Professor studies mammoths, early Alaskans

July 30, 2011 

David Yesner may have the biggest mammoth collection in Alaska. Plastic toy mammoths, elegant carved ivory mammoths, fluffy stuffed mammoths. Hundreds of such figures and, as a professional matter, a sizable trove of real mammoth parts.

"They're the iconic symbol of the ice age," he said. "And Alaska's official state fossil."

Few know more about those fossils than Yesner. The University of Alaska Anchorage anthropology professor arguably has as much hands-on experience with the woolly pachyderms -- or at least parts of them -- as any Alaskan since the since the dawn of time.

Yesner is fascinated by animals of yore and the people who shared the ancient landscape. On Friday night, he will give a talk at the Anchorage Museum sharing some of his prodigious knowledge about mammoths, early Alaskans and how they interacted -- if they did.

His lecture will coincide with the opening of a small new exhibit at the museum, connected to the big "Mammoths and Mastodons: Titans of the Ice Age" exhibit from Chicago's Field Museum. The Field exhibit, an extensive overview of elephants' extinct cousins, contains relatively few items from Alaska. The smaller show, "The Mammoth Hunters," will focus on objects discovered in Alaska -- artifacts recovered and preserved due, in no small part, to Yesner's efforts.

LUCKY HUNCH

As a kid in New Haven, Conn., where his father was a professor at Yale University, Yesner became interested in the study of the past through National Geographic. He would later be featured in that magazine.

In the summer of 1972, he made his first trip to Alaska, working on a dig in the Aleutian Islands. He taught for a while at Anchorage Community College, then at the University of Maine.

"But my main thoughts were always for Alaska," he said.

In 1987, his wife, geologist Kristine Crossen, took a post with UAA and he returned to the state. He became a full-time member of the UAA faculty in 1991 and, more recently, associate dean of the university's graduate school.

In 1989, University of Alaska Fairbanks anthropologist Charles Holmes came into Yesner's office with items found near the top of an 80-foot hill 20 miles north of Delta. They included bones of birds, larger mammals and a piece of mammoth tusk. Holmes had been drawn to take a close look at the site by spots of black stain indicating fire pits -- and, ergo, people.

It's rare to find well-preserved bones in Alaska, Yesner said. The soil in much of the state tends to be acidic, dissolving most animal matter.

"Here was a different situation," Yesner said. "It was under six feet of glacial silt, so deep that acid hadn't penetrated."

They quickly assembled a team of fellow scientists and students and arranged for "big grants."

"It was a hunch," Yesner said. "But it turned out to be right."

HUNTER'S PARADISE

Broken Mammoth, as the spot was named, was the first excavation in Alaska of a well-preserved archaeological site of such antiquity, more than 13,000 years old. It gave modern Alaskans a window into the lives of very early Alaskans.

Global warming changed Alaska's ecology about 14,000 years ago, Yesner said. Sea levels rose. The Bering Land Bridge began to dissolve. The tundra and grassland favorable to mammoths and horses were rapidly replaced by poplars and cottonwood.

"Think the aspen parkland around Yellowstone," he said. "It was ideal for bison and elk. It was a hunter's paradise."

But uninviting for mammoths. The state's official fossil departed from Alaska's mainland well before the populations died off in Asia and the Lower 48.

There's scant evidence that Alaskans hunted any stragglers when the first people arrived. And whether people were the reason for the extinction of mammoths anywhere is debated.

Evidence from the Delta dig, however, shows that people certainly picked up and used old bones and ivory that they found, including the fragments that gave the site its name.

There's a common assumption that these ancient high spots were briefly occupied by passing hunters scanning the landscape for game.

Yesner called that "a facile observation." Broken Mammoth contained lots of cooking pits, not just a one-night campfire. It also held a wide variety of skinning, scraping and puncturing tools, including eye needles (cutting-edge technology at the time), toggles for holding tunics together and other evidence of clothing being made.

The abundance of swans and geese bones at the site indicate that the birds were mass harvested with nets, a technique requiring sophisticated, labor-intensive manufacturing skills and many hands.

Yesner's conclusion: "I think women and kids were doing a lot of the work here, not just male task groups. There were whole households at the site, and they were there for months rather than weeks."

PRIBILOF PACHYDERM

The hunter's paradise of Interior Alaska disappeared after a few thousand years.

"Alaska was at its warmest ever about 9,000 years ago," Yesner said. "Then it cooled off rapidly to the point of a neo-ice age."

Temperatures plunged. The Bering Strait may have frozen over. Spruce and willow came in. Caribou became the biggest herd species.

"I think the Interior was abandoned about 7,000 years ago, and people moved to the coast," Yesner said.

There were still mammoths in Alaska but not around humans. In 2003, with fellow UAA anthropologist Douglas Veltre, Yesner recovered mammoth fossils from a lava tube cave on St. Paul Island. One tusk is in the "Mammoths and Mastodons" exhibit, but most pieces are held by the Alaska Museum of Natural History.

These Pribilof Island mammoths were small though not "dwarf" in size, Yesner said. There couldn't have been much grass for grazing; perhaps they ate seaweed.

The St. Paul fossils dated to about 5,700 years ago, half as old as the newest mammoth fossils from mainland Alaska. Since there were no people living in the remote islands until the Russian era, hunters could not have played a role in their extinction.

"The advent of polar bears could have been a factor," said Yesner. The neo-ice age saw the bears extend their range southward along the coast. "The evidence is sketchy but who knows? Maybe they did."

Yesner isn't the only one fascinated by mammoths. Theories about their extinction flourish, including the idea that they were wiped out when a comet struck the Earth.

Perhaps Broken Mammoth will eventually shed light on that cataclysmic scenario. "The sediments from the site have yet to be analyzed," Yesner said. "There's still a lot of analysis yet to be done."

But no more digging. Last summer the final field excavations at the site came to an end.

"We filled in the holes and planted grass," Yesner said. "Now I'm trying to write the book."


Reach Mike Dunham at mdunham@adn.com or 257-4332.

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