Philip Coelho and James McClure have an interesting article, “The Evolution of Human Cooperation,” in the latest issue of the Journal of Bioeconomics 18(1)(2016): pp. 65–78I.
The article argues that the strategic behavior predicted in game theory (the essence of homo economicus) reflects just the last evolutionary step in human evolution. A much older primitive brain system relied on the necessity of cooperation without cognition. Simple organisms cooperate all the time without engaging in strategic behaviors. Such is our primitive past.
That is, humans are mainly an old-brain system with deep instinctual behaviors for cooperation.
Over time this old brain grew with evolution, adding layers of calculating possibilities—feints and deceptions. The more modern brain is the problem child, fallen from the Garden of Eden. The modern brain knows evil through plotting treachery toward others in an effort to selfishly gain more resources and propagate faster. But this later system relies upon that earlier system that cooperated without conscious plan:
"Strategic behaviors are a consequence of large brains and cognition, while these in turn are the results of the success of hominid cooperation in the ancestral environment that allowed the acquisition of protein and the resultant growth in brain-power." (p. 76)
This is an interesting idea, and helpful to think about. My query is: I was under the impression that the growth and evolution of the human brain did not mainly enhance human logic or rationality. Rather, the growing human brain was needed to discern human intentions—picking up subtle clues in body language, tone of voice, and other characteristics that would indicate whether the another person is sincere or fraudulent. This gives rise to intuition about others, as well as strong emotional reactions to things we dislike.
Adam Smith’s model was based on human instincts, operating within human institutions, that gave rise to institutional rules. It isn’t the big rational brain that takes us to economic development, it is the big emotional brain that does, by grounding exchange and institutions in human sentiments.