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Tallis in Wonderland

How Did We Get To Be So Different?

Raymond Tallis grasps the grip our hands have on our humanity.

Readers with long memories may recall that your columnist has a special affection for the human hand. Way back in 2001, he reflected on ‘Carpal Knowledge: The Natural Philosophy of the Caress’ in Issue 33. In 2008, he raised ‘Some Points About Pointing’ in Issue 70. And more recently (but how distant it now seems!), at the beginning of the Covid pandemic, he took the opportunity provided by reflections on handwashing to invite readers to use their hands to applaud those very same structures (Issue 138, ‘Philosophy in the Time of Plague, Pt.1’).

My return to the hand has been prompted by my recent experience of talking at the triennial meeting of the International Federation of Societies of Hand Surgeons at the ExCel Centre in London. The Centre was populated by hundreds of surgeons, physiotherapists, occupational therapists, clinical psychologists, nurses, bioengineers, and many others devoted to using their hands (and heads and hearts) to the restoration and even transplantation of hands, which are so central to our interaction with the material world and with each other. The convergence of science, clinical acumen, dexterity, ingenuity, insight, compassion, and humanity was humbling. The vast collective of hands present and absent mobilized to restoring the structure and functions of damaged hands was a heartening example of how we can work together for mutual benefit. It has prompted me to rehearse with you a story (perhaps a ‘Just So’ story) which I first set out in The Hand: A Philosophical Inquiry into Human Being (2003), regarding the role played in the emergence of our distinctive human nature by this astonishingly versatile organ of manipulation, of palpation (it’s the chief organ of the fifth sense), of prehension – in which manipulation and cognition combine to reveal the nature of that which is handled – and of communication, realized in countless gestures.

The Genesis of Humanity

Those of us who are able to see what is in front of our eyes acknowledge the vast gulf between humans and even our nearest primate kin. It’s the difference between persons and organisms. Various types of theists account for this difference by claiming that humankind was The Chosen Species, hand-made by God in his own image. This explanation is not available to secular humanists. The power of Darwin’s explanation of the origin of species has been reinforced by discoveries made in the century and a half since it was published in the book of that name. The filling-in of the fossil record, carbon dating, evidence of continental drift, and genomics, have all supported his brilliant hypothesis of the emergence of the apparent design of organisms in the absence of a designer. This leaves a challenge for those like me who reject theism, embrace Darwinism, and yet acknowledge the distinctive nature of humanity: that of finding a biological account of what it was that set us on the road to becoming creatures whose lives are in many respects distant from biology.

The story I set out in The Hand begins 4-8 million years ago. Climate change in Africa resulted in our primate ancestors leaving the jungle for the savannah. They adapted to this move by gradually assuming an upright gait which made the head the watchtower of the body and sight the dominant sense. More directly relevant to my Just So story, is that bipedality liberated the hand from being “a locomotor prop to become a delicate explorer of space” as Charles Sherrington expressed it.

The hand thus liberated was also a significant improvement on that of other primates. There were three important upgrades: full opposability of thumb and index finger; freer movement of individual fingers, particularly the index finger; and increased innervation (concentration of touch-sensing cells) at the finger-tips, making them the most sensitive skin surface in the animal world. These features transformed the capability of the hand as an organ of manipulation, opening up a huge range of possible grips involving hands, working individually or together; they enhanced its capacity as a sense organ, and consequently as an organ of prehension; and they enabled it to acquire an eloquence expressed through a multitude of gestures. Bipedalism was particularly important for the latter development: a quadruped gesturing to a friend would topple over – especially if the gesture were maintained. And signals from an upstanding body are more visible.

Someone might think an upgraded hand operating in more favourable circumstances would incrementally open up only modest differences between humans and our nearest primate kin (who were an early form of chimpanzee). They might say that it would hardly explain the vast gulf between animal organisms and human persons – expressed most strikingly in the fact that humans, unlike animals, live in an environment of their own making, a landscape of artefacts remote from nature; of buildings, machinery, institutions, and so on. They might argue that it would not account for the difference between the history of chimps, in which the technology available to them millions of years ago was pretty well the same as it is now, and the history of humanity, in which only a few centuries separate primitive steam power from nuclear energy and hand-held devices that enable us to speak to a chosen ear a thousand miles away without raising our voices. Millions of years of evolution of non-human primates haven’t delivered anything much more impressive than the use of stones to crack nuts, or sticks to ‘fish’ for termites. Even less, they might argue, can an upgraded hand account for our capacity, unique among nature’s creatures, to think in abstract and universal terms – for example, to speak of ‘nature’, or put the world in inverted commas, or measure its diameter. So how then do we account for our being set on a path along which we diverge, with accelerating speed, from our primate cousins?

