This paper asks whether population growth is conducive to the sustainability of cooperation. A simple model is developed in which farmers who live around a circular lake engage in trade with their adjacent neighbors. The payoffs from this activity are governed by a prisoner’s dilemma “rule...

Consider a population of farmers who live around a lake. Each farmer engages in trade with his m adjacent neighbors, where m is termed the "span of interaction." Trade is governed by a prisoner’s dilemma "rule of engagement." A farmer’s payoff is the sum of the payoffs from the m...