How agent-based models can be used to investigate the evolution of social complexity in the past: A test of circumscription theory in the Valley of Oaxaca

Alice Williams


Complex societies with multiple levels of hierarchy and extended populations of unrelated individuals emerged relatively recently in the human past. How and why these complex societies formed from small-scale groups of people are fundamental questions to ask in archaeology. Attempts to explain this shift have often been verbally argued without explicit testing. The aim of this research is to test different hypotheses at a regional level by comparing the output from agent-based models with archaeological data. The emergence of increasingly complex social organisation as a beneficial trait at both the individual and group level will be understood within an evolutionary framework. Agent-based models will simulate the actions of individual villages (whether to move or accept a subordinate position) based on the costs and benefits of their situation. It is predicted that increasing the costs of moving (through increasing levels of environmental circumscription) will increase the rate at which hierarchical societies form as a successful strategy. In addition, it is predicted that a model based on real-world environmental data will be comparable with the archaeological record. Archaeological and environmental data from the Valley of Oaxaca in Mexico will be used to test these predictions. The data spans 3,000 years from early small-scale villages to the formation and collapse of the first state-level society in Mesoamerica, and is ideal to investigate changes in social complexity over time. This research shows how agent-based models can be used to link micro- with macro-level processes in the past to understand why some human societies evolved higher levels of social complexity than others.