How Ivory Detectives Handle a Tusk Job

ALL it takes is a $250,000 microscope, a two-bit protractor, and a bit of good fortune to come up with a method of saving ivory-bearing wildlife. At least that's what scientists at the United States Fish & Wildlife Service's National Forensics Laboratory hope will be the result of the elegantly simple means they've found to tell the difference between ivory from modern Asian and African elephants and that of their forefathers, the mastodons and mammoths.

Since at least 13 million pounds of ancient ivory still exist worldwide (it was preserved in the Arctic regions of Siberia and Alaska), unscrupulous exporters have been able to pass off banned elephant ivory as the legal variety. There was no scientific means to say nay.

Edgard Espinoza and Mary-Jacque Mann discovered that there is a perceptible difference between the two. Within so-called ``Schreger lines'' in cross sections of ivory tusks are microstructures called dentinal tubules. The density of these tubules in mammoths and mastodons is roughly twice what it is in modern elephants. This affects the angle of the Schreger lines, which are consistently less than 90 degrees in ancient ivory and consistently more than 110 degrees in modern ivory. The Espinoza-Mann hypothesis has stood up to the test of more than 10,000 samples.

Now it needs to be proven in court. ``We're still waiting for our chance to be heard,'' says Dr. Espinoza, a Chilean-born forensics specialist who taught at the university level in California before joining the lab last year. ``The expectation is that there will be a precedent-setting case in which the method is determined to be legally valid.''

Meanwhile, he says, there has been an ``enormous'' deterrent effect in that importers of ivory products ``have chosen not to fight it.'' More than 90 percent of the ivory samples he sees now are in fact from mammoths and mastodons.

Now, scientists here are looking for a way to pinpoint when the elephant from which ivory was taken was killed. Such ivory taken before 1976 (when the importation of Asian elephant ivory to the US was banned) is still legal. Another lab priority is resolving how to identify rhinoceros horn once it's been ground into powder.

``I feel swamped,'' Espinoza says. ``But not for one minute is it a boring or a dull job.''

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