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Why Are People Left (or Right)?



The first time you picked up pastels as a toddler, you probably felt more comfortable and naturally drawing with one of your hands than with the other.

With the exception of the small number of truly ambitious people – those who can use their right and left hands with equal ease – people usually have a dominant hand (and side of their body) that they prefer for daily tasks.

But why is that?

Related: Left people smarter?

Most people – about 85 to 90% – are right-handed, and there is no population on Earth where left-handers are the majority.

This uneven cleavage has had historical disadvantages for lions. They had to use scissors, desks, knives and notebooks that were designed with justice in mind. Many leftists were forced, by their natural inclination, to write with their right hands (including some famous examples such as the English King George VI). They were discriminated against and viewed with suspicion as seen in the language used to describe lions. "Right" in English obviously means "right." The etymology of the word "sinister" can be traced to the Latin word for "left." While the stigma against left-handers has faded in most places, scientists are still confused by the right-hand division. Researchers are still trying to understand what makes people prefer one hand over the other and why the righteous dominate.

At the individual level, it is possible to determine handiness in the earliest stages of development. Scientists reported in 2005 and in the journal Neuropsychologia that fruits would show a preference for the hand in the womb (by sucking on the thumb of one hand), fornication that continues even after they are born.

Although there is no right or left gene, DNA appears to play a role in the human . In a recent study published in Brain: A Journal of Neurology researchers at Oxford University examined the DNA of about 400,000 people in the UK and found that four areas of the genome were commonly associated with left-handedness. Three of these four regions have been involved in brain development and structure. Some researchers hope that studying the biological differences between left and right can shed light on how the brain develops specializations in the right and left hemispheres.

The Right Things

Trying to answer the question of transmission from an evolutionary point of view is also complicated. Researchers can find leaks in the archaeological record by looking for specific anatomical features in prehistoric skeletons, such as asymmetry in the size and density of the bones of the arm and by examining prehistoric instruments.

"If you know how the instrument was handled and how it was used, then you can look at the wear marks," to determine whether the left or right used the tool, said Natalie Womini, a senior scientist at the Max Planck Institute for Human Science history in Germany. Scientists can even look at the direction of the diagonal scratches of on the fossilized teeth to see which hand people use to rip meat or animal skins out of their mouths .

Rights have dominated as far as archaeological records, as researchers can see, for about 500,000 years says Womini. The Neanderthals, our already missing human cousins, were also far right.

This makes humans quite strange among animals. Several non-human species, such as the other great apes, are transmitted individually, but the division between righteous and leftist is usually closer to 50-50.

What caused our right-hand variety to develop and continue? From an evolutionary point of view, if the right hand develops because there is an advantage, then you can expect leftists to disappear completely, Uomini told Live Science. She added that there are some disadvantages of left-handed people, such as a higher incidence of occupational accidents. In a study published in 201

3 in Brain: A Journal of Neurology researchers linked the left hand to learning disabilities.

But there is a leading theory that explains why leftists maintain a permanent minority: the fight hypothesis.

"The idea is that in hand-to-hand combat or in gunfire there is an evolutionary advantage to being a left-hander of a minority," Womini said. "If you are left-handed, you have a surprising advantage because most people are used to fighting right-handed." This left advantage has been shown in one-on-one sports as fencing, scientists reported in 2010 in the journal Laterality .

If this hypothesis is correct, it would mean that, although the disadvantages of left-handedness were significant enough to keep lions in the minority, the advantage of left-wingers in the battle at least gave them a chance to fight for possible extinction.

Originally published by Live Science .


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