Agent Based Modelling of Communication Costs: Why Information Can Be Free

Abstract. In this chapter we examine the costs and benefits of sharing information, using a simple spatial agent model. The information concerns the agents ’ food. The costs are for the signaling agent in terms of more competition over food, and the benefits are for the receiver in terms of access to more food. We will show that under some conditions agents that communicate do better — that is, have more offspring — than agents that do not. 1 Why We Have Language What purposes, other than facilitating the sharing of information, can language have served? First, it may not have evolved to serve any purpose at all. It is possible that language is just a side effect of the large human brain — a spandrel or exaptation — that only became useful later. If language is adaptive, this does not necessarily mean that it is adaptive for the purpose of communication. For example Dennet (1996) and Chomsky (1980) have stressed the utility of language in thinking. Also, there are different ways to view communication. The purpose of language according to Dunbar (1993), is to replace grooming as a social bonding process and in this way to ensure the stability of large social groups. Why would anyone think that communication might be a bad thing? Because communication is a form of altruism, it is a giving up of information to one’s competitors. Remember, even friends are competitors in a biological sense, as they share the same food resources and mating opportunities. Consequently, many people find it unlikely that such altruism could evolve (Dessalles 2000; Marshall and Rowe 2003). In the next section we will show how communication can be viewed in terms of costs and benefits. We will discuss some theories that fit in this framework and propose a slightly different approach. In the next section we will discuss communication in relation to parenting (kin-selection) and foraging abilities. We will then describe the experiment we used to show that communication is indeed a good thing