European‑introduced smallpox in ancient Chile

Researchers analyzing bone fragments from two 16th‑century mummies discovered at the Camarones site in northern Chile identified ancient smallpox (Variola) viral DNA. The genomes, dated between 1492 and 1631, belong to an extinct lineage (CAM9) that sits evolutionarily between medieval European strains and later variants, providing direct molecular evidence that the disease was brought to the New World by European colonizers during the Spanish conquest.

The study examined 13 bone samples, with clear infection signals in two individuals, suggesting they were part of the same outbreak. Comparison with historic and modern variola genomes confirms the lineage’s intermediate position, illustrating rapid spread through immunologically naïve Indigenous populations. The authors estimate that smallpox caused the deaths of three to four million Indigenous people, representing up to 90 % of some groups.

The findings settle a long‑standing debate about the origin of smallpox in the Americas, while raising questions about the precise pathways of introduction—whether via early Spanish settlers or the trans‑Atlantic slave trade—and the speed of the disease’s spread through Indigenous trade networks.