As long as all Sapiens living in a particular locality believe in the same stories, they all follow the same rules, making it easy to predict the behaviour of strangers and to organise mass-cooperation networks. Sapiens often use visual marks such as a turban, a beard or a business suit to signal ‘you can trust me, I believe in the same story as you’. Our chimpanzee cousins cannot invent and spread such stories, which is why they cannot cooperate in large numbers.
