Robert Trivers, was explaining how, from an evolutionary perspective, even altruism was really just a sophisticated form of selfishness, based on the principle of “I'll scratch your back and you scratch mine.” In a much-cited paper, he described what he called “reciprocal altruism” as an ancient evolutionary strategy that could be seen in the behavior of fish and birds, and he interpreted human altruism in the same way.
Reciprocal altruism.
