A number of archaeologists have suggested that significant climatic change with environmental and social consequences occurred between 1000 and 400 years ago in the Indo-Pacific region. We investigate this premise by examining the archaeological record of changes in hunter-gatherer economies in three geographically distinct coastal regions of tropical northern Australia. These case studies support the argument that Aboriginal mollusc exploitation reflects the altered local ecological habitats that accompanied broader coastal environmental change over the last few thousand years. Overlap between the phases and timing of climatic and behavioural changes within each region suggests that, given regional variation in the nature and of these changes, there was an associated human response to late Holocene climatic variability.
These case studies establish that archaeological and environmental evidence mutually support the argument for climate change influencing cultural change in northern Australia. We suggest that, while a direct physical link between environmental change and the interpretations of significant cultural change in the archaeological record have yet to be demonstrated unambiguously in this region, the analysis of mollusc exploitation has the potential to provide the direct link that is currently missing between changes in climate, environment and human responses over the last millennium.
Keywords: Arnhem Land, hunter-gatherer economies, mollusc exploitation, middens
Archaeological sites have the potential to act as archives that record significant information on palaeoclimatic conditions to augment standard pollen and coral core palaeoclimate indicators (Sandweiss 2003). This becomes particularly useful in areas where few standard palaeoenvironmental studies exist, as is the case for the tropical north Australian coast, especially for the Late Holocene period. Some archaeologists argue that, in the Indo-Pacific region, significant climatic change between 1000 and 400 years ago had considerable environmental and social consequences. Most of these studies have dealt with horticulturalist societies, however, and the impact on hunter gatherer societies is less-well studied (cf. Habede and David 2004).
In tropical north Australia, radiometric dating indicates that substantial changes occurred in the shell-fishing practices of hunter-gatherer groups after approximately 1000 calibrated years ago (Bourke 2003, 2004; Brockwell et al. 2005; Faulkner 2006; Faulkner and Clarke 2004; Hiscock 1997, 1999). This paper presents an overview of the archaeological record of changes in hunter-gatherer economic and social practices in three geographically distinct regions of tropical northern Australia (Figure 1). This is done so within the context of what is known of significant phases of climate change in order to explore the relationship between human behaviour and climate change in the late Holocene.
Holocene patterns of climatic and environmental change
In the absence of detailed regional or location specific palaeoclimatic data, this discussion draws on information from the broader Indo-Pacific region to provide the context for this paper. It is widely acknowledged that there has been an increase in climatic variability in the Australasian region in the last few thousand years, in particular from approximately 2000 BP to the present (Gagan and Chappell 2000:44; Gagan et al. 1994; Kershaw 1983, 1995; Lees 1992a; Prebble et al. 2005:367-9; Shulmeister 1999:82; Wasson 1986). Many of the longer-term trends in climate change that have occurred during the period spanning the mid Holocene to the present day (Figure 2) are related to the El Nino/Southern Oscillation (ENSO) cycle, which has strongly influenced climatic patterns in Australia (Jones et al. 1999; McGlone et al. 1992; Shulmeister and Lees 1992), and at present represents the principal source of inter-annual climatic variability within the Indo-Pacific region (Allan et al. …