Over the years, a couple of dozen descendants of the Chumash Indians have complied with the odd requests of their old friend John Johnson, a leading scholar of the tribe's culture and head of the anthropology department at the Santa Barbara Museum of Natural History. After all, what harm could come from parting with a few of their hairs or letting him swab the inside of their cheeks for a saliva sample?
What emerged from Johnson's DNA studies are tantalizing clues that link some of today's Chumash with settlers of coastal regions from Alaska to Tierra del Fuego more than 10,000 years ago.
"It's mind-boggling," said Ernestine De Soto, a 68-year-old nurse whose rare strain of DNA matches that found in ancient remains thousands of miles from the Santa Barbara area, where her family has lived for centuries. "I've always known I was Chumash, but this is something else."
Johnson's work, along with studies by archeologists and geneticists nationwide, adds more strong evidence to a theory that challenges long-held assumptions about when and how the first Americans arrived.
Ever since it was articulated by a 16th century Spanish missionary to South America, the prevailing theory has been that the first inhabitants of the Americas were big-game hunters who crossed a 1,000-mile land bridge from Asia, slogging down into the Great Plains through an inland corridor created by receding glaciers.
A number of scientists believe some may have trudged from Asia and then built boats that, over hundreds of generations, took them to spots where they put down roots along the length of the Pacific Coast.
"We're dealing with the whole period when glaciers began melting and people first became able to enter the Americas from Asia," said Johnson, who addressed a scholarly conference about his findings over the weekend at UC Santa Barbara. "Who were these first people that arrived in California?"
To Johnson and his colleagues, the answer involves centuries-old records from California missions, bones found at sites ranging from China to Chile, and a tooth extracted from a 10,300-year-old jawbone discovered in a place called On Your Knees Cave on an island off Alaska.
Found in 1996, the tooth from Prince of Wales Island wound up in a lab at UC Davis, where doctoral student Brian M. Kemp tried for two years to extract its DNA -- a feat frequently made impossible in old bones because of natural decay. But this tooth had been protected for millennia by cave walls and cold. Finally, Kemp succeeded.
The tooth yielded the oldest DNA sample in the Western Hemisphere.
"It was fantastic," recalled Kemp, now a researcher at Vanderbilt University in Tennessee. "When I first got the DNA out of this tooth, it looked different. I didn't immediately recognize it as a pattern frequent in the Americas."
In fact, as Kemp and others pored over a database of DNA patterns from 3,500 Native Americans, they found just 1% that exhibited the same distinctive markers. Some of the samples were drawn from living people and others from ancient bones. More than half were from the Cayapa tribe of Ecuador. Others were from tribes in Mexico and the southern reaches of Chile.
Four matching samples, it would turn out, were from Chumash descendants living along California's Central Coast.
Johnson had started collecting DNA 14 years ago, approaching Chumash descendants whose family trees he traced by painstakingly scouring records of births, baptisms, marriages and deaths compiled over two centuries by the Franciscan friars of California missions.
"Though there are no full-blooded Chumash left, he could go to the records and determine that this person is a direct maternal descendant of this particular Chumash woman in this mission or that village," said Joseph Lorenz, a molecular anthropologist collaborating with Johnson on a paper to be published in the Journal of California and Great Basin Anthropology.
Verifying such links is important because researchers mainly seek mitochondrial DNA -- the sequence in all of us that is inherited only from our mothers. It's easier to extract from cells. And, except for periodic mutations, it stays much the same from generation to generation, allowing a journey directly to a family's roots without distracting side trips.
Johnson acknowledged his sample is small but said it still points to just one conclusion: "My hypothesis is that the Chumash descended from a very early coastal migration that resulted in the distribution of people down to the tip of South America."
Other experts familiar with his research agree, although they acknowledge that physical evidence is difficult to find. After all, they note, the melting glaciers put a lot of early prime beachfront real estate under water.