Overdone overkill - the archaeological perspective on Tasmanian megafaunal extinctions

Abstract

The reasons for megafaunal extinction in Australia have been hotly debated for over 30 years without any clear resolution. The proposed causes include human overkill, climate, anthropogenic induced habitat change or a combination of these. Most protagonists of the human overkill model suggest the impact was so swift, occurring within a few thousand years of human occupation of the continent, that archaeological evidence should be rare or non-existent. In Tasmania the presence of extinct megafauna has been known since the early twentieth century (Noetling, 1912; Scott, 1911, 1915) with earlier claims of human overlap being rejected because of poor chronology and equivocal stratigraphic associations. More recent archaeological research has not identified any megafauna from the earliest, exceptionally well-preserved late Pleistocene cultural sites. In 2008 however an argument for human induced megafaunal extinctions was proposed using the direct dates from a small sample of surface bone from two Tasmanian non-human caves and a museum sediment sample from an unknown location in a cave, since destroyed by quarrying (Turney et al., 2008). Turney et al. (2008) supplemented their data with published dates from other Tasmanian caves and open sites to argue for the survival of at least seven megafauna species from the last interglacial to the subsequent glacial stage. To investigate the timing of extinctions in Tasmania and examine the latest claims, new excavations and systematic surveys of limestone caves in south central Tasmania were undertaken. Our project failed to show any clear archaeological overlap of humans and megafauna but demonstrated that vigilance is needed when claiming survival of megafauna species based on old or suspect chronologies. The results of our six-years of fieldwork and dating form the first part of the present paper while, in the second part we assess the data advanced by Turney et al. (2008) for the late survival of seven megafauna species. A model of human prey selection and the reasons for the demise of a range of marsupials, now extinct, are discussed in the third part of the paper.