One obvious explanation is increased brain size. The human brain is about three times bigger than that of chimps, with much of the additional neural circuitry being located in the neocortex, where many of our abstract reasoning processes are co-ordinated. However, a stand-alone expansion of the brain would not deliver much in the way of the kind of differences we need to explain. The brain has to be attached to a body that has the possibility of a different kind of interaction with the world, and, indeed with itself. Enter the hand.

Study of hands by Albrecht Dürer (detail)

Not Just Waving But Also Evolving

The more sophisticated human hand, liberated from the burden of being a locomotor prop, is clearly equipped to be a uniquely effective organ of communication. Pointing, waving, threatening gestures, are just a few of the countless ways in which the hand may mediate the sharing of experience. It has been plausibly suggested that speech, which has a central role in creating and maintaining the community of human minds, may have originated with gestures. (Michael Corvallis’s brilliant exposition of this idea – and his TED talk ‘Evolution’s Great Mystery: Language’ – is a great place to start.) Even if one does not accept this story, it is difficult to deny the contribution of a gesture as apparently simple as pointing to creating the fabric of a shared world woven out of trillions of cognitive handshakes. Wherever pointing is understood, minds meet. And the combination of full opposability of thumb and fingers, the free movement of individual fingers (particularly the index finger) and of sub-groups of fingers (fractionated finger movements), and the different modes of cooperation between the hands, have made the human paw into a professor of grasping, seizing, pulling, plucking, picking, pinching, pressing, patting, poking, prodding, fumbling, squeezing, crushing, throttling, punching, rubbing, scratching, groping, stroking, fingering, drumming, clapping, shaping, lifting, washing, flicking, catching, writing, typing (this)… the list is endless.

So far, so conventional. But, as I argue in The Hand, there are more profound consequences of the uniqueness of the hand which enable it to have a distinctive role in the progressive divergence of hominids from nature – to the point where we eventually adopt a stance from which we can look at, and act upon, nature from a virtual outside – and so in the evolution of the human organism into a full-blown embodied (or am bodied) subject. A given grip or gesture is chosen from a wide range of grips and gestures. We manipulate our hands explicitly to serve explicit purposes. There is also the meta-touching of richly innervated finger-tips by other equally richly innervated finger-tips. This higher-level tactile awareness – in which exquisitely sensitive touchers feel themselves touching each other – is elaborated in the cooperative activity of the hands of an individual, in which there is often a hierarchical relationship between the two partners.

Most importantly, this lays the groundwork within the body for a differentiation between agent and patient – between that which does and that which is done to – thence to that between subject and object, and eventually, between the I and the It of the body. In short, courtesy of the hand, the hominid body is infected with a full-blown sense of agency and selfhood. This is the hidden hinterland behind the hand’s becoming what Aristotle called the ‘tool of tools’. Our unique digits ultimately made possible our digital world.

It would be absurd to suggest that agency and selfhood are entirely absent in our primate kin. In a famous experiment, George Gallop observed the behaviour of chimpanzees placed in front of a mirror after they had had red marks put on their faces under anaesthetic. They were puzzled by the marks and attempted to rub them off, thereby showing that they have an inchoate sense of their bodies as being themselves. This and other observations suggest that non-human primates are close to the point at which humans, several million years ago, set off on their unique path to individual and shared self-consciousness.

Signing Off

This then is the outline of a biological account of how we have increasingly become distanced from our biology. That account will, of course, acknowledge the contribution of the brain but will not regard the latter as the sole determinant of our special nature. Indeed, we may imagine an iterative process whereby the increased capabilities of the hand shaped the functioning of the brain, and the latter further increased the capability of the hands. The disproportionate representation of the hand in the brain is a testament to this: the thumb alone requisitions more motor cortex than the entire leg.

William Paley, an eighteenth century theologian, famously argued for the existence of God on the grounds of the apparent design in nature. If while crossing a muddy field you came across something as clever, intricate, and useful as a watch, he said, you would conclude that there must be a watchmaker. In The Blind Watchmaker (1986) Richards Dawkins counter-argued that the ‘watchmaker’ was the blind laws of nature operating along the lines set out by Darwin. This, however, leaves it rather difficult to explain the origin of sighted watchmakers who populate our environment with artefacts. I have tried to account for ourselves by suggesting that the hand had a hand in this.

Raymond Tallis’s latest book, Freedom: An Impossible Reality is out now.