In the Wall Street Journal, Matt Ridley argues that human beings haven’t flourished because of anything we do individually. Rather, it is our ability to share and to building upon previous ideas of others–it is our “collective intelligence”:

The notion that exchange stimulated innovation by bringing together different ideas has a close parallel in biological evolution. The Darwinian process by which creatures change depends crucially on sexual reproduction, which brings together mutations from different lineages. Without sex, the best mutations defeat the second best, which then get lost to posterity. With sex, they come together and join the same team. So sex makes evolution a collective and cumulative process in which any individual can draw on the gene pool of the whole species. And when it comes to gene pools, the species with gene lakes generally do better than the ones with gene ponds—hence the vulnerability of island species to competition with continental ones.

It is precisely the same in cultural evolution. Trade is to culture as sex is to biology. Exchange makes cultural change collective and cumulative. It becomes possible to draw upon inventions made throughout society, not just in your neighborhood. The rate of cultural and economic progress depends on the rate at which ideas are having sex. . . . So here is the answer to the puzzle of human takeoff. It was caused by the invention of a collective brain itself made possible by the invention of exchange. . . . Prosperity consists of getting more and more narrow in what you make and more and more diverse in what you buy. Self-sufficiency—subsistence—is poverty.

Ridley concludes that this inexorable building upon prior ideas by sharing them is ultimately a “cheery” one (he points to reduced child mortality and increased per capita income worldwide), despite the occasional setbacks.