Structure and Dynamics

Turchin’s article achieves significant progress in the modeling of demographic cycles as a basic feature of complex agrarian systems' dynamics. He suggests an extremely simple model accounting for an unusually high percentage of the political-demographic variation, including some features for which earlier models failed to account. Rather than modeling the recovery phase of the demographic cycle as starting immediately after the demographic collapse, which is not observed in reality, the recovery phases of Turchin’s model are, more accurately, separated from those of collapse by significant periods of internal warfare that blocks recovery growth. Such intercycles, systematically observed in the agrarian political-demographic dynamics, represent a problem that Turchin has managed to solve in a very elegant and compelling way.