Overview
- Researchers reported in Science on Thursday that DNA from two naturally mummified people buried at Camarones in northern Chile produced the earliest known variola virus genomes from the Americas.
- The two genomes are nearly identical and define a now-extinct lineage called CAM9 that sits evolutionarily between medieval European strains and later variants, pointing to Old World introduction during colonization.
- Genomic analysis shows mutations that inactivated genes used by related poxviruses to infect animals, indicating the virus had begun to specialize on humans before these 16th-century infections.
- The team found a long period of viral change up to the 1500s, a slowdown in evolutionary rate during major colonial-era epidemics, and a later acceleration after widespread vaccination, but the exact human routes that carried the virus south remain unresolved.
- Authors stress the need for more ancient samples and stronger local collaboration and lab capacity to refine transmission histories and to address ethical concerns about sample stewardship and extractive research practices.