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 (AD 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. In a 2002 publication, we 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. 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 that 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 more continuous sequence of hearth ages across the MCA period than those with a single, more restricted water source. We hypothesise that Aboriginal people abandoned the drier locations for periods lasting up to several hundred years and returned only when climatic conditions ameliorated. At the better watered locations, there is no evidence for similar periods of abandonment. Thus, late Holocene environmental changes may have had a direct influence on patterns of human occupation in the semi-arid rangelands of Australia.2 page(s