A virus that became woven into the human genome
Buried within the bones of Iron Age and medieval Europeans, scientists have found something quietly astonishing: the genomic signatures of viruses that still live within us today. Researchers from the University of Vienna and University of Tartu have reconstructed ancient genomes of HHV-6A and HHV-6B — herpesviruses that infect nearly all of humanity in early childhood — proving that these pathogens have been weaving themselves into human DNA, and passing through human generations, for at least twenty-five centuries. The discovery reframes these viruses not as modern medical curiosities but as ancient companions in the long human story, their fates and ours entangled since before recorded history.
- A team screened nearly 4,000 skeletal samples from archaeological sites across Europe, a painstaking search made harder by the fact that only 1% of people carry the chromosomally integrated viral copies most likely to survive in ancient remains.
- Against those odds, eleven ancient viral genomes were recovered — the oldest from a young girl in Iron Age Italy dating to between 1100 and 600 BCE — shattering assumptions that these viruses were only recently identified pathogens.
- The genomes revealed that HHV-6A and HHV-6B diverged in a critical way: HHV-6B retained the rare ability to insert itself permanently into human chromosomes and be inherited like any other genetic trait, while HHV-6A appears to have lost this capacity long ago.
- That inherited integration is not merely evolutionary trivia — carrying HHV-6B in every cell of the body has been linked to angina and heart disease, giving this ancient genomic archaeology direct relevance to modern clinical risk.
- Ancient carriers have now been identified from the British Isles for the first time, offering a historical anchor for why inherited HHV-6 is more prevalent in Britain today than elsewhere in Europe.
Buried in the bones of people dead for millennia is a story about viruses and humans that science has only just begun to read. Researchers from the University of Vienna and University of Tartu have reconstructed the genomes of HHV-6A and HHV-6B — two herpesviruses that still infect roughly 90% of children by age two — from archaeological remains more than two thousand years old. Published in Science Advances, the work offers the first direct genomic proof that these viruses have been living inside human bodies, and integrating into human DNA itself, since at least the Iron Age.
What makes HHV-6 unusual among viruses is its capacity to insert itself directly into human chromosomes, transforming a viral infection into an inherited trait passed from parent to child like any other genetic legacy. About one in a hundred people today carries these integrated copies in every cell of their body. It is precisely these inherited cases — rare in living populations — that are most likely to leave detectable traces in ancient skeletal remains, making them the key to unlocking the deep history of the virus.
The international team screened nearly four thousand skeletal samples from sites across Europe. Despite the long odds, they recovered eleven ancient viral genomes. The oldest belonged to a young girl from Iron Age Italy, dating to between 1100 and 600 BCE. Others came from medieval England, Belgium, Estonia, Italy, and early historic Russia. The Belgian site of Sint-Truiden was particularly striking, yielding evidence of both viral types circulating within the same medieval population.
Comparing these ancient sequences with modern viral genomes allowed the researchers to trace where integrations had occurred in human chromosomes and how they persisted across centuries. The data also revealed a meaningful divergence: HHV-6B retained its ability to integrate into human DNA, while HHV-6A appears to have lost this capacity at some point in the distant past — two closely related viruses that evolved along different trajectories while coexisting with the same hosts.
The implications reach into the present. Carrying an inherited copy of HHV-6B has been linked to angina and heart disease, and ancient carriers have now been identified from the British Isles for the first time — a finding that may help explain why integrated HHV-6 is more common in Britain today than elsewhere in Europe. When these viruses were first discovered in the 1980s, they seemed like newly identified pathogens. The ancient DNA record has rewritten that story entirely, revealing a coevolution stretching back at least twenty-five centuries and still shaping human health today.
Buried in the bones of people who died thousands of years ago is a story about viruses and humans that scientists have only just begun to read. Researchers from the University of Vienna and University of Tartu have reconstructed the genomes of human betaherpesvirus 6A and 6B—two viruses that still infect most of us today—from archaeological remains more than two millennia old. The work, published in Science Advances, offers the first direct genomic proof that these viruses have been living inside human bodies, and sometimes integrating into human DNA itself, since at least the Iron Age.
HHV-6B is a virus most people encounter in early childhood. It infects roughly 90 percent of children by age two and is the leading cause of febrile seizures in young kids, a condition known as roseola infantum or "sixth disease." Like other herpesviruses, it typically causes a mild illness and then settles into a dormant state that lasts for life. What makes HHV-6 unusual, though, is that it can do something most viruses cannot: it can insert itself directly into human chromosomes. When this happens, the viral DNA becomes part of the host's own genetic code and can be passed down to offspring like any other inherited trait. Today, about one in every hundred people carries these inherited viral copies in every cell of their body—a living record of an ancient infection that became woven into the human genome.
