Evidence for a Regional Human Behavioural Response to the Medieval Climatic Anomaly in Australia

There is a growing amount of evidence for environmental impacts on human behaviour linked to the Medieval Climatic Anomaly (A.D. 800 - 1350). For example, Jones and others (1999) reported striking correlations between drought and changes in subsistence, population, exchange, health, and interpersonal violence from four regions of western North America, and the collapse of Classic Maya cities in Mesoamerica is roughly coincident with this time period (Neff et al. 2006). In Australia, however, there is relatively little known paleoenvironmental evidence for the MCA, let alone any impacts it may have had on Aboriginal populations. We previously reported radiocarbon determinations obtained from heat-retainer hearths (or earth ovens) from a single location in far northwestern New South Wales, Australia, which suggested a cessation in hearth construction during a period that coincides with the Medieval Climatic Anomaly (Holdaway et al. 2002). In this paper, we present the results of further investigation of the temporal and spatial patterns of Aboriginal occupation in this region during the Holocene. The analysis of more than 150 radiocarbon age determinations obtained from hearths at five sampling locations throughout western New South Wales suggests that the human response to this climatic shift varied regionally in ways that may reflect the local availability of water. Locations with multiple and/or abundant water sources exhibit a sequence of hearth ages that show periods of more and less intensive hearth construction that correlate with late Holocene climatic fluctuations including the MCA, suggesting that they provide a more complete record than that preserved in regions with more ephemeral water sources. We hypothesise that Aboriginal people abandoned some drier locations for periods lasting up to several hundred years while other better watered areas were abandoned for shorter periods of time. People returned when climatic conditions ameliorated.