DNA extracted from the remains of a centuries-old mummy in Chile has provided the strongest scientific evidence to date that European colonists introduced smallpox to the Americas. This finding offers a significant confirmation of the longstanding historical understanding of how the virus spread during the early phases of European colonization.

The study was led by Shigeki Nakagome, a geneticist at Trinity College Dublin, who analyzed bone samples excavated from an archaeological site in Camarones, located in northern Chile. From 13 bone fragments collected at the site, the team identified signs of smallpox infection in the leg bones of an adult man and woman, both estimated to be between 18 and 35 years old. Genetic dating places their deaths between 1492 and 1631, a period coinciding with the height of the Columbian exchange when Europe and the Americas experienced extensive cultural and biological interactions.

Nakagome’s analysis showed that the strain of smallpox found in these individuals evolved in Europe, supporting the hypothesis that the virus was introduced to the New World by European colonizers. Patricia Foster, a biologist at Indiana University, highlighted the significance of the discovery, noting that while the presence of smallpox in the Americas following colonization was long accepted, this research provides direct genetic evidence confirming the origin and transmission pathway.

Historians have also suggested that smallpox may have spread through transatlantic slave trade routes originating in Africa, which would have contributed to the virus's expansion across the Americas. However, the current genetic data points primarily to European origins in the cases examined.

Smallpox epidemics had a devastating impact on indigenous populations throughout the Americas, contributing to the deaths of millions who lacked prior exposure and immunity to the disease. This vulnerability played a critical role in the demographic and societal changes that occurred during and after contact with European colonists.

Smallpox remains notable in medical history as the first human infectious disease eradicated globally. The World Health Organization declared smallpox eradicated in 1980, following the last naturally occurring case reported in Somalia in 1977. The new genetic findings add a vital chapter to understanding the disease’s historical spread and its profound consequences during the early modern period.