Bones from two of the largest, most complete woolly mammoth skeletons ever found in North America have intrigued researchers since they were excavated from farmyards in Kenosha about 10 years ago. But they are increasingly fascinating to archeologists, not for the light they shed on woolly mammoth lineage, but for the secret they may hold about the earliest Americans.
The bones are scored with cuts apparently made by humans who butchered the elephant cousins for food. And they are almost 15,000 years old–1,000 years earlier than the accepted presence of humans in the Americas.
Since archeologists David Overstreet of Marquette University and Dan Joyce of the Kenosha Public Museum revealed the findings to a highly skeptical scientific community, the evidence has grown, and with it agreement from other researchers.
Dubbed the Schaefer and Hebior mammoths after the farms where they were discovered, each skeleton exhibits about 10 marks that, under scrutiny of a scanning electron microscope, are convincing cuts from man-made tools.
The bones were found in wild disarray, as if they had been scattered after a feast–not in the connected skeleton shapes of mammoths that died undisturbed. Geological analysis suggests the bones hadn’t moved since they settled to the bottom of an ice age pond.
A few rough stone tools were found touching the bones, and experts who have reviewed the site agree they are the same age as the mammoths.
And Tom Stafford, whose Colorado radiocarbon bone-dating labs are widely acknowledged as the best in the business, has dated the Schaefer and Hebior bones at about 15,000 years old.
“All of these lines of evidence point in the same direction–that somebody in southeastern Wisconsin was mucking about with mammoths 15,000 years ago,” Overstreet said.
Today the Schaefer bones are preserved in the Kenosha Public Museum, where a 13-foot cast of the Hebior mammoth towers in a glass atrium.
Joyce’s workspace is littered with the bones of a mammoth’s front leg. The massive 2-foot radius and ulna are littered with score marks, cuts and dents that look man-made even to the untrained eye.
But 15,000 years ago, a wall of glacial ice ran through the area. Mammoths, mastodons and giant beaver wandered a scrubby landscape dotted with spruce. Streams and ponds of glacial melt-water were plentiful, and temperatures ranged from bitter cold to balmy in summer.
Overstreet and others speculate that early Americans purposely lived near the glaciers, subsisting on the abundant water and game.
Joyce imagines an early American plunging a spear into the belly of the Schaefer mammoth and darting away from the angry wounded beast–then trailing the animal at a safe distance for days, watching as it made its way to shallow water to cool its fever and cleanse its wound. He imagines a tribe butchering the carcass, stripping meat from the ribs, disarticulating the toes to reach the fat pad they enclose and dragging away the front legs to a camp at higher ground.
The early American may never be found, but his existence is gaining plausibility as experts review the Kenosha evidence, published in small, peer-reviewed journals.
Archeologist Ronald Mason of Lawrence University in Appleton, Wis., praised the careful excavation and analyses as “first-rate.” One of many relenting skeptics, he said, “I am surprised at the antiquity of these finds Overstreet has made. I was very suspicious of them for a long time and had many an argument with him.”
Now he calls the mammoths a major archeological find.
“I’m convinced Overstreet’s really got something remarkable there,” Mason said. “Now we just want to find some distinctive or diagnostic artifacts with those mammoths, and he hasn’t done that yet.”
For many archeologists, butcher-mark evidence doesn’t mean much without context, and the wedge-shaped tools found near the mammoth bones are of the sort that are quickly made, easily discarded and say little useful about their makers.
Without a pattern of other contemporaneous human habitation sites, or varied human artifacts associated with the bones, they can’t begin to speculate on the mammoth-eaters’ origins or culture.
By about 13,500 years ago, humans were liberally spread throughout North America. They are known as Clovis people after the spear points they made by the thousands–called Clovis points–which barely varied across the continent.
`Clovis First’ in doubt
Many archeologists now question the time-honored “Clovis First” theory that the Clovis people were the first humans in the Americas, having crossed the Bering Strait land bridge into Alaska a few hundred years earlier.
The hard evidence for human habitation in the Americas before the Clovis people is far more sparse and tenuous, and archeologists regard new claims with suspicion. As Northern Arizona University paleontologist Larry Agenbroad puts it: “Tread lightly–the ice is thin in the pre-Clovis arguments.”
Purported pre-Clovis human sites pop up often and are routinely debunked. However, a few pre-Clovis claims haven’t crumbled under scrutiny–sites in Chile, Virginia and Pennsylvania have garnered some credibility and some criticism. And compared with these, Mason believes the Kenosha sites exhibit the most convincing evidence.
In addition, after studying hundreds of possible pre-Clovis sites, archeologist James Dixon of the University of Colorado at Boulder decided that the Kenosha sites were among the strongest candidates for North American pre-Clovis human habitation.
Nonetheless, scientists fret that the Kenosha mammoth feasts are not repeated elsewhere in the prehistoric record.
“When you have one site that’s unique, it’s a problem, but when you see a pattern–similar tools, similar age, in different places–then the evidence becomes stronger,” said University of Wisconsin-Madison archeologist James Stoltman. “So the problem with the Kenosha find is that at that age it’s virtually one of a kind in North America–and you can’t just parachute into Wisconsin from outer space.”
Finds called incomplete
He called the Kenosha finds “incomplete, but the strongest evidence so far for the very oldest sites.”
Arizona archeologist Vance Haynes said he has not abandoned the Clovis First theory but finds the Kenosha results intriguing.
He suggested that the Kenosha investigators follow the example of the researchers who, after discovering the original Clovis-like artifacts in 1926, “invited scientists from all over the continent to come and look. So the top archeologists in the nation came to look at this site and bought it.
“When you have a site that is so important to determining when the New World was peopled, this is the kind of scrutiny you want to have.”
Two other Kenosha mammoths, christened Fenske and Mud Lake, date to 16,000 years ago and exhibit hundreds of convincing butcher marks. But they haven’t been fully excavated, so Joyce has only some of their bones and no geologic or stone tool evidence to link them to humans.
Joyce may get his new evidence soon. He will begin full excavation of the Mud Lake mammoth this year. If he finds tools, or a largely dismembered skeleton, the evidence for the Kenosha mammoth-eaters will be that much stronger and more confounding. Scientists can’t account for Wisconsin humans 15,000 years ago, and a date 1,000 years earlier would be even harder to explain.
