Gisela Grupe1, Dominika Klaut1, Markus Mauder2, Peer Kröger2, Amei Lang3, Christoph Mayr4,5, Frank Söllner5. 1. Biozentrum, Ludwig-Maximilians-Universität München, Germany. 2. Lehrstuhl für Datenbanksysteme und Data Mining, Ludwig-Maximilians-Universität München, Germany. 3. Vor- und Frühgeschichtliche Archäologie und Provinzialrömische Archäologie, Ludwig-Maximilians-Universität München, Germany. 4. Institut für Geographie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany. 5. Department für Geo- und Umweltwissenschaften, Ludwig-Maximilians-Universität München, Germany.
Abstract
RATIONALE: Due to the spatial heterogeneity of stable isotope ratios of single elements measured in attempts to georeference bioarchaeological finds, multi-isotope fingerprints are frequently employed under the assumption that similar isotopic signatures are indicative of similar shared environments by the individuals studied. The extraction of the spatial information from multi-isotope datasets, however, is challenging. METHODS: Gaussian mixture clustering of six- to seven-dimensional isotopic fingerprints measured in archaeological animal and human bones was performed. Uncremated animal bones served for an isotopic mapping of a specific reference area of eminent archaeological importance, namely the Inn-Eisack-Adige passage across the European Alps. The fingerprints consist of 87 Sr/86 Sr, 208 Pb/204 Pb, 207 Pb/204 Pb, 206 Pb/204 Pb, 208 Pb/207 Pb, and 206 Pb/207 Pb ratios, and δ18 Ophosphate values in uncremated bone apatite, while the thermally unstable δ18 O values of human cremations from this region were discarded. RESULTS: The bone finds were successfully decontaminated. Animal and human isotope clusters not only reflect individual similarities in the multi-isotopic fingerprints, but also permit a spatial allocation of the finds. This holds also for cremated finds where the δ18 Ophosphate value is no longer informative. To our knowledge, for the first time Pb stable isotopes have been systematically studied in cremated skeletal remains and proved significant in a region that was sought after for its ore deposits in prehistory. CONCLUSIONS: Gaussian mixture clustering is a promising method for the interpretation of multi-isotopic fingerprints aiming at detecting and quantifying migration and trade.
RATIONALE: Due to the spatial heterogeneity of stable isotope ratios of single elements measured in attempts to georeference bioarchaeological finds, multi-isotope fingerprints are frequently employed under the assumption that similar isotopic signatures are indicative of similar shared environments by the individuals studied. The extraction of the spatial information from multi-isotope datasets, however, is challenging. METHODS: Gaussian mixture clustering of six- to seven-dimensional isotopic fingerprints measured in archaeological animal and human bones was performed. Uncremated animal bones served for an isotopic mapping of a specific reference area of eminent archaeological importance, namely the Inn-Eisack-Adige passage across the European Alps. The fingerprints consist of 87 Sr/86 Sr, 208 Pb/204 Pb, 207 Pb/204 Pb, 206 Pb/204 Pb, 208 Pb/207 Pb, and 206 Pb/207 Pb ratios, and δ18 Ophosphate values in uncremated bone apatite, while the thermally unstable δ18 O values of human cremations from this region were discarded. RESULTS: The bone finds were successfully decontaminated. Animal and human isotope clusters not only reflect individual similarities in the multi-isotopic fingerprints, but also permit a spatial allocation of the finds. This holds also for cremated finds where the δ18 Ophosphate value is no longer informative. To our knowledge, for the first time Pb stable isotopes have been systematically studied in cremated skeletal remains and proved significant in a region that was sought after for its ore deposits in prehistory. CONCLUSIONS: Gaussian mixture clustering is a promising method for the interpretation of multi-isotopic fingerprints aiming at detecting and quantifying migration and trade.
Authors: Claudio Cavazzuti; Tamás Hajdu; Federico Lugli; Alessandra Sperduti; Magdolna Vicze; Aniko Horváth; István Major; Mihály Molnár; László Palcsu; Viktória Kiss Journal: PLoS One Date: 2021-07-28 Impact factor: 3.240