Cause and Effect of Left-handedness

South Asians, such as the Indians, Southeast Asians like the Filipinos, and Eastern Europeans like the Romanians and Czechs are more likely to be left-handed.  Western and Northern Europeans and Africans are less apt to be left-handed, so went the conclusion on the demographics of left-handedness.

Here’s more on this left-handed incidence- it is more likely to appear in identical twins and in people with neurological disorders, like Down’s syndrome, autism, mental retardation, epilepsy, and dyslexia.  This is aside from the occurrence of left-handedness in geniuses.  (So take your pick, all ye southpaw readers.)

What causes left-handedness?  Just this year, the gene deemed most likely to increase the odds of left-handedness was discovered.  Other theories, mostly pointing to an accident of birth, are also contributing to the study.

One theory is about testosterone.  Its levels during pregnancy shape the brain.  A fetus exposed to high levels of testosterone has more neurons drifting to the brain’s right hemisphere, which is the center of language and handedness. The brain’s right hemisphere thus becomes highly developed and the fetus is more likely to be left-handed since it is the brain’s right hemisphere that controls the body’s left side.

Another cause given is the rising age of motherhood.  Older mothers are more liable to give birth to left-handed children, according to studies at the University College London.

So far there are only theories as more studies are needed to make these foolproof.  It is therefore easier to simplify the occurrence of left-handedness by saying that some are left-handed by choice because their right hands are impaired or that it’s like saying that some have blue eyes while others have them brown because they are born with it.

Neurological disorders aside, there are also theories on the effect of left-handedness on the way a person thinks.  Anecdotes point out that right-handed persons need to finish a task before starting another while left-handed ones have the ability to multi-task.  The former analyzes a problem by breaking it down to pieces one at a time, the latter synthesizes a problem by looking at the whole and using patterns to find a solution.

Chris MacManus (author of the book Right-Hand, Left-Hand) who spearheaded the study at the University College London theorizes that the increase in left-handed people could have corresponding intellectual advances in the fields of mathematics, sports, and the arts.

It may look like being left-handed could go either way, from neurological disorder to genius.  But then as in everything else, it isn’t a sweeping conclusion.  So are there right-handed geniuses and fools.  The point here is more of anecdotal prevalence.

It may have been the difference of the left-handed from the right-handed and the ancient bias against left-handedness that impelled all these research and studies.

Time was when those who were left-handed were looked upon as bad for marriages.  The left hand had even been associated with the devil, which was thought to baptize his followers with his left.

In ancient Rome when salt was a prized commodity and spilling it was bad luck, one was supposed to throw some of the spilled salt over the left shoulder to ward off bad luck and appease the devil.

Another myth about the left is that when the right eye twitches, one would see a friend; if it were the left eye that twitches, one would see an enemy.  Well, if both eyes twitch, one better see a doctor, as we know now.

Passing or pouring wine with the left hand is bad luck and toasting someone with the left is as good as a curse.  If this were true, there would be no need for some of our politicians to go to great lengths or spend a fortune to destroy their enemies.  A left-handed toast will do.

But here’s the unkindest cut of all- the right hand was the male symbol and the left hand the female symbol.  One can take heart and safely suppose that a right-handed male wove this yarn in his far-from-genius left hemisphere of a brain.

(7 Oct 2007)