Archaeologists claim to have found the oldest known artefact in the Americas, a scraper-like tool in an Oregon cave that dates back 14,230 years.
The tool shows that people were living in North America well before the widespread Clovis culture of 12,900 to 12,400 years ago, says archaeologist Dennis Jenkins of the University of Oregon in Eugene.
Studies of sediment and radiocarbon dating showed the bone's age. Jenkins presented the finding late last month in a lecture at the University of Oregon.
His team found the tool in a rock shelter overlooking a lake in south-central Oregon, one of a series of caves near the town of Paisley.
Kevin Smith, the team member who uncovered the artefact, remembers the discovery. "We had bumped into a lot of extinct horse, bison and camel bone – then I heard and felt the familiar ring and feel when trowel hits bone," says Smith, now a master's student at California State University, Los Angeles. "I switched to a brush. Soon this huge bone emerged, then I saw the serrated edge. I stepped back and said: 'Hey everybody — we got something here.'"
Whether the cave dwellers were Clovis people or belonged to an earlier culture is uncertain. None of the Clovis people's distinct fluted spear and arrow points have been found in the cave.
"They can't yet rule out the Paisley Cave people weren't Clovis," says Jon Erlandson, an archaeologist at the University of Oregon who wasn't involved in the research.
The only other American archaeological site older than Clovis is at Monte Verde in Chile, which is about 13,900 years old.
Last year, Jenkins and colleagues reported that Paisley Cave coprolites, or fossilized human excrement, dated to 14,000 to 14,270 years ago1. That report established the Paisley Caves as a key site for American archaeology.
Analysis of ancient DNA marked the coprolites as human. But in July, another group argued that the coprolites might be younger than the sediments that contained them2.
This team, led by Hendrik Poinar of McMaster University in Hamilton, Ontario, also questioned the 2008 report because no artefacts had been found in the crucial sediments. The Oregon team strongly disputed the criticisms3.
Laid to rest?
The dating of the bone tool, and the finding that the sediments encasing it range from 11,930 to 14,480 years old, might put these questions to rest. "You couldn't ask for better dated stratigraphy," Jenkins told the Oregon meeting.
"They have definitely made their argument even stronger," says Todd Surovell, an archaeologist at the University of Wyoming in Laramie who was not involved in the research.
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Other researchers questioned whether the cave's inhabitants would have been mainly vegetarian, as the coprolites suggested4. In his recent lecture Jenkins noted other evidence reflecting a diet short on meat but including edible plants such as the fernleaf biscuitroot Lomatium dissectum.
In late September, a group of archaeologists who study the peopling of the Americas met with federal officials and a representative of the local Klamath tribe to review the evidence at Paisley Caves. The specialists spent two days examining sediments, checking the tool, and assessing other plant and animal evidence.
"It was an impressive presentation," says David Meltzer, an archaeologist at Southern Methodist University in Dallas, Texas, who attended the meeting. "This is clearly an important site, but there are some tests that need to be done to seal the deal." One key, he says, is to better understand how the specimens got to the cave.
Dalton, Rex. 2009. "Oldest American artefact unearthed". Nature. Posted: November 5, 2009. Available online: http://www.nature.com/news/2009/091105/full/news.2009.1058.html
1. Gilbert, W.T.P. et al. Science 320, 786-789 (2008).
2. Poinar, H. et al. Science 325, 148 (2009).
3. Rasmussen, M. et al. Science 325, 148 (2009).
4. Goldberg, P., Berna, F. & Macphail, R.I. Science 325, 5937, 148 (2009).