Voluntary Exchange and Specialization

Evolutionary psychologists have assumed that it is rare for conditions to exist in which two people simultaneously have value to offer to each other. But this is just not true, because people can value highly what they do not have access to. And the more they rely on exchange, the more they specialize, which makes exchange still more attractive. Exchange is therefore a thing of explosive possibility, a thing that breeds, explodes, grows, auto-catalyzes. It may have been built upon an older animal instinct of reciprocity, and it may have been greatly and uniquely facilitated by language — I am not arguing that these were not vital ingredients of human nature that allowed the habit to get started. But I am saying that barter — the simultaneous exchange of different objects — was itself a human breakthrough, perhaps even the chief thing that led to the ecological dominance and burgeoning material prosperity of the species.

– Matt Ridley