Stone tools offer new insights into first Oregonians

Stone tools offer new insights into first Oregonians »Play Video
Dennis Jenkins and examples of stone tools found in Paisley Caves

GRANTS PASS, Ore. (AP) — Stone tools and human DNA from ancient caves in Oregon offer new evidence of how some of the first Americans spread through the continent: Quite apart from the better-known Clovis culture, a separate group occupied the West.

Archaeologists reported Thursday they have dated broken spear points from the caves to about 13,200 years ago, as old as much different stone tools found elsewhere from the Clovis culture.

University of Oregon archaeologist Dennis Jenkins says that indicates the Clovis style of chipping stone tools was not the mother of Stone Age technology.

He says the two styles were developed independently by different groups that may have taken separate routes through the continent after crossing the Ice Age land bridge from Asia.

The findings appeared Thursday in the online edition of the journal Science.

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Press release from the University of Oregon

Archaeological work in Oregon's Paisley Caves has found evidence that Western Stemmed projectile points -- darts or thrusting spearheads -- were present at least 13,200 calendar years ago during or before the Clovis culture in western North America.

In a paper in the July 13 issue of Science, researchers from 13 institutions lay out their findings, which also include substantial new documentation, including "blind-test analysis" by independent labs, that confirms the human DNA pulled earlier from human coprolites (dried feces) and reported in Science (May 9, 2008) dates to the same time period.

The new conclusions are based on 190 radiocarbon dates of artifacts, coprolites, bones and sagebrush twigs meticulously removed from well-stratified layers of silt in the ancient caves. Absent from the Paisley Caves, said the project's lead researcher Dennis L. Jenkins of the University of Oregon's Museum of Natural and Cultural History, is diagnostic evidence of the Clovis culture such as the broad, concave-based, fluted Clovis projectile points.

The radiocarbon dating of the Western Stemmed projectiles to potentially pre-Clovis times, Jenkins said, provides new information in the decades-old debate that the two point-production technologies overlapped in time and may have developed separately. It suggests that Clovis may have arisen in the Southeastern United States and moved west, while the Western Stemmed tradition began, perhaps earlier, in the West and moved east.

One example, he said, is the discovery of Clovis points below Western Stemmed points at Hell Gap, Wyo. While this example suggests that Clovis was older in that location than Western Stemmed, the new Paisley Caves evidence indicates that Western Stemmed are at least the same age as Clovis (about 12,800-13,000 years old) in the northern Great Basin of Oregon -- about 1,000 miles west of Hell Gap.

At least three other Western sites -- Cooper's Ferry in Idaho and Nevada's Smith Creek Cave and Bonneville Estates Rockshelter -- also contain only Western Stemmed points in deposits of this age.

"From our dating, it appears to be impossible to derive Western Stemmed points from a proto- Clovis tradition," Jenkins said. "It suggests that we may have here in the Western United States a tradition that is at least as old as Clovis, and quite possibly older. We seem to have two different traditions co-existing in the United States that did not blend for a period of hundreds of years."

The origin of humans in the Americas has long suggested early migration out of Siberia and eastern Asia, very possibly across a temporary land bridge between Russia and Alaska.

In more recent years, Jenkins' UO colleague Jon Erlandson has been building evidence -- a lot of it emerging from the Channel Islands off California -- of a Late Pleistocene sea-going people following a "kelp highway" from Japan to Kamchatka, along the south coast of Beringia and Alaska, then southward down the Northwest Coast to California. Kelp forests are rich in seals, sea otters, fish, seabirds, and shellfish such as abalones and sea urchins.

The new paper doesn't address the routes early migrants may have taken, but the additional evidence found in the DNA of the coprolites continues to point to Siberia-east Asian origins. Again, as in 2008, the human mitochondrial DNA -- passed on maternally -- was from haplogroup A, which is common to Siberia and found, along with haplogroup B, in Native Americans today.

DNA cannot be directly dated with radiocarbon technology. Instead, researchers extracted components of the diet eaten by the early inhabitants and washed potentially contaminating carbon out of the coprolites with distilled water. The digested fibers and carbon fraction were then radiocarbon-dated separately and the results compared.

