By Christopher Joyce
The value of elephant ivory has skyrocketed in the past few years. That's led to a huge increase in elephant poaching in Africa and, in turn, created new urgency to stop the trade. And as poachers have become savvier, scientists have devised more sophisticated methods of catching the thieves.
A pound of ivory is now worth more than $1,000, with wildlife experts attributing the rise in price largely to consumers, especially in Asia, who have new money to spend on ivory carvings.
Trying to stop the trade is messy because different countries banned ivory trade at different times. So some ivory taken before those bans went into effect may be legal to trade. There also have been a few legal sales of stockpiled ivory over the past decade. So it can be hard to tell whether a piece of ivory in a shipping container or on someone's bookcase is legal or not.
That's something geochemist is trying to fix. At the University of Utah, Uno worked out a way to "date" a piece of ivory by measuring how much radioactive carbon it contains.
"We use the adage 'you are what you eat' in the type of work we do," Uno says.
Here's how it works. Nuclear bomb tests in the 1950s and '60s pumped a lot of radiocarbon into the atmosphere. This radioactive carbon went everywhere — including into plants that elephants eat.
Since bomb testing ended in the '60s, that radiocarbon has been slowly dwindling. Scientists can chart its decline year by year. More....