Changes in the immune system genes of First Nations people in Canada, reported in Nature Communications this week, may be linked to the introduction of European-borne epidemics in the 1800s.
First Nation populations declined after European contact, and it has been suggested that infectious disease was a major factor. Ripan Malhi and colleagues partnered with indigenous communities to compare ancient and modern populations, before and after Europeans arrived. The authors analysed the DNA of 25 individuals who lived in British Columbia around 1,000 to 6,000 years ago and 25 modern individuals from the same region. The results suggest a 57% drop in population size after European contact. Immune system gene variants that appeared to be advantageous in ancient individuals then decreased in frequency in the modern individuals.
These findings may be connected to infectious disease epidemics of the 1800s, introduced from Europe. The authors speculate that smallpox is a likely candidate, although other diseases such as measles or tuberculosis are also possible.