Sunday, August 15, 2004

LEFTIES -- (previously published in the Pioneer)

This appeared in the Pioneer in 1999

Laterality is the word used to describe the "specialized functioning in each hemisphere of the brain or in the side of the body which each controls" (Britannica). The most familiar example of this is called "handedness", the way that most of us favour the use of one hand over the other. But there is "handedness" in the way we use our eyes and our feet too.

You can check which of your two eyes is dominant by a simple test. Hold the forefinger of one hand about six inches away from your face, parallel with your nose. With both eyes open, centre the finger on some distant object like a vase or a lamp across the room from you. Close first one eye then the other. You will find that one of the eyes will reveal a view of the finger correctly centred on the vase or lamp while the other eye will show the finger displaced to one side. The eye with which you see the finger correctly centred is considered the dominant one. It does not necessarily follow that the side on which your hand is dominant will be the same one on which your eye is dominant.

According to the encyclopaedia, about three-quarters of right-handed and one third of left-handed people are right-eye dominant. Though the great majority of people are right-handed, there is no evidence to show that one side or the other is in any sense "better". Some famous lefties are: Napoleon, Einstein, Oprah Winfrey and Bill Gates.

I used to want to train my left hand for writing with so that I would have back-up in case I lost the use of my right hand. But it was a strain. Even now, I find that though I can form letters and if I concentrate hard, draw a simple object, it's not comfortable. My right hand rests nearby, "watching" as its companion does the thing that it does so much better. I can actually feel my right hand's tension and disapproval! It's as if the two hands have come to an understanding that this one will do a certain kind of work and the other one, the left one, well ... it accepts its place as the junior in this unique partnership they have, as the manual extremities of my body.

Of course, when both hands are engaged in using a key board, they are equally responsible. Sometimes I wonder if my left-hand feels happy about that or whether it would prefer to live a more indolent life. There was a time when I wanted to learn the guitar. To play it I needed to use my left hand to press down the strings of the guitar to form chords. One of the reasons I didn't progress very far was that I found it too difficult to think with my left hand. I could practically hear it, whining and complaining that this job of remembering chord arrangements and pressing down on the sharp steel strings was too much for it. It didn't mind the piano, however and for a while, both hands played happily together. But then I moved out of the house in which there was a piano and my musical education braked to a halt.

It is not clear to scientists what the purpose, if any, of laterality is. Why should there be a bias in favour of any one side? Why isn't everyone ambidextrous? Why aren't there as many lefties as righties? So far, there are no obvious answers. Some scientists believe that any child can be trained to prefer to use one particular hand. In recent years, however, there has been a movement away from interfering with a child's spontaneous preferences. I have certainly noticed that I meet more lefties nowadays, in India, than I used to. I believe this is because parents are no longer preventing their children from favouring their left hands, which used to be a traditional taboo.

Handedness interests me. It is a difference with which people are born, something they do not choose. The problems of adjustment they have in a world in which all kinds of ordinary implements are created for righties, from scissors to knives to the fixed writing tablets on academic-hall chairs to spiral binders, are the result of belonging to a minority. Though we are constantly pressurized to succumb to the demands of majority groups, here is an example of a naturally occurring group of people, which is completely normal but different.

Lefties gain some advantages by being different -- in sports or in battle, for instance, a lefty can sometimes win because righties are too used to being amongst other righties. The fact that there are lefties thriving amidst overwhelming numbers of righties is a reminder that being different does not mean being wrong. Lefties represent nature's celebration of variety. They are a challenge to the forces of vicious conformity that cause so much of the world's torment and bloodshed today.


Anonymous said...

Our 2nd most favorite organ – the BRAIN!!
Theres a nice write up on left handedness in “mapping the mind” by rita carter, univ of California press 1999 pgs 46 – 47.

Surprising features are that even in good ole cave dwelling days (remember?) the analysis of tools, pictures, fractures of baboon skulls have all clearly depicted that right handedness was the norm as far back as we can go! Today 5 – 8 % of the population is believed to be left handed

The body is mapped to the cortex, and is often displayed by observing a homunculus, or a human model proportioned to the projections of the motor. However there is contralateral connectivity– ie – all signals from the left side get fed to the right hemisphere and vice versa. So when you get a stroke on the right side of the brain – the paralysis will be reflected on the left side – arm – leg or whatever depending on where you pop the clot and which region you damage.

Whereas 95 percent of right handers have language firmly embedded in their left hemisphere – left handed people really vary much more in the way their brains are organized! Only 70 percent have their language center in the left hemisphere - the remaining 30 percent have language in both hemispheres.

Handedness is well established even before the “little mistake” comes out – usually within 15 weeks of gestation they start showing right thumb sucking preference making people to accept that there might be a genetic component to this and that it is of no great significance.

Un42n8ly there are several lines of evidence to promote the HYPOTHESIS that a shift in cerebral dominance (whether you become left or right handed) might be a consequence of some pre or peri natal disturbances. Usually left handers die 9 years earlier than right handers – and there seems to be links that a variety of physical abnormalities including asthma, bowel and thyroid complaints, dyslexia, migraine and allergies that can be traced to developmental or immune dysfunction.

The more interesting and perhaps absolutely unrelated issue of handedness – is that of chirality in chemistry. A sugar molecule and its mirror reflected sugar molecule structure are actually very different in their chemical properties. Thus amino acids that work in biological systems are all left handed – and I think sugars are all right handed (remember in chemicals this nomeneclature is all very arbitary). Or to go to more mundane things like screwing – phew – a screw and its mirror image actually have very different properties. Watch what happens when you try to screw er try to move a screw in the mirror versus in your hand. The standard way to do it is to hold your three fingers of your right hand to represent the three axes and the corresponding image in mirror – or your left hand. Now rot8 the thumb towards the first finger and watch how the screw moves compared to what happens in the mirrorThe right hand mitt doesn’t fit the left handed one and I believe this business is called “parity” and has some terrifying consequences in quantum physics too where asymmetry in certain situations has been depicted and some guys got the nobel prize when they showed this. gt

Amrobilia said...

Oooooooooo! Some comment that! (Above)

"...come with us 'cause I'm left-handed, that's the hand to use...well, never mind!"

Paul 'Mc'Cartney n John 'Mc'Eenroe...two left-handed Macs! Try a left-handed guitar, dear. It might work. Your left had, then, would only have to strum. Or take up tennis!