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Investigating Lapita subsistence and pottery use through microscopic residues on ceramics: methodological issues, feasibility and potential

This thesis presents the results of experimental and archaeological investigations of microscopic plant residues on Lapita pottery from the western Pacific Islands. Lapita is a critical phase in the culture history of the Pacific region and has been associated with the development and spread of a subsistence system based on the cultivation of tropical starch crops, particularly those in the taro-yam complex. However, few archaeobotanical remains been recovered from Lapita sites to lend empirical support to this model. This study explores whether microscopic starch granules, calcium oxalate crystals and other plant microremains on Lapita potsherds can provide direct evidence for the preparation and consumption of staple plant foods, as well as important clues to the function and use of pottery in Lapita society, matters which remain the subject of some debate. This research was undertaken in two main phases. The first involved a series of technical studies aimed at developing methods for recovering and identifying starch and raphide residues on archaeological pottery. Changes to starch during cooking and charring under different heat and moisture conditions were examined to understand how granules survive differentially depending on cooking method and food type. Various methods used to extract native starch granules from charred residues were then tested and a procedure based on a weak oxidising treatment was developed for use on the archaeological residues. The reliability of calcium oxalate raphide analysis, which is much less developed than that of starch, was also critically assessed. Issues with previous identifications of raphides in Pacific microfossil assemblages were highlighted. Morphological criteria were presented for identifying aroid raphides more accurately and chemical tests were developed to differentiate them from naturally-occurring calcite crystals, which were abundant in the sites analysed. The second phase of research analysed microscopic residues on Lapita and post-Lapita potsherds from archaeological sites in the Mussau and Anir Islands (PNG), the Reef Islands (Solomon Islands), New Caledonia, and the Samoan Archipelago. Despite the generally small quantities of residue recovered from the archaeological samples, several sherds with possible use-related starch residues were identified. These initial results indicate that ceramic vessels, including both plain and dentate-decorated Lapita wares, were employed in a variety of tasks involving the cooking and/or consumption, and storage or preparation of starch-based foods. It was also found that these were among the activities performed at the ‘special purpose’ stilt house structure at the ECA site, which raises questions about the possible social or ritual status of staple starch resources in Lapita society. One of the most significant findings to emerge from this study was of taro (Colocasia esculenta) starch granules on sherds from the ERA Lapita site (Anir, New Ireland), and granules identified tentatively as taro on sherds from RF-2 (Reef Islands) and Mulifanua (Samoa). A number of unidentified morphotypes were also present on the Lapita and post-Lapita sherds, suggesting that a variety of plants not among the key root crops were also exploited. These may include some of the many fruits and nuts attested in archaeobotanical assemblages from Pacific sites. The ceramic residue data complement starch and phytolith evidence recovered from cultural sediments from RF-2, which demonstrate the presence and probable exploitation of a suite of crop plants typically associated with the Lapita ‘economic package’. In addition to taro, these include at least one cultivated species of Eumusa banana, non-domesticated (seeded) Australimusa bananas, bamboo, and possibly also Canarium, coconut, and sago. These data support models suggesting that Lapita groups were cultivating and transporting subsistence plants, including at least one of the major root crop complexes, and associated knowledge of their production and preparation across the western Pacific from the mid-late Holocene. This study demonstrated that analyses of microscopic starch residues on archaeological ceramics from the Pacific region can yield significant insights into vessel use and plant exploitation. Further methodological refinements should aim to increase starch yields, which will enable stronger associations between residues and vessel uses to be established. Expansion of reference collections is also required so that more precise identifications of the specific plant foods involved can be achieved.