Quantitative measurements of stable isotopes have been used extensively in the fields of biology, ecology, geology as well as in forensic investigation and identification (Hobson 1999, Ehleringer & Matheson 2007). The use of natural abundance of isotope variation as geographic tracers has also been established to determine the provenance of food commodities, such as beef, dairy products and beverages (Kelly et al. 2005). Stable isotope analysis of light elements, especially of hydrogen, carbon and oxygen isotopic ratios is applied for food authenticity control for more than 20 years (Bauer-Christoph et al. 1997). Those methods rely on a database of authentic samples, which can be used for the comparison of data from commercial products with them.
Different isotopes in elephant tusks have also been evaluated and used to determine the geographic source of ivory (Van der Merwe et al. 1988, Vogel et al. 1990). Although some of the tested isotopic systems showed a clear distinction between several different populations of the African elephant (Van der Merwe et al. 1990, Cerling et al. 1999, 2003), past sampling effort was reportedly low and the metrics did not fully incorporate the natural variability into the subsequent summary statistics (Jackson et al. 2011).
The data stored in www.ivoryid.org derived from a newly collected, unprecedentedly large and unique sample set (715 samples) of elephant ivory (Loxodonta africana, Elephas maximus) throughout the species’ range of distribution in Africa and Asia. These new data were used to construct a nominal assignment framework with a focus on Africa, aiming to predict the provenance of ivory of unknown origin.