Findings in Oregon Caves Shed New Light on Early Americans

Conducting archaeological research in Oregon's Paisley Caves, a team of research scientists led by Dennis L. Jenkins of the University of Oregon's Museum of Natural and Cultural History has found evidence that an early stone implement technology, known as "Western Stemmed" projectile points (darts or thrusting spearheads), were manufactured at least 11,070 to 11,340 radiocarbon years ago, making them concurrent with or possibly earlier than the Clovis culture (dated to 13,000 calendar years ago) in North America. They have also confirmed, through additional DNA testing, that the early occupants of the caves had ancestral Siberia-East Asian origins, and that they were using the caves as far back as at leat 12,450 radiocarbon years ago. 

The research results, published In a paper in the July 13 issue of Science, also include substantial new documentation, including "blind-test analysis" by independent labs, confirming that the human DNA extracted in previous research from human coprolites (dried feces) present in the caves were dated to the same time period.

The researchers obtained 190 radiocarbon dates on artifacts, human coprolites (dried feces), bones and sagebrush twigs within layers of silt deposited over thousands of years in the  caves. The broad, concave-based, fluted Clovis projectile points often associated with early Americans who lived about 12,000 – 13,000 years ago were not found in the caves.

The dating of the Western Stemmed projectile points to possibly pre-Clovis times adds new data to digest in the ongoing debate about the starkly different production technologies overlapping in time and whether or not they developed separately. The results even suggest that the Clovis culture may have developed or originated in the Southeastern region of the United States and moved westward, while the Western Stemmed tradition originated, perhaps earlier than the Clovis, in the West and moved eastward.

"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."

Western Stemmed points and Clovis points differ mostly in terms of their hafting portions, the part of the stone point that connects to a shaft. Stemmed points are narrower or constricted at their bases, whereas the hafting portions of Clovis points (pictured right) are not narrow, but thinned width-wise through removal of large flakes from their bases. 

"These two approaches to making projectile points were really quite different," Davis said, "and the fact that Western Stemmed point-makers fully overlap, or even pre-date Clovis point makers likely means that Clovis peoples were not the sole founding population of the Americas."

It is interesting to note in this context that Clovis technology has only been found in the New World, whereas Western Stemmed technology is similar to stone technology seen in northeastern Asia.

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

Dating

Past studies of the Paisley Caves have also reported very early dates from human coprolites with ancient DNA, but questions arose about whether those samples could have been contaminated, and whether they were found in true context with artifacts from the same era. So the researchers did an exhaustive examination of the stratigraphy, which is one of Davis' specialties.

"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."

Davis conducted microscopic analysis of the soil using a "petrographic" microscope, to eliminate any indications that liquid – such as water or urine from humans or animals –  may have moved down from higher layers into the lower layers, thus "contaminating" or compromising the integrity of the dating of the soil. They also analyzed the silt where the stem points were found and bracketed above and below those layers to determine if the radiocarbon dates synchronized.

The result: "The stemmed points were in great context," Davis said. "There is no doubt that they were in primary context, associated with excellent radiocarbon dates." The new dating was valid.

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Dennis Jenkins, an archaeologist at the University of Oregon Museum of Natural and Cultural History, holds a human coprolite (dried feces) taken from Oregon's Paisley Caves. The sample dates to about 13,000 years ago. [Photo by Jim Barlow]

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Re-Modeling Origins

The origin of humans in the Americas has long been thought by many scientists to be connected to early migration out of Siberia and eastern Asia, likely across the temporary land bridge (Beringia) between present-day Russia and Alaska, a corridor that existed across the present-day Bering Strait during the last Ice Age. In recent years, however, Jon Erlandson, also of the University of Oregon, has advanced a theory of Late Pleistocene sea-going people following a "kelp highway" from Japan to Kamchatka, along the south coast of Beringia and Alaska, and then moving southward down the Northwest Coast to California. This would be a natural path to take as Kelp forests are rich in such food resources as fish, shellfish, seals, sea otters, and seabirds.

Moreover, the additional new evidence from the coprolite DNA continues to support Siberia-East Asian origins.  As was suggested in the earlier 2008 research, the human DNA was identified with haplogroup A, which is common to Siberia and found, along with haplogroup B, in Native Americans today. But the traditional model of origins, which advances the notion of a single migration with a singular technology, may be challenged. It cannot explain the presence of two separate and distinct stone tool technologies at the end of the last glacial period.

"Given these recent results from Paisley Caves, it's clear that we need to come up with some better models," Davis said.

The details of the study report can be found in the July 13, 2012 issue of Science, a publication of the American Association for the Advancement of Science, a non-profit organization.

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Displayed in the hand of University of Oregon archaeologist Dennis Jenkins are three bases for Western Stemmed projectiles from the Paisley Caves in Oregon. The bases date to some 13,000 years ago. [Photo by Jim Barlow]

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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.

The 18 co-authors with Jenkins and Davis on the study 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 and Michael Hofreiter of the University of York in the United Kingdom; 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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Photo, Second from top, right: Classical Clovis point. Locutus Borg, Wikimedia Commons.

Republished with permission from Popular Archaeology