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.
Johnson's evidence "suggests the Pacific Coast is a primary conduit linking north and south," said University of Pennsylvania anthropologist Theodore Schurr. The DNA results, he said, are additional pieces of evidence in a case that has been building for about 10 or 15 years.
In 1999, Johnson announced that human bones found 40 years earlier at Arlington Springs on Santa Rosa Island off the Ventura County coast were 13,000 years old, making them the oldest human remains in North America.
Even that long ago, Santa Rosa would have been an island, so the presence of the bones suggested that boats were in use along the coast in that ancient time. Nobody is sure of the dates, but some scientists believe the migrations from Asia along inland routes in North America had not yet started.
In 1997, scientists presented their findings of prehistoric settlements at the Monte Verde site in coastal Chile. Estimates of their age ranged from 12,500 to 33,000 years old.
Some linguists have contended that the sheer number of Native American languages -- at one point there were 88 between Baja California and Oregon -- indicate settlement for at least 20,000 years, well before the retreat of the glaciers would have allowed travel by foot.
Johnson's findings intrigue Jonathan Cordero, a sociologist at California Lutheran University who has a distant relative with the rare DNA. Johnson traced the relative's ancestry to Escolastica Maria, a Chumash woman who was baptized at Mission Santa Barbara when she was 40, in 1788.
"This confirms a lot of Native American stories about origins," Cordero said. "The Aztecs, for instance, say their ancestors came from the north, and this is certainly consistent with that."
Meanwhile, the field is brimming with unanswered questions. Could inland and coastal migrations have taken place at the same time? Just when did people first embark from Asia? And are there Asians whose DNA is a match for the stuff that their ancestors theoretically carried all the way down to Chile? Only one known match -- in China -- has been made.
To Ernestine De Soto, whose mother was the last native speaker of Chumash, a bigger question yet arises when she ponders her link to an ancient tooth in Alaska and tribesmen in an Ecuadoran village.
"When are they going to link us all?" she asked.