In a discovery that sheds new light on the human conquest of the New World, a team of scientists says that bones from an ancient woman who lived on the Channel Islands off Ventura County could be the oldest human remains ever found in North America.
The extraordinary discovery provides important clues to a critical yet mysterious period in human history--the end of the last major ice age--when nomadic people began populating the Americas but left little evidence about who they were or where they came from.
The woman's bones, subjected to recent reexamination after spending the better part of four decades in storage, join a growing body of ancient skeletal remains that challenges traditional theories that the first visitors came here from northern Asia by way of a land bridge to Alaska. The new evidence suggests that the first settlers could have been Polynesians or southern Asians who arrived by boat. Some of the recent remains have features more typical of Europeans, scientists say.
"Bottom line is she may be the earliest inhabitant of North America we have discovered. It's a find of national significance," said John R. Johnson, curator of anthropology at the Santa Barbara Museum of Natural History, part of the team involved in the research.
The skeletal remains consist of two thigh bones scooped from a gully at Arlington Canyon on Santa Rosa Island 40 years ago. They were tested in the 1960s and kept in their original soil before being encased in plaster and stored in the basement of the Santa Barbara museum. Researchers at the museum and Channel Islands National Park recently decided to subject the bones to sophisticated DNA and radiocarbon testing methods that were not available when the bones were discovered.
The tests were performed by Stafford Research Laboratories in Boulder, Colo., one of the nation's preeminent carbon dating labs. The results showed that the bones are probably 13,000 years old, 1,400 years older than previously thought. That would make the so-called Arlington Springs woman slightly older than the oldest known human skeletons in North America, which came from Montana, Idaho and Texas, scientists say.
Other members of the research team included scientists from the University of California, Lawrence Livermore National Radiocarbon Laboratory, and the National Park Service. Results of the investigation have not yet been submitted to peers for critical review and have not been published in scientific journals. But a paper describing the experiment presented March 30 at the fifth California Islands Symposium at the Santa Barbara museum has fueled excitement among leading scholars in the field.
Two sets of tests were performed on the bones and have produced differing estimates of their age. The first set was performed by the Stafford lab and R. Ervin Taylor, chairman of the anthropology department at UC Riverside, another respected expert in the carbon dating of skeletons. Those tests produced an age of 11,000 years. Thomas W. Stafford, a research geochemist who runs the Stafford lab, performed a second set of tests on another piece of leg bone that was in better condition. That test isolated a protein common to bones and analyzed the remaining amino acids, which indicated an age of about 13,000 years. Additional tests on a lump of charcoal and a mouse jawbone, found beside the leg bones in the same stratum of soil, confirmed that age, Stafford said.
Taylor said he hopes to double-check the older date by testing the same portion of femur that Stafford used. But he vouched for the other man's expertise. "He has a very good track record, he has scientific credibility and he does a lot of work on bones from the New World. You take his data seriously," Taylor said.
Either way, the bones from Santa Rosa Island join an exclusive group of skeletons from the very earliest people to arrive in the Western Hemisphere. In those days, the colonizers would have seen continent-sized glaciers and woolly mammoths. The sea level was 360 feet lower than it is today. The northern Channel Islands near Ventura and Santa Barbara counties were joined in a contiguous land mass that scientists refer to as Santa Rosae.
The bones were found in a canyon on the island that ancient peoples have inhabited on and off for thousands of years. A short distance from the site is Daisy Cave on San Miguel Island, where a handful of flints, stone chips and charcoal--some nearly as old as the woman's bones--have been found. It is possible she may have lived there and walked across a canyon, now underwater, to the current Santa Rosa Island where she died, said Don Morris, archeologist for Channel Islands National Park.
"It's pretty incredible. Arlington woman presses right back into this time of the early migration of the New World. She could be the oldest skeleton in North America," Stafford said.
The bones found on the island could help rewrite a key chapter of human history. Until a couple of years ago, most scientists thought the earliest people to reach the New World arrived about 11,500 years ago, probably by walking across a land bridge where the Bering Strait now separates Alaska from Siberia. History books describe them and their descendants as the Clovis peoples, big-game hunters who left stylized spear points that enabled archeologists to track their migration south through parting glaciers along the Rocky Mountains into the present-day United States and Latin America.
