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Detective double feature: when animals fall prey to human criminals, wildlife sleuths get on the case.

When animals fall prey to human criminals, wildlife sleuths get on the case.

Tsk, Tsk, Tusks

It's a raw morning in Baltimore Harbor. Two U.S. Fish and Wildlife Service inspectors shiver as they pry open a crate, but what they find inside makes them steam.

The crate is filled with dozens of ivory statues. Elephant ivory, no doubt, from the tusks of African elephants, an endangered species. In the early 1980s, poachers were slaughtering 70,000 elephants a year. But in 1989, when only 750,000 members of the species remained, lawmakers banned the trade of elephant ivory in the U.S.

Back on the dock, the owner of the crate senses that he might be in trouble. He quickly steps in to defend himself. "These statues," he says, "are carved from the tusks of woolly mammoths."

Mammoths? Haven't they been extinct for 10,000 years?

That's right, says the crate owner. But there are plenty of mammoths buried in glaciers for ivory traders to dig up. And unlike elephant ivory, the ivory from these ancient animals is perfectly legal to sell.

The story sounds plausible, but slightly suspicious. How can the inspectors know the truth? For help, they put in a call to the wildlife detectives.


At the National Fish and Wildlife Forensic Laboratory in Ashland, Oregon, 18 men and women investigate hundreds of cases like the tusk tale every year. The work they do is key to solving and preventing crimes against animals protected by laws like the Endangered and Threatened Species Acts.

The sleuths are masters of forensics, the scientific examination of crime evidence. Says the lab's director, Ken Goddard, "You don't need forensics to identify a whole elephant: trunk, ears, big rear end--hey, it's an elephant. But we don't seize whole elephants, we seize ivory."

What kind of ivory was still the question in this case. At the time, "there was no technique for telling if it was really mammoth ivory," recalls forensic scientist Ed Espinoza. Tusks, after all, are simply teeth. And all mammal teeth are made of the same mineral, dentine--whether they're from an ancient woolly mammoth, an elephant, or even you.

So Espinoza and his colleague Mary-Jacque Mann pulled out their high-tech tools. First, they examined museum specimens of elephant and mammoth ivory to see if they could find some distinguishing characteristic. They tried using scanning electron microscopes, X-ray machines, elaborate chemical analysis equipment .... But in the end, what solved the case was a combination of good-old-fashioned eyepower and a 25-cent protractor.

When you look at any cross section of ivory, explains Mann, you can see lines radiating from the center (see photos, above, right). These lines mark the position of hollow tubules in the dentine, which form as teeth grow.

After staring at specimen after specimen, Mann and Espinoza noticed that the angles formed by the crossing lines in mammoth ivory always measure less than 90 degrees. In elephant ivory, they noticed, the angles are always larger--greater than 115 degrees. Not exactly high-tech science, but it was enough to crack the case.

Mann and Espinoza trained airport and harbor inspectors to measure the angles with protractors. The inspectors wouldn't even have to slice cross sections out of the ivory; wherever statue carvers cut into ivory, the tubule angles are revealed.

Suddenly, it was easy to distinguish mammoth ivory from elephant ivory. Word got around fast. And within almost no time, the bogus "mammoth" ivory went the way of the mammoths themselves: It disappeared.

The detective work of the forensics lab is one reason the ivory ban has been such a success. African elephants are bouncing back--so well, in fact, that some people think governments should make ivory trade legal again. By selling ivory legally, they argue, African countries could make the money needed to preserve their unique environments and wildlife.


The case of the lone wolf began last September 30, and it isn't closed yet.... Seems a hunter just south of Yellowstone National Park came upon a prowling animal. Thinking the animal was a coyote--and so, fair game--he shot it. But then he took another look. Up close, the animal looked an awful lot like a gray wolf--an animal protected from hunting by the Endangered Species Act.

The hunter turned himself in. But the rangers were more interested in knowing where this "wolf" came from than in prosecuting the remorseful hunter. The reason? Gray wolves haven't been seen anywhere near Yellowstone since the 1920s, when U.S. rangers hunted the species to the point of near extinction (see SW 2/8/91, p. 2). If the killed animal was indeed a gray wolf, where on earth did it come from?

To track down the dead animal's origin, the rangers called on the wildlife detectives. Right away, Steven Fain, the scientist in charge of the case, figured there were only three possibilities:

* The animal could be a pet--half-wolf, half-dog--turned loose by a careless owner. (Wolves and dogs are so closely related that they can interbreed.)

* The animal could be a Canadian gray wolf that migrated south from upper Montana.

* Or, most intriguing of all, the animal could be a descendant of the old Yellowstone gray wolf population. "If so," says Fain, "I'd just be astounded."

So would many nearby ranchers. Right now, they're howling mad about a plan by the U.S. Park Service to reintroduce mating pairs of gray wolves to the area. They fear the wolves will kill their livestock. If the wolves already live in the area, the ranchers could argue that the reintroduction plan is unnecessary.

Fain had to pick his way carefully through the evidence in this controversial case. A molecular biologist, he decided to look directly at some molecules--samples of the dead animal's DNA.

DNA is the molecule with all the instructions that make you a unique individual. But you do share certain characteristics--and DNA--with your relatives and with other members of your species.

Same goes for wolves. By comparing the dead animal's DNA with that of other animals, Fain might be able to determine if it is indeed a wolf or a member of some other species.


First Fain compared the animal's DNA to DNA from coyotes and seven different dog breeds. No match. "So we're calling it a wolf," he says.

But which wolf population did it come from? To find out, Fain compared the DNA to DNA from wolves in Montana, Alaska, and Minnesota. Again there were no matches.

Taking another tack on the investigation, Fain's partner, Bonnie Yeats, compared the wolf's skull with skulls from other wolf populations. Once more, there were no matches. The Yellowstone animal belongs to none of the nearby wolf populations.

Yet it still appears to be a wolf. Could it possibly be a descendant of the original Yellowstone wolves? And how do you prove it when you have no known living members of that population to test?

Fain has one hope. He's collecting all the vintage wolf skulls and hides he can get his hands on--from hunters, scientists, and museums. If he manages to get enough undegraded DNA from these samples, he'll be able to run his analysis.

And if the DNA matches closely enough, the evidence will point to an incredible story: a population of wolves thought to be wiped out from the wilderness, actually surviving unnoticed for 70 years. Then the new mystery will be: Where are they all hiding?
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Title Annotation:biological forensics
Author:Pope, Greg
Publication:Science World
Article Type:Cover Story
Date:Apr 2, 1993
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