"Through replicating data we were able to confirm the authenticity of what is the oldest direct evidence for humans in the Americas," said co-author Michael "Michi" Hofreiter, a biologist in DNA laboratory of the University of York in the United Kingdom. "The results of this study are exciting, because they show that the hypothesis that the Clovis people were the first Native Americans, which has been the prevailing idea for the last decades, is wrong. Now researchers need to come up with a new model for the settling of the Americas."

The only significant aging difference in 12 such tests involved a camelid coprolite (ice-age llama) that was dated through its contents to about 14,150 years ago, while its water-soluble extract was dated to 13,200 years ago. This sample was found below a mud lens that contained one of the Western Stemmed points and human coprolites dated to between 13,000 and 13,200 years ago.

The meticulous methodology used, Jenkins said, was done to address criticism that the 2008 findings may have been compromised by contamination, such as the leaching of later DNA from humans by water and rodent urine downward through the caves' many layers. The new evidence indicates this form of contamination is not a good explanation for the pre-Clovis human DNA.

"We continued to excavate Paisley Caves from 2009 through 2011," the authors wrote in Science. "To resolve the question of stratigraphic integrity, we acquired 121 new AMS [accelerator mass spectrometry] radiocarbon dates on samples of terrestrial plants, macrofossils from coprolites, bone collagen and water soluble extracts recovered from each of these categories. To date, a total of 190 radiocarbon dates have been produced from the Paisley Caves."

The UO's archaeological field school, operated by the Museum of Natural and Cultural History, returned to the Paisley Caves, under Jenkins' direction, in 2002 to test conclusions made by UO anthropologist Luther Cressman. Based on discoveries of artifacts he found in the caves in 1938-1940, Cressman claimed he'd found evidence of Pleistocene occupation by humans. That claim, based on technologies at the time, was not readily accepted. He died in April 1994, still claiming that he had proven his case.

The Paisley Caves are in the Summer Lake basin near Paisley, about 220 miles southeast of Eugene on the east side of the Cascade Range. The complex includes eight westward-facing caves, all wave-cut shelters, on the highest shoreline of pluvial Lake Chewaucan, which rose and fell in periods of greater precipitation during the Pleistocene, or last glacial period.

"Following the recession of lake waters, the caves began to accumulate different kinds of terrestrial sediments," said co-author Loren Davis, an archaeologist at Oregon State University in Corvallis. "The caves contain a series of deposits that were created by the combination of wind, gravity, water-borne and biological processes. Archaeological evidence suggests that humans visited the cave many times, leaving behind material traces in the form of stone tools, lithic chipping debris, organic craft items, food wastes and even coprolites. These cultural materials were entombed largely as they were left behind as sediments continued to accumulate."

The archaeological field school is a program of the UO's Museum of Natural and Cultural History, which was established in 1936 by the Oregon Legislative Assembly as the official repository for state-held anthropological collections.

"Oregon is a unique place, with a special geomorphology and rich cultural history," said Kimberly Andrews Espy, vice president for research and innovation at the UO. "The research conducted by professor Jenkins and his team helps to tell the story of early human migrations into North America and demonstrates how the UO's long-running summer archaeological field school continues to provide research and training opportunities for students and yield important scientific results 76 years after its founding.”

The National Science Foundation (grant 0924606), Danish Research Foundation, U.S. Bureau of Land Management, UO archaeological field school, UO Museum of Natural and Cultural History, Oregon State University Keystone Archaeological Research Fund, Bernice Peltier Huber Charitable Trust and University of Nevada, Reno, Great Basin Paleoindian Research Unit were primary funders of the fieldwork.

