Adaptive Factors in the Evolution of Signaling Systems

Abstract

Many of the chapters in this book have approached human language with an eye to its unique features, such as recursive syntax, or a large learned lexicon. We propose to take a wider view, seeing human language as one among many animal communication systems, and focusing on the selective pressures affecting the origin and maintenance of such systems. The possibility that human language arose from animal communication through a process of evolutionary change demands that we attend to the conceptual problems at the heart of our current understanding of animal signalling. In doing so we may throw light upon not only the origins of human language, but also its character. The chief theoretical problem that comes to light when we look at the evolution of communication is accounting for the amount of honesty that is apparently involved (Johnstone, 1997; Noble, 2000a). Let us specify a hypothetical communicative scenario, such as a warning call to alert other animals about an approaching predator, or a display to advertise one's suitability as a mate. We can then construct a game-theoretic model, which allows us to consider the advantages and disadvantages of communicative and non-communicative behaviour in our scenario. There usually turns out to be a tempting payoff for cheats, liars, bluffers, or free-riders, which means that communication should not be evolutionarily stable. It can therefore be difficult to use the model to explain the apparent prevalence of real-world communication in the situation we are modelling.