Evolution of Cooperation in Evolutionary Robotics: the Tradeoff between Evolvability and Efficiency

In this paper, we investigate the benefits and drawbacks of different approaches for solving a cooperative foraging task with two robots. We compare a classical clonal approach with an additional approach which favors the evolution of heterogeneous behaviors according to two defining criteria: the evolvability of the cooperative solution and the efficiency of the coordination behaviors evolved. Our results reveal a tradeoff between evolvability and efficiency: the clonal approach evolves cooperation with a higher probability than a non-clonal approach, but heterogeneous behaviors evolved with the non-clonal approach systematically show better fitness scores. We then propose to overcome this tradeoff and improve on both of these criteria for each approach. To this end, we investigate the use of incremental evolution to transfer coordination behaviors evolved in a simpler task. We show that this leads to a significant increase in evolvability for the non-clonal approach, while the clonal approach does not benefit from any gain in terms of efficiency.