Genetic analysis of ancient mummy DNA recovered in Chile has provided the firmest evidence to date that European colonization introduced smallpox to the Americas. The study, published in the journal Science, examined bone samples from an archaeological site in northern Chile, revealing genetic traces of the virus that align with European strains.
Researchers identified evidence of smallpox infections in DNA from bone fragments belonging to an adult man and woman. Dating of these remains placed their deaths between 1492 and 1631. Scientists compared the genes of this ancient strain to other versions, fitting it genetically between medieval European strains and later variants. This molecular evidence strongly suggests that the smallpox strains present in the Americas evolved from European sources.
Smallpox was historically one of the deadliest infectious diseases, eradicating approximately one-third of those infected and leaving survivors with scars. Before its global eradication in 1980, the virus caused widespread devastation, particularly in the Americas, where Indigenous populations had no prior immunity.
While historical accounts and administrative records have long documented the impact of smallpox brought by colonizers, killing millions and decimating native populations, this new genetic evidence offers a direct scientific link. The presence of these strains in an area with no prior documented history of the disease raises new questions about the routes of transmission, potentially involving Indigenous trading networks that predated European arrival.
Scholars suggest that the exact population responsible for bringing smallpox to the Americas remains unclear, as European settlers arrived in various waves after Christopher Columbus's explorations in 1492. The disease could also have spread through Africa via the slave trade. The study of different viral strains also offers insights into the virus's evolution, revealing how it adapted to become more virulent.
The research highlights the profound human cost of the disease. The two individuals studied were between 18 and 35 years old and likely died from the infection. The findings underscore the devastating effect smallpox had across the Americas, contributing to population collapse and making Indigenous communities more vulnerable to European conquest.