The Puzzle of Left-Handedness (19 page)

23

The Morbid Views of Abram Blau

With his 1946 book
The Master Hand
, New York psychoanalyst Abram Blau earned the dubious honour of having launched into the world some of the most stark and insulting ideas about left-handedness ever expounded by a serious and influential scientist.

Blau, a professor and head of child psychiatry at the Mount Sinai Hospital in Manhattan, was a fervent supporter of the then dominant behaviourist movement in psychology, which teaches that practically all human characteristics are determined by environmental influences. Behaviourists regarded concepts such as consciousness, will and character as of little importance, since ultimately even these were shaped by an individual’s reactions to impulses reaching him from outside. You could fully understand a human being only by taking a close look at what he did in his environment.

Of course not even the most fanatical behaviourist could deny that inherited characteristics existed. They were known to reside in the chromosomes and in
DNA
, although when Blau published his book no one yet knew the structure of
DNA
or how it functioned. Nevertheless, the behaviourists claimed, our genetic material merely confers on us a wide range of possible behaviours. How a person actually develops from birth onwards, what specific behaviour he will display and which characteristics, is determined almost entirely by the formation of habits based on reward and punishment. In Blau’s own words: ‘Heredity is involved only to the extent that it is a valuable reservoir awaiting to be exploited. The particular choice, direction, and nature of the skill finally achieved are quite outside the province of the germ plasm.’

Reward and punishment are responses to behaviours that people exhibit based on impulses that reach them. Desirable or successful beha viour is thereby reinforced, while undesirable or unproductive conduct is steadily and relentlessly reined in. The world of the behaviourist therefore works according to the principle ‘child sees dog, child pats dog, dog bites child, child stays away from dogs in future’. The remarkable thing about behaviourism is not its insistence that rewards and punishments have an influence on our behaviour. Everyone knows that learning by experience is important, if only because it teaches us to keep our hands off hot stoves and strange dogs. What sets behaviourism apart is the way it regards the mechanism of reinforcement and suppression as absolute and downplays the phenomena that accompany it – inheritance, for example, and other biological influences.

As a dyed-in-the-wool behaviourist, Blau naturally attributed the prevalence of right-handedness to social pressure and the formation of habits. In his view it went like this. In the early Bronze Age an enormous amount of time and effort was needed to make tools such as knives and sickles. As a result these were expensive items, cared for meticulously and often handed down from parent to child. Implements like sickles can be used properly only in one hand or the other, and because they were so difficult to replace, no one was going to let a left-hander use them in ways for which they were not intended. So along with tools and the skills required in wielding them, hand preference was passed down from one generation to the next. This effect was further reinforced, Blau believed, by the fact that once the first tools had been invented, one-sided specialization came to have many advantages over ambidextrous development. It would be easier to reach a certain level of dexterity with any given tool if one or other hand were used consistently, and the better trained that hand was, the more easily a person could learn other skills using it.

Blau still had to explain why hand preference was constant through-out history as a cast-iron rule, even among people who had little or nothing in the way of expensive tools. He could not take refuge in Lamarck’s belief that acquired characteristics can be inherited, since that view had been discredited by Darwin’s
Origin of Species
. Blau claimed the explanation lay in the fact that people pass down their elaborate cultures to a subsequent generation. Unlike other animals, we spend years bringing up our children. Therefore, he wrote, ‘culture represents the com bination of past social experience and mass learning, [so] each human infant takes over this culture where the previous generation left off. In a literal sense, man’s experience becomes immortalized, and part of the property is transmitted to his heirs.’ This is plainly true, but it doesn’t explain anything. The great value of cultural inheritance, the key to its effectiveness, is its flexibility. Cultures differ in all possible respects from each other and from those of previous generations, where as right-handedness is always and everywhere the unchanging norm.

Anyone looking at right-handedness the way Blau did is bound to see left-handedness as an objectionable aberration, a pathological consequence of a wilful rejection of the cultural heritage on offer, or the result of a shortcoming of some kind that makes it impossible for an individual to develop into a socially healthy person.

