Cooperation, conflict and the evolution of communication

This paper presents a general model that covers signaling with and without conflicts of interest between signalers and receivers. Krebs and Dawkins (1984) argued that a conflict of interests will lead to an evolutionary arms race between manipulative signalers and sceptical receivers, resulting in ever more costly signals; whereas common interests will lead to cheap signals or "conspiratorial whispers." Previous simulation models of the evolution of communication have usually assumed either cooperative or competitive contexts. Simple game-theoretic and evolutionary simulation models are presented; they suggest that signaling will evolve only if it is in the interests of both parties. In a model where signalers may inform receivers as ro the value of a binary random variable, if signaling is favored at all, then signalers will always use the cheapest and the second cheapest signal available. Costly signaling arms races do not get started. A more complex evolutionary simulation is described, featuring continuously variable signal strengths and reception thresholds. As the congruence of interests between the parties becomes more clear-cut, successively cheaper signals are observed. The findings support a modified version of Krebs and Dawkins's argument. Several variations on the continuous-signaling model are explored.