 On Spencer’s account, social evolution unfolds through four universal stages. These are 1) “primitive” societies characterized by casual political cooperation, 2) “militant” societies characterized by rigid, hierarchical political control, 3) “industrial” societies where centralized political hegemony collapses, giving way to minimally regulated markets and 4) spontaneously, self-regulating, market utopias in which government withers away. Overpopulation causing violent conflicts between social groups fuels this cycle of consolidation and reversal to which no society is immune.