The first direct ESR dating of a hominin tooth from Atapuerca Gran Dolina TD-6 (Spain) supports the antiquity of Homo antecessor

This work illustrates the challenges of dating human teeth by means of the ESR method, with the main pitfalls that are sometimes inherent to this specific application (e.g., systematic μCT-scanning of fossil hominin teeth; limited knowledge about the original sedimentary environment for teeth coming from old excavations; heterogeneous spatial distribution of the U-series elements in dental tissues). We identified several sources of uncertainty that may directly impact the accuracy of the age result. In particular, a slight contamination of dentine (<6%) in the enamel fragment measured by ESR was found to induce a significant age underestimation (33%) if not taken into consideration. It indeed caused not only a DE underestimation (by about 8%), but also produced a massive internal dose rate overestimation (by a factor of about 3.5). In contrast, other sources of uncertainty, such as the heterogeneity of the sedimentary environment, the variability of the water content over time, the previous μCT-scanning of the tooth or the potential preferential creation of unstable NOCORs in the ESR signal, showed here a limited impact on the final age result. Given our current understanding of the ESR method and the existing uncertainties associated with the evaluation of the DE and dose rate, this is probably as far as we can presently go in the dating study of ATD6-92 sample.