The 84th Annual Meeting of the American Association of Physical Anthropologists (2015)

Risk minimization and a late Holocene increase in mobility at Roonka Flat, South Australia: an analysis of lower limb diaphyseal shape


1Department of Anthropology, University of New Mexico, 2Department of Sociology, Anthropology, and Social Work, Texas Tech University, 3Department of Archaeology, Flinders University, Adelaide, Australia, 4Department of Anthropology, Science Centre, South Australian Museum, Adelaide, Australia

March 27, 2015 , Archview Ballroom Add to calendar

The Roonka Flat skeletal sample from South Australia includes the remains of Aboriginals buried throughout the Holocene (8,000 – 200 BP), and thus provides the ability to test how humans were affected by climate change in the prehistory of this continent. The development of the El Niño Southern Oscillation (ENSO) ~4 kya caused significant changes in climate, vegetation, and faunal assemblages between the early Holocene and the late Holocene. Archaeological deposits show the appearance of a lighter, more flexible toolkit corresponding with the transition from wetter and warmer conditions pre-ENSO to cooler and dryer climate post-ENSO. This has been interpreted as being indicative of a risk-minimization strategy that leads to an increase in foraging mobility. This was tested by examining changes in lower limb external diaphyseal shape between pre-ENSO and post-ENSO skeletons from Roonka Flat. Anteroposterior diameter and mediolateral diameter were used to construct midshaft shape indices for femora and tibiae. If populations living in South Australia became more mobile, then post-ENSO skeletons should exhibit more ovular lower limb diaphyses. Results from the femur demonstrate significantly more ovular diaphyses post-ENSO. These data are consistent with the risk-minimization model, indicating that South Australians became more mobile post-ENSO to better exploit a less productive environment by expanding their foraging radii. The temporal shift toward more ovular diaphyses is more notable in females than males. This is consistent with Australian Aboriginal ethnographies that show both sexes being intensely involved in hunting and capturing game animals.

Funding for this project was provided by Texas Tech University's FY13 CAHSS grant.