SOURCE-AREA DETERMINATION OF ELEPHANT IVORY BY ISOTOPIC ANALYSIS

RECENT international efforts to conserve the African elephant Loxodonta africana prompted us to seek an appropriate method for determining the area from which individual tusks were derived. Trace element analysis of ivory has indicated the potential of chemical analysis for source identification1, but recent isotopic studies of African mammals2-5 suggest another approach. Stable carbon isotope ratios (13C/12C) in elephant bone collagen clearly reflect the mixture of C3 foliage and C4 grasses in the diet, and are directly proportional to the density of C3 browse2. Furthermore, nitrogen isotope ratios (15N/14N) in bone collagen of African mammals are related to rainfall or water stress3-5. Strontium isotopes (87Sr/86Sr) in bone or ivory can be expected to reflect local geology6,7. Here we report on a study of ivory and bone samples from different regions of Africa demonstrating the feasibility of trivariate isotopic analysis to identify the area in which an elephant lived, thus providing a potentially powerful tool for the control of illegal trading in ivory. © 1990 Nature Publishing Group.