Anatomies: A Cultural History of the Human Body (24 page)

The most important way in which our hands have informed our intelligence is by giving us a readymade numbering system. The Roman numerals I, II, III and IIII may be based on the upheld fingers, with the symbol for five, V, based on the shape made by the thumb and the forefinger when the whole hand is held up. So-called ‘denary’ counting is based on the ten fingers and thumbs, and most other popular number bases, such as binary and bases four, twelve and twenty, are based on various combinations of limbs and digits. Even an octal system used by some Native American cultures begins with the hands: it counts not the peaks that our fingers make but the valleys in between them.

No animal has evolved with more than five digits since the terrestrial vertebrates (reptiles, birds and mammals) branched off on their own evolutionary path at the beginning of the carboniferous period 360 million years ago. But why do we have as many as five? As we have seen before, nature tends to furnish us with as many of the parts as we need, and where these are replicated, as with eyes and ears, it is for a good reason. So what do the five fingers do – either individually or together in various combinations – that gives them all a role?

In counting, each finger is exactly equivalent. But for most other tasks, they are as varied as the tools on a Swiss Army knife. The index finger is the best pointer because of its length and the dedicated muscle that straightens it. It is also more manoeuvrable than the other fingers. The index finger belonging to Inspector Bucket in Dickens’s
Bleak House
is so versatile that it is almost a character in its own right, a confidant for Bucket as he puts it to his lips, to his ears, and rubs it over his nose before wagging it before a guilty man. ‘The Augurs of the Detective Temple invariably predict that when Mr Bucket and that finger are in much conference, a terrible avenger will be heard of before long.’

The middle finger, though a little longer than the index, is a poor pointer: try it and you’ll find that it is hard to straighten this finger while holding the others out of the way. But it has other uses. The Romans called it the digitus impudicus, the finger of impudence – perhaps they took over the custom of giving people ‘the finger’ from the Greeks. It is also called the digitus medicus because Roman physicians were apparently in the habit of using it to stir medicines. Next comes the digitus annularis, which we still call the ring finger, ‘annulus’ being the Latin for a little ring. It has this function for symbolic reasons rather than because it is especially adapted to the task. The ancients believed (incorrectly) that this finger was directly linked to the heart by a special vein. The little finger is called auricularis, because even it is not useless: it is just the right size for cleaning out the auricle of the ear.

Finally, there is the thumb, ‘the father of technology’, according to Raymond Tallis. It is our having an opposable thumb – meaning to say we can employ it in opposition to the other fingers – that greatly increases the capability of the hand, so that it is able to exert a wide variety of grips. Montaigne, in his note ‘On thumbs’ in the
Essays
, gives a correct derivation for the French for thumb,
pouce
, from the Latin
pollere
, meaning to excel in strength. He also offers a spurious but nonetheless apt alternative name,
anticheir
(derived from the Greek, it would mean ‘opposed to the hand’); both terms are revealing about the unique importance of this digit.

But it is the opposed thumb together with the mutually independent operation of the fingers that really gives us our dexterity. The names of individual fingers hint at dedicated uses for each of them, but there is so much more they can do in their many permutations, from the way the forefinger and thumb delicately pinch in order to pick a flower or remove a contact lens, to the carefully balanced use of all five to wield a pair of chopsticks. Add to this the dizzying speed of other manipulations – of cards by a trickster, of strings by a guitarist – which earns its own special name of prestidigitation.

Palms have been ‘read’ for millennia, but the practice has only recently been put to the scientific test. The tradition was perhaps made respectable by Aristotle when he observed carelessly in his
Historia Animalium
that the life line across the hand seemed to be longer in long-lived persons. Why should it be the hand that reveals our fate? It seems simply that the palm of the hand contains a suitable number of legible features and is easily offered for inspection. In 1990, scientists at the Bristol Royal Infirmary looked at the life-line length of 100 consecutive autopsies. Surprisingly, perhaps, they did find a correlation between the length of the life line and the age of death. But it was not quite the evidence for the veracity of palm-reading that it might seem. As the scientists point out: ‘With increasing age we all become more wrinkly.’ In their paper, they admit that a better idea would be to monitor the life-line length of a number of subjects over a lifetime, preferably, they add tongue-in-cheek, ‘with investigators meeting every 10 years in exotic locations to report preliminary results’. Such a study has yet to be undertaken.

