their neighbouring area. Mriganka Sur has partly rewired the eyes of a ferret to the auditory cortex of its brain rather than the visual cortex, and in some rudimentary way it can still ‘see’, but not very well. Although you might think it remarkable that the ferret can see at all after such surgery, there is disagreement whether Sur’s experiment reveals more about the plasticity of the brain or the limits of that plasticity.42
If the modular mind is real, then all you have to do to understand the special features of the human mind is to dissect the brain to find out which bits have ‘hypertrophied’ in the past few million years—which modules and therefore which instincts are disproportionately big. Then you will know what makes human beings special. If only it were so easy! Almost everything in the human brain is bigger than in the chimpanzee brain. Human beings apparently do more seeing, more feeling, more moving, more balancing, more remembering and even more smelling than chimps. Far from finding a normal chimpanzee brain with a huge, turbo-charged thinking-and-speaking device attached to it, you find, if you look inside the human skull, more of everything. Closer inspection reveals that there are certain subtle disproportions. In primates generally, compared with rodents, the bits that do smelling have shrunk dramatically and the bits that do seeing have grown. The neocortex has grown at the expense of the rest. But even here the disproportion is not very marked. Indeed, since the neocortex develops last, and the frontal regions last of all, you could simply explain the big human brain as a chimp brain that has been grown for longer. In its extreme form this theory holds that the brain expanded, not because expansion was demanded by the requirement for it to do new functions – specifically language or culture – but because something required the enlargement of the brain stem itself and a bigger cortex came along as a passenger for the ride. Remember the lesson of the IQ domains in the ASPM gene: it is genetically easy just to make every part of the brain bigger. Once the big brain was there, hey presto, 50,000 years ago, Homo sapiens suddenly discovered he could use it to make bows and arrows, paint cave walls and think about the meaning of life.43
This idea has the advantage of again taking the species down a Cartesian peg – away goes the reassuring notion that humankind was the subject, rather than the object, in its own evolutionary story. But it is not necessarily incompatible with the idea of a modular mind. In fact, you could just as easily turn the logic on its head and argue that human beings were under selective pressure to develop more processing power in the parts of the brain needed for one function – language, say – and the easiest way for the genome to respond was to build a bigger brain generally. The ability to do more seeing and have a greater repertoire of moves was thrown in free. Besides, even a language module is hardly likely to be isolated from other functions. It needs fine discrimination of hearing, finer control of movement in the tongue, lips and chest, greater memory, and so on.44
Scientific theories, however, like empires, are at their most vulnerable when they have vanquished their rivals. No sooner had the modular mind triumphed than one of its main champions started dismantling it. In 2001 Jerry Fodor published a remarkable little book called The Mind Doesn’t Work That Way, which argued that though breaking down the mind into separate computational modules was by far the best theory around, it did not and could not explain how the mind works.45 Pointing out the ‘scandalous’ failure of engineers to build robots capable of routine tasks like cooking breakfast, Fodor gently reminded his colleagues how little had yet been discovered and chided Pinker for his cheerful optimism that the mind was explained.46 Minds, said Fodor, are capable of abducting global inferences from the information supplied by the parts of the brain. You may see, feel and hear raindrops with three different brain modules linked to different senses, but somewhere in your brain resides the inference: ‘it is raining’. In some inevitable sense, then, thinking is a general activity that integrates vision, language, empathy and other modules: mechanisms that operate as modules presuppose mechanisms that don’t. And almost nothing is known about the mechanisms that are not modular. Fodor’s conclusion was to remind scientists just how much ignorance they had discovered: they had merely thrown some light on how much dark there was.
But at least this much is clear. To build a brain with instinctive abilities, the Genome Organising Device lays down separate circuits with suitable internal patterns that allow them to carry out suitable computations, then links them with appropriate inputs from the senses. In the case of a digger wasp or a cuckoo, such modules may have to ‘get the behaviour right’ first time and may be comparatively indifferent to experience. But in the case of the human mind, almost all such instinctive modules are designed to be modified by experience. Some adapt continuously throughout life, some change rapidly with experience then set like cement. A few just develop to their own timetable. In the rest of this book, I propose to try to find the genes responsible for building – and changing – these circuits.
PLATONIC UTOPIA
One of the besetting sins of the nature-nurture debate has been the habit of utopianism, the notion that there is one ideal design of society that can be derived from a theory of human nature. Many of those who thought they understood human nature promptly turned description to prescription and set out a design of the perfect society. This practice is common to those on the nature side of the debate as well as those on the nurture side. Yet the only lesson to be drawn from utopian dreaming is that all utopias are hells. All attempts to design society by reference to one narrow conception of human nature, whether on paper or in the streets, end in producing something much worse. I propose to end each chapter mocking the utopia implied in taking any theory too far.
William James and the protagonists of instinct did not, as far as I can discern, write a utopia. But Plato’s Republic, the father of all utopias, is in many ways close to a Jamesian dream. It is imbued with a similar nativism. The Republic has been called a ‘managerial meritocracy’ in which the same education is available to all, so the top jobs go to those with the innate talent for them.47 In Plato’s metaphorical republic (probably never intended as a political blueprint), everything is governed by strict rules. The Rulers, who make policy, are assisted by the Auxiliaries, who provide a sort of civil and defence service. Together these two classes are called the Guardians, and they are chosen on merit, which means on native talent. But to prevent corruption, the Guardians live lives of austere asceticism, unable to own property, to marry, or even to drink from gold cups. They live in a dormitory, but their miserable existence gladdens their hearts because they know it is for the good of the society as a whole.
Karl Popper was not the first, nor will he be the last, philosopher to call Plato’s dream a totalitarian nightmare. Even Aristotle pointed out that there was not much point in a meritocracy if merit did not bring rewards – of wealth and sex as well as power: ‘Men pay most attention to what is their own: they care less for what is common.’48 Plato’s citizens were expected to accept any spouse nominated by the state, and (if female) to suckle any baby. Some chance. But grant Plato the backhanded compliment of having this insight, at least: even the meritocracy is an imperfect society. If all people receive the same education, then the differences in their abilities will be innate. A truly equal-opportunity society merely rewards the talented with the best jobs and relegates the rest to doing the dirty work.
CHAPTER THREE A convenient jingle
Professors are inclined to attribute the intelligence of their children to nature, and the intelligence of their students to nurture.
