Exchange is to cultural evolution as sex is to biological evolution

The Rational Optimist by Matt Ridley on progress through connectivity.

If culture consisted simply of learning habits from others, it would soon stagnate. For culture to turn cumulative, ideas need to meet and mate. The 'cross-fertilization of ideas' is a cliche, but one with unintentional fecundity. 'To create is to recombine' said the molecular biologist Francois Jacob. Imagine if the man who invented the railway and the man who invented the locomotive could never meet or speak to each other, even through third parties. Paper and the printing press, copper and tin, the wheel and steel, software and hardware. I shall argue that there was a point in human prehistory when big-brained, cultural, learning people for the first time began to exchange things with each other, and that once they started doing so, culture sudddenly became cumulative, and the great headlong experiment of human economic 'progress' began. Exchange is to cultural evolution as sex is to biological evolution.