But recent discoveries point to an earlier colonization of the Western Hemisphere. A campsite known as Monte Verde in southern Chile was occupied 12,500 years ago. At the Cactus Hill site in Virginia, scientists found stone tools and charcoal that may date back 15,500 years, said archeologist Rob Bonnichsen, director of the Center for the Study of First Americans at Oregon State University in Corvallis.
"What we are starting to realize is the earliest people in the New World came in thousands of years earlier in time. The peopling of the Americas is looking much more complicated," said Douglas W. Owsley, head of the physical anthropology department at the Smithsonian Institution's National Museum of Natural History.
"We used to feel very confident that Clovis was the first peoples, but other new finds coming to light are documenting that there were people in the Americas before Clovis. The Americas were colonized in more than one event," said D. Gentry Steele, anthropologist at Texas A & M University.
These discoveries challenge the theory that the first migrants slogged over land through passages in receding glaciers. Travel along that route would have been slow and perilous and does not account for widespread distribution of humans at such an early date, the experts said.
Scientists increasingly postulate that the original colonizers of the New World might have taken a coastal route. Where glaciers stopped at the water's edge, protein-rich seafood was abundant and the visitors could travel by boats. The bones from the island woman bolster that hypothesis, Bonnichsen said.
"The broad significance is it puts humans in a maritime setting in western North America 13,000 years ago. It demonstrates the use of boats," Bonnichsen said. "This Arlington Springs find is really a significant find in terms of providing support for that larger theoretical idea."
The new discovery is likely to be controversial in part because many scientists say that the old skeletons found in the past few years around the Western United States do not resemble modern Native Americans. Detailed examinations of the skulls reveal slender faces, narrower brain cavities, high foreheads and slightly protruding chins that are more typical of Caucasoid peoples.
Some of them bear striking resemblance to a very ancient race called the Ainu, a maritime people who were forerunners of Polynesians and long ago occupied Japan and China, Owsley said.
In contrast, Native American people and their ancestors have features common to Eskimos and people of northern Asia, including round, flatter faces and pronounced cheekbones, Owsley said.
Many Native American groups strongly object to the theory that others got here first. In some cases, including one major one in the Northwest, tribes have successfully invoked the 1990 Native American Graves Protection and Repatriation Act to force researchers to return old skeletons for reburial before they can be tested.
Paul Varela, executive director of the Chumash Interpretive Center in Thousand Oaks, said oral traditions passed down through generations of Central Coast Indians confirm that they were the first inhabitants of California.
"If you ask a Chumash person, they will tell you they have been here forever. We've always been here," Varela said.
In part to resolve such questions, UC Davis anthropologist David Glenn Smith said he hopes to begin DNA testing by summer on bones from 18 very old North American skeletons, including the Arlington Springs woman. The testing would go far in determining the ancestry and closest living relatives of America's first inhabitants.
"This is the foggiest piece of time. We're trying to answer that question: Who got here first?" Stafford said.
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Scientists are finding an increasing number of ancient human skeletons in the Western Hemisphere that suggest the first migrants arrived much earlier than previously thought. Here are some sites where the oldest discoveries have been made:
*Ages are in radiocarbon years, a scientific measurement of the rate of radioactive decay that does not correspond to a calendar year.
Source: UC Riverside, Stafford Research Laboratories Inc., Texas A & M University
Site: Santa Rosa Island, California
Age of Bones*: 10,960
Site: Anzick, Montana
Age of Bones*: 10,240-10,940
Site: Buhl, Idaho
Age of Bones*: 10,675
Site: Mostin, California
Age of Bones*: 10,470
Site: Arroyo Frias River, Argentina
Age of Bones*: 10,300
Site: Horn Shelter and Wilson-Leonard, Texas
Age of Bones*: 10,000
Site: On-Your-Knees Cave, Prince of Wales Island, Alaska
Age of Bones*: 9,730
Site: Spirit Cave, Nevada
Age of Bones*: 9,350-9,460
Site: Wizard Beach, Pyramid Lake, Nevada
Age of Bones*: 9,110-9,515
Site: La Brea Tar Pits, Los Angeles
Age of Bones*: 9,000
Site: Kennewick, Washington state
Age of Bones*: 8,410
* Dates are in radiocarbon years, a scientific measurement of the rate of radioactive decay that does not correspond to a calendar year.
Source: UC Riverside, Stafford Research Laboratories Inc., Texas A & M University