A mammoth task: stable isotope analyses as a tool to prevent illegal trade of elephant ivory

Although mammoth ivory was claimed as a substitute to elephant ivory, there are several issues with the current methods to differentiate the two ivory, which provided a loophole to laundering and illegal trade. To contribute to developing efficient tools to distinguish ivory samples, we applied a relatively cheap and fast protocol using stable isotope ratios of carbon ( δ 13 C), hydrogen ( δ 2 H), nitrogen ( δ 15 N), oxygen ( δ 18 O), and sulfur ( δ 34 S). We compared the isotope ratios of the two ivory types and found statistically significant ( p -value<0.01) differences in the Wilcoxon tests for δ 2 H, δ 18 O, δ 13 C and δ 34 S, but no significant difference for δ 15 N. There was no overlap between δ 2 H and a small overlap for δ 18 O, while δ 13 C, δ 15 N, and δ 34 S of most mammoth samples were within the larger isotopic range values of the elephant samples. The PCA also pointed to a higher contribution of δ 2 H (96.9%) followed by δ 18 O (2.7%) to differentiate the ivory types. Our results showed SIA as an efficient tool to distinguish elephant and mammoth ivory, and we recommend using a multi-elements SIA approach focusing on δ 2 H and δ 18 O. While it is essential to address the social issues related to the ivory trade, including reducing human-elephant conflict and increasing financial support to Siberian carver communities, alternatives for natural ivory should also be sought, combined with strict policy changes to combat illegal trade and protect the African and Asian elephant populations.