive evidence or any proven neurobiological marker that causes a person to be left-handed or right-handed. However, They do coincide in pointing out that, in the fetal stage, humans already begin to develop a preference for one hand or the other. Other theories suggest that, during ultrasounds performed on pregnant women, it can be distinguished whether a baby will be right-handed or left-handed by observing which hand he has closer to his mouth most of the weather.

10% of the world population preferably uses the left hand

Although science still does not know exactly many questions about left and right handed people, it has been able to provide several interesting data. As I have mentioned 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-handed", but would have been born left-handed but would have been corrected to use the hand right.

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 common practice during the beginning of the Spanish Franco regime.

The historical misfortune of left-handed people

It is not the only historical outrage that lefties have suffered. People with this particularity have been especially repudiated at different times, under the stigma of being possessed by the devil, or by false stereotypes that branded them criminals and thugs.

It is not surprising, then, that this persecution of left-handers culminated in certain - let us say - "pedagogical" methods to correct this alleged deviation. Many old left-handers in Spain remember with regret how they were pressured and forced to write with the right hand in their school years, converted to right-handed even against their nature.

Scientific studies

Various investigations have attempted to explain why some people are left-handed and others are right-handed, and their brain, biological and psychological differences.

Right-handed people are “more skilled”

Entering scientific matters, it should be noted that, according to a study carried out at the University of Ontario, “Right-handers are more skilled compared to left-handers, who tend more to be ambidextrous; to execute with more skill both hands ”. In other words, the researchers say that people who preferentially use the left hand are much more skilled with the right than the right-handers 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-handed people, with which they end up developing a greater ability to control their "bad hand".

Lefties live fewer years, on average

One of the aspects on which science has deepened the most is on the longevity of left and right handed people. And it is that, as has been shown, left-handers tend to live about nine years less on average than right-handers. But why does this happen? There are several hypotheses that try to explain this difference.

One of the most widespread is that it is possible that left-handers are more likely to suffer some minimal alterations during their development, which would make them more prone to suffer from certain diseases.

Genetics come into play

Yes, it seems that there is already data that suggests 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 preferring to use the left hand. This variant, named LRRTM1, is also a predictor of schizophrenia. That is, people who have this genetic variable are at greater risk of suffering from this neurological disease.

In any case, the relationship between having this genetic variation with having schizophrenia it has only been slightly correlated; It is not known exactly what role this gene plays in the multitude of characteristics and propensities that the individual will develop during his life. In fact, the degree of correlation between left-handedness and having this gene is still being studied.

Cross laterality and brain differences

The differences between the left-handed and right-handed brain contribute to delving into the few answers and many unknowns about laterality of human beings. As we have already explained in previous articles on Psychology and Mind, our brain consists of two hemispheres, right and leftAlthough 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 feel we thrilled. And to all this, what about 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 left-handed people, things get a bit complicated, since the activity related to writing is more evenly distributed between both hemispheres.

It will be necessary to continue researching around this question to continue providing interesting data on the causes of laterality and the differences between left-handed and right-handed. For now we are left with more questions than certainties.