www.pnas.org/cgi/doi/10.1073/pnas.1614938113
Radiocarbon Dating Of Seized Ivory Confirms Rapid Decline In African Elephant Populations And Provides Insight Into Illegal Trade (2016)
Carbon-14 measurements on 231 elephant ivory specimens from 14 large ivory seizures (?0.5 ton) made between 2002 and 2014 show that most ivory (ca. 90%) was derived from animals that had died less than 3 y before ivory was confiscated.
PNAS
Cerling, T.E., Barnettea, J.E., Chessona, L.A., Gobush, K.S., Uno, K.T., Wasser, S.K., Xui, X., Douglas-Hamilton I.
Summary
Carbon-14 measurements on 231 elephant ivory specimens from 14 large ivory seizures (?0.5 ton) made between 2002 and 2014 show that most ivory (ca. 90%) was derived from animals that had died less than 3 y before ivory was confiscated. This indicates that the assumption of recent elephant death for mortality estimates of African elephants is correct: Very little “old” ivory is included in large ivory shipments from Africa. We found only one specimen of the 231 analyzed to have a lag time longer than 6 y. Patterns of trade differ by regions: East African ivory, based on genetic assignments of geographic origin, has a much higher fraction of “rapid” transit than ivory originating in the Tridom region of Cameroon–Gabon–Congo. Carbon-14 is an important tool in understanding patterns of movement of illegal wildlife products.