Read: The Evolution of Cooperation
Of course, I already heard about Axelrod's computer tournament of strategies in the Prisoner's Dilemma during my studies. Game theory and experimental economics were among the courses I attended. To hear about the Evolution of Cooperation was inevitable. However, second hand reports tend to twist the facts a bit. Indeed, one fact I thought I knew about tit for tat was wrong. Or at least only valid under very specific circumstances.
So finally, I read the first hand research: Robert Axelrod's edited collection of published papers on his computer tournament and its implications. The text is surprisingly accessible. On second thought, of course it is. It was meant for the general audience and not only for academics. Consequently, I really enjoyed reading about something I already knew (at least in principle). The book has some very insightful illustrations. I only regret that I did not mention this research in my intermediate microeconomics course this winter. I really should have.