Co-authors with Jenkins, Davis and Hofreiter were: Thomas W. Stafford of University of Copenhagen in Denmark and Stafford Research Laboratories in Colorado; Paula F. Campos of the University of Copenhagen and the Science Museum of the University of Coimbra in Portugal; Bryan Hockett of the Bureau of Land Management, Nevada; George T. Jones of Hamilton College in New York; Linda Scott Cummings and Chad Yost of the PaleoResearch Institute in Colorado; Thomas J. Connolly of the UO Museum of Natural and Cultural History; Robert M. Yohe II and Summer C. Gibbons of California State University; Johanna L.A. Paijmans of the University of York; Brian M. Kemp of Washington State University; Jodi Lynn Barta of WSU and Madonna University in Michigan; Cara Monroe of WSU and the University of California, Santa Barbara; and Maanasa Raghaven, Morten Rasmussen, M. Thomas P. Gilbert and Eske Willerslev of the Center for GeoGenetics at the University of Copenhagen.

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Stone tools focus picture of ancient Americans
JEFF BARNARD,Associated Press Writer

GRANTS PASS, Ore. (AP) — Stone tools and human DNA from ancient caves in Oregon offer new evidence of how some of the first Americans spread through the continent: quite apart from the better-known Clovis culture, a separate group that may have occupied the West.

Archaeologists said Thursday that using multiple techniques, they have dated broken obsidian spear points from Paisley Caves to about 13,200 years ago, as old as much different stone tools from the Clovis culture found in the southeast and interior United States. Radio-carbon dating of human DNA from coprolites — ancient desiccated human feces — shows people lived in the caves as early as 14,300 years ago.

The dates indicate that the Clovis style of chipping stone was not the mother of Stone Age technology, as others have theorized, and that the two styles were developed independently by different groups, said Dennis Jenkins, an archaeologist with the University of Oregon's Museum of Natural and Cultural History who led the excavations. That development may have happened in the Ice Age region of Beringia, where Siberia and Alaska were linked, before the two groups migrated south, he said.

The findings by an international team of scientists from the U.S., Britain and Denmark were reported online Thursday in the journal Science.

The Clovis culture is named for elegantly chipped stone points found at a site uncovered in 1929 near Clovis, N.M. The bases are distinctly concave where they were tied to the wooden shafts of spears or throwing darts for hunting. The style found in Oregon is known as western stemmed projectile points, for their thick bases and their discovery throughout the western U.S.

"The big 'aha!' here, or the primary significance of this is that ... we have demonstrated that these western stemmed tradition points are the same age as Clovis," Jenkins said in a teleconference with reporters. "There is no evidence of Clovis or any precursor to Clovis in the caves currently, and so that suggests that you've got here, at the exact same time, at least two technologies."

Until now, most western stemmed projectiles with accurate dating have been younger than Clovis artifacts, leading to theories the two technologies evolved from a single source. The new evidence directly goes against that idea. Jenkins said it appears more likely they evolved independently.

Jenkins said the findings suggest those groups of people may have taken separate routes after crossing the Ice Age land bridge from Asia. Those making western stemmed projectiles may have gone down the coast, while the Clovis people traveled through an ice-free corridor in the interior U.S.

But not all experts are convinced.

David Meltzer, professor of prehistory at Southern Methodist University, said the study clearly showed western stemmed projectiles existed at the same time as Clovis. And he said it put to rest any doubts about whether earlier findings of human DNA at Paisley Caves were contaminated by contact with the modern people excavating the site. But he was not ready to say that the stone points showed separate ancient migrations of people through the continent.

"Points are not people," he said. "Just because two ways of fashioning projectile points are different doesn't mean different populations any more than different groups of people drive Hummers rather than Priuses."

Jenkins and others reported in 2008 that they found coprolites in the Paisley Caves that dated back 14,300 years, the oldest radio-carbon-dated human DNA in North America. The DNA was genetically linked to people from Asia as well as modern Indians.

The caves are a string of shallow depressions washed out of an ancient lava flow by the waves of a lake that comes and goes with the changing climate near the town of Paisley, Ore. The caves have been excavated since the 1930s by archaeologists and looted by artifact hunters.

Jenkins and his team went back the past three summers and dug more, this time outfitted in the special suits, respirators and rubber gloves used by high-tech factory workers to assure they did not contaminate anything. They confirmed the dates through radio-carbon dating of the coprolites, bones and plants and through their placement in the layers of dirt built up over the millennia.

Copyright 2012 The Associated Press.