DNA tracks ancient Alaskan's descendants

10,300 YEARS OLD: Tests of Southeast Natives challenge prior anthropological results.

December 28, 2008 

NewsPaleontologist Tim Heaton holds a plastic cast of a human lower jaw at the site of a cave dig on Prince of Wales Island in 1998.

ERIK HILL / ANCHORAGE DAILY NEWS Buy Photo

An ancient mariner who lived and died 10,000 years ago on an island west of Ketchikan probably doesn't have any close relatives left in Alaska.

But some of them migrated south and their descendents can be found today in coastal Native American populations in California, Mexico, Ecuador, Chile and Argentina.

That's some of what scientists learned this summer by examining the DNA of Tlingit, Haida and Tsimshian Indians in Southeast Alaska.

Working with elders at a cultural festival in Juneau, they interviewed more than 200 Native Alaskans who allowed them to swab tiny amounts of saliva from their cheeks to capture their mitochondrial DNA, the genetic material that's passed from mothers to children.

Preliminary examination of those cell particles indicates:

• None of the participants possessed DNA similar to that extracted from On Your Knees Cave man, the 10,300-year-old Alaskan whose remains were discovered 12 years ago in a shallow cavern on Prince of Wales Island.

• But some participants appear to be closely linked genetically to coastal Indian tribes in British Columbia and Washington state, in spite of anthropological studies that claim Tlingits were originally an Interior people, like the nearby Athabascans.

"We haven't seen connections inland yet ... looking at just the very first couple of samples," said Washington State University Assistant Professor Brian Kemp, the molecular anthropologist who led the research. "That doesn't mean we won't. But right now we only have these long-distant connections."

Apparently On Your Knees Cave man only has long-distant relatives too.

AN ANCIENT TRAVELER

Bones of the ancient Alaskan were first discovered in 1996 by Alaska paleontologist Tim Heaton during an archaeological survey on the northern tip of Prince of Wales, the nation's third largest island.

They are among the oldest human remains ever found in North America -- a 13,000-year-old woman's partial skeleton was discovered 50 years ago in an island cave off the south coast of California -- and the oldest ever discovered in Alaska.

Heaton's team recovered a male pelvis, three ribs, a few vertebrae and a toothy, broken jaw, along with some ancient tools. With the help of archaeologist E. James Dixon, they eventually pieced together the caveman's story.

His teeth indicate he died in his prime, possibly in his early to mid-20s. The content of his bones revealed that his primary food came from the sea. The nearby stone tools, consisting of materials not found on the island, suggest a long-distance traveler, a mariner.

Then the geneticists went to work. Laboring two years as a graduate student, Kemp finally succeeded in extracting mitochondrial DNA from one of the caveman's teeth, the oldest DNA sample ever recovered in the Americas at the time.

It clearly placed On Your Knees Cave man in the "haplogroup-D" branch of the human family tree.

GENETIC TRAILS

Population geneticists trace all humans alive today back to common ancestors who lived in Africa about 60,000 years ago. As they migrated north out of Africa, then east and west across Asia and Europe, the common DNA they carried with them would occasionally mutate.

Different populations that migrated to different destinations carried different sets of mutations, which scientists have categorized into haplogroups and sub-haplogroups. The first people to migrate to the Americas all belonged to one of five primary haplogroups: A, B, C, D or X.

Just knowing that On Your Knees Cave man was a D reduced the chances that he would have any close relatives still living among present-day Native Alaskans, Kemp said. Previous DNA sampling of Eskimos, Athabaskans and Southeast Indians had traced nearly all of them to haplogroup A, with a tiny scattering of Bs.

The only known haplogroup D people in Alaska were the Aleuts. But that made them only distant relatives to On Your Knees Cave man -- very distant, since scientists believe the D mutation appeared for the first time about 50,000 years ago in Asia.

On closer inspection, however, Kemp found that On Your Knees Cave man belonged more specifically to the genetic sub-group D4H3, which may have shown up as recently as 20,000 years ago. Still, it's an exclusive group. Less than 2 percent of all Native Americans share that signature.

Aleuts living today don't appear to be that closely related to the caveman, Kemp said. Of the 163 tested so far, none were D4H3.

"The Aleuts are more closely related to the On Your Knees Cave individual than anyone who is not a member of D," he said. "But that has nothing to do with what happened in the Americas. It happened way before."

According to Kemp's research, part of what happened in the Americas is this:

Some of the caveman's relatives decided to head south from Alaska. Members of his specific genetic lineage have been found among the Chumash people of Southern California, the Cayapa of Ecuador and the Yaghan of Tierra del Fuego.

The fact that most of them landed at seaside destinations lends a lot more credence to scientists who believe the Lower 48 states and South America were populated first by coastal mariners -- Ice Age migrants from Asia who skirted around land-blocking glaciers in Alaska as early as 20,000 years ago

TLINGIT MYSTERY

Did some of those first Alaskans remain behind in the North? In terms of present-day Native Alaskans who might share the same specific genetic marker as On Your Knees Cave man, the jury is still out, Kemp said.

That's because genetic genealogy is still in its infancy. Very few Native Americans have been checked so far.

The DNA testing of 234 Southeast Alaska Indians that occurred in June -- one of the largest samples ever collected in the Americas -- nearly doubled all the previous data scientists had on Alaska Native populations, Kemp said.

It's possible the right person with the right match simply hasn't been tested yet, said Rosita Worl, president of the Sealaska Heritage Institute, the nonprofit Southeast Alaska Native group that sponsored the research.

It's also possible that the Tlingits and Haidas -- migrating either from the south or the Interior -- arrived in Southeast Alaska after the cave man's people had already passed through.

Worl's research suggests that the Tlingits of today used to be two separate populations. Tlingit society has long been divided between two groups, called "moieties" -- the Eagles and the Ravens -- based on the mother's ancestry. It's possible that one group preceded the other.

"Our oral traditions always talk about the presence of an older population being here when they arrived," said Worl, a Juneau-based Tlingit who teaches cultural anthropology at the University of Alaska Southeast.

"The hypothesis is that the Eagles and the Ravens represent two different populations."

Kemp is anxious to continue his research on his Tlingit DNA samples, to see if the matrilineal branches based on DNA match the matrilineal branches based on culture.

"We collected as much information as we could about individual moieties," Kemp said. "So a cool test will be to see if it (matches) the population genetics. And that may clarify the separate origins."

Find George Bryson online at adn.com/contact/gbryson or call 257-4318.

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