virus anthropology

Ancient Viruses Lurking In Your DNA: What Iron Age Skeletons Reveal About Herpes Evolution

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Hidden inside the chromosomes of millions of people are traces of ancient viruses that infected our ancestors thousands of years ago. New research on Iron Age and medieval skeletons has just provided the clearest genetic proof yet that some herpesviruses have been evolving with and within humans for at least 2,500 years.[1][2]

These findings are not just a curiosity of ancient DNA. They change how scientists think about common childhood infections, genetic inheritance, and the long-term arms race between humans and viruses.

Meet the Virus in Question: Human Herpesvirus 6

The new study focuses on Human betaherpesvirus 6A and 6B (HHV‑6A and HHV‑6B), closely related viruses that most people encounter in early childhood.[2][4]

  • HHV‑6B is best known for causing roseola infantum, a usually mild childhood illness marked by high fever and rash.
  • HHV‑6A is less well understood but has been investigated for possible links to neurological conditions and immune dysfunction.

What makes HHV‑6 unusual is its ability, in rare cases, to integrate into human chromosomes. When this happens in egg or sperm cells, the viral DNA can be passed from parent to child like any other genetic feature. This condition is known as inherited chromosomally integrated HHV‑6 (iciHHV‑6).[2][5]

Modern genetic surveys suggest that around 1% of people worldwide may carry such integrated HHV‑6 in every cell of their body. Until recently, however, this deep relationship between herpesviruses and human DNA was inferred mostly from present-day genomes, not from directly observed ancient viral DNA.

How Iron Age Skeletons Open a Window to Viral Deep Time

To move from inference to direct evidence, an international team led by researchers at the University of Vienna and the University of Tartu screened nearly 4,000 ancient human skeletal samples from archaeological sites across Europe.[2][3][5]

The team focused on skeletal parts known to preserve DNA well, such as inner ear bones and teeth, then used high-throughput sequencing and bioinformatic screening to look for viral genetic fragments mixed in with human DNA.[2]

From this large dataset, they successfully reconstructed 11 ancient HHV‑6 genomes—the first time complete or near-complete ancient herpesvirus 6 genomes have ever been recovered.[2][3][5]

The Oldest Case: A Girl from Iron Age Italy

The oldest viral genome came from a young girl buried in what is now Italy between roughly 1100 and 600 BCE, during the Iron Age.[2][3][4][6] That single genome pushes direct evidence of HHV‑6 infection back more than 2,500 years.

Additional ancient viral genomes came from individuals in:

  • Medieval England,
  • Belgium,
  • Estonia,
  • Italy, and
  • Early historic Russia.

Both HHV‑6A and HHV‑6B were identified in medieval remains from several of these regions.[2][3][4][6]

When Infections Become Inheritance

By reconstructing the full viral genomes, the researchers could determine where in the chromosome the virus had integrated. Comparing these patterns with modern human genetic data revealed something striking: some viral integrations occurred thousands of years ago and have been passed down through generations ever since.[2][3][5]

In other words, certain people walking around today are carrying viral DNA that can be traced back to infections in Iron Age or medieval Europeans. The virus is no longer just an invader; it has become part of the human genomic landscape.

This provides the first time-stamped, ancient DNA confirmation of what geneticists had long suspected from modern data: that HHV‑6 has been evolving alongside humans since at least the Iron Age and likely since much earlier phases of human evolution.[2][3][4][5]

Two Viruses, Two Evolutionary Paths

The study also shows that HHV‑6A and HHV‑6B have not followed identical evolutionary trajectories.[2][3][4]

  • HHV‑6B still integrates into human chromosomes today and is found as inherited integrations in a fraction of modern individuals.[2][4][5]
  • HHV‑6A, by contrast, appears to have lost its ability to integrate into human DNA relatively early in its history.[2][3][4]

This divergence illustrates how even closely related viruses can adopt different strategies when adapting to the same host species. While one lineage maintains the capacity to become a permanent genomic hitchhiker, the other seems to have shifted away from that mode of interaction.

Are These Ancient Viral Stowaways Dangerous?

For most people, HHV‑6 infection in childhood causes mild or no symptoms, and recovery is complete.[4] However, like other herpesviruses, HHV‑6 can persist in the body in a latent state and reactivate under certain conditions, such as immune suppression.

