Читать книгу The Rational Optimist: How Prosperity Evolves - Matt Ridley, Matt Ridley - Страница 21

Anthropologists advance two theories to explain the appearance in Africa of these new technologies and people. The first is that it was driven by climate. The volatility of the African weather, sucking human beings into deserts in wet decades and pushing them out again in dry ones, would have placed a premium on adaptability, which in turn selected for new capabilities. The trouble with this theory is first that climate had been volatile for a very long time without producing a technologically adept ape, and second that it applies to lots of other African species too: if human beings, why not elephants and hyenas? There is no evidence from the whole of the rest of biology that desperate survival during unpredictable weather selects intelligence or cultural flexibility. Rather the reverse: living in large social groups on a plentiful diet both encourages and allows brain growth.

The second theory is that a fortuitous genetic mutation triggered a change in human behaviour by subtly altering the way human brains were built. This made people fully capable of imagination, planning, or some other higher function for the first time, which in turn gave them the capacity to make better tools and devise better ways of making a living. For a while, it even looked as if two candidate mutations of the right age had appeared – in the gene called FOXP2, which is essential to speech and language in both people and songbirds. Adding these two mutations to mice does indeed seem to change the flexibility of wiring in their brain in a way that may be necessary for the rapid flicker of tongue and lung that is called speech, and perhaps coincidentally the mutations even change the way mice pups squeak without changing almost anything else about them. But recent evidence confirms that Neanderthals share the very same two mutations, which suggests that the common ancestor of Neanderthals and modern people, living about 400,000 years ago, may have already been using pretty sophisticated language. If language is the key to cultural evolution, and Neanderthals had language, then why did the Neanderthal toolkit show so little cultural change?

Moreover, genes would undoubtedly have changed during the human revolution after 200,000 years ago, but more in response to new habits than as causes of them. At an earlier date, cooking selected mutations for smaller guts and mouths, rather than vice versa. At a later date, milk drinking selected for mutations for retaining lactose digestion into adulthood in people of western European and East African descent. The cultural horse comes before the genetic cart. The appeal to a genetic change driving evolution gets gene-culture co-evolution backwards: it is a top-down explanation for a bottom-up process.

Besides, there is a more fundamental objection. If a genetic change triggered novel human habits, why do its effects appear gradually and erratically in different places at different times but then accelerate once established? How could the new gene have a slower effect in Australia than in Europe? Whatever the explanation for the modernisation of human technology after 200,000 years ago, it must be something that gathers pace by feeding upon itself, something that is auto-catalytic.

As you can tell, I like neither theory. I am going to argue that the answer lies not in climate, nor genetics, nor in archaeology, nor even entirely in ‘culture’, but in economics. Human beings had started to do something to and with each other that in effect began to build a collective intelligence. They had started, for the very first time, to exchange things between unrelated, unmarried individuals; to share, swap, barter and trade. Hence the Nassarius shells moving inland from the Mediterranean. The effect of this was to cause specialisation, which in turn caused technological innovation, which in turn encouraged more specialisation, which led to more exchange – and ‘progress’ was born, by which I mean technology and habits changing faster than anatomy. They had stumbled on what Friedrich Hayek called the catallaxy: the ever-expanding possibility generated by a growing division of labour. This is something that amplifies itself once begun.

Exchange needed to be invented. It does not come naturally to most animals. There is strikingly little use of barter in any other animal species. There is sharing within families, and there is food-for-sex exchange in many animals including insects and apes, but there are no cases in which one animal gives an unrelated animal one thing in exchange for a different thing. ‘No man ever saw a dog make fair and deliberate exchange of a bone with another dog,’ said Adam Smith.

I need to digress here: bear with me. I am not talking about swapping favours – any old primate can do that. There is plenty of ‘reciprocity’ in monkeys and apes: you scratch my back and I scratch yours. Or, as Leda Cosmides and John Tooby put it, ‘One party helps another at one point in time, in order to increase the probability that when their situations are reversed at some (usually) unspecified time in the future, the act will be reciprocated.’ Such reciprocity is an important human social glue, a source of cooperation and a habit inherited from the animal past that undoubtedly prepared human beings for exchange. But it is not the same thing as exchange. Reciprocity means giving each other the same thing (usually) at different times. Exchange – call it barter or trade if you like – means giving each other different things (usually) at the same time: simultaneously swapping two different objects. In Adam Smith’s words, ‘Give me that which I want, and you shall have this which you want.’

