Tracking the Dynamics of Prehistoric Urbanism in Tonga using Geospatial Technologies

Abstract

Urbanisation is a concept that is yet to be deeply considered by archaeologists investigating past settlements in the Pacific despite evidence of large populations and complex social institutions on many islands that have been linked to urbanisation in other parts of the world. This, in part, is because of the fundamental changes to Pacific societies that followed European interactions in the nineteenth century and the challenges of collecting archaeological data using traditional field survey techniques in remote and tropical environments. Recent advances in geospatial technologies are improving the efficiency of data collection in challenging environments allowing researchers to investigate the complete lifecycle of ancient sites and generate new insights into their functions and scale. New geospatial data captured over the Pacific Island of Tongatapu, Kingdom of Tonga, presents a fresh opportunity to explore urbanisation in the Pacific. The archaeological landscape of Tongatapu consists of nearly 3,000 years of archaeological remains ranging from the middens of the first settlers, to the monumental architecture of the Tu'i Tonga dynasty that emerged 700 years ago and spread their influence throughout the western Pacific. Many of these archaeological features are observable in geospatial data, facilitating the efficient and cost-effective construction of large geospatial databases that can be used to investigate settlement dynamics throughout the 3000 years people have resided on Tongatapu.Despite the potential that large geospatial databases of archaeological features undoubtedly hold, their use in archaeology remains focussed on prospection; the prevailing view is that they are yet to make substantial contributions to the types of questions that archaeologists typically ask about past societies. As a response, archaeologists are starting to adopt a new 'urban science' approach to integrate theoretical advances in settlement growth and urbanisation with large geospatial databases to investigate the complex interplay between agglomeration, institutional development, and built environment morphology over extended periods of time. In this thesis, I build large geospatial databases and urban science to investigate earthwork form and function, estimate past population, and track the growth and emergence of the Tongan low-density urban system. I find that earthworks on Tongatapu required substantial investments of labour that required complex organisational structures to oversee construction and logistics. I also find that earthworks are a suitable proxy for human habitation with different types of structures indicating different land uses. I then determine that - based on earthwork remains-the Tongan population was likely larger than previously considered. I propose that this larger population was maintained via long distance trade networks and settlement agglomeration where-for the first time-I identify that settlements on Tongatapu showed many of the characteristics associated with urban settlements in other parts of the world. Radiocarbon data presented in the thesis indicates these processes began prior to archaic state development further highlighting how groups of people living together in settlements create innovative solutions to manage increasingly larger groups of people. The results presented in this thesis highlight the important contribution that Pacific landscapes can make to understanding the complex interplay between settlement growth, agglomeration, and institutional development, given the presence of large populations, hierarchical societies, and vast distributions of archaeological built remains on many island groups. I also demonstrate how new advances in spatial analysis can leverage the large geospatial databases that geospatial technologies can produce to present a methodological and theoretical framework that can be used by other archaeologists to better understand settlement growth in other societies