Overview
- A study published Thursday in Science recovered variola virus DNA from two naturally mummified Inca individuals excavated in northern Chile and reported the earliest known New World smallpox genomes.
- Genomic analysis places the recovered viruses in an extinct lineage between medieval European strains and later variants, supporting a European introduction of smallpox after 1492.
- The two viral genomes were nearly identical, which indicates the individuals were likely infected in the same outbreak or by the same circulating strain.
- Researchers found mutations that inactivated genes used to infect non-human species and report a long period of evolution through the 16th century followed by slowed change during colonial epidemics and renewed diversification after vaccination began in 1796.
- The finding corroborates historical accounts of catastrophic Indigenous mortality, highlights the value of pathogen DNA from mummies, and the authors call for more ancient samples across the Americas to map how the disease spread and evolved.