Reliability in communication systems and the evolution of altruism

The evolution of a communication system depends on the existence of individuals which gain from it, that is the senders of the signals and their receivers. These two share a common interest about which they communicate. Common interests of this kind form the basis of the communication between such individuals as a sexual pair, parents and their offspring, and members of a flock or group which feed, roost or breed together. It is less often realised that individuals which are usually regarded as conflicting in their interests — for example, prey and predator, sexual rivals, a parasite and its host — may also share a common interest which may form the basis for the evolution of a communication system between them. Warning coloration, warning calls and other signals which are given by a prey species towards a predator (Smythe, 1970; Alcock, 1975) and also threat display among rivals, are some examples of signals exchanged between individuals which mainly conflict in their interest.