Reply to Thomas: Diffusion of military technologies is a plausible explanation for the evolution of social complexity, 1500 BCE–AD 1500

We thank Thomas for his comments (1) on our recent paper, in which we show that a very simple model can explain a remarkably high proportion of variance in historical data on the origins and spread of macrostates in Afroeurasian history (2). The core of Thomas’s critique is that our model is “too simple and too abstract” (1). We, however, see model simplicity as a desirable feature in developing theory that is both grounded in sociological mechanisms and tested with historical data. Too many previous attempts at theory building in the social sciences have foundered as a result of being highly complex and including in them too many mechanisms. The ability of our simple model to accurately predict data speaks for itself.