Nature or nurture?

One would like to believe that it was nature. I was more comfortable writing with my left-hand once there was no pressure to write with the right. The problem with the nature theory is that even when the parents are left-handed, many children are not. Another problem with this theory is that people can be changed, as I was.

Even if it is nature that makes people left-handed, there is tremendous pressure (read nurture) to make people use the right hand. It is interesting that almost all cultures of the world regard left-handedness as negative and, therefore, left-handed persons are "encouraged" to conform to the right-handed majority. Yet so many left-handers are great achievers (see box).

While most human beings are right-handed, in animals and plants, it seems that handedness is evenly divided. Roughly half of them are left-handed and 50 per cent right-handed. Thus, our direct ancestors, the chimpanzees, do not display any preference for handedness as a species and are 50/50 either way. The phenomenon is easy to observe in fiddler crabs and lobsters.

Both have a dominant claw, which is used for fighting, and a smaller feeding claw. Fifty per cent of the crabs have the dominant claw on the left side and the remaining have it on the right side.

Sangrur scientist’s theory

Look at pinecones, and you will see that the left-centric and right centric cones are equal in number. Handedness comes accross in so many fascinating ways once you are conscious about it.

All this seemed quite remote till I met Dr Amar J.S. Klar, a scientist from Sangrur, who has been studying the sex life of yeast cells for 25 years in the USA and is a leading authority on handedness, as the issue of selection of which hand to use is referred to.

Dr Klar has been studying how single cells change their personality. He has examined this fundamental biological building block and his team has seen how a yeast cell divides itself into two dissimilar cell types — one an identical copy of the parent and the other with changing sex. While all cells in a body have the same DNA, they perform different functions. Yeast cells are studied because of their simplicity and because they double in 90 minutes.

Answering a question about whether human hand utilisation is specified genetically or culturally, Dr Klar says that people feel it has to do with genes, but there is no evidence to corroborate that since classical genetics does not explain it. This led psychologists to maintain that it was a learnt behaviour.

Right-handed gene

Dr Klar maintains that there is just one gene for right-handedness (which he wants to discover) and that about 80 per cent of the population has it. Those who don’t have the gene can either be right-handed or left-handed.

As yet, this is only a hypothesis, but it is a fundamentally elegant one. He plans to test the genes of a hundred families in which at least one parent is right-handed and two of the children are left-handed.

The argument against this hypothesis is that cultures can interfere, as they did in my case. Also half of the children of left-handed parents are not left-handed and there is no race in which the majority of the people are left-handed. However, Dr Klar maintains that he has a random recessive model, which explains this fact.

He says that the right-handed gene is present in human beings and it acts as a signpost to tell them to act in a particular direction. In order to explain it he takes the analogy of a fork on a highway. If there is no signpost, it is probable that 50 per cent of the traffic will take the left turn and the other 50 per cent will take the right. If there is a signpost, most of the traffic will head where it wants to go. If the signpost is damaged, many would take one path, whereas others could land up taking the wrong one. Thus, if both parents are right-handed, 7.6 per cent of the children would take the left-handed route and in case of one right-handed and one left-handed parent, 19.6 per cent of the children would be left-handed. This is similar to the findings of the only three-generation study of handedness done by him.

Unlike human beings, animals lack the right-handed gene and 50 per cent of them are left-handed and the remaining right-handed. Thus, only human beings are predominantly right-handed.

Speaking about schizophrenia and bipolar disorder, he says that these diseases have genetic links. But we inherit culture, so DNA and genetics alone cannot be held responsible.

Handedness has often been related to the dominance of one or the other hemisphere of the brain. The brain consists of two hemispheres that are mirror images in terms of size and shape but different as far as the nervous system is concerned. The left side of the brain controls the right side of the body and vice-versa.

The dominant hemisphere of the brain is the one in which the so-called language functions are controlled. This is the emotional and creative side of the brain. For right-handed persons — who constitute 97 per cent of the total population — the dominant hemisphere is on the left side. For ambidextrous or left-handed ones, the dominant hemisphere is the right one.

Many readers might have seen the movie, A Beautiful Mind, which is the story of a schizophrenic, John Nash, who won the Nobel Prize in 1994. He shared it with two other economists for the 1950 doctoral dissertation he wrote at Princeton University on game theory. Nash visited India last month. He is a brilliant left-handed person. His son, too, is left-handed and also a schizophrenic. Dr Klar pointed out that actor Russell Crowe who played Nash is right-handed in the movie. So much for a realistic depiction. However, the one-time The New York Times reporter and Columbia University Professor Sylvia Nasar’s book A Beautiful Mind is brilliant. It won the 1998 National Book Critics Circle Award for Biography and was also nominated for the Pulitzer Prize.

Who is left-handed?

Being left-handed means having a preference for using the left hand for a variety of tasks, including reaching, throwing, pointing, catching. It also implies a preference for using your left foot for tasks such as kicking. However, there are no hard and fast rules for determining which hand or foot the lefthander prefers to use for a particular task. Most will prefer to use the left hand or foot for delicate work.

One may also have a dominant left eye, preferring to use the left eye for telescopes, camera sights, and microscopes. In general, being left-handed means having a dominant right side of the brain, though even this is not clear-cut.

Life is tough for lefties

Most tools, utensils, office equipment and dishes are made for the right-handed person. There are tools for left-handed persons, but most must be specially ordered from retailers who specialise in them. There are no such stores in India, but there are certain places from which you can order a number of left-handed goods, including scissors, peelers, tin openers, Swiss knives and even pens!

Left-handed compliments

That Crowe did not depict a left-handed man is hardly surprising since we tend to ignore such things often. However, most left-handed persons wish that the languages would ignore them. The word left comes from Anglo-Saxon lyft, which means weak or broken. Let’s look at some other expressions: Roget’s Thesaurus gives the following synomons for left: unskillfulness: clumsy, awkward, gauche, gawkish; stuttering... butter-fingered, "left-handed"....

Of course, a left-handed compliment is an insult; a baby from the left side of the bed is an illegitimate baby; a left-handed marriage is an immoral and adulterous sexual liaison; a left-handed wife is a mistress; a left-handed diagnosis is a wrong one and so on. The expression southpaw is also used for left-handed people.

In Hindi too we use the expression "baayen haath ka khel," which means an easy task.

Of blouse buttons

Now that we have become aware, we might wonder if all women are lefties, since the buttons of ladies’ blouses are on the left, while those on men’s shirts are on the right. In fact, there are more male lefties than female, but the button arrangement goes back to the Victorian age when a gentleman would dress himself, while a lady would have her maids.

As the accompanying list shows, there are many lefty achievers in the world. Of course, there could also be such a list of right-handed persons too! Admit it, we are fascinated by such questions as how we behave and different behaviour is often distinctive.