- Published on
Ancient DNA From Chilean Mummies Reveals Who Brought Smallpox to The Americas
- Authors
- Name
- DeepHorus
Scientists have uncovered the first solid genetic evidence that smallpox was brought to the Americas by European colonizers, confirming a long-held historical assumption. Researchers from Ireland and Chile discovered variola virus DNA on two naturally mummified corpses in northern Chile, dating between 1492 and 1631 CE. This breakthrough provides direct molecular proof that smallpoxâa disease that devastated Indigenous populations with no prior immunityâwas introduced by Europeans soon after their arrival.
Smallpox, caused by the variola virus, is thought to have killed roughly 4 million Indigenous people in the Americas following European contact. Until now, the evidence for this catastrophic population decline relied solely on historical records. The new study, published in Science, offers the first ancient genetic evidence of the pathogen, a feat made difficult by DNA degradation over centuries.
The two mummies, recovered from the Atacama Desert in Chile, yielded nearly identical virus genomes, suggesting both individuals were infected at the same time. The virus lineage, named CAM9, fits neatly between medieval European strains and modern variants, placing it in South America very shortly after Europeans arrived. 'The CAM9 genomes serve as a snapshot of viral evolution,' said genomicist Shigeki Nakagome of Trinity College Dublin, 'helping us understand evolutionary changes before and after smallpox reached the Americas.'
The study also revealed that the virus's mutation rate slowed dramatically for two centuries after its introduction to the Americas, then sped up again in the 19th centuryâlikely due to widespread vaccination drives. Biological anthropologist Constanza de la Fuente Castro from the University of Chile noted the challenges: 'We are working with DNA that is in low concentration and has accumulated damage over time. This is affecting our ability to recover it, but it is also challenging to analyze.'
Lead researcher Nakagome called the discovery 'a remarkable moment for the entire team,' emphasizing the difficulty of recovering ancient viral DNA. The findings not only clarify the history of smallpox spread but also demonstrate how viruses adapt to major human events like colonization and vaccination. 'It suggests that major changes in human demography and epidemiology may have influenced the adaptive landscape of the virus,' he added.
Beyond its scientific significance, the study underscores the value of archaeological resources in the Global South. The researchers are calling for better funding and resource balance between the Global North and South, so that discoveries like these can be analyzed and preserved in their countries of origin. 'I have known people working for decades in ancient DNA in South America who have sometimes been completely pushed out by foreign researchers,' de la Fuente Castro said.
Looking ahead, the CAM9 genomes offer a unique opportunity to trace viral evolution over centuries. This research highlights how ancient DNA can illuminate the human past, while also serving as a reminder of the need for equitable scientific collaboration. As the team continues their work, they hope to uncover more clues about how smallpox shaped global history.
