Science is still baffled by left-handedness

If you happen to be left handed, you are part of a small but stable population of people that has always been part of any human culture on the planet, however, scientists still don't know for sure why people are left handed or why it occurs in only a small part of the population.

Choosing one hand over the other has evolutionary benefits, since it's faster and easier for the brain to focus on one hand as the 'dominant' one, rather than splitting its attention between both. Many animal species have been found to favour one hand (or should I say paw) over the other, so we're not unique in that, but humans are, apparently, one of the few species that tend more towards right-handedness than left-handedness. The majority of species that develop a 'handedness' show a more even split.

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Violaine Llaurens, an evolutionary biologist at the National Center for Scientific Research (CNRS) in France, says that between 5 and 20 per cent of people are left-handed, according to LiveScience.

"In every population of the world studied so far, we always find a minority of left-handed people," Llaurens told LiveScience.

Whether left-handedness is genetic, or environmental, or possibly due to some kind of damage, is unknown though. There's a lot of evidence out there that points to all of these possibilities.

Some ideas have been put forward that all human brains are inherently right-handed, but someone can become left-handed by the brain having to 're-wire' itself after damage suffered during development in the womb, or possibly during birth. Not all scientists agree with this hypothesis though. There are other health problems that seem to be more common in left-handed people, though, such as schizophrenia and attention deficit disorder, and also immune system problems, but that doesn't represent proof.

There can be some specific evolutionary advantages to being left-handed, as Llaurens tells LiveScience, since if it is rare, it can represent an advantage in a fight. This would mean that a left-handed warrior could survive more battles and thus be able to pass on his left-handed genes to more children. In modern times, this can also give an advantage in sports, potentially making left-handed athletes more successful. Also, there seems to be a predisposition towards high intelligence for left-handed people. Apparently, Isaac Newton, Charles Darwin, Benjamin Franklin and Albert Einstein were all left-handed.

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Chances are, as with many aspects of human beings, the reason for left-handedness is probably going to end up being due to a combination of different factors, both genetic and environmental. It's also possible that changes or alterations in our brains could be responsible too (according to a news article from a few years ago, someone who's right-handed can be made to favour their left using magnetic stimulation).

Are you left handed? Do you show any of the advantages or disadvantages that are apparently associated with it?

(Photo courtesy: Dave King/Getty Images)

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