Giacomo Frigerio - Endogenous incentives reshape the stability of cooperation

Abstract of the talk: Evolutionary game theory offers a powerful framework for studying how behaviours evolve in biological populations, and how strategies such as cooperation and defection spread more generally. In recent years, this framework has attracted increasing attention in statistical mechanics, where tools from non-equilibrium dynamics, phase transitions, and complex systems have been used to describe how collective behaviour emerges from microscopic strategic interactions. Evolutionary game theory, however, typically assumes that payoffs are fixed or shaped by external environmental variables. The speaker will introduce an endogenous-feedback framework in which the game played coevolves directly with the population state: the payoff matrix is a time-dependent function of the level of cooperation. This allows strategic incentives to be continuously reconstructed by the collective behaviour they generate. Even in the simplest case of linear and instantaneous feedback, the model reveals feedback-induced regimes, termed chimera games, in which stable cooperation arises despite being incompatible with the predictions of standard fixed-game dynamics. He will further show that delayed feedback can destabilize these equilibria and generate sustained oscillations, while nonlinear feedback reshapes equilibrium structure and introduces path dependence. Finally, he will discuss how cooperation can be promoted, suppressed, or destabilized by incentives generated endogenously by the population itself. Date: 27th May, 2026.