That is precisely what Blau thought. Left-handedness, he believed, was caused by ‘an inherited deficiency, faulty upbringing, or emotional negativism’. Of the three, the latter was undoubtedly Blau’s favourite. He regarded left-handedness as ‘nothing more than an expression of infantile negativism’, comparable to ‘contrariety in feeding and elimination, retardation in speech, and general perverseness insofar as the infant with meagre outlets can express it’. In adulthood sufferers from left-handedness were no less unpleasant individuals, since their characters were a combination of rebellious stubbornness, secretive superstition, parsimony, an obsession with cleanliness and excessive rigidity in a more general sense. All this – how could it be otherwise – was in most cases the fault of emotional neglect by a loveless ‘refrigerator mother’ of the kind people at the time held responsible for childhood autism. Blau believed therapy would produce beneficial results in such cases, even though it might be ineffective in eliminating left-handedness once it had been imprinted, leaving it in place as a kind of mental fossil. With small children it was important to stamp out left-handed tendencies with care and tact. Only if the child absolutely refused to switch to its right hand was it better to leave it to stew in its own juice.

Anyone making such bold claims needs to have what it takes to defend them, and Blau did not. His only grounds for rejecting the inheritance theories of his time about the development of left- and right-handedness was the absence of positive evidence. To a certain extent he had a point, since there seems to be no neat Mendelian pattern of inheritance for left- and right-handedness such as exists for fair and dark hair or blue and brown eyes. One thing he overlooked, however, was that his own theory too was built on quicksand, or rather on wild, unverifiable assumptions about life in the Bronze Age.

Moreover, it remains unclear why the development of hand preference, which Blau regarded as culturally determined, would lead to an overwhelming predominance of right-handedness in all times and all places. Perhaps that is the unstated reasoning behind his characterization of its hereditary basis as a ‘valuable reservoir’: we have a strong innate tendency towards the right. But if this is what Blau means by a reservoir, then he and his behaviouristic thinking fall at the first hurdle and hand preference is simply inherited.

Blau developed his notion of left-handedness as a sign of a disturbed personality based on his experiences with several left-handed patients, but to conclude that their left-handedness was caused by the disorders that brought them to him is absurd. You might as well conclude that wealth is a threat to mental health because poor people so rarely consult expensive psychoanalysts.

In his pitiless conclusions and pronouncements, Blau was guided more by unfounded prejudice than by the products of scientific curiosity. This is clear from the research he carried out among fewer than 400 schoolchildren in an attempt to verify his theories. He found nothing to support his claims, but the failure of his study did not deter him in the least. His book is replete with the kind of heedless, pseudo-scientific bar-room talk that inspired the endless stream of tasteless jokes about psychiatrists and psychoanalysts which continue to do the rounds to this day.

24

Thwacking and Hurling

That heredity must be bound up in one way or another with the origin and continued existence of our one-handedness is undeniable. However, we still have no idea what the nature of its involvement might be, or why right-handedness ultimately became the norm, let alone an explanation as to where all this left-handedness keeps coming from.

We don’t even know for certain how long ago right- and left-handedness arose, nor when they settled into the lopsided ratio of nine to one, even though there are a number of indications that the distribution we see today goes back a very long way. Among cave paintings such as those at Altamira, Lascaux and Pech Merle, works of art up to 25,000 years old, we find a large number of handprints. Some are positive, made by first pressing the hand into ochre or some other dyestuff and then against the wall, like a stamp. Most marks of this type are of the right hand. Others are negative, drawn with a piece of charcoal around a hand laid flat against the wall, or by blowing powdered paint across it. These negative prints are mostly of a left hand, suggesting that the right hand drew around the left or served as a platform from which to blow the paint powder at it.

Further clues come from stone tools, which are far older. Many archaeologists claim, based on their shapes and the location of marks of wear and tear, that the people who made these tools an estimated 200,000 years ago included roughly the same proportions of right- and left-handed individuals as we see today. Not all archaeologists agree on this, incidentally.

Evidence going back much further still is provided by the baboon skulls that have been found in the vicinity of the remains of our presumed distant relative
Australopithecus africanus
. We’re now talking about some two to three million years ago. Although he was small of stature,
africanus
could successfully hunt baboons because he knew how to use a large bone or sturdy stick as a club. Most of the baboon skulls he discarded have a hole smashed in them with a blunt instrument of some kind, usually on the left side, as if the unfortunate creature was clubbed to death by a right-handed primate. None of this amounts to solid proof, but at the very least there’s no evidence that modern man is any different from his ancestors as far as hand preference is concerned.

