Ivory and Isotopes: How Atomic Radiation Can Help Scientists Combat Poaching

Rennett Stowe via Wikimedia Commons

The radioactive legacy of the A-bomb era has given scientists a powerful forensic tool that may aid in the worldwide struggle against wildlife poaching.

As the Cold War began heating up in the late 1940s, the U.S. and the Soviet Union tested dozens of nuclear devices in remote locations for over a decade.  Bikini Atoll.  Castle Bravo.  Tsar Bomba.  Cumulatively, these explosions sent titanic amounts of carbon-14 isotopes streaming into the atmosphere.  Once released, carbon-14 behaves like any other carbon molecule.  It joins with oxygen to form C02 and works its way in to organic materials such as bones, teeth, and hair through normal respiration and ingestion processes even as its radioactive signature remains.  Trace elements from those old detonations are still circulating in the food chain today, and the abrupt rise and subsequent gradual decline of atmospheric carbon-14 is known as the “bomb curve.”

Carbon-14 decays by 50% at a predictable, and thus measurable, rate.  By gauging the levels of carbon-14 inside the tusks and pelts of slaughtered elephants, scientists can now determine (within a range of 4 – 16 months) when the animal was killed and thus whether or not the kill fell outside of international poaching guidelines.  The new study, led by researchers at the University of Utah, was published Monday in the journal Proceedings of the National Academy of Sciences.

As any high school chemistry student can tell you, scientists have been using carbon’s half-life to date objects for over half a century now.  But although the method itself isn’t new, it has not, up until this point, held such direct implications for a thorny current event such as wildlife trafficking.  In 1973, the Convention on the International Trade in Endangered Species (CITES) established strict restrictions on the sale and trade of numerous imperiled species.  Enforcement, however, depends on whether the animal was killed before or after its inclusion on the list.  For instance, CITES listed the rhino in 1977.  Possessing an artifact from a rhino killed before 1977 would be legal.  But anyone who owns or trades a body part from a rhino killed after 1977 would be subject to full prosecution.  You can probably predict the longstanding problem: How can one prove the age of a particular specimen?  No doubt hundreds of ivory traders have wiggled off the hook for lack of definitive evidence.

This latest study, then, aims to solve that problem by creating a scientific litmus test that will actually stand up in court.  By dating a horn or tusk’s carbon-14 content against the bomb curve and then cross-referencing the results with DNA samples (to prove the animal’s country of origin), international authorities will have better proof with which to convict offenders.  The findings couldn’t have come at a better time: Ivory trading has been booming in recent years.  According to National Geographic, poaching reached its highest levels in more than a decade in 2011, resulting in the loss of 90% of the elephants in Central Africa alone.  On Monday, President Obama signed an executive order to fund and assist African officials who are fighting a rising tide of slaughter.  An estimated 30,000 elephants were killed last year, yielding close to 24.3 tons of illegal ivory.

Incorporating carbon dating methodologies may very well lead to better enforcement that can disrupt some of the larger trading networks and curb poaching instances in the short- and medium-term.  Nothing lasts forever, though — especially not carbon-14.  The researchers are quick to note that in around 15 years, the radioactive isotope will have tailed off enough to match pre-atomic era background levels, nullifying its usefulness as a carbon benchmark.  Given that limited time frame, let’s hope that wildlife officials press the advantage while they can.  It’s remarkable (and remarkably ironic) that by subjecting Mother Nature to all of those mushroom clouds last century, humanity provided itself with a strange ricochet opportunity to combat one of the most egregious environmental travesties of this century.

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