Evolutionary game theory and the tower of Babel of cooperation: Altruism, free-riding, parasitism and the structure of the interactions in a world with finite resources

Abstract: The study of the evolution of cooperative behaviours --which provide benefits to others-- and altruism --which provides benefits to others at a cost to oneself-- has been on the core of the evolutionary game theoretical framework since its foundation. The fast development of the theory during the last years has improved our knowledge of the issue, but carried attached a diversification of concepts which affected communication between scientists. Furthermore, the main root of conflict in the struggle for life identified by Darwin, the limited amount of resources present in any ecosystem, which is assumed to keep a constant population size in most game theoretical studies, has only recently been taken into account as explicitly influencing the evolutionary process. This review concerns about both issues, the conceptual diversification during the last years and the new results of the resource dependent models. In extenso: After a historical introduction, a review of the most important concepts is carried out. Then it is shown that pairwise interactions and additive fitness determine prisoner's dilemmas (PDs) or harmony games, that two altruists interacting together may determine a PD, and that the interaction environment of the most cooperative and less selfish individual in any population is always a PD. After that, it is shown that in addition to altruists versus free-riders, the combination of free-riders and parasites determines a fundamentally different PD. Computer simulations are then carried out to show that random exploration of parasitism, free-riding and altruism enables coexistence of the three strategies without the need of reciprocating, punishing or rewarding strategies. To finish, the problem of the limitation of resources is reviewed, showing that...