Deadly sheeppox DNA was hiding in the parchment of the 1,000-year-old York Gospels

Parchment is skin, and skin keeps records its makers never intended. A University College Dublin-led team reports that sheeppox virus DNA survives in the York Gospels, an illuminated manuscript about 1,000 years old from the early Anglo-Saxon period, and in other medieval books from Britain and continental Europe. ScienceDaily’s posting of the UCD release calls it the first genetic evidence that this destructive disease was spreading through European sheep flocks.

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Louis L’Hôte, a PhD candidate at UCD, is lead author. Kevin G. Daly, an