Epidemics from Europe that killed thousands of indigenous Canadians in the nineteenth century have left their signatures in the genomes of people in Canada today.
Ripan Malhi at the University of Illinois in Urbana–Champaign, Michael DeGiorgio at Pennsylvania State University in University Park and their colleagues sequenced the genomes of 25 modern Tsimshian people, who live in coastal British Columbia and Alaska and are among Canada's First Nations. The authors compared the genomes with the DNA of 25 people who lived in the same region between 6,000 and 1,000 years ago. They found that most of the modern Tsimshian people had different versions of immune-system genes, including an HLA gene, from their ancestors. Moreover, the team found an overall decrease in genetic diversity, which probably signifies a sudden population decline of about 57% around 175 years ago.
This is close to historical accounts that suggested a 70% decrease due to a smallpox epidemic.