The Rational Optimist (P.S.)

by Matt Ridley

The Harappan people ate a lot of fish and grew a lot of cotton, things they had in common with citizens of another valley on the far side of the world. Caral in the desert of the Supe Valley in Peru was a large town with monuments, warehouses, temples and plazas. Discovered in the 1990s by Ruth Shady, it lies in a desert crossed by a river valley and was only the biggest of many towns in the area, some of which date from more than 5,000 years ago – the so-called Norte Chico civilisation. For archaeologists there are three baffling features of the ancient Peruvian towns. First, their people had no cereals in their diet. Maize was yet to be invented, and although there were several domesticated squashes and other foods, there was nothing so easily accumulated and stored as the grain which was the staple of Mesopotamia. The idea that cities are made possible by largescale hoarding of grain thus takes a blow. Second, the Norte Chico towns have yielded no pottery of any kind: they were ‘preceramic’. This surely made both the storage and the cooking of food more difficult, again undermining one of the favourite tenets of archaeologists trying to explain how cities began. And third, there is no evidence of warfare or defensive works. So the conventional wisdom that cereal stores made cities possible, that ceramic containers made them practical and that warfare made them necessary takes quite a knock from Norte Chico. So what was driving people together into these South American t...