Quantifying the Duration and Impact of Human-Megafauna Overlap in Australia

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With support from NSF's Archaeology Program, Prof Gifford Miller and Australian collaborators will conduct fieldwork in NW Australia to define the human context surrounding eggshell fragments from two giant bird species, the extinct megafaunal bird Genyornis, and the extant Australian emu (Dromaius). The Western Australia field campaign offers a unique opportunity to firmly establish the interactions between humans and extinct giant animals, and to quantify the duration of human-megafauna overlap. Previous fieldwork by Miller's team documented early human use of Genyornis eggs as a food source, cooking, and later burning some of the eggshells in their fires. This is the first secure evidence of human predation on the Australian megafauna. Australian archaeologists experienced in early human occupation sites will accompany the team to derive secure relations between the burnt eggshell and human activity.A central goal of this project is to apply four independent dating methods to firmly define the duration of human-megafauna overlap; a team of US and Australian dating experts has been assembled to accomplish this goal. A major innovation is development of a protocol to measure trace levels of uranium isotopes in eggshells, capitalizing on recent developments in mass spectrometry that have greatly improved detection levels. In conjunction with these measurements, the stable isotopes of oxygen, carbon and nitrogen contained in the mineral and organic constituents of the eggshells allow characterization of the status of climate and the birds' diet. By analyzing Dromaius eggshells from birds living long before human colonization of Australia up through the present day it will be possible to evaluate independently changes in both climate and any dietary shifts that may have occurred. Such datasets allow the separation of impacts related to climate change from those due to human colonization. Comparing the dietary feeding strategies of the extinct Genyornis with co-existing Dromaius will help understand why one giant bird became extinct whereas the other adapted to the same stressors and remains extant.The colonization of Australia is an important element in the larger story of World prehistory. More generally, it is essential to understanding the footprint of human colonization of landscapes never before visited by humans, and the adaptability of humans to alien environments. This research has the potential to resolve long-standing disputes whether human dispersal was along the coasts to southern Australia and then inland, or through the continental interior. The dispersal pattern from a founding population provides constraints on both adaptation and social structures. Dating these events in early human history has been hampered by a lack of reliable dating tools. A key aspect of the proposed research is to test and refine U/Th dating of avian eggshell. If successful, the addition of this powerful dating tool will reinvigorate not only the study of early human sites in Australia, but it also will have profound effects in archaeological studies across Africa and Eurasia where ostrich eggshells are common elements of many archaeological sites beyond the range of 14C dating. This research captures the imagination of the general public. Miller has already facilitated related TV and popular media outreach activities, and will continue to do so.