Classes of communication and the conditions for their evolution.

Evolution of communication is conceptualized as a coevolutionary process in which evolution of signaler and that of receiver occur in an interdependent manner. Three classes of communication, mutualistic, altruistic, and exploiting, are distinguished depending on who gains a benefit or suffers a cost from successful communication. Communication is also dichotomized according to whether individuals are innately able to send and receive relevant signals or they have to acquire those signals culturally. We develop two-locus haploid models that represent the coevolutionary nature of the evolution of communication, and derive the conditions under which communicators can invade a population of non-communicators and those under which a population of communicators is evolutionarily stable against the invasion by non-communicators for each of the three classes of communication. Analysis of the models reveals that interaction among siblings enables the invasion of communication and that the optimal probability of interaction with siblings depends on the class of communication and the mode of signal transmission. In addition, cultural exploiting communication is more likely to invade a population of non-communicators than is genetic exploiting communication under certain circumstances.