Barter is a lot more portentous than reciprocity. After all, delousing aside, how many activities are there in life where it pays to do the same thing to each other in turn? ‘If I sew you a hide tunic today, you can sew me one tomorrow’ brings limited rewards and diminishing returns. ‘If I make the clothes, you catch the food’ brings increasing returns. Indeed, it has the beautiful property that it does not even need to be fair. For barter to work, two individuals do not need to offer things of equal value. Trade is often unequal, but still benefits both sides. This is a point that nearly everybody seems to miss. In the grasslands of Cameroon, for example, in past centuries the palm-oil producers, who lived on the periphery of the region on the poorest soils, worked hard to produce a low-value product that they exchanged for cereal, livestock and iron with their neighbours. On average it took them thirty days to afford the price of an iron hoe that had cost its makers just seven person-days of work. Yet palm oil was still the most profitable product they could make on their own land and with their own resources. The cheapest way for them to get an iron hoe was to make more palm oil. Or imagine a Trobriand island tribe on the coast that has ample fish and an inland tribe that has ample fruit: as long as two people are living in different habitats, they will value what each other has more than what they have themselves, and trade will pay them both. And the more they trade, the more it will pay them to specialise.

Evolutionary psychologists have assumed that it is rare for conditions to exist in which two people simultaneously have value to offer to each other. But this is just not true, because people can value highly what they do not have access to. And the more they rely on exchange, the more they specialise, which makes exchange still more attractive. Exchange is therefore a thing of explosive possibility, a thing that breeds, explodes, grows, auto-catalyses. It may have built upon an older animal instinct of reciprocity, and it may have been greatly and uniquely facilitated by language – I am not arguing that these were not vital ingredients of human nature that allowed the habit to get started. But I am saying that barter – the simultaneous exchange of different objects – was itself a human breakthrough, perhaps even the chief thing that led to the ecological dominance and burgeoning material prosperity of the species. Fundamentally, other animals do not do barter.

I still don’t quite know why, but I have a lot of trouble getting this point across to both economists and biologists. Economists see barter as just one example of a bigger human habit of general reciprocity. Biologists talk about the role that reciprocity played in social evolution, meaning ‘do unto others as they do unto you’. Neither seems to be interested in the distinction that I think is vital, so let me repeat it here once more: at some point, after millions of years of indulging in reciprocal back-scratching of gradually increasing intensity, one species, and one alone, stumbled upon an entirely different trick. Adam gave Oz an object in exchange for a different object. This is not the same as Adam scratching Oz’s back now and Oz scratching Adam’s back later, or Adam giving Oz some spare food now and Oz giving Adam some spare food tomorrow. The extraordinary promise of this event was that Adam potentially now had access to objects he did not know how to make or find; and so did Oz. And the more they did it, the more valuable it became. For whatever reason, no other animal species ever stumbled upon this trick – at least between unrelated individuals.

Do not take my word for it. The primatologist Sarah Brosnan tried to teach two different groups of chimpanzees about barter and found it very problematic. Her chimps preferred grapes to apples to cucumbers to carrots (which they liked least of all). They were prepared sometimes to give up carrots for grapes, but they almost never bartered apples for grapes (or vice versa), however advantageous the bargain. They could not see the point of giving up food they liked for food they liked even more. Chimpanzees and monkeys can be taught to exchange tokens for food, but this is a long way from spontaneously exchanging one thing for another: the tokens have no value to the chimpanzees, so they are happy to give them up. True barter requires that you give up something you value in exchange for something else you value slightly more.

This is reflected in the ecology of wild chimpanzees. Whereas in human beings, each sex eats ‘not only from the food items they have collected themselves, but from their partners’ finds,’ says Richard Wrangham, ‘not even a hint of this complementarity is found among nonhuman primates.’ It is true that male chimps hunt monkeys more than females do and that having killed a monkey, a male sometimes allows others to share it if they beg to, especially a fertile female or a close partner to whom he owes a favour. But the one thing you do not see is trade of one food for another. There is never barter of meat for nuts. The contrast with human beings, who show an almost obsessive interest not just in sharing food with each other from an early age, but in swapping one item for another, is striking. Birute Galdikas reared a young orang-utan in her home alongside her daughter Binti, and was struck by the contrasting attitudes to food sharing of the two infants. ‘Sharing food seemed to give Binti great pleasure,’ she wrote. ‘In contrast, Princess, like any orang-utan would beg, steal and gobble food at every opportunity’.

My argument is that this habit of exchanging, this appetite for barter, had somehow appeared in our African ancestors some time before 100,000 years ago. Why did human beings acquire a taste for barter as other animals did not? Perhaps it has something to do with cooking. Richard Wrangham makes a persuasive case that control of fire had a far-reaching effect on human evolution. Beyond making it safe to live on the ground, beyond liberating human ancestors to grow big brains on high-energy diets, cooking also predisposed human beings to swapping different kinds of food. And that maybe got them bartering.