7 March 2025
Benjamin Allen
Emmanuel College, Boston
The evolution of cooperation has been a major question in evolutionary theory since Darwin. It has also been the focus of intense disputes over the merits of different methodological approaches. I will review the four major theoretical approaches to the evolution of cooperation: multilevel selection, inclusive fitness, population genetics, and evolutionary game theory. Crucially, these approaches differ in the level at which the explanation applies, and in how they relate to the notion of "actor". I will examine the question of whether these are mathematically equivalent, and critically evaluate previous claims of such equivalence. I will then outline a new mathematical approach to the evolution of cooperation and other social behavior, which synthesizes and extends the four existing frameworks. In this new approach, the notion of "actor" is extended from individuals to collectives, and the outcome of evolution reflects an aggregation over individual and collective interests across scales.