Cave painting of Appaloosa horses with handprints, roughly 20,000 years old, at Pech Merle, France.

In the past hundred years or more, two theories have been propounded that are mainly concerned with the question of how it comes about that most of us favour the right hand. Both are based on natural selection. The idea is that during a specific period in the course of the evolution of our species, right-handedness offered advantages over both left-handedness and ambidextrousness in the struggle for survival. Right-handers therefore propagated themselves more successfully in the long run, perpetuating characteristics that occurred in an increasing proportion of the population until ultimately left-handedness and two-handedness almost ceased to exist.

In 1871 that same Thomas Carlyle whom we have to thank for the terms left and right in politics lost the use of his right hand to paralysis. He was 75 years old. Even at that age he had a restless, creative spirit, and the effort involved in learning to eat and especially to write with his still perfectly serviceable left hand set him thinking. Where could that strange specialization of the right hand come from, if the left hand was in theory no less capable? Might it have to do with other asymmetrical properties of the human body?

Of course the obvious thought was that it must have something to do with the heart, traditionally imagined as located in the left side of the chest cavity. There lay the germ of Carlyle’s theory. In a fight, a person using his left hand to defend himself and his right to attack is better placed to protect his own vital organs, especially the heart, than a person using the opposite tactic. Right-handedness could therefore have arisen in the mists of time as a result of the invention of the shield, which offers greater protection if carried on the left arm. The right hand would then automatically be called upon to take charge of the complicated business of swiftly striking out while parrying an enemy’s thrusts. It goes without saying that those who happened to have more highly developed motor functions in their right arms and hands were at an advantage. Right-handers therefore had a greater chance of survival and so gradually became dominant. Ultimately this led to the well-known ratio of 90 per cent right-handedness, 10 per cent left-handedness.

The time was ripe for such a notion, it seems, since in the same year, quite independently of Carlyle, Englishman P. H. Pye-Smith published exactly the same idea in the medical journal
Guy’s Hospital Reports
. This is rather odd, since even in those days a doctor ought to have known that the heart is only very slightly to the left of centre. Any extra protection afforded by carrying a shield on the left side would be infinitesimal; it certainly wouldn’t confer a decisive evolutionary advantage. The shield theory, therefore, however attractive in its simplicity, did not stand up to scrutiny. Carlyle’s idea could not be correct anyhow, if right-handedness is as old as those baboon skulls suggest.
Australopithecus africanus
may have been quite a dab hand with a length of wood or a large bone, but he definitely didn’t invent the shield. Even more fatal to the theory is the fact that later, long after modern man evolved, many peoples never used shields, yet right-handedness is as common among them as it is elsewhere.

Much more recent, and far better thought through, is the argument advanced since around 1980 by American neurobiologist William H. Calvin that he calls his ‘Throwing Madonna theory’. The story starts in the far distant past when our ancestors slowly began to develop in the direction of modern man.

Once, millions of years ago, our distant African forebears left their homes in the tropical trees, abandoning the forest for life on the plains. They had probably lived mainly on a diet of fruit up to that point, plus whatever else they could find to eat among the leaves of the trees, including the occasional small animal. In other words their diet was similar to that of the apes today. Whatever their reasons for forsaking their ancestral environment, once down on the ground in open tropical savannah it must have been a good deal harder for them to find sufficient food. Far fewer plants grew there than in the damp and diverse forest. They were able to solve the problem by extending the range of their foraging and by adjusting their diet: more tubers and roots, more small animals. The new skill of running came into play, combined with the well-developed hands of the forest-dweller that had been theirs for millions of years. Those hands were free for the collection and transport of food and soon proved their worth by grabbing animals like mice and rabbits, which lived, like our ancestors, on grassy plains.

