Modelling hominin dispersals with agent-based modelling

Abstract

The early dispersals of hominins have been a major focus of Palaeolithic research in the last 50 years. In this dissertation I have applied a formal modelling technique, simulation, to a selection of archaeological research topics concerning hominin dispersals in order to test the suitability of this tool for formal theory development and hypothesis testing. Therefore, the aims of this research are twofold. The archaeological aim is to improve our understanding of hominin dispersals in the Pleistocene, whilst the methodological contribution was achieved by employing a relatively unknown and underused (in archaeology) computational tool.

An overview of the existing data pertinent to the topic of Pleistocene hominin dispersals demonstrated that the current methodology used for researching hominin dispersals, that is data analysis paired with conceptual modelling, is unlikely to solve many of the existing research questions highlighting the need to assess a wider range of scientific tools in order to progress. To that end, two case studies were developed using a specific simulation technique: agent-based modelling. The first case study was used to evaluate if, and under what conditions, the early ‘Out of Africa’ dispersal could lead to a specific demographic pattern reflected in a disparity between two regions with different stone tool traditions known as the Movius line. The model comprises a dynamic environmental reconstruction of Old World vegetation in the timeframe 2.5-0.25 Ma, coupled with standard biological models of population growth and dispersal. It is demonstrated that, under a wide sweep of both environmental and behavioural parameter values, the demographic consequence of dispersal is not a gradual attenuation of the population size away from the point of origin but a pattern of ecologically driven local variation in population density. The second case study looks at the relationships between climate change, migration and the evolution of behavioural plasticity or versatility among hominins. The agent-based model investigates the dynamics between individuals with different adaptations (including ‘versatilist’ individuals) within a non-homogenous population. The results show that dispersal accelerates the evolution of versatilism in the population, therefore promoting a more flexible range of adaptations. In addition, a set of scenarios was tested in which a dispersal wave crosses an environmental barrier. The results do not support the common intuition that such barriers shape the composition of hominin populations. The methodology presented here opens a new route to understanding large-scale spatiotemporal patterns in the archaeological record as well as to testing many of the previously proposed factors affecting early hominins’ lives. It has the potential to provide new insights into a number of ongoing debates, in particular on the relationship between different processes involved in shaping the past such as demographics and cultural complexity. This study also highlights the potential of simulation studies for testing complex conceptual models and the importance of building reference frameworks based on known proxies in order to achieve more rigorous model development in Palaeolithic archaeology and beyond.

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Identifiers

ORCID for Fraser Sturt: orcid.org/0000-0002-3010-990X

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