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The short version

  • Scientists identified smallpox DNA in naturally mummified remains from northern Chile, confirming the virus arrived with European colonists rather than originating locally.
  • The viral strain dates between 1492 and 1631 C.E., aligning with early Spanish conquests and suggesting a specific lineage that emerged around 1296 C.E. before dying out.
  • Previous attributions of skin lesions on the remains to arsenic exposure are now reinterpreted as symptoms of smallpox, supported by the genetic findings.

Researchers have uncovered the first direct molecular evidence confirming that European colonists introduced smallpox to the Americas. The discovery comes from the analysis of naturally mummified remains found in northern Chile, belonging to two individuals likely of Inca descent who lived during the early Spanish colonial period. While historians have long suspected this transmission route due to the devastating demographic collapse among Indigenous populations, the new findings provide concrete biological proof that had previously been elusive.

The study, published recently in Science, focused on bone samples collected decades ago from a site known as Camarones 9. Initially, the team sought to sequence human DNA to trace ancestry and looked for signs of tuberculosis. Instead, they discovered well-preserved fragments of ancient smallpox virus DNA within the skeletons of a woman aged 30 to 35 and a man aged 18 to 20. The viral genetic material was remarkably intact, unlike the degraded human DNA, allowing scientists to pinpoint its origins with high precision.

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Genetic analysis reveals that the smallpox strain found in these Chilean mummies is most closely related to European variants. Dating places the outbreak between 1492 and 1631 C.E., a window that supports the theory of introduction via Spanish forces who captured the Inca emperor in Peru during the 1530s. The nearly identical viral samples from both individuals suggest they succumbed to the same strain, indicating a localized epidemic event rather than sporadic cases.

This molecular evidence also prompts a reevaluation of physical findings at the burial site. Some skeletons previously showed skin lesions that experts attributed to chronic arsenic exposure. However, given that smallpox causes deep, pus-filled sores that scab over, these marks may actually be signs of the viral infection. The discovery underscores how biological data can rewrite historical narratives, offering a clearer picture of how the virus spread and evolved.

Broader analysis of the virus’s evolutionary history suggests it originated roughly 1,500 years ago, likely jumping from an animal host to humans. The specific strain identified in Chile emerged around 1296 C.E. but eventually died out before the 20th century. Other lineages persisted for centuries, with some modern strains tracing back to variants circulating in Europe during the 1600s and 1700s. The virus appears to have lost genes over time, potentially increasing its lethality as it adapted to human hosts.

The impact of smallpox on Indigenous societies was catastrophic, with estimates suggesting up to 95 percent mortality in some regions. This demographic devastation significantly facilitated European colonization efforts across the Americas. While the disease was eradicated globally in 1980, understanding its historical spread remains crucial for contextualizing the profound biological and social changes that occurred during the colonial era.

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  • Smithsonian Magazine↗Smallpox DNA Hidden for Centuries in Mummies Found in Chile Suggests European Colonists Brought the Virus to the Americas