"Ivory poachers may have finally met their match: forensic science. A study just published by PNAS describes a carbon-dating technique making it possible to determine the age of elephant tusks—and thus whether a particular piece of ivory has been acquired illegally."
"The method involves measuring the radiocarbon—a radioactive isotope of carbon—at the base of a tusk to learn when the elephant died. Kevin Uno, the lead author on the study and a postdoctoral researcher at the Lamont-Doherty Earth Observatory, broke down how it all works: "Plants absorb carbon dioxide and it gets locked into the leaf. Then some elephant walks by, eats that plant, and then builds its tissue, either tusk or hair, from the plant it ate.""