Ancient genomes add direct evidence to a long-held historical account
Researchers studying mummified remains from northern Chile have recovered smallpox DNA from two Inca-era individuals and linked the virus to a lineage associated with Europe. The finding, reported in coverage of the work by New Scientist, is significant because it moves the story of smallpox in the Americas beyond historical inference and into direct molecular evidence.
For decades, historians and archaeologists have relied mainly on written accounts and demographic collapse to understand how Old World diseases spread after European arrival in the Americas. Smallpox has long been considered one of the most consequential of those pathogens. What had been missing was direct biological proof from human remains showing that the virus present in the Americas matched strains circulating in Europe. According to the reported findings, that gap has now narrowed substantially.
The team, led by Shigeki Nakagome of Trinity College Dublin, analyzed bone from mummies recovered at the Camarones 9 archaeological site in northern Chile. The site, discovered in 1957, yielded dozens of wrapped and buried bodies over time. While the researchers initially set out to examine human DNA, they also searched for ancient pathogen material and found viral fragments matching variola, the virus that causes smallpox, in two individuals.
Why these two mummies matter
The two people identified in the report were a woman estimated to have died at age 30 to 35 and a man estimated to have died at age 18 to 20. Radiocarbon dating placed one of the deaths between 1492 and 1631, a period that overlaps with the earliest phase of European colonization in the Americas. That timing matters because it fits the historical window in which epidemic disease is believed to have spread rapidly across Indigenous populations.
Researchers then reconstructed the viral genomes and compared them with both ancient and modern smallpox samples. The reported conclusion was that the Chilean viruses belonged to a lineage that included early medieval and early modern European strains. In practical terms, that comparison strengthens the case that the infections were introduced from Europe rather than representing an older, previously unrecognized American lineage.
Nakagome described the result as the first direct molecular evidence that smallpox was introduced into the Americas through European colonization. That is a carefully framed claim, but an important one. Historians have long considered the scenario highly likely. The new data do not merely align with that story; they biologically anchor it.
A pathogen that reshaped the continent
The importance of the finding is not limited to virology. Smallpox was one of the central biological forces in the colonial transformation of the Americas. As summarized in the source report, historical estimates suggest epidemic disease killed an enormous share of Indigenous people after European contact. Scholars have argued that the demographic shock weakened political structures, devastated communities, and accelerated colonial conquest.
Smallpox was especially destructive because populations in the Americas had no previous exposure and therefore no inherited or acquired immune familiarity with the virus. In Eurasia, smallpox had circulated for centuries, repeatedly infecting populations and shaping patterns of immunity, mortality, and social response. In the Americas, the virus encountered communities without that background. The result was catastrophic mortality.
The source text quotes Matthew Ward of the University of Dundee, who was not involved in the research, emphasizing that epidemic waves in the Americas were among the most important events in history. That framing underscores why this paper matters beyond a single pathogen identification. It provides a molecular checkpoint for one of the largest human upheavals of the early modern era.
What ancient DNA can and cannot tell us
Ancient pathogen genomics has become a powerful tool for revisiting historical disease narratives. By extracting and sequencing fragments of viral or bacterial DNA from human remains, scientists can test assumptions that once depended on symptoms described in texts, burial patterns, or population declines. In this case, the method allowed the team to connect skeletal remains from Chile to a broader evolutionary history of variola.
Still, ancient DNA evidence rarely answers every question at once. The reported study appears to identify a strong European connection, but it does not by itself map the exact route of transmission, the number of introduction events, or the speed with which the disease moved through particular regions. Epidemics often spread in waves, and pathogens can travel faster than armies or settlers through trade, migration, or displacement.
Even so, the value of the result is clear. Instead of relying only on circumstantial historical reconstruction, researchers now have viral genomes from the Americas that fit within a European smallpox lineage. That makes the colonial transmission hypothesis far more concrete.
Implications for historical and scientific research
The study also points to a broader trend in archaeology and historical biology: old collections can yield new discoveries when analyzed with modern tools. The Camarones 9 mummies were discovered decades ago, but advances in sequencing and contamination control have made it possible to ask questions that would have been technically out of reach when the remains were first excavated.
That matters for museums, archives, and long-studied burial sites worldwide. Human remains collected in the 20th century may still contain recoverable genetic traces of diseases that shaped wars, migrations, trade routes, and empire. Reexamining those collections could refine timelines for plague, influenza, tuberculosis, or other pathogens that influenced major historical transitions.
In the case of smallpox, the Chilean evidence deepens a grim but essential part of the historical record. The virus was eradicated globally in the 20th century through vaccination, yet its historical consequences remain visible in demographic collapse, disrupted cultures, and the architecture of colonial rule. Discoveries like this do not change that history, but they make its mechanics easier to prove and harder to dismiss.
The central takeaway is straightforward: the long-accepted account that smallpox arrived in the Americas with Europeans now has direct genomic support from Inca-era mummies. For science, that is a methodological milestone. For history, it is a sharper confirmation of how disease traveled with empire and altered the fate of entire societies.
This article is based on reporting by New Scientist. Read the original article.
Originally published on newscientist.com