This sounds more pleasant than it would have been in reality. An individual with sufficient determination can get the better of a mouse on open ground, but a rabbit is just as nimble, larger and much faster. Like most other animals of the savannah, rabbits are more than a match for humans or hominids equipped with nothing but their bare bands. We are too slow and lumbering, too vulnerable to attacks by large predators. So these early humans cannot have had a particularly meaty diet; they must have been vegetarians most of the time. This in itself is something of a problem, since little energy can be derived from plant material, especially if eaten raw. Being a vegetarian on the ancient savannah meant working long and hard for relatively few calories. Man’s prospects did not look good.

Nevertheless, this comparatively slow hunter-gatherer proved himself unprecedentedly energetic. Some two million years ago
Homo habilis
spread from Central Africa across the entire African continent with phenomenal speed and within less than half a million years his successor,
Homo erectus
, inhabited large parts of the globe, fertile or barren, rainy or dry. Eventually he could be found in practically all regions that are warm enough for humans to survive without clothing or heated dwellings. He even settled in areas where it was virtually impossible for him to get by on roots, tubers, nuts and seeds, since they are not productive enough in those environments or simply do not grow in sufficient quantities.

So man must have survived on the flesh of birds and small animals. Meat is a far more compact and digestible form of energy than plant matter, and it’s available everywhere. In all environments, whether the frozen wastes near the poles, the tundra or arid sandy deserts with extreme variations in temperature, it’s possible to find edible species of animal that are adapted to the prevailing conditions. The largely vegetarian gatherer who from time to time catches a hare must therefore, Calvin claims, have developed in this period into a competent hunter who gathered plant material to supplement a meaty diet.

The surprising thing about all this is that the forerunners of modern man spread so far out across the globe long before hunting implements such as the spear or the bow and arrow were invented. How did our ancestors get hold of enough animals to feed themselves? Calvin suggests we need to look at various differences between our methods of hunting and those of today’s apes, which are still limited to their original tropical environments.

One such difference is the impressive arsenal we eventually developed, but here we are looking at a time before weapons were invented. Second, it’s often claimed that what made the difference was language, perhaps the most spectacular cultural artefact that humans possess and apes lack, since it’s said to have brought about decisive improvements in cooperation between individual hunters. But this does not stand up to scrutiny either. During a hunt, language is not used to any significant extent, as we can see from the success of animals that hunt in packs, such as wolves. They are living proof that ancient techniques like surrounding, driving and wearing to exhaustion can be applied without the slightest hint of language. In fact when people go hunting their conversations usually have nothing to do with the hunt. They talk about the ordinary things in life: relationships, work and money. As soon as they start seriously stalking their prey, they keep their mouths firmly shut. The quarry does not understand what people are saying, but it hears them all the better for that.

There’s a third difference between humans and apes, however, and Calvin believes that it’s of huge significance. People are capable of throwing accurately. Apes sometimes throw stones, but always more or less indiscriminately. Humans use one arm as a sling of sorts, and this enables them to hit a small target many metres away with considerable force. The capacity to throw in this way gave the otherwise rather unimpressive
erectus
a deadly prehensile claw with a range of at least twenty metres.

The well-aimed throw has a considerable effect on hunting success, and in evolutionary terms it’s a skill that can spread through a species extremely quickly. The connection with highly nutritious food is so direct that it exerts enormous selective pressure. Anyone who can throw even a little better than the next individual has a far greater chance of survival and is therefore more likely to pass on his superior throwing ability to a new generation. If, that is, the throwing skill is rooted in something heritable.

Partially reconstructed skull of
Homo erectus
, with a modern human skull behind it.
Erectus
had a relatively small cranium but was nevertheless a competent hunter.

This does appear to be the case. Success in well-aimed throwing relies on a powerful capacity for control, which is lodged in the brain. A good throw requires the thrower to develop and implement a plan of action for dozens of muscles, based on his observation of the course and speed of the prey, the weight of the stone in the hand and a great deal more besides. Nature has little to show that can compare to man’s accuracy in throwing. Neurons, the electrical switches of which our brains are composed, are not particularly good at such tasks, being relatively slow and imprecise, but if a great many neurons share the same job speed and accuracy increase markedly. Though individually no more than approximations, average results from hundreds of neurons produce extremely accurate estimates, and by having several groups of neurons work simultaneously we avoid the need to spend so much time waiting for intermediate results. The trick is to bring a huge amount of brain capacity to bear. But to do that, of course, you need to have a large brain.