title: Investigating human geographic origins using dual-isotope (87Sr/86Sr, δ18O) assignment approaches.
abstract: Substantial progress in the application of multiple isotope analyses has greatly improved the ability to identify nonlocal individuals amongst archaeological populations over the past decades. More recently the development of large scale models of spatial isotopic variation (isoscapes) has contributed to improved geographic assignments of human and animal origins. Persistent challenges remain, however, in the accurate identification of individual geographic origins from skeletal isotope data in studies of human (and animal) migration and provenance. In an attempt to develop and test more standardized and quantitative approaches to geographic assignment of individual origins using isotopic data two methods, combining 87Sr/86Sr and δ18O isoscapes, are examined for the Circum-Caribbean region: 1) an Interval approach using a defined range of fixed isotopic variation per location; and 2) a Likelihood assignment approach using univariate and bivariate probability density functions. These two methods are tested with enamel isotope data from a modern sample of known origin from Caracas, Venezuela and further explored with two archaeological samples of unknown origin recovered from Cuba and Trinidad. The results emphasize both the potential and limitation of the different approaches. Validation tests on the known origin sample exclude most areas of the Circum-Caribbean region and correctly highlight Caracas as a possible place of origin with both approaches. The positive validation results clearly demonstrate the overall efficacy of a dual-isotope approach to geoprovenance. The accuracy and precision of geographic assignments may be further improved by better understanding of the relationships between environmental and biological isotope variation; continued development and refinement of relevant isoscapes; and the eventual incorporation of a broader array of isotope proxy data.
authors.affiliation: Faculty of Earth and Life Sciences, Vrije Universiteit, Amsterdam, The Netherlands.|Faculty of Archaeology, Leiden University, Leiden, The Netherlands.
authors.forename: Jason E
authors.identifier: http://orcid.org/0000-0002-8821-805X
authors.initials: JE
authors.lastname: Laffoon
authors.affiliation: Faculty of Archaeology, Leiden University, Leiden, The Netherlands.
authors.forename: Till F
authors.initials: TF
authors.lastname: Sonnemann
authors.affiliation: Department of Computer & Information Science, University of Konstanz, Konstanz, Germany.
authors.forename: Termeh
authors.initials: T
authors.lastname: Shafie
authors.affiliation: Faculty of Archaeology, Leiden University, Leiden, The Netherlands.
authors.forename: Corinne L
authors.initials: CL
authors.lastname: Hofman
authors.affiliation: Department of Computer & Information Science, University of Konstanz, Konstanz, Germany.
authors.forename: Ulrik
authors.initials: U
authors.lastname: Brandes
authors.affiliation: Faculty of Earth and Life Sciences, Vrije Universiteit, Amsterdam, The Netherlands.
authors.forename: Gareth R
authors.initials: GR
authors.lastname: Davies
mesh_terms: D000328:Adult; D001641:Bicuspid / Q000737:chemistry; D017691:Caribbean Region; D002648:Child; D003462:Cuba; D003743:Dental Enamel / Q000737:chemistry*; D005260:Female; D049690:History, Ancient; D063426:Human Migration / Q000266:history*; D006801:Humans; D016013:Likelihood Functions; D008962:Models, Theoretical; D010103:Oxygen Isotopes / Q000032:analysis*; D010161:Paleodontology / Q000379:methods*; D013325:Strontium Isotopes / Q000032:analysis*; D014300:Trinidad and Tobago; D014687:Venezuela
chemical_list: D010103:Oxygen Isotopes; D013325:Strontium Isotopes