To find evidence of this ancient integration, an international team screened nearly four thousand skeletal samples from archaeological sites across Europe. The work was painstaking. As Meriam Guellil, the lead researcher at Vienna's Department of Evolutionary Anthropology, explained, finding these viral sequences in ancient remains is extraordinarily difficult because only about one percent of people carry integrated copies—the very cases most likely to survive in the archaeological record. Despite these odds, the team identified and reconstructed eleven ancient viral genomes. The oldest came from a young girl who lived in Iron Age Italy between 1100 and 600 BCE. The others spanned centuries and continents: both types of HHV appeared in medieval England, Belgium, and Estonia, while HHV-6B also turned up in samples from Italy and early historic Russia. The Belgian site of Sint-Truiden yielded the most cases, with both viral species circulating within the same medieval population.
What the ancient genomes revealed is a portrait of deep coevolution. By comparing the recovered sequences with modern viral genomes, the researchers could pinpoint where in the chromosomes the viruses had integrated and trace how those integrations persisted across generations and centuries. Some integrations had occurred so long ago that they had been passed down through thousands of years of human history. The data showed something else striking: HHV-6A appears to have lost its ability to integrate into human DNA at some point in the distant past, while HHV-6B retained this capacity. This suggests the two viruses, though closely related, evolved along different trajectories while coexisting with their human hosts.
The implications extend beyond evolutionary curiosity. Charlotte Houldcroft, a geneticist at the University of Cambridge, noted that carrying an inherited copy of HHV-6B has been linked to angina and heart disease. The ancient genomes also revealed that inherited forms of both viruses are more common in Britain today than elsewhere in Europe—and now, for the first time, there is archaeological evidence of ancient carriers from the British Isles. Understanding how these viruses integrated into the human genome in the past may help explain why some people today carry them and what health consequences that inheritance carries.
When HHV-6A and HHV-6B were first discovered in the 1980s, they seemed like newly identified pathogens. The ancient DNA work has rewritten that story. Genetic data from modern populations had long suggested these viruses might have been evolving alongside humans since our species migrated out of Africa. Now there is concrete proof. The genomes recovered from Iron Age remains and medieval burials provide the first direct evidence that HHV-6 has maintained a presence in human populations for at least twenty-five centuries, integrating into our chromosomes, being inherited, and shaping the genetic landscape of disease susceptibility across generations and continents. What began as a search through thousands of archaeological samples has opened a new chapter in understanding how viruses and humans have written their histories together.
Citas Notables
These ancient genomes now provide the first concrete proof of their presence in the deep human past.— Meriam Guellil, University of Vienna
Carrying a copy of HHV-6B in your genome has been linked to angina and heart disease.— Charlotte Houldcroft, University of Cambridge
La Conversación del Hearth Otra perspectiva de la historia
Why does it matter that we found these ancient viral genomes? We already know the virus exists today.
Because it proves something we could only guess at before—that this virus has been living inside us for thousands of years, not just decades. It changes how we think about what's "natural" to the human body.
You mentioned that only one percent of people carry inherited copies. That seems rare. Why would scientists focus on such a small group?
Exactly because it's rare and ancient. Those inherited copies are like time capsules. If a virus integrated into someone's chromosome two thousand years ago, and their descendants kept passing it down, we can actually see that lineage in the DNA. It's the only way to prove the integration happened in the deep past.
The article mentions HHV-6B is linked to heart disease. Does that mean everyone with the inherited virus will get angina?
Not necessarily. The link exists, but inheritance is just one factor among many. What matters is that we now know this virus has been part of some human genomes for millennia. If we understand why certain populations carry it more than others, we might understand disease patterns better.
Why did HHV-6A lose the ability to integrate while HHV-6B kept it?
That's the real mystery. They're closely related viruses, but they evolved differently while living in the same human populations. The ancient genomes show us that divergence happened, but not why. That's a question for the next study.
Does this change how we should think about treating these viruses today?
It reframes the question. Instead of asking how to eliminate a virus that infects ninety percent of children, we might ask why it's so successful at coexisting with us, and what role the inherited copies play in modern health. That's a different conversation entirely.