 The following subsections provide a brief illustration of the use of evolutionary game theoretic models to explain two areas of human behavior. The first concerns the tendency of people to share equally in perfectly symmetric situations. The second shows how populations of pre-linguistic individuals may coordinate on the use of a simple signaling system even though they lack the ability to communicate. These two models have been pointed to as preliminary explanations of our sense of fairness and language, respectively. They were selected for inclusion here for three reasons: (1) the relative simplicity of the model, (2) the apparent success at explaining the phenomenon in question, and (3) the importance of the phenomenon to be explained.