War, resource competition and development

A growth model is set up where war, population, and technology interact endogenously, capturing some trends observed throughout long-run human history. Agents compete for food for their survival. In environments with scarce resources -- meaning high population density, and/or low levels of technology -- agents allocate more of their time to fight for resources, which translates into a higher probability of war. Because technology is an input both in food production and conflict, technological progress exerts two opposing effects on killing: on the one hand, it mitigates resource scarcity, making war less likely; on the other hand, if war breaks out it is deadlier the more advanced is the level of technology. An economy may transit onto a path of peaceful prosperity where standards of living are rising, and the probability of war approaches zero. In the transition, however, it may pass a phase of excessive killing, as rising living standards have not yet made war an improbable event, but rising levels of technology have made war extremely lethal if and when it breaks out. A preliminary quantitative exercise indicates that the model can replicate an inversely U-shaped pattern of war and genocide deaths seen worldwide over the 20th century. Many of the underlying mechanisms also seem consistent with some important stylized facts of growth and war, in particular in 20th century Europe