Brilliant people, be they anthropologists, psychologists or economists, assume that brilliance is the key to human achievement. They vote for the cleverest people to run governments, they ask the cleverest experts to devise plans for the economy, they credit the cleverest scientists with discoveries, and they speculate on how human intelligence evolved in the first place.
They are all barking up the wrong tree. The key to human achievement is not individual intelligence at all. The reason human beings dominate the planet is not because they have big brains: Neanderthals had big brains but were just another kind of predatory ape. Evolving a 1200-cc brain and a lot of fancy software like language was necessary but not sufficient for civilization. The reason some economies work better than others is certainly not because they have cleverer people in charge, and the reason some places make great discoveries is not because they have smarter people.
Human achievement is entirely a networking phenomenon. It is by putting brains together through the division of labor — through trade and specialisation — that human society stumbled upon a way to raise the living standards, carrying capacity, technological virtuosity and knowledge base of the species. We can see this in all sorts of phenomena: the correlation between technology and connected population size in Pacific islands; the collapse of technology in people who became isolated, like native Tasmanians; the success of trading city states in Greece, Italy, Holland and south-east Asia; the creative consequences of trade.
Human achievement is based on collective intelligence — the nodes in the human neural network are people themselves. By each doing one thing and getting good at it, then sharing and combining the results through exchange, people become capable of doing things they do not even understand. As the economist Leonard Read observed in his essay "I, Pencil' (which I'd like everybody to read), no single person knows how to make even a pencil — the knowledge is distributed in society among many thousands of graphite miners, lumberjacks, designers and factory workers.
That's why, as Friedrich Hayek observed, central planning never worked: the cleverest person is no match for the collective brain at working out how to distribute consumer goods. The idea of bottom-up collective intelligence, which Adam Smith understood and Charles Darwin echoed, and which Hayek expounded in his remarkable essay "The use of knowledge in society", is one idea I wish everybody had in their cognitive toolkit.