[4J1-GS-5] Agents:

[4J1-GS-5-05] Evolution of fear and food rewards in prey-predator dynamics

〇Yuji Kanagawa¹, Kenji Doya¹ (1. Okinawa Institute of Science and Technology Graduate University)

Keywords:ALIFE, RL

Animal brains have evolved to help us survive and reproduce more offspring. The reward system is the most fundamental brain function for this purpose, evaluating external stimuli and providing learning cues to reinforce positive behaviors like eating and drinking while avoiding dangerous ones. While the reward system is the foundation of higher-order brain functions such as intelligence and consciousness, the environmental conditions under which these functions evolved remain unclear. Previously, we have studied how food-intake rewards and fatigue evolve in dynamically fluctuating populations using large-scale simulations of reinforcement learning agents with genetically encoded reward weights. However, our previous study did not observe the evolution of negative rewards for less-nutritious or poisonous foods leading to avoidance behaviors. In this study, we introduce predators that can eat prey in the simulation environment and investigate how negative rewards for observing predators can evolve under predator-prey dynamics. In experiments, we observed negative rewards for observing threats have evolved in the predator-prey setting, while negative rewards for threats have not evolved for static harmful obstacles. This result suggests that predators are critically important for the evolution of negative rewards for avoidance behaviors.