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

Why are some people right-handed and others left-handed?

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

Nowadays, we also coincide with several celebrities and illustrious characters who used their left hand to write, such as the late Hugo Chavez, or four of the last seven presidents of the United States, including Barack Obama.

Science investigates the peculiarities of left-handers and right-handers

They were all left-handed. Judging by this introduction, one might think that history has left us great left-handed personalities. Perhaps more capable of governing countries? With better artistic and creative talents? For decades, science has been investigating the incidence of this peculiarity.

Approximately, it is often said that 90% of the population is right-handedthat is, they use their right hand and right foot as a priority. A much smaller percentage, 10%, are left-handed. 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 depending on whether they are left-handed or right-handed.

Left-handed or right-handed: what is the cause of this characteristic?

As recognized by neuroscience experts, there is no definitive evidence or any proven neurobiological marker that causes a person to be left-handed or right-handed. However, they do agree However, they do agree that, in the fetal stage, humans already begin to develop a preference for one hand or the other.. Other theories point out 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 is closer to the mouth most of the time.

10% of the world's population preferentially uses the left hand.

Although science does not yet know exactly how many questions about left-handed and right-handed people are known, it has been able to yield several interesting facts. As I 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 right hand.

In fact, until a few decades ago, many people were forced to be left-handed, until a few decades ago many people were forced, by 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

This is not the only historical outrage that left-handed people 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 of them as criminals and crooks.or by false stereotypes that branded them as criminals and thugs.

It is not surprising, then, that this persecution of left-handers culminated in certain - shall we say - "pedagogical" methods to correct this supposed deviation. Many elderly left-handers in Spain recall with regret how they were pressured and forced to write with their right hand during their school years, being reconverted to right-handedness even against their nature.

Scientific studies

Several studies have tried to explain why some people are left-handed and left-handed. why some people are left-handed and others are right-handedand their brain, Biological and psychological differences.

Right-handed people are "more right-handed".

Going into scientific matters, it is worth noting that, according to a study conducted at the University of Ontario, "right-handed people are more right-handed compared to left-handed people, who tend to be ambidextrous; to execute with more skill both hands". In other words, the researchers claim that people who preferentially use their left hand are much more skilled with their right hand than right-handers with respect to their left hand.

This could be explained by the fact that left-handed people have been forced, from an early age, to handle utensils and tools designed for right-handed people, so they end up developing right-handed dexterity.This could be explained by the fact that left-handed people have been forced, from an early age, to handle utensils and tools designed for right-handers, thus developing a greater ability to control their "bad hand".

Left-handers live shorter lives, on average

One of the aspects on which science has delved more deeply is the longevity of left-handed and right-handed people. And the fact is that, as has been demonstrated, left-handed people tend to live about nine years less on average than right-handed people.. But why does this happen? There are several hypotheses that attempt to explain this difference.

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

Genetics comes into play

Yes, it seems that there is already data pointing to the fact that the preference for one hand or the other 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 of preferring to use the left hand. This variant, named LRRTM1, is also a predictor of schizophrenia. In other words, people with this genetic variable have a higher risk of suffering from this neurological disease.

However, the relationship between having this genetic variation and having schizophrenia has only been weakly 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 or her lifetime. In fact, the degree of correlation between left-handedness and possession of this gene is still being studied.

Cross laterality and brain differences

The differences between left-handed and right-handed brains contribute to deepen the few answers and many unknowns about the laterality of human beings. As we have explained in previous articles of Psychology and Mindour brain consists of two hemispheres, right and left, and although the brain operates globally, each of these hemispheres is specialized in certain functions.

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It is often said, although it is a somewhat unscientific simplification, that the left side of the brain is in charge of processing numerical and logical information, while the right hemisphere is more linked to creativity and the way we feel and get excited. And what about writing? In more than 80% of the population, writing is more closely linked to activity in the left hemisphere, which in turn governs our brain's ability to write.which in turn governs our right side (yes, even if it sounds counterintuitive). These people, therefore, are right-handed. In the case of left-handed people, things get a bit more complicated, since the activity related to writing is more evenly distributed between both hemispheres.

Further research on this issue will be necessary to continue to provide interesting data on the causes of laterality and the differences between left-handed and right-handed people. For the time being, we are left with more questions than certainties.