Individual selection leads to collective efficiency through coordination

Abstract

Evolutionary game theory shows that social interactions involving coordination between individuals are subject to an "evolutionary trap." Once a suboptimal strategy has evolved, mutants playing an alternative strategy are counterselected because they fail to coordinate with the majority. This creates a detrimental situation from which evolution cannot escape. To determine how this problem materializes in a model with a greater degree of realism than conventional game-theoretical models, we simulate the life and the long-term evolution of a population of individuals playing a two-player coordination game, using the framework of evolutionary robotics. We first confirm the existence of an evolutionary trap in a simple setting. We then, however, reveal that this problem disappears in a more realistic setting where individuals need to coordinate with one another. In this setting, robots evolve an ability to adapt plastically their behavior to one another, as this improves the efficiency of their interaction. This ability has an unintended evolutionary consequence: a genetic mutation affecting one individual's behavior also indirectly alters their partner's behavior because the two individuals influence one another, which is called an "indirect genetic effect." Consequently, pairs of partners can virtually change strategy together with a single mutation, and the evolutionary barrier between alternative strategies disappears. This finding reveals a general principle that could play a role in nature to smoothen the transition to efficient collective behaviors in all games with multiple equilibriums.