For centuries, Dolgan nomads have brought back mammoth ivory from their summer wanderings.

BUIGUES HAD TOLD me that in Siberia he often felt like an 18th-century explorer, and now, on the helicopter, it was easy to see why, as our polyglot crew sailed over seas of snow aboard a smelly, cramped, fragile-seeming craft, scanning the horizon. The scrubby forest had given way to open tundra, illegible to my unaccustomed eyes. Were we flying a hundred feet above the ground, or a thousand? The landscape fractured into patterns of abstraction, vast matrices of polyhedrons and faceted surfaces of lakes, flecked with gray and white like hewn granite. Cresting a hill, we startled a herd of gray smudges that bolted away en masse across the snow. "Reindeer!" Buigues shouted above the engine's din. Suddenly, Siberia seemed anything but barren: an icy Serengeti.

The tribesmen couldn't be far off. Dolgans live on reindeer. They hunt reindeer, herd reindeer, eat reindeer meat, drink reindeer milk, ride on reindeer's backs, drive reindeer-drawn sleighs, wear clothes and shoes made of reindeer skins. When a Dolgan man has to urinate, he goes out into the herd and pisses into the animals' mouths, so that the reindeer will have a source of salt. Even the Dolgans' houses are made of reindeer hides, stretched on wooden frameworks and mounted on sled runners—so that they can be pulled across the tundra, by reindeer. (On the Taimyr, I lived on reindeer, too, since this is what every meal at Restaurant Bar seemed to consist of. Over the course of a week, I sampled chopped reindeer, reindeer cutlets, reindeer entrecôte, reindeer with egg, reindeer without egg, reindeer sausage, and reindeer Stroganoff—all of it similarly gray and stringy.)

Twenty millennia ago, a helicopter flying across the Taimyr would have startled herds of mammoths. Prehistoric elephants—not just the woolly mammoths of Siberia, but others, such as American mastodons—were a common sight across the northern half of the globe. Most scientists think that, like their modern cousins, they must have been highly intelligent animals, gentle unless provoked. You wouldn't have wanted to provoke a woolly mammoth without good reason—they stood up to 11 feet at the shoulder, with tusks as long as 13 feet. Prehistoric people hunted them for their meat and ivory, but they also seem to have observed them as carefully as human beings have ever observed an animal: From Siberia to Utah, they chipped their images onto cliff faces, scratched them onto flat rocks, and painted them on cave walls. Mammoths, one might guess, were in some ways the reindeer of Stone Age man.

One of the Dolgan reindeer-pulled mobile homes sat atop a low swell ahead of us, behind a feeble windbreak of dead branches. As our helicopter touched down, sending up a spray of snow, a tiny, Asiatic-looking man, hooded in white reindeer fur, came staggering out, a pair of huskies at his heels. Buigues jumped out, a Discovery Channel cameraman close at hand. He made a few inquiries in Russian, and then we were off again in search of the missing brigade. The herdsman, left behind in his barely post-Pleistocene surroundings, gave hardly an upward glance. Already, the Dolgans are used to the paleontologist- and cameraman-bearing helicopters that occasionally drop from the sky. As Buigues told me proudly, "They very quickly learned to perform for the cameras, to do as many takes as the producers wanted." If you asked some of these Dolgans how they earn a living, they might honestly be able to say reindeer herding, ice fishing, and the Discovery Channel.

We never did find the lost brigade. We did, however, come across some mammoth remains, of a sort, that afternoon. We had stopped in the village of Novorybnoye, the Taimyr's largest Dolgan settlement. As soon as we landed, we were surrounded by a crowd of people of all ages, dressed in an assortment of cold-weather gear: fur parkas, beaded-leather moccasin boots, cast-off Russian army pants, a hat with the Adidas logo. The ever-present huskies marked their territory on the helicopter's landing gear.

An old woman pushed her way toward me through the crowd, muttering something to our interpreter: "She have something she want to sell you." Reaching deep into some inner recess of her oversize down parka, she produced a knotted thong of greasy reindeer leather, on which were strung four chunky pieces of old ivory—mammoth ivory. The yellowing bars and rings were pierced with well-worn holes, and deeply notched in strange crosshatching patterns. They were bridle fittings, used by the Dolgans to adorn—what else?—their reindeer.

While carcasses like the Jarkov mammoth are very rare, the bones and tusks of long-dead mammoths are so plentiful on the Siberian tundra that the natives carve them into buttons, knife handles, and utensils of every sort. For centuries, they've sold the ivory to traders who've shipped it to far corners of the world. Every summer the ivory merchants come out to Siberia from Moscow and St. Petersburg, and each year Russia legally exports about five or six tons of mammoth ivory, which American craft suppliers sell for $20 to $150 a pound, depending on quality.

As for the Dolgans, whose world contains no living creature remotely resembling a mammoth, their traditional belief is that the bones belong to a species of giant burrowing mole that dies instantly on contact with the air or sunlight. Most of them now accept the official paleontological explanations. But even so, the mammoth remains for them a mysterious being, gifted with terrifying powers. When the Dolgans remove a skeleton's tusks, they sacrifice a dog or a white reindeer, lest the animal's vengeful spirit return from deep underground, seeking revenge.