What’s the project about? Costly signals, such as peacock’s tail, are signals that impose a cost on their bearer but do not endow any direct benefit. The evolution of such costly signals is an enduring puzzle in evolutionary theory, and their positive role in facilitating honest communication is usually appealed to explain their evolution. In this project, we aim to study how costly signals can evolve in simple evolutionary models due to the density-dependent selection of costly traits and how they can facilitate cooperation. In this computational project, we will use agent-based simulations to study the co-evolution of costly signals and cooperation.