title: The joker effect: cooperation driven by destructive agents.
abstract: Understanding the emergence of cooperation is a central issue in evolutionary game theory. The hardest setup for the attainment of cooperation in a population of individuals is the Public Goods game in which cooperative agents generate a common good at their own expenses, while defectors "free-ride" this good. Eventually this causes the exhaustion of the good, a situation which is bad for everybody. Previous results have shown that introducing reputation, allowing for volunteer participation, punishing defectors, rewarding cooperators or structuring agents, can enhance cooperation. Here we present a model which shows how the introduction of rare, malicious agents--that we term jokers--performing just destructive actions on the other agents induce bursts of cooperation. The appearance of jokers promotes a rock-paper-scissors dynamics, where jokers outbeat defectors and cooperators outperform jokers, which are subsequently invaded by defectors. Thus, paradoxically, the existence of destructive agents acting indiscriminately promotes cooperation.
authors: Departament d'Enginyeria Informàtica i Matemàtiques, Universitat Rovira i Virgili, 43007 Tarragona, Spain. alexandre.arenas@urv.cat
authors: Alex
authors: A
authors: Arenas
authors: Juan
authors: J
authors: Camacho
authors: José A
authors: JA
authors: Cuesta
authors: Rubén J
authors: RJ
authors: Requejo
mesh_terms: D003299:Cooperative Behavior; D005716:Game Theory; D006801:Humans; D008954:Models, Biological; D009154:Mutation / Q000235:genetics; D011157:Population Dynamics