Another obvious feature of the hand is the length of the fingers in relation to one another. They were once thought to denote five (not Shakespeare’s seven) ages of man, from the little finger of youth to the ring finger at the time of marriage to the longer fingers of maturity and finally to the decline of the thumb. In 1875, a German anatomist and anthropologist named Alexander Ecker observed that women’s index fingers tend to be longer than their ring fingers, while men’s are the other way round. This was such a curious finding that others rushed to confirm it – which they did, but when nobody could work out what it actually meant, the information was quietly ignored. This was the case until 1983, when Glenn Wilson at the Institute of Psychiatry in London responded to an invitation from the
Daily Express
to contribute to a survey of ‘changing attitudes of women in the 1980s’. His questionnaire to female readers asked about their assertiveness and competitive instincts, and requested, by the by, that they measure the lengths of their fingers. The results showed some tendency for women with a low index to ring finger ratio to be more assertive, in other words the women with more male-like fingers behaved more like men (it having been taken as read, it seems, that assertiveness is essentially a male attribute). This discovery confirmed finger ratio as a convenient indicator of the level of testosterone to which a person has been exposed in the womb. Research based on finger ratios has mushroomed, and they have now been used in studies of sexual selection, sexual orientation, fertility, spatial reasoning, sporting ability, musical talent, autism (which occurs primarily in males), and success in financial trading. In 2010, investigators at the University of Warwick obtained results to suggest that men with long index fingers are less likely to get prostate cancer. It seems the hands have much to tell us yet.

The most pervasive and most divisive conclusion we have drawn from our hands is that one is better than the other. Preferment of the right hand develops very early in life. There is evidence that at fifteen weeks’ gestation most of us exhibit a preference for sucking our right thumb. Tracking a number of subjects before and following birth, Peter Hepper at Queen’s University Belfast found that the prenatal right-handers all kept their right-handedness as children. Most of the left-handers retained their preference for the left, but some switched to the right.

It clearly disturbs us on some deep level that we possess these two sets of limbs that appear to be entirely symmetric and yet are generally asymmetric in use. This imbalance is one of the oldest bases for discrimination: between left and right. The Bible repeatedly declares a bias in favour of God’s (and everybody else’s) right hand and against the left. Arbitrarily, it seems, in the gospel according to Matthew, God demands that those ‘on the left hand, Depart from me, ye cursed, into everlasting fire’, while those on his right ‘inherit the kingdom’. A wide vocabulary exists to label or insult left-handers, and in many languages the very terms ‘left’ and ‘right’ are loaded with bias. From other European languages, and sometimes quite ancient roots, English alone has acquired the terms gauche, sinister and cack-handed, the last being a reference to the custom in predominantly right-handed societies of reserving the left for wiping away faeces or ‘caca’. I even have a book on symmetry that contains this entry in the index: ‘laevo-, see under: dextro-’. The political left, incidentally, which may or may not have this pejorative connotation according to your own political views, originates in the layout of the French Assembly, where, after 1789, the revolutionaries sat on the left wing.

Left-handers are in a minority, but the true size of the minority is uncertain. In 1942, the psychologist Charlotte Wolff could write without pausing for reflection that ‘in these days not more than 2 to 3 per cent of the population are left-handers’. Recent studies suggest, by contrast, that up to a third of children would develop as natural left-handers in the absence of external influences. This matches the apportionment of left- and right-handedness in Palaeolithic man inferred from the way they shaped their axes. But in many environments, there is strong social pressure to be right-handed – even left-handers must shake hands with their right, for example – so the observed proportion of left-handers is often much less than this. United States army recruits, for example, report only 8 per cent of left-handers in their ranks.

