Introduction

The aim of this chapter is twofold. First, to outline how recent developments in cooperation theory are so similar to the communication network concept (McGregor, 1993) that a unified terminology would be useful to facilitate exchange of ideas. Second, we argue that the communication network concept provides an evolutionary framework to predict the widespread occurrence of phenomena that until now have been discussed in the context of highly developed cognitive abilities. This creates a problem: as it stands, there appear to be no words in cooperation theory that were not developed in the human context and hence do not include a cognitive component. We have to use definitions that only constitute the functional aspects of phenomena (like tactical deception and indirect reciprocity) and ignore the mechanistic aspects (i.e. theory of mind, intentionality) that are commonly part of the definitions. We ask readers always to keep in mind that our definitions never imply any specific cognitive abilities. We illustrate our ideas with data on the mutualism between the cleaner wrasse Labroides dimidiatus and its ‘client’ reef fish, which visit cleaners to have ectoparasites removed from their surface, gills and mouth (reviewed by Losey et al., 1999; Côté, 2000).

Cooperation provides a challenge to evolutionary theory because it often involves apparently altruistic behaviour. Hamilton (1964) provided a framework to understand why altruism between kin can be evolutionary stable; specifically, an altruist gains indirect fitness benefits from its action.