Bshary, Redouan

2008, Bshary, Redouan, Bergmueller, Ralph

The evolution and stability of helping behaviour has attracted great research efforts across disciplines. However, the field is also characterized by a great confusion over terminology and a number of disagreements, often between disciplines but also along taxonomic boundaries. In an attempt to clarify several issues, we identify four distinct research fields concerning the evolution of helping: (1) basic social evolution theory that studies helping within the framework of Hamilton’s inclusive fitness concept, i.e. direct and indirect benefits, (2) an ecological approach that identifies settings that promote life histories or interaction patterns that favour unconditional cooperative and altruistic behaviour, e.g. conditions that lead to interdependency or interactions among kin, (3) the game theoretic approach that identifies strategies that provide feedback and control mechanisms (protecting from cheaters) favouring cooperative behaviour (e.g. pseudo-reciprocity, reciprocity), and (4) the social scientists’ approach that particularly emphasizes the special cognitive requirements necessary for human cooperative strategies. The four fields differ with respect to the ‘mechanisms’ and the ‘conditions’ favouring helping they investigate. Other major differences concern a focus on either the life-time fitness consequences or the immediate payoff consequences of behaviour, and whether the behaviour of an individual or a whole interaction is considered. We suggest that distinguishing between these four separate fields and their complementary approaches will reduce misunderstandings, facilitating further integration of concepts within and across disciplines.

2007, Johnstone, Rufus A., Bshary, Redouan

Intraspecific cooperation and interspecific mutualism often feature an asymmetry in the scope for exploitation. We investigate the evolution of indirect reciprocity in an asymmetric game, loosely modelled on interactions between cleaner fishes and clients, in which ‘actors’ can choose to help or to exploit a ‘recipient’ that approaches them, while recipients can only choose whether or not to approach an actor (based on the observation of its behaviour towards others). We show that when actors vary in state over time, in a manner that influences the potential gains from exploitation, an equilibrium is possible at which recipients avoid actors whom they have observed exploiting others in the past, and actors help when the potential gains from exploitation are low but choose to exploit when the potential gains are high. In this context, helping is favoured not because it elicits reciprocal altruism (‘help so that you may be helped’), but because it facilitates profitable exploitation (‘help so that you may gain the opportunity to harm’). The cost of helping one recipient is thereby recouped through exploitation of another. Indirect reciprocity is thus possible even in asymmetric interactions in which one party cannot directly ‘punish’ exploitation or ‘reward’ helping by the other.