The systematic elimination of left-handedness is not what it used to be, though. Listening one day to the statistical curiosities that are the staple fare during boring moments of test match commentary, I was surprised to learn that the first time in cricketing history that the first four men put in to bat were all left-handers was in 2000 – since when it has happened twenty-eight times. On the face of it, this is most odd, given that the statistical record goes back to 1877. It could be down to a chance occurrence of gifted left-handed batsmen, but it’s far more likely to be a reflection of the fact that we are now less apt to penalize left-handers in all walks of life. In many sports, of course, being left-handed can give an advantage because all players, even other left-handers, are more accustomed to playing against right-handers.

More insidious pressures remain, however. Almost every one-handed activity, from zipping trousers to using a cash machine, has a cultural bias in favour of right-handers. A visit to Anything Left-Handed, the shop of the Left-Handers Club, which once occupied premises in London’s Soho but now trades online, hints at the extent of the iniquity. There are scissors, tin openers, fountain pens and much else in the tiny shop and in its reverse-paginated catalogue. There are also products where many people would never suspect a bias – rulers and tape measures (numbered from right to left), corkscrews (turning anti-clockwise for a better purchase), kitchen knives (serrated on the other side of the blade). The shop also stocks CDs of music played by left-handers, although I’m not sure how you are supposed to hear the difference. But I’m disappointed to find it does not have Ravel’s dazzling
Piano Concerto for the Left Hand
. The work was written for Paul Wittgenstein, the brother of the philosopher Ludwig, who lost his right arm in the First World War. When Ravel had finished the work, Wittgenstein proclaimed it too difficult and demanded changes. ‘I am an old hand at the piano,’ he joked. ‘And I am an old hand at orchestration,’ Ravel snapped back. Other left-handed pianists hanker for a reversed keyboard with the deep notes on the right allowing the left to carry the melody for once. While we are at the keyboard, we might note that the size of the hands can also affect the kind of music that gets written. Rachmaninov had hands that could span an octave and a half, which puts some of his compositions literally beyond the reach of many daintier players.

The discrimination designed into so many everyday objects may be rather more than an inconvenience. In 1989, the psychologist Stanley Coren surveyed a large number of students at the University of British Columbia and found that a left-hander was almost twice as likely as a right-hander to have a car accident, and half again as likely to have an accident while using a tool of some kind. Coren attributed the cause not to innate clumsiness of southpaws, but to design that is consciously or unconsciously biased to suit right-handers. He estimated that left-handers’ life expectancy was reduced by eight months in this way.

The hands are not our only handed body parts. Inside the human trunk, asymmetry is the norm. The heart is on the left and the liver is on the right. The stomach lies to the left. The left lung has two lobes, the right has three. There are little-noticed external differences, too. Our hair falls to one side or another. The left breast is usually a little larger than the right. The left testicle usually hangs lower than the right, even though the right one is generally heavier. The reasons for this aren’t firmly established, but it has been known for a long time: the majority of Classical statues confirm it.

In a way, it is the presence of symmetry in the body at all that is more remarkable than when it breaks down. The process of embryonic development is one of progressive loss of symmetry. The fertilized egg is spherically symmetric, but with each cell division it loses some symmetry. As organisms that must live under the influence of gravity, we quickly lose any top–bottom symmetry. With locomotion necessarily comes the need to move forward, and so a sense of front and back, which causes us to lose symmetry in this direction. That leaves only the symmetry in the third dimension, from side to side. Here there is no distorting environmental influence, and so the symmetry seen in the embryo can persist. Yet occasionally, this tidy bilateralism is subverted, and something grows on one side but not on the other. To see why this is, we must look more closely at what happens in the developing embryo.