– which greatly increase the velocity of javelins – appear by 18,000 years ago. Bows and arrows came soon afterwards. ‘Microburin’ borers were used for drilling the holes in needles and beads. Of course, stone tools would have been only a tiny tip of a technological iceberg, dominated by wood, which has long since rotted away. Antler, ivory and bone were just as important. String, made from plant fibres or leather, was almost certainly in use by then to catch fish and rabbits in nets or snares, and to make bags for carrying things in.
Nor was this virtuosity confined to practicalities. As well as bone and ivory, shells, fossil coral, steatite, jet, lignite, hematite, and pyrite were used to make ornaments and objects. A flute made from the bone of a vulture dates from 35,000 years ago at Hohle Fels and a tiny horse, carved from mammoth ivory and worn smooth by being used as a pendant, dates from 32,000 years ago at Vogelherd – both in Germany. By the time of Sungir, an open-air settlement from 28,000 years ago at a spot near the city of Vladimir, north-east of Moscow, people were being buried in clothes decorated with thousands of laboriously carved ivory beads, and even little wheel-shaped bone ornaments had appeared. At Mezherich, in what is now Ukraine, 18,000 years ago, jewellery made of shells from the Black Sea and amber from the Baltic implied trade over hundreds of miles.
This is in striking contrast to the Neanderthals, whose stone tools were virtually always made from raw material available within an hour’s walk of where the tool was used. To me this is a vital clue to why the Neanderthals were still making hand axes, while their African-origin competitors were making ever more types of tool. Without trade, innovation just does not happen. Exchange is to technology as sex is to evolution. It stimulates novelty. The remarkable thing about the moderns of west Asia is not so much the diversity of artefacts as the continual innovation. There is more invention between 80,000 and 20,000 years ago than there had been in the previous million. By today’s standards, it was very slow, but by the standards of Homo erectus it was lightning-fast. And the next ten millennia would see still more innovations: fish hooks, all sorts of implements, domesticated wolves, wheat, figs, sheep, money.
If you are not self-sufficient, but are working for other people, too, then it pays you to spend some time and effort to improve your technology and it pays you to specialise. Suppose, for example, that Adam lives in a grassy steppe where there are herds of reindeer in winter, but some days’ walk away is a coast, where there are fish in summer. He could spend winter hunting, then migrate to the coast to go fishing. But that way he would not only waste time travelling, and probably run a huge risk crossing the territory of another tribe. He would also have to get good at two quite different things.
If, instead, Adam sticks to hunting and then gives some dried meat and reindeer antlers – ideal for fashioning hooks from – to Oz, a coastal fisherman, in exchange for fish, he has achieved the goal of varying his diet in a less tiring or dangerous way. He has also bought an insurance policy. And Oz would be better off, because he could now catch (and spare) more fish. Next Adam realises that instead of giving Oz raw antlers, he can give him pieces of antler already fashioned into hooks. These are easier to transport and fetch a better price in fish. He got the idea when he once went to the trading point and noticed others selling antlers that had already been cut up into easy segments. One day, Oz asks him to make barbed hooks. And Adam suggests that Oz dries or smokes his fish so it lasts longer. Soon Oz brings shells, too, which Adam buys to make jewellery for a young woman he fancies. After a while, depressed by the low price fetched by hooks of even high quality, Adam hits on the idea of tanning some extra hides and bringing those to the trading point, too. Now he finds he is better at making hides than hooks, so he specialises in hides, giving his antlers to somebody from his own tribe in exchange for his hides. And so on, and on and on.
Fanciful, maybe. And no doubt wrong in all sorts of details. But the point is how easy it is to envisage both opportunities for trade among hunter-gatherers – meat for plants, fish for leather, wood for stone, antler for shells – and how easy it is for Stone Age people to discover mutual gains from trade and then to enhance that effect by further specialising and further dividing labour. The extraordinary thing about exchange is that it breeds: the more of it you do, the more of it you can do. And it calls forth innovation.
Which only raises another question: why did economic progress not accelerate towards an industrial revolution there and then? Why was progress so agonisingly slow for so many millennia? The answer, I suspect, lies in the fissile nature of human culture. Human beings have a deep capacity for isolationism, for fragmenting into groups that diverge from each other. In New Guinea, for instance, there are more than 800 languages, some spoken in areas just a few miles across yet as unintelligible to those on either side as French and English. There are still 7,000 languages spoken on earth and the people who speak each one are remarkably resistant to borrowing words, traditions, rituals or tastes from their neighbours. ‘Whereas vertical transmission of cultural traits goes largely unnoticed, horizontal transmission is far more likely to be regarded with suspicion or even indignation,’ say the evolutionary biologists Mark Pagel and Ruth Mace. ‘Cultures, it seems, like to shoot messengers.’ People do their utmost to cut themselves off from the free flow of ideas, technologies and habits, limiting the impact of specialisation and exchange.
Ricardo’s magic trick
Divisions of labour beyond the pair bond had probably been invented in the Upper Palaeolithic. Commenting on the ten thousand mammoth-ivory beads with which the clothing of two 28,000-year-old child corpses at Sungir in Russia were decorated, the anthropologist Ian Tattersall remarks: ‘It’s hardly probable that these young people had made their richly adorned vestments themselves. It’s much more likely that the sheer diversity of material production in their society was the result of the specialisation of individuals in different activities.’ The carvers of mammoth beads at Sungir, the painter of rhinoceroses at Chauvet, the striker of blades from rock cores, the maker of rabbit nets – perhaps these were all specialists, exchanging their labour for that of others. Perhaps there had been different roles within each band of human beings ever since the first emergence of modern people over 100,000 years ago.
It is such a human thing to do, and so obvious an explanation of the thing that needs explaining: the capacity for innovation. Specialisation would lead to expertise, and expertise would lead to improvement. Specialisation would also give the specialist an excuse for investing time in developing a laborious new technique. If you have a single fishing harpoon to make, there’s no sense in building a clever tool for making harpoons first, but if you have to make harpoons for five fishermen, then maybe there is sense and time-saving in first making the harpoon-making tool.
Specialisation would therefore create and increase the opportunities for gains from trade. The more Oz goes fishing, the better he gets at it, so the less time it takes him to catch each fish. The more hooks Adam the reindeer hunter makes, the better he gets at it, so the less time he takes to make each one. So it pays Oz to spend his day fishing and buy his hooks off Adam by giving him some fish. And it pays Adam to spend his day making hooks and get his fish delivered by Oz.
And, wonderfully, this is true even if Oz is better at hook-making than Adam. Suppose Adam is a clumsy fool, who breaks half his hooks, but he is an even clumsier fisherman who cannot throw a line to save his life. Oz, meanwhile, is one of those irritating paragons who can whittle a bone hook with little trouble and always catches lots of fish. Yet it still pays Oz to get his hooks made for him by clumsy Adam. Why? Because with practise Adam has at least become better at making hooks than he is at fishing. It takes him three hours to make a hook, but four hours to catch a fish. Oz takes only an hour to catch a fish, but good as he is he still needs two hours to make a hook. So if each is self-sufficient, then Oz works for three hours (two to make the hook and one to catch the fish), while Adam works for seven hours (three to make the hook and four to catch a fish). If Oz catches two fish and swaps one for a hook from Adam, he only has to work two hours. If Adam makes two hooks and uses one to buy a fish from Oz, he only works