Analyzing the DNA of elephants may help trace the origins of ivory being sold illegally, information researchers hope will help foil such trade.
Conservation experts say that elephants continue to be killed for their tusks despite a longtime ban on sales of elephant ivory.
Use of the new system to trace the origins of each piece of ivory can help police determine areas where large-scale hunting is going on.
A research team led by Samuel Wasser of the University of Washington developed the method. Their findings are reported in Monday's issue of Proceedings of the National Academy of Sciences.
Wasser said that while airplanes allow easy tracking of elephants on the open plains of Africa, it's harder to determine if there are losses in forests where many of the giant animals live.
"My colleagues working in the forests are saying, 'There are no elephants left here,'" Wasser said in a statement. "That's the problem in the forest you don't notice the change in population until it's so dramatic that it's almost too late to do anything about it."
The scientists collected DNA _ the genetic information in cells that codes for different types of life _ from elephant droppings and skin samples collected in 16 African nations.
With that information they were able to create a DNA-based reference map to assign tusk origin using genetic differences in elephants from one location to another.
Using that material, they can determine generally where a piece of ivory came from, so officials can be alerted to regions that need increased surveillance.
The sale of most new ivory was banned in 1989 to reduce the slaughter of elephants in Africa, where the population had plummeted. The ban has helped in the species' recovery in several nations.
Online sales of illegal ivory continue, however, including in the United States.
Consumers still can legally buy items like chess sets and cutlery fashioned from antique ivory as long as the sales are accompanied by permits and certification documents. In recent years some countries have sought permission to sell ivory that they contend came to them legally and that has accumulated. If such sales are allowed the new identification method could help determine if these countries then replace the stock with illegally harvested ivory, the researchers said.
The research was supported by the U.S. Fish and Wildlife Service, the Gordon and Betty Moore Foundation, the Bosack Kruger Charitable Trust, the National Institutes of Health, the International Elephant Foundation and the Woodland Park Zoo in Seattle.