Ancient parchment reveals centuries-old sheeppox DNA in European manuscripts

The Conversation and its partner researchers examine parchment—the durable writing material made from animal skins—and reveal that DNA can survive in parchment for well over a thousand years. From Maltese workshop observations to large-scale genomic analyses of parchment from central and western Europe, the study uncovers traces of disease-causing pathogens, notably sheeppox virus, in documents such as the York Gospels and the Corpus Glossary. The work raises intriguing questions about historical infections in livestock and how domestication and trade may have shaped pathogen evolution. The original study underscores parchment as a valuable, albeit fragile, archive of ancient biology.

• Ancient-DNA preserved in parchment is detectable long after production
• Parchment from AD 700–1400 yields traces of sheeppox virus DNA
• Three York Gospels pages contained viral DNA requiring careful surface erasure sampling
• Findings illuminate medieval livestock disease, animal domestication, and pathogen evolution

Author: The Conversation; Author provided: Kevin-Daly

Parchment as a biological archive

Humans and domesticated animals have lived in close contact for millennia, with parchment representing a robust, portable medium that allowed societies to record histories before mass-printed paper. In this study, researchers leveraged first-hand workshop experience from Malta to describe the conversion process from skins into parchment: soaking skins in lime-rich water, removing flesh and hair with blades, and stretching skins on frames to form taut membranes that are then smoothed for use. The authors highlight that parchment does not merely store written records; it also preserves biological material from the animals used to make it, including DNA, which can survive for centuries when archived properly. This positional combination of archaeology and genomics makes parchment a unique time capsule for both history and biology.

DNA survival and its implications for ancient pathogens

The authors report that DNA can persist in parchment even when fragmented, enabling retrospective biomolecular analyses centuries later. This raises the possibility that pathogens present at the time of an animal’s death could leave traceable genomic signatures in parchment. The study frames parchment as a potential reservoir of historical infection data, complementing other ancient DNA sources such as bones and teeth, and expands the scope of what researchers can learn about past livestock health and disease.

Sheeppox DNA in medieval parchments

Two projects based at the University of York and the Bodleian Library in Oxford analyzed parchment skins originating largely from central and western Europe, dating roughly AD 700–1400. The team found robust evidence for sheeppox virus DNA across a surprising proportion of parchments: 32 folia showed hints of the pathogen. Most notably, within the York Gospels—one of the rare pre-Norman Conquest gospels to survive the Reformation era—three pages contained viral DNA. The sampling process for this priceless artifact was tightly controlled, using erasers to remove only a minuscule parchment surface area for biomolecular extraction, demonstrating that careful, low-impact techniques can yield valuable genetic information from fragile historical materials.

Beyond parchment: older viral genomes

The investigation extended to other sources, including two sheep teeth from the Eurasian steppe about 3,700 and 3,200 years old, which also housed pathogen DNA. The Roman author Columella’s On Agriculture describes a “pusula” disease in sheep, which researchers now interpret as sheeppox, implying a long history of the pathogen in European flocks. Using the ancient viral DNA, the team estimated the divergence of sheeppox from related Capripoxviruses, with a median age around 5,000 years. These findings suggest that domestication and pastoralism across Eurasia created ecological opportunities for Capripoxviruses to adapt to new hosts, shaping modern pathogen distributions and risks.

Ongoing relevance and future work

Although sheeppox is currently uncommon in Europe, outbreaks in southern Europe since 2024 highlight the importance of understanding the biology of Capripoxviruses to guide interventions and anticipate how pathogens may evolve to infect new hosts. The researchers also propose expanding ancient genome analyses to parchments from other regions, including goatskin documents, which may reveal further insights into host range and historical viral evolution. A key unresolved question is cross-contamination during parchment preparation; distinguishing between true ancient infection signatures and artefacts remains a critical area for methodological refinement.

Conclusion

By combining biological data with the documentary record preserved in parchment, the study offers a nuanced view of how early agriculture and animal husbandry intersected with infectious disease dynamics. It demonstrates parchment’s value as a living archive, capable of informing both archaeology and epidemiology about ancient life and its lessons for today’s animal health and disease preparedness.