Landscapers were digging a hole for a fish pond in the front yard of a Boulder (Colorado, USA) home last May when they unerthed some 13,000-year-old lost tools. They had stumbled onto a cache of more than 83 ancient tools buried by the Clovis people - ice age hunter-gatherers who remain a puzzle to anthropologists. The home's owner, Patrick Mahaffy, thought they were only a century or two old before contacting researchers at the University of Colorado-Boulder. "My jaw just dropped," said CU anthropologist Douglas Bamforth, who is leading a study of the find. "Boulder is a densely populated area. And in the midst of all that to find this cache." The cache is one of only a handful of Clovis-age artifacts uncovered in North America, said Bamforth.
     The Mahaffy Cache consists of 83 stone implements ranging from salad plate-sized, elegantly crafted bifacial knives and a unique tool resembling a double-bitted axe to small blades and flint scraps. The tools reveal an unexpected level of sophistication, Bamforth said, describing the design as 'unnecessarily complicated,' artistic and utilitarian at the same time. What researchers found on the tools also was significant.
     All 83 artifacts were shipped to the anthropology Professor Robert Yohe of the Laboratory of Archaeological Science at California State, Bakersfield for protein residue tests that were funded by Mahaffy. Biochemical analysis of blood and other protein residue revealed the tools were used to butcher camels, horses, sheep and bears. "I was somewhat surprised to find mammal protein residues on these tools, in part because we initially suspected that the Mahaffy Cache might be ritualistic rather than a utilitarian," said Yohe. "There are so few Clovis-age tool caches that have been discovered that we really don't know very much about them."
     That proves that the Clovis people ate more than just woolly mammoth meat for dinner, something scientists were unable to confirm before. The study is the first to identify protein residue from extinct camels on North American stone tools and only the second to identify horse protein residue on a Clovis-age tool, said Bamforth.
     The cache was buried 18 inches deep in a coarse, sandy sediment overlain by dark, clay-like soil and appear to have been cached on the edge of an ancient stream, and was packed into a hole the size of a large shoe box. The tools were most likely wrapped in a skin that deteriorated over time, Mahaffy said. "The kind of stone that's present - the kind that flakes to a good sharp edge - isn't widely available in this part of Colorado. It looks like they were storing material because they knew they would need it later," said Bamforth. Bamforth believes the tools had been untouched since the owners placed them there for storage.
     One of the tools, a stunning, oval-shaped bifacial knife that had been sharpened all the way around, is almost exactly the same shape, size and width of an obsidian knife found in a Clovis cache known as the Fenn Cache from south of Yellowstone National Park, said Bamforth. "Except for the raw material, they are almost identical," he said. "I wouldn't stake my reputation on it, but I could almost imagine the same person making both tools."
     A 'reasonable guess' is that the Clovis carried supplies of high-quality stone through game-rich but stone-poor regions where the material would be needed to make new tools, said Bruce Huckell, senior research coordinator at the University of New Mexico's Maxwell Museum of Anthropology. But when asked about the tools' use in butchering camels, Huckell said blood residue tests can be controversial. "Certainly it's exciting to see reports that indicate that a part-stone tool was used to butcher a particular animal in the remote past," Huckell said. "[But it's] not a method that has met with universal acceptance among archaeologists."
     Mahaffy wants to donate most of the tools to a museum but plans to rebury a few of them in his yard. "These tools have been associated with these people and this land for 13,000 years," he said. "I would like some of these tools to stay where they belong."

Sources: EurekAlert! (25 February 2009), Associated Press, Yahoo! News (26 February 2009), National Geographic News (27 February 2009)