Ancient DNA From Two Chilean Mummies Provides First Genetic Proof Smallpox Arrived From Europe
Viral DNA from two colonial-era mummies in northern Chile shows smallpox reached the Americas from Europe, in a newly named extinct lineage called CAM9.
Overview
Researchers have recovered viral DNA from two mummified bodies in northern Chile that provides the first direct molecular evidence that smallpox reached the Americas from Europe, according to ScienceAlert. The study, published in the journal Science, identifies a previously unknown, now-extinct viral lineage the researchers named CAM9, according to Popular Archaeology.
What We Know
The two naturally mummified individuals were recovered at the Camarones 9 site near Camarones Cove on Chile’s northern coast, according to Discover Magazine and Cyprus Mail. They are believed to have died between 1492 and 1631, according to ScienceAlert. One was a woman between 30 and 35 years old; the other was a man between 18 and 20 years old, according to Cyprus Mail, and both were naturally mummified and buried in bundle fashion wrapped in camelid wool, per the same report.
The study, led by Bruno Romero González, a geneticist and doctoral student at Trinity College Dublin, according to Cyprus Mail, extracted viral DNA from leg bone fragments in both bodies, according to Euronews. Researchers screened 13 bone samples from the site, and only these two tested positive for the virus, according to Discover Magazine, a detail also reported by Euronews.
The two viral genomes recovered were nearly identical, “indicating the individuals were likely infected during the same outbreak or by the same circulating strain, providing rare direct molecular evidence of a smallpox strain circulating in colonial-era South America,” according to Popular Archaeology. Genetically, the newly designated CAM9 lineage sits between medieval European strains and the later variola variants that circulated in subsequent centuries, according to Euronews and Cyprus Mail, placing its evolutionary position squarely between the disease’s Old World origins and its later American history.
Shigeki Nakagome, a geneticist at Trinity College Dublin and study co-author, said: “The CAM9 genomes serve as a snapshot of the viral evolution, helping us understand which evolutionary changes had already occurred before smallpox reached the Americas,” according to ScienceAlert. He added: “Recovering ancient viral DNA is extremely challenging, so seeing clear evidence that these individuals were infected with smallpox was a remarkable moment for the entire team,” per the same report.
Study co-author Constanza de la Fuente Castro, a biological anthropologist at the University of Chile, according to Euronews, said the finding is “literally written into biological evidence that we can still recover and read today,” per the same report. She also noted that working with ancient pathogens is difficult, saying: “We are working with DNA that is in low concentration and has accumulated damage over time,” according to ScienceAlert.
Patricia Foster, a biologist at Indiana University who was not involved in the study, told Euronews: “Nobody would ever question that smallpox came to this hemisphere from colonisation, but this proves it.”
Romero González said: “The earliest documented smallpox outbreak in the Americas occurred on the island of Hispaniola in 1518, while it was being settled by the Spanish,” according to Cyprus Mail. That report also notes the Spanish conquest under Francisco Pizarro toppled the Inca emperor in the 1530s, providing the historical backdrop for the disease’s spread into the Andean region where the Camarones mummies were later found.
Smallpox epidemics are estimated to have killed three to four million people across the Americas following European contact, disproportionately affecting Indigenous populations with no prior immunity, according to Popular Archaeology and Discover Magazine.
What We Don’t Know
The underlying Science paper, titled “The genomic identity of early smallpox in South America,” was not directly accessible for this report, so additional technical detail in the publication itself — beyond what is described in the secondary coverage cited above — has not been independently verified here. It also remains unclear exactly how or when the CAM9 lineage went extinct, or how widely it circulated beyond the Camarones region before disappearing from the historical and genetic record.
Analysis
The finding does not overturn the long-established historical consensus that European colonization introduced smallpox to the Americas — contemporary written accounts from the conquest era already describe outbreaks following contact. What the Camarones genomes add is direct molecular confirmation, recovered from the bodies of people who were themselves infected, that ties a specific, datable viral lineage to that historical narrative rather than relying solely on documentary sources.