Laffoon Jason E, Sonnemann Till F, Shafie Termeh, Hofman Corinne L, Brandes Ulrik, Davies Gareth R
Faculty of Earth and Life Sciences, Vrije Universiteit, Amsterdam, The Netherlands.
Faculty of Archaeology, Leiden University, Leiden, The Netherlands.
PLoS One. 2017 Feb 21;12(2):e0172562. doi: 10.1371/journal.pone.0172562. eCollection 2017.
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.
在过去几十年里，多种同位素分析应用方面取得的重大进展极大地提高了在考古人群中识别非本地个体的能力。最近，大规模空间同位素变异模型（同位素景观）的发展有助于改进对人类和动物起源的地理定位。然而，在人类（和动物）迁移与来源研究中，从骨骼同位素数据准确识别个体地理起源方面仍然存在持续挑战。为了尝试开发和测试更标准化、更定量的利用同位素数据进行个体起源地理定位的方法，针对环加勒比地区研究了两种结合87Sr/86Sr和δ18O同位素景观的方法：1）区间法，使用每个地点固定同位素变异的定义范围；2）似然赋值法，使用单变量和双变量概率密度函数。这两种方法用来自委内瑞拉加拉加斯已知来源的现代样本的牙釉质同位素数据进行了测试，并进一步用从古巴和特立尼达回收的两个未知来源的考古样本进行了探索。结果强调了不同方法的潜力和局限性。对已知来源样本的验证测试排除了环加勒比地区的大部分区域，并使用两种方法都正确地将加拉加斯突出显示为可能的起源地。积极的验证结果清楚地证明了双同位素方法在地理来源研究中的总体有效性。通过更好地理解环境和生物同位素变异之间的关系；持续开发和完善相关的同位素景观；以及最终纳入更广泛的同位素替代数据，可以进一步提高地理定位的准确性和精确性。
