Nuclear bombs mark tusks and teeth

摘要

Efforts to date elephant tusks and other illegally traded animal products could benefit from the nuclear testing carried out in the middle of the cold war. Radioactive carbon blasted into the atmosphere from weapons testing in the 1950s and 60s eventually made its way into plants and then into animals, producing a radiation spike that can serve as a reference point in time. Kevin Uno at the University of Utah in Salt Lake City and his colleagues measured radioactive carbon-14 in animal samples. The researchers could accurately determine the age of elephants' tusks and molars, and of hippopotamuses' canine teeth. Multiple samples from individual teeth showed how carbon isotopes were deposited as teeth grew, which correlates with the types of vegetation that animals consumed. Carbon measurements could be used to help detect tusks and other products from animals killed since anti-poaching laws were introduced. They could also reveal fluctuations in an animal's diet.