DOI: 10.7910/dvn/uhifdk
title: Stone artefacts and human ecology at two rockshelters in Northwest Thailand

description: This thesis documents the interaction of stone artefact technology and local environmental contexts during the late Pleistocene and Holocene at two rockshelters in the uplands of northwest Thailand. Previous work has been divided over the importance of environmental influences in human forager technology in mainland Southeast Asia. It has also been limited by the use of typological methods that are poorly suited to the flaked stone artefact technology of the region. Typological methods have not performed well because of the paucity of formal types in these assemblages. This has left a gap in our understanding of prehistoric human- environment relations. Advances in archaeology and human behavioural ecology have allowed for a more robust articulation between archaeological evidence and behaviours relating to environmental change. Three general models were developed from optimal foraging theory: a patch choice model, a central place model and an optimal dispersion model.

Developments in stone artefact analysis have produced reliable links between specific technological attributes of artefacts, behaviours relating to technological organisation and strategies of risk management. These advances were applied here to explore different dimensions of technological organisation by investigating the three foraging models. An experiment was conducted to test which variables are most indicative of risk reduction at the assemblage level for flaked stone artefacts in mainland Southeast Asia. These variables were then recorded from stone artefacts recovered from archaeological deposits at Ban Rai Rockshelter and Tham Lod Rockshelter. Although relatively close to each other, there are stark contrasts in the local availability of resources at these two sites because of the rugged landscape. These contrasts were used to refine the three models and produce synchronic hypotheses to test with the stone artefacts. A palaeoecological record was constructed by analyzing oxygen and carbon isotopes in freshwater bivalves recovered from the two sites. This allowed for further refinement of the three models and production of diachronic hypotheses about the relationship between stone artefact technological organisation and environmental change.

The result of the hypothesis testing suggested that people were simultaneously optimising their response to climatic conditions and local resource availability, but in a way that was not consistently predicted by the existing models. This inconsistency was resolved by introducing a model of risk management and stone artefact reduction that includes a point of inflection so that environmental constraints can result in more than one optimum strategy. This work has vindicated previous claims that mainland Southeast Asian foragers were sensitive to environmental changes, especially over the Pleistocene-Holocene boundary. This work has found no support for previous claims that Pleistocene technologies were flake-based while Holocene industries were cobble- based. The results have important implications for understanding mainland Southeast Asian prehistory, including introducing of a suite of effective methods and techniques for human palaeoecology and stone artefact analysis, identifying potential causes and probable timing of technological and subsistence changes throughout the region as well as demonstrating the resilience and vulnerability of human groups to environmental variability.