Fig. 1. Detail from Raphael’s School of Athens. Plato, on the left, holds a copy of his dialogue the Timaeus and points to the heavens. Aristotle holds a copy of his Ethics and gestures to the world around him, although with the palm of his hand facing down he also seems to be saying, ‘Plato, my friend, keep your feet on the ground.’

      Economics in particular could benefit from this approach, for economics needs to put the body back into the economy. Rather than assuming rationality and an efficient market – the unfortunate upshot of which has been a trading community gone feral – we should study the behaviour of actual traders and investors, much as the behavioural economists do, only we should include in that study the influence of their biology. If it turns out that their biology does indeed exaggerate bull and bear markets then we have to think anew about how to alter training programmes, management practices, even government policies in order to counteract it.

      At the moment, though, I fear we have the worst of both worlds – an unstable biology coupled with risk-management practices that increase risk limits during the bubble and decrease them during the crash, plus a bonus scheme that rewards high-variance trading. Today nature and nurture conspire in creating recurrent disasters. More effective policies will have to consider ways of managing the biology of the market. One way to do that may be to encourage a more even balance within the banks between men and women, young and old, for each has a very different biology.

      WHAT UNITES US

      To begin the story I want to tell, we need to get a better understanding of how brain and body cooperate in producing our thoughts and behaviour, and ultimately our risk-taking. The best way to do that is to look at what might be called the central operation of our brain. What might that be? We may be tempted to answer, given our heritage, that the central, most defining feature of our brain is its capacity for pure thought. But neuroscientists have discovered that conscious, rational thought is a bit player in the drama that is our mental life. Many of these scientists now believe that we are getting closer to the truth if we say that the basic operation of the brain is the organisation of movement.

      That statement may come as something of a shock – I know it did for me – even a disappointment. But had I learned its truth earlier than I did, I would have saved myself years of misunderstanding. You see, it is common when starting out in neuroscience to go looking for the computer in the brain, for our awesome reasoning capacities; but if you approach the brain with that goal you inevitably end up disappointed, for what you find is something a lot messier than expected. For the brain regions processing our reasoning skills are inextricably tangled up with motor circuits. You tend to get a bit annoyed at the lack of simplicity in this architecture, and frustrated at the inability to isolate pure thought. But that frustration comes from starting out with the wrong set of assumptions.

      If, however, you view your brain and body and behaviour with a robust appreciation of the fact that you are built to move, and if you let that simple fact sink in, then I am willing to bet you will never see yourself in quite the same way again. You will come to understand why you feel so many of the things you do, why your reactions are often so fast as to leave conscious thought behind, why you rely on gut feelings, why it is that during the most powerful moments of your life – satisfying moments of flow, of insight, of love, of risk-taking, and traumatic moments of fear, anger and stress – you lose any awareness of a split between mind and body, and they merge as one. Seeing yourself as an inseparable unity of body and brain may involve a shift in your self-understanding, but it is, I believe, a truly liberating one.

      Evolutionary biologists frequently look back over our past and try to spot the small advances here and there, the minor differences between us and our animal cousins, which might account for humans’ phenomenal ascent to the top of the food chain. They have found, not surprisingly, that many of these advances occurred in our body: the growth of vocal cords, for instance; or an opposable thumb, which gave us the manual dexterity to make and use tools; even an upright posture and a lack of fur – the former, it has been argued, minimising the body surface exposed to the midday sun, the latter making the cooling of our body so much easier, and both together permitting us to lope after swifter but fur-covered prey until it collapsed from heat exhaustion. On the African savannah we did not need to outrun or outfight our prey, so this theory claims, merely outcool it.

      Many of the advances leading to our dominance over other animals did indeed take place in the body, which over time became taller, straighter, faster, cooler, more dextrous and much more talkative. Other advances of equal importance occurred in the brain. According to some evolutionary accounts, human prehistory was driven by the growth of our neo-cortex, the rational, conscious, newest and outermost layer of the brain. As this brain structure blossomed, we developed the ability to think ahead and choose our actions, and in so doing became liberated from automatic behaviours and an animal enslavement to immediate bodily needs. This story of the brain’s evolution and the increasingly abstract nature of human thinking is for the most part correct. But it is also the subplot of the evolutionary story that is most prone to misunderstanding. It can too easily imply that our bodies became ever less important to our success as a species. An extreme example of this view can be found in science fiction, where future humans are frequently portrayed as all head, a bulbous cranium sitting atop an atrophied body. Bodies, in sci-fi and to a certain extent in the popular imagination, are seen as relics of a bestial prehistory best forgotten.

      The very existence of such a story, lurking in the popular imagination, is yet another testament to the staying power of the ancient notion of a mind–body split, according to which our bodies play a secondary and largely mischievous role in our lives, tempting us from the path of reason. Needless to say, such a story is simplistic. Body and brain evolved together, not separately. Some scientists have recently begun to study the ways in which the lines of communication between body and brain became more elaborate in humans compared to other animals, how over time the brain became more tightly bound to the body, not less. With the benefit of their research we can discern another story about our history that is at once more complete and far more intriguing – that the true miracle of human evolution was the development of advanced control systems for synchronising body and brain.

      In modern humans the body and brain exchange a torrent of information. And the exchange takes place between equals. We tend to think it does not, that information from the body constitutes nothing more than mere data being input into the computer in our head, the brain then sending back orders on what to do. The brain as puppet master, the body as puppet, to change analogies. But this picture is all wrong.