Because natural selection is driven by competition, cooperation and altruism were the issues that most troubled Darwin, and the evolutionary theorists who have followed him. Recent studies of conflict within genomes also require upgrades on classical theory.
Much of the cooperation and conflict in nature concerns resource allocation. Here we consolidate existing theory for the evolution of resource transfers of fixed amount between individuals. We also extend inclusive fitness theory to address cooperation and conflict among any evolving actors that share control over a resource pool, and that influence how resources are allocated. This allows better prediction of evolutionary dynamics, and extends theory to include the evolution of actors that are neither donor nor recipient, greatly expanding its scope. We show that under adaptive evolution, conflict is an evolutionary attractor even between initially cooperating actors, and that adaptations for both cooperation and conflict are likely to evolve in the same context, with conflict likely to follow cooperation on an evolutionary time scale. Our framework encompasses cooperation and conflict both among organisms, and also among reproducing sub-units and genetic elements. It is therefore applicable to intra-genomic interactions and evolutionary transitions in individuality.