Russian archaeologists have discovered the remains of the world's oldest known Arctic settlement - a Siberian riverfront site that they say could help determine when humans first arrived in the Americas.
The 30,000-year-old site - twice as old as any previous Arctic dig - includes a rhinoceros bone shaped into a spear that shows a "striking resemblance" to spear points found by archaeologists in Clovis, N.M.
The findings by the Russia Academy of Sciences may prompt a re-examination of popular theories about when humans first came to the Americas. Expert opinions vary, but most think the immigrants first crossed the Bering Strait land bridge about 15,000 years ago.
The Russian findings may change that, experts say.
"We'll have to come up with a whole new way of looking at things," said Michael L. Kunz, an archaeologist with the Bureau of Land Management in Fairbanks, Alaska, who reviewed the study.
The Russian team's findings show the Americas may have been settled much earlier than previously thought - possibly 25,000 years ago - by the same tribal groups that inhabited their Yana River site.
"In theory, the Yana people may have crossed over the land bridge," the researchers wrote. Their findings were published today in Science.
Human migration to the Americas remains one of archaeology's biggest mysteries. Until now, the oldest place in the Bering region with evidence of human habitation was Broken Mammoth, a 14,000-year-old site in central Alaska.
"It pushes back, by 10,000 years or more, evidence of human habitation of an Arctic region in that part of the world," said William W. Fitzhugh, director of the Smithsonian Institution's Arctic Studies Center.
Fitzhugh, who has traveled to the Yana River site, said the area was never covered with the glaciers that swept over much of North America during the last ice age, making it a better candidate for an archaeological dig. The stone tools and bones unearthed there were preserved in tundra soils, rather then being swept away by glaciers that melted 10,000 years ago.
The Bering Strait land bridge also submerged when the glaciers melted, but many archeologists think people continued to migrate across the 56-mile strait, making their way in boats or on foot when the waterway froze each winter.
In two years of field work, the Russian researchers collected hundreds of pieces of stone quartz, slate and granite, along with hundreds of bones and bone fragments near the Yana River.
The researchers did not respond to e-mail and calls and were unavailable last week. But in their findings, they say that the shaping of the rhinoceros foreshaft into a spear point means hunters who inhabited the site may have shared the technology with those who settled in North America.
"Presumably, Siberian hunters brought the technology of foreshafts with them when they entered the New World," the researchers wrote in their study.
The artifacts include residues that show evidence of butchering and cooking horse meat, along with the foreshaft from the now-extinct woolly rhinoceros.
The researchers acknowledged that any direct connection between their site and the Clovis site is tenuous because the Yana River site is about 3,000 miles from Clovis and about 16,000 years older. But they say the way the rhinoceros bone was shaped to make a spear shows a "striking resemblance" to foreshafts made from ivory found in Clovis, N.M.
Clovis is the earliest universally accepted culture in the Americas, dating to about 13,000 years ago.
The rhinoceroses became extinct in Siberia and never reached North America, so ivory was likely substituted for the animal's horn, according to the researchers.
Some experts expressed skepticism about the findings and particularly at any links between the Yana River site and Clovis.
"They seem to be searching around for a connection to Clovis, and I think that's a shot in the dark," said James Adovasio, an archaeologist at Mercyhurst College.
The Yana River site, about 1,300 miles from the Bering Strait, is too far from the Americas to be considered in the debate about North American settlement, said C. Loring Brace, a University of Michigan archaeologist. "I don't see that it tells us anything specific about the peopling of the New World," he said.
But arctic archaeologists say there is no way to determine how far early settlers may have migrated to reach North America.
The settling of the Americas remains one of archaeology's most intriguing mysteries. Some archaeologists think it occurred long before the Clovis people and may have involved multiple entry points.
An archaeological site in Meadowcroft, Pa., shows evidence of human habitation 16,000 years ago, although some archaeologists contest that dating. Evidence showing settlers in Monte Verde, Chile, 15,000 years ago is also controversial. Some studies indicate that people arrived as early as 19,000 years ago - by boat from Europe.
But traditionalists have scoffed at those theories.
"A lot of it is guesswork more than anything else," Brace said.
Analyzing the shapes and characteristics of 1,800 skulls in a 2001 study, Brace concluded that the first humans to arrive in North America were aborigines from Japan who crossed the Bering Land Bridge 15,000 years ago. His findings were published in Proceedings of the National Academy of Sciences.