Since the work of Maynard Smith and others, it has been realised how game theory can model natural selection. Evolutionary game theory replaces the concept of rational players with the population dynamics of behavioural programs and can be used to understand the strategic and genetic foundations of the endless chronicle of invasions and extinctions which punctuate evolution. In short, it describes when to escalate a conflict, how to elicit cooperation, why to expect a balance of the sexes, and how to understand natural selection in mathematical terms.