To what extent high resolution mCT-scanning of hominin fossil remains may impact ESR and Radiocarbon dating results?

Abstract

In palaeoanthropological research, the study of human fossils is conditioned by the necessity to cause minimum damage to these rare and valuable remains. In this context, micro-computerized tomography (µCT) scanning of fossils is nowadays routinely used to record a high resolution 3D reconstruction of samples, enabling to obtain critical information about the morphology or internal structure of the fossil, and create a digital archive of fossils that may be destructively analysed later. While these destructive analyses may be carried out for a wide range of purposes, including palaeodiet or palaeoenvironment reconstructions, mobility studies, ancient DNA and Geochronology, the potential impact of µCT scanning on the analytical results has been very little investigated so far. In the present lecture, we present the most recent results on our methodological investigations focused on Radiocarbon and Electron Spin Resonance (ESR) dating, which can both be directly applied to fossils. While Radiocarbon dating is the most widely used for any fossils younger than 50 ka, ESR can take over for older specimens. In particular, the latter has become very popular over the last couple of decades, with the dating of several key human fossils, such as those from Jebel Irhoud, (Morocco), Atapuerca Gran Dolina (Spain), Rising Star (South Africa) or Milsiya (Israel). It is therefore crucial to establish whether µCT scanning has a negative impact on the associated ESR and Radiocarbon analysis, and, if any, to determine how this impact can be reduced. With this purpose in mind, we carried out a series of tests with various conventional µCT instruments and using a range of acquisition parameters. The main experimental results will be presented and discussed in this talk, as well as their implications for palaeoanthropological research, taking a few recent case studies as examples.