Population and Warfare: A Test of the Turchin Model in Puebloan Societies

Ecologist Peter Turchin and anthropologist Andrey Korotayev (2006) propose that pre-state societies exhibit a deterministic relationship between population size and incidence of internal warfare or sociopolitical instability. We examine their model with data from Southwest Colorado between A.D. 600 and 1300 and find that it fits well during those periods when this area is a more or less closed system. It fits poorly during the time from about A.D. 1000-1200 when this area is heavily influenced first by the spread of the Chacoan system, and then, by its collapse and the local political reorganization that follows. The model is helpful in isolating periods in which the relationship between violence and population size is not as expected. The mechanisms by which it achieves its success need to be elaborated, a task we begin here.