They found that various tissues that formed at the same time had the same levels if carbon-14.

The four oldest samples were from animals that died from 1905 to 1953, and they had the least carbon-14 because they died before atmospheric nuclear weapons tests.

“With an accurate age of the ivory, we can verify if the trade is legal or not,” said Uno.

“Currently 30,000 elephants a year are slaughtered for their tusks, so there is a desperate need to enforce the international trade ban and reduce demand.”