JUDY WOODRUFF: Finally tonight, a new weapon in the fight against ivory smuggling. Our story comes from Julian Rush, science correspondent for Independent Television News.
JULIAN RUSH: Selling ivory isn't illegal as long as it comes from an elephant that died before 1947. Until now, that's been difficult to prove, so the market for ivory has continued to drive poaching.
ALAN ROBERTS, National Wildlife Crime Unit: All the elephant ivory that is taken has at one stage been on the front of a live elephant. Somebody's killed the elephant to obtain the ivory and very often killed the game wardens to obtain the elephant in the first place. People who are prepared to do this, it's organized crime.
JULIAN RUSH: Dating ivory needed an expert eye, and forgers have got very good at carving new ivory and faking it to look antique. Now, from a tiny sample, scientists can tell old from new and all because of something that happened in the 1950s.
One radioactive element in the fallout from the nuclear bomb tests of the era was Carbon-14. Every mushroom cloud, it seems, had a silver lining.
The sample is carefully prepared for analysis. Until the nuclear era, Carbon-14 in the atmosphere was at a constant level, but the nuclear bomb tests suddenly added extra Carbon-14 to the atmosphere. And because it's taken up into the bones and tissue of every plant and animal on Earth, the scientists can detect it.
PROFESSOR GORDON COOK, Scottish Universities Environmental Research Centre: If we find that the level of Carbon-14 is enriched, then we know that that animal, the elephant, was alive during the nuclear era, and therefore the ivory that we've analyzed is illegal ivory.