It takes only a few minutes for Daryl Fedje and Quentin Mackie to go back in time more than 50 centuries.

The two Canadian researchers have been investigating the theory of how and when the first people arrived in the Americas. Their recent work has confirmed the presence of human settlements on the northwest coast about 5,000 years earlier than previously believed. And they strongly suspect it goes back even further.

The pair scramble up through the old-growth forest in British Columbia's remote Haida Gwaii islands where they have found evidence of ancient campsites. Below them lies a deep depression in the forest floor where a Haida longhouse once stood, perhaps 500 years ago.

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But they are looking for something much, much older. Moving up the slope, they look at the landscape as it would have been thousands of years earlier, before the towering cedar and spruce grew up.

"That's the old wave-cut shoreline at the base of those trees," says Dr. Mackie, a University of Victoria anthropology professor, pointing to a forest-covered terrace above.

"You have to [imagine] the landscape without the trees," says Dr. Fedje, a Parks Canada archeologist, explaining how they spot places that would have made good camp or village sites long ago.

For the past two decades, he has been searching mountainsides and beneath the seas for evidence that the first peoples who came from Asia across the Bering land bridge went south into the Americas by following the coast – not on an interior route further east, as previously thought.

He thinks he has found his proof in this wild and beautiful landscape off the northwest coast of B.C., just south of the Alaska Panhandle.

"From an archeological perspective, we can say people have been [on these islands] 12,700 years," Dr. Mackie says, standing next to a small pit trench dug by Gwaliga Hart, a Haida student who is assisting their research this summer.

"On this site," Dr. Fedje adds, "we dug down just over a metre and found a wealth of material."

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The site, which has barely been explored yet, is so rich that in the first load of dirt he lifted on his shovel, Mr. Hart exposed 10 or 15 pieces of hand-chipped stone tools.

"That was probably the most productive shovel test I've ever seen," Dr. Mackie marvels.

Moving up the slope, the crew dug another, smaller pit, and again hit layers of stone implements, including the beautifully made head of an adze (a wood carver) that, at an estimated 6,000 years, is thought to be the oldest tool of its kind ever found on the B.C. coast.

"You could have cut down trees with that, or used it to carve dugout canoes," Dr. Fedje says.

They feel sure that even older sites will be found on the terraces farther inland, up the slope.

"Up there is where the 10,500-year-old sites are," Dr. Fedje says, looking up to the next terrace. "We haven't really had a chance to look there yet."

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This progression of use is typical throughout Haida Gwaii, and it is leading scientists to reimagine both how and where the peopling of the Americas began. The orthodox view – that North Americans first came south along an ice-free corridor east of the Rockies – has given way to a theory that they travelled along the coastline.

What's more, Dr. Fedje and Dr. Mackie hypothesize that the earliest people were not roving bands of hunters, who moved fast as they pursued herds of game, but rather were family groups that settled on the landscape, establishing villages that lasted for thousands of years.

If their theory is correct, settlements should have existed between Haida Gwaii and the B.C. mainland, in an area now drowned under Hecate Strait. And they have found tantalizing evidence for that, both above and below the tide line.

"There's very strong evidence for central Hecate Strait being a suitable place for humans and animals 16,000 to 17,000 years ago," Dr. Fedje says. "The proof isn't there yet, but the story will come."

In one cave, they found a 14,500-year-old bear skull – and nearby it, an elegant stone spear point.

The archeologists also dropped a bucket over the side of a Coast Guard vessel anchored in a nearby inlet, where remote sensing told them that a salmon river had once carved a channel. From more than 50 metres down, on the sea floor, groping blindly, they dredged up a stone knife.

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It has not yet been dated, but Dr. Fedje says the chance that it was dropped from a canoe relatively recently – in the past few thousand years – seems remote. He thinks it more likely it is one of many items left at an ancient site. Until more underwater archeology is done, however, that remains only a beguiling theory.

He says the picture emerging on Haida Gwaii clearly supports the theory that people slowly populated the west coast, gradually moving south.

"There are several sites in the Americas 14,000 to 15,000 years old," Dr. Mackie agrees, referring to the earliest evidence of humans in Chile. "If you want people to get [that far south], you have to give them a few thousand years to get there. … If you do that, they must have got into the Americas 16,000 years ago."

Just this month, in fact, proof was found in an Oregon cave of a human presence there 14,000 years ago.

Captain Gold is a Haida elder who several years ago found what has turned out to be one of the richest archeological sites on the islands, where thousands of artifacts have been collected.

He says the oral history of his people tell of a time when ice covered the land. He believes archeological research will one day unearth proof that such stories are fact, not myth.

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"I'm waiting for science to catch up to oral history," he says.

"We are seeing a convergence," Dr. Fedje says, "and it's absolutely fascinating."

Mark Hume is a member of The Globe and Mail's Vancouver bureau.