The Impact of Inequity Aversion on the Evolution of Cooperation

Cooperation underlies complex behaviors across biological and artificial systems, ranging from microbial colonies to human societies, embodied intelligence, and swarm intelligence. These cooperative mechanisms are increasingly reflected in intelligent collectives such as autonomous combat swarms, industrial robotic clusters, and human-machine collaborative networks. While fairness is often regarded as a product of human cognitive and emotional control, experimental evidence suggests it is typically instrumental, supporting the maintenance of cooperation rather than pursued as an intrinsic value. This paper introduces a strategy updating model based on inequity aversion (IA), in which individuals tend to cooperate with peers exhibiting similar payoff levels. A sufficient condition is derived under which cooperation becomes evolutionarily stable in public goods games on random regular networks. Numerical simulations validate the theoretical predictions and further demonstrate the impact of IA sensitivity on the emergence of cooperation. The findings highlight IA as a key emotional mechanism underlying the dynamics of intelligent group behavior.