Edinburgh Napier University

  The Neolithic was marked by a transition from small and relatively egalitarian groups, to much larger groups with increased stratification. But the dynamics of this
remain poorly understood. It is hard to see how despotism can arise without coercion, yet coercion could not easily have occurred in an egalitarian setting. Using a quanti-
tative model of evolution in a patch-structured population, we demonstrate that the interaction between demographic and ecological factors can overcome this conundrum.
We model the co-evolution of individual preferences for hierarchy alongside the degree of despotism of leaders, and the dispersal preferences of followers. We show that voluntary leadership without coercion can evolve in small groups, when leaders help to solve coordination problems related to resource production. An example is coordinating construction of an irrigation system. Our model predicts that the transition to larger despotic groups will then occur when: 1. surplus resources lead to demographic
expansion of groups, removing the viability of an acephalous niche in the same area
and so locking individuals into hierarchy; 2. high dispersal costs limit followers' ability
to escape a despot. Empirical evidence suggests that these conditions were likely met
for the first time during the subsistence intensification of the Neolithic.