Genetic research has shed new light on what happened to indigenous people after European contact — and demonstrated just how long at least one group has inhabited their traditional lands.
A paper published Tuesday in Nature Communications used genetic material found in the collections of the Canadian Museum of History to conclude that the Lax Kw'alaams and Metlakatla First Nations near Prince Rupert, B.C., have been living in the same area for at least 6,000 uninterrupted years.
That same material also contained DNA that had evolved to help protect the people against disease from local pathogens, said lead author Ripan Malhi of the University of Illinois.
"We saw that there was signal of positive selection on this gene related to immunity," he said.
"That can be interpreted as the ancient group had adapted to their environments. Because the gene was involved in immunity, we can infer that maybe it was adapted to the pathogens in their ancient environments."
However, Malhi and his team found that the occurrence of that DNA began to fall in human remains from about the time of European contact. Most modern members of those communities no longer have that DNA, Malhi said.
"After Europeans arrived and changed the environment, those genetic variants that were possibly adapted to the environment were no longer well-suited."
Malhi said the data suggests that the old DNA was actually harmful in the new, European-influenced environment.
"It would have been not neutral, but possibly had some detriment."
Malhi's research is so far unable to pinpoint exactly how that genetic detriment worked. He points out oral history from those communities tells of massive disease outbreaks at about the time of contact.
"We don't know what the mechanism is. We can infer there's a possibility that it might be associated with smallpox."
First Nations were also being affected by warfare and massive social and cultural change at the same time.
It's hard to estimate exactly how much life was lost. Malhi's research indicates that between 125 and 225 years ago, those First Nations lost about 57 per cent of their genetic diversity.
"It suggests a huge drop in population."
Malhi's research was conducted with the full co-operation of the two First Nations involved. Two members of those communities travelled back to the research lab at the university to observe the handling and study of the human remains, which consisted mostly of materials such as bone and teeth fragments.
The results have also been shared with the communities.
Malhi is currently extending his work to look at the genetic consequences of European contact on other First Nations in Alaska, California and Mexico.
— Follow Bob Weber on Twitter at @row1960
Bob Weber, The Canadian Press
Note to readers: This is a corrected story. An earlier version had the lead author's first name spelled incorrectly.