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Climate in Your Dinner

Our latest contributor is Georgia Roberts. Georgia is currently in the second year of her PhD at La Trobe University, Melbourne, Australia, and holds a Masters in Archaeological Science from Australian National University.

Investigations of Seasonality in the Archaeological Record of Southwestern Tasmania, Australia

Stable isotope analysis can support a range of zooarchaeological research. One such application is investigating seasonality – assessing the season of death of individual animals. When these animals are associated with archaeological sites, we can use this data to infer season of site use.

The rugged limestone karst landscape of southwestern Tasmania, Australia, contains several archaeological cave sites with exceptional preservation. This region has been described as an archaeological ‘province’ sharing many characteristics, including distinctive faunal collections, dominated by Bennett’s wallaby (70% by Minimum Number of Individual [MNI] counts) and the Common Wombat (27% MNI). The current project focusses on two of these sites – Warreen Cave and Bone Cave.

Related archaeological sites in southwestern Tasmania. Adapted from Cosgrove et al. 2010.

Related archaeological sites in southwestern Tasmania. Adapted from Cosgrove et al. 2010.

The wilderness of southwestern Tasmania.

The wilderness of southwestern Tasmania.

Wombat teeth are continuously growing, capturing the isotopic signature of the surrounding environment in the enamel as it forms. The mandibular incisor is the longest tooth (6-7cm) and records approximately 18 months of isotopic data. By sequentially sampling the enamel, a high-resolution record of local climate (δ18O) and vegetation (δ13C) can be retrieved. By assessing seasonal variation in modern analogues, the data can be used to determine season of death and thus inferred season of site use.

Sequential sampling of tooth enamel along the mandibular incisor from a modern Common wombat.

Sequential sampling of tooth enamel along the mandibular incisor from a modern Common wombat.

Dr Anne Pike-Tay and colleagues (Pike-Tay et al. 2008) used odontochronological analysis to identify that Bennett’s wallabies, the primary prey species, had been killed in the same season throughout the chronology of each site – autumn/winter for Warreen Cave and summer for Bone cave. My PhD uses stable isotopic analysis of Common wombat (Vombatus ursinus) teeth to test this trend, investigating when and how wombats were being utilised by Tasmanian Aboriginal people at the end of the Pleistocene (35,000 to 11,500 years ago).

Tasmanian Common Wombats – female with joey.

Tasmanian Common Wombats – female with joey.

This research is supported by the La Trobe University Faculty of Humanities and Social Sciences Internal Funding Scheme, the Australian Archaeological Association Research Grant Scheme and Dr Michael Gagan of the Earth Environment Stable Isotope Laboratories (Australian National University).

References

Cosgrove, R., Field, J., Garvey, J., Brenner-Coltrain, J., Goede, A., Charles, B., Wroe, S., Pike-Tay, A., Grün, R., Aubert, M., Lees, W., O’Connell, J., 2010. Overdone overkill – the archaeological perspective on Tasmanian megafaunal extinctions. Journal of Archaeological Science 37, 2486–2503.

Pike-Tay, A., Cosgrove, R., Garvey, J., 2008. Systematic seasonal land use by late Pleistocene Tasmanian Aborigines. Journal of Archaeological Science 35, 2532–2544.

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