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. Last Updated: 07/27/2016

Fossils Lead to Prehistoric Puzzle

WASHINGTON -- It was a bleak steppe, too dry to ice over and too cold for anything to grow but willow scrub and a rippling sea of grass. Mammoth ate the grass, and so, perhaps, did horses and reindeer. Wolves prowled the herds.

There, above the Arctic Circle at a bend in northern Russia's Usa River, near Finland, early humans may have made camp more than 35,000 years ago to butcher and eat mammoth and perhaps live. At Mamontovaya Kurya, scientists have unearthed 123 mammal bones and seven stone artifacts that are more than 20,000 years older than the next earliest traces of human habitation ever unearthed in the frozen Arctic. One mammoth tusk was marked with grooves, apparently gouged by a human-held chopping tool.

The discovery, reported Sept. 6 in the journal Nature, presents a startling anomaly that could change the way science perceives Eurasian prehistory, for the ancient campers are not easily explained by current migration theories regarding either anatomically "modern" humans or their most immediate European predecessors, the Neanderthals.

Why would modern humans, who spread through Eurasia 30,000 to 40,000 years ago, have bothered colonizing the inhospitable far north so early, when kinder latitudes beckoned? And how could Neanderthals survive in a sub-zero environment requiring organizational expertise beyond anything demonstrated by the archaeological record?

Archaeologists from the project began working at Mamontovaya Kurya in 1993 because local people for hundreds of years had regarded the site as a rich repository of mammoth bones, said geologist Jan Mangerud of Norway's University of Bergen. Mangerud is a senior scientist supervising a joint Russian-Norwegian team that has been exploring the Usa River region for several years. He did not participate directly in the Mamontovaya Kurya discoveries.

"It's a bend in the river, and archaeologists know that wherever there are a lot of bones, there might be human artifacts," he said. Progress was sporadic, he added, as the water table frequently rose above the artifacts, flooding the site during the summer digging season.

The river also presented another problem for scientists, according to Washington University anthropologist Erik Trinkaus, because moving water makes it difficult to authenticate any archaeological trove.

"With a river deposit in the Arctic, you not only have things getting washed out or redeposited," he said. "The river moves bones and tools around in the deposits, and the dates are on the bones."

Trinkaus said this confusion could prevail even with the grooved tusk, because when "you roll bones around in river gravel, you can get patterns that look a lot like what people do. We've had a number of cases like this, and people just throw up their hands."

The excavation team, led by Pavel Pavlov of the Russian Academy of Sciences and John Inge Svendsen of the University of Bergen, sought to answer this misgiving, suggesting in the Nature article that the original campsite -- about 36,000 years old -- was undercut by the river until the entire bank dropped intact into the gravel-bottomed channel. Deposits built up atop the artifacts, the researchers said, and were later washed away, re-exposing them.

The overwhelming majority of the bones were from mammoths and included two tusks, a lower jaw and at least seven ribs. Among a scattering of other bones were a reindeer antler, two horse teeth and the forepaw of a wolf.

The team also found seven stone artifacts, including a "side-scraper," used to remove flesh from hides, a stone knife or "hand-ax," and five chipped fragments. The grooved tusk, from a female mammoth between 6 and 8 years old, was scored with a "sharp stone edge, unequivocally the work of humans," the researchers wrote.

But what kind of humans? Mangerud said Mamontovaya Kurya did not yield enough artifacts to identify a stoneworking "style" typical of either modern humans or Neanderthals. The oldest previously known modern human site in the region is 296 kilometers southwest of Mamontovaya Kurya and about 8,000 years newer. There is no Neanderthal site in the vicinity.

Identifying the pioneers is important, however, because radiocarbon dating of the bones puts the site right in the middle of a mysterious transition period in prehistory in which modern humans were sweeping across Eurasia to displace Neanderthals, masters of Ice Age Europe for 100,000 years. Nothing before Mamontovaya Kurya had suggested that any event in this transition, however trivial, could have been played out so far north in such a hostile environment.