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Forensic Science

DNA testing exposes scale of ivory trafficking networks

Genetic analysis of seized elephant tusks finds that whole families of elephants are affected

by Laura Howes
February 15, 2022 | A version of this story appeared in Volume 100, Issue 7


A map of most of Africa with blue lines linking countries in eastern and western central Africa.
Credit: Nat. Hum. Behav.
The map shows how over time genetic evidence (blue lines) can link ivory seizures in different countries.

Illegal ivory trafficking is a big business. Conservationists estimate that poachers kill about 55 African elephants a day. But while experts believe that only a handful of organizations are running the enterprise, finding the evidence to help prosecute the ringleaders is difficult. DNA sequencing to map family relationships among elephants whose tusks are seized could help build cases against smugglers (Nat. Hum. Behav. 2022, DOI: 10.1038/s41562-021-01267-6).

Samuel K. Wasser, co-executive director of the Center for Environmental Forensic Science at the University of Washington, led the new work. Wasser has tracked these networks using DNA for many years, and he and his colleagues previously showed that tusks from the same elephant were separated and smuggled in different shipments (Sci. Adv. 2018, DOI: 10.1126/sciadv.aat0625). The researchers have now expanded the approach to look for close familial links among tusks to identify parents, offspring, and siblings.

Wasser’s team sequenced over 4,000 elephant tusks from 49 ivory seizures that occurred between 2002 and 2019. “When we did that, it was astounding,” Wasser says. “We had dozens of shipments that were tightly connected by multiple familial matches.” The researchers found close family members represented in samples in shipments even years apart. According to Wasser, that suggests that the same criminal organizations have been operating for decades, with poachers targeting the same populations year after year.

Despite a global ban on ivory trade in effect since 1990, illegal sales of elephant ivory continue. Traffic, a nongovernmental organization that manages the Elephant Trade Information System, a database of seizures of ivory and other elephant products, says tracking and understanding the trade is complicated because shipments make several stops along the way to their destinations around the world. Experts estimate that law enforcement seizes only about 10% of ivory smuggled annually.

“The global effort to combat these illicit crimes is paramount to protecting our environment,” says John Brown III, a criminal investigator with Homeland Security Investigations, part of the US Department of Homeland Security. He has collaborated with Wasser and his team. Once criminals get their shipment into a container and onto a ship, the likelihood of getting caught is low, he says.

Brown has worked on environmental crime for over 25 years, with a focus on transnational organized crime in Africa and Southeast Asia. He says that just three to five organizations are believed to dominate the trade but that evidence is needed to connect seizures made in different jurisdictions to help law enforcement make convictions. If countries don’t collaborate, Wasser says, “we’re just essentially dealing with a whack-a-mole situation.”

In November, DNA sequencing by Wasser’s team helped identify a wildlife trafficking network and led authorities in the Democratic Republic of the Congo to seize ivory and pangolin scales worth approximately $3.5 million. As part of the same operation, two men were arrested in the US and indicted by a federal grand jury on charges related to trafficking elephant ivory and white rhinoceros horns.


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