Meals and menus : a study of change in prehistoric coastal settlements in South Australia

Abstract

Current research into the causes of prehistoric coastal adaptation in southern Australia has emphasized the influence of the marine environment without considering other environmental or cultural factors which may also direct economic growth. The research described here considers the case of prehistoric settlement in swamps and coastal margins in South Australia in an effort to explain shifts in subsistence strategies in terms of the process of adaptation. The 19th century ecology of the area is first reconstructed with reference to primary resources available in the sea, lagoon, and swamps. Against this information, the local ethnography is used to propose broad subsistence strategies by which the annual food quest may have operated during the late prehistoric occupation. The archaeological implications are considered in light of this information. The archaeological record of settlement spans the last 10,000 years and can be divided into two cultural horizons. The first is an Early Holocene occupation which is distributed widely in association with swampside exploitation. The second horizon begins at 6000BP and can be divided into two primary occupation phases. The Early Phase (6000-1300BP) is represented in discrete monospecific middens of either Plebidonax or the mussel Brachidontes located mostly on hinddune surfaces. Both molluscs are locally extinct. The Late Phase by contrast is characterized by large deposits of several extant reef gastropods at a variety of localities throughout the coastal margin. Furthermore, a microlithic component flourishes during the Early Phase of occupation, but is absent later. This evidence indicates significant changes in occupation intensity and subsistence technologies which cannot be linked to Mid-Holocene sea level adjustments. Other explanations are therefore considered. To resolve this problem, estimates are made of the size and organization of primary shellfishing groups operating in each of the two occupation phases. Growth rings of Plebidonax in single meals are examined to 1) determine contemporaneity of collection events represented by individual refuse heaps occurring in clusters, and 2) to estimate the pattern of seasonal occupation. This study concludes that successive rather than contemporaneous campsite visitations· may have occurred during late winter. This pattern contrasts with ethnographic documentation of a summer and autumn occupation during the late Phase. Having isolated the contents of single meals within both phases, the size of the group dining has been estimated on the basis of standard human energy requirement with the conclusion that significant changes in group size have occurred between the occupation phases. The total number of shellfish meals consumed in the study area is calculated from survey and excavated data. These figures confirm a marked increase in consumption rates which correlates with increases in the duration of seasonal occupation, and further suggest that improvements in the marine biosphere and collection proficiencies are responsible. A biometric analysis of the food refuse reveals that shellfish collection in the Early Phase was exclusively intertidal, whereas subsequent use of marine resources could only have resulted from both inter- and subtidal exploitation. Together, these data are considered to document sharp changes in consumer behaviour after about 1300BP, including longer duration of seasonal occupation of the coastal margin, an increase in resident population, an expansion of the menu, and the emergence of a more complex subsistence organization. An explanation for this reorganization is seen in changes in swamp resources, whose importance to Holocene subsistence economies is firmly documented in ethnographic account and archaeological deposits. Pollen sequences from five dated peat deposits have been used to reconstruct Holocene water levels. From this information, increases in coastal exploitation are seen to correlated with a decline in water levels in the swamps and improvements in aquatic biota inhabiting the coast following blocked drainage there. The coastal adaptation is therefore seen as an attempt to maximize resources in the face of shrinking supplies in the swamps. The subsistence technology is considered to account for the loss of microlithic component at a time economic growth is indicated by independent data. To accomplish this, manufacturing technologies of the Small Tool Tradition are traced from the Mid-Holocene settlement in order to identify possible adaptive advantages of the tradition. When this information is considered in light of an Early Holocene tool kit, which includes wooden and stone implements, the emergence of a microlithic component appears to ·reflect a major retooling to accommodate the introduction of the spearthrower and a redesigned spear. The disappearance of the microliths is suggested to be related to attempts to increase hunting efficiencies following a period of regional stress in the environment. The marine economy is therefore seen as a final development in late prehistoric settlement of southeastern Australia.