In individuals with inherited chromosomally integrated HHV‑6, every cell carries a copy of the viral genome. Research in living populations has linked iciHHV‑6 to potential risks, including complications in organ transplantation and possible roles in inflammatory or neurological conditions, although many questions remain open.[5]

The new ancient DNA study does not directly answer whether carries of inherited HHV‑6 were sicker than their contemporaries. Skeletal remains rarely preserve clear signatures of such infections. However, by proving that integrated HHV‑6 has persisted across millennia, the research strengthens the case for studying how these viral sequences might influence modern health and immune function.[2][5]

What This Reveals About Virus–Human Coevolution

Viruses and humans are locked in a long-term evolutionary dance. The new findings offer a rare, time-resolved glimpse into that relationship.

1. Direct evidence, not just modern clues

Previously, estimates about how long HHV‑6 has been associated with humans came from patterns in present-day genomes and molecular clock models. Some genetic data hinted that the virus may have been evolving with humans since our species’ migration out of Africa.[2][4]

By recovering actual ancient viral genomes from Iron Age and medieval remains, researchers now have concrete proof that HHV‑6 was already established in human populations at least 2,500 years ago.[2][3][5]

2. Viruses can shape—and be shaped by—our genomes

The fact that HHV‑6 can integrate into human chromosomes, remain there for thousands of years, and be transmitted like any other genetic trait underscores how infectious agents can become long-term genomic residents. Over evolutionary timescales, such integrations can potentially influence:

  • Regulation of nearby human genes,
  • Immune responses, and
  • Susceptibility or resistance to other pathogens.

Other viruses, especially retroviruses, have left far more extensive footprints in our DNA, with endogenous retroviral sequences making up a notable fraction of the human genome. HHV‑6 shows that even non-retroviral DNA viruses can leave enduring marks.[4][5]

3. Ancient DNA as a tool for infectious disease history

The study also highlights how advances in ancient DNA technology are transforming the history of disease. By screening thousands of archaeological samples, scientists can now detect rare viral sequences and reconstruct the deep evolution of pathogens that leave no obvious skeletal lesions.[2][5]

This approach is already reshaping our understanding of plague, tuberculosis, and other diseases. HHV‑6 adds to the growing list of pathogens whose ancient genomes can now be studied directly rather than inferred.[4][5]

Why This Matters Today

Beyond satisfying scientific curiosity, there are several reasons why tracing herpes evolution through Iron Age skeletons matters for modern medicine and public health.

  • Refining risk estimates: Knowing how long inherited HHV‑6 has persisted—and how often it has arisen independently—helps calibrate studies of its impact on disease risk today.[5]
  • Improving transplant and infection management: Because HHV‑6 can reactivate under immune suppression, understanding its long-term human history and integration patterns can inform how clinicians monitor at-risk patients.[5]
  • Anticipating future viral behavior: The contrasting evolutionary paths of HHV‑6A and HHV‑6B highlight how viral strategies can shift over time, a lesson that is highly relevant for emerging infections and long-term pandemic planning.[2][3][4]

Looking Ahead: What Questions Remain?

While the new research answers the “how long” question for HHV‑6 in humans, it opens up several new lines of inquiry.[2][5]

  • How far back in time do HHV‑6 integrations really go—could they predate the Iron Age, and can future work push the timeline deeper?
  • Do different integration sites in the human genome have distinct health consequences?
  • How often have HHV‑6 integrations arisen independently in different human populations around the world?

Addressing these questions will require combining large-scale modern genomic datasets with expanded ancient DNA sampling from beyond Europe.

Conclusion

Iron Age skeletons, medieval burials, and modern genomes are telling a coherent story: some herpesviruses have been part-time invaders and part-time passengers in human DNA for at least 2,500 years.[2][3][4][5]

Far from being a fleeting childhood infection, Human Herpesvirus 6 has left a durable imprint on our chromosomes—one that still shapes the biology of people living today. As ancient DNA research advances, we are likely to discover that many more viruses, once thought of only as enemies, are in fact long-standing companions written into our genetic code.

Further Reading

References

  1. https://www.aol.com/articles/scientists-analyzed-ancient-dna-discovered-133000511.html
  2. https://www.sciencedaily.com/releases/2026/01/260106224628.htm
  3. https://www.eurekalert.org/news-releases/1111344
  4. https://www.discovermagazine.com/iron-age-dna-reveals-a-herpesvirus-that-still-infects-humans-today-48490
  5. https://www.science.org/doi/10.1126/sciadv.adx5460
  6. https://archaeology.org/news/2026/01/08/common-childhood-virus-detected-in-iron-age-remains/

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