Biden, Xi and the evolution of cooperation Feb 07,2021 - Last updated at Feb 07,2021 CLAREMONT, California — I do not know whether US President Joe Biden, Chinese President Xi Jinping, and their foreign-policy advisers have read Robert Axelrod’s classic book on international relations, “The Evolution of Cooperation”. But they should heed Axelrod’s central insight about how countries can benefit from cooperation and punish cheating. Through countless simulations, Axelrod, now a professor emeritus at the University of Michigan, found that the most beneficial long-term strategy for an actor such as a nation-state is to cooperate first and then play tit-for-tat. In other words, a country will gain in the long run if it offers a goodwill gesture and then responds in kind to its opponent’s subsequent moves.