We trace the difference between the ways in which apes and humans co-operate to differences in communicative abilities, claiming that the pressure for futuredirected co-operation was a major force behind the evolution of language. Competitive co-operation concerns goals that are present in the environment and have stable values. It relies on either signalling or joint attention. Future-directed co-operation concerns new goals that lack fixed values. It requires symbolic communication and contextindependent representations of means and goals. We analyse these ways of co-operating in game-theoretic terms and submit that the co-operative strategy of games that involve shared representations of future goals may provide new equilibrium solutions.
Co-operationHuman beings as well as animals co-operate in order to reach common goals. There are many ways of co-operating, some of which may not merit being called 'co-operation' in the literal sense of the word. Among these one may count the more or less instinctive co-ordination of behaviour that emerges among ants building heaps or honeybees gathering food. On the opposite side of the scale, we find co-operation that builds on elaborate long-term planning and an open discussion of the means and the goal. In this article, we will compare and elucidate the similarities and differences between humans and apes as concerns co-operation. There is no doubt that apes co-operate, but, as we will argue, humans are able to do so in more flexible ways. Our aim is to spell out the crucial role of communication for different kinds of co-operation.To co-operate is to work together for a joint benefit. A group of agents is co-operating when the agents together employ a certain means, or series of actions, to achieve a common goal. Co-operation can be achieved directly by a co-ordination of behaviour. It can also arise indirectly through a mutual sharing of representations of means and goal. It is vital for true co-operation that all the participants are actively involved. For instance, when a person manipulates other people in order to reach his goal, we do not say that the others are co-operating with him. This is the case even if the goal is of use to them all. Co-operation demands that all the Thanks to Joëlle Proust, Bernhard Schroeder, and the participants of the seminar at LUCS for helpful comments. A shorter and in several respects different version of this paper has been published as 'Co-operation in Apes and Humans' (2003).