A Simulation Model of Fission–Fusion Dynamics and Long-Term Settlement Change

Abstract

Archaeological analyses often detect abrupt changes over time in the hierarchy of settlement sizes and the spatial distribution of residential units. These transformations have been explained looking at a variety of possible causes, from climatic changes to the sudden release of slowly cumulating political tensions. While many of these models offer plausible explanations for specific historical contexts, a broad-breadth model is desirable if cross-cultural analysis is sought. This paper tackles this problem by starting from the theoretical proposition that human groups are characterised by a non-linear relationship between size and per-capita fitness. Increasing group size has beneficial effects, but once a certain threshold is exceeded, negative frequency dependence will start to predominate leading to a decline in the per-capita fitness. Such a relationship can potentially have long-term implications in the spatial structure of human settlements if individuals have the possibility to modify their fitness through group fission–fusion dynamics. I will illustrate the equilibrium properties of these dynamics by means of an abstract agent-based simulation and discuss its implication for understanding long-term changes in human settlement pattern. Results suggest that changes in settlement pattern can originate from internal dynamics alone if the system is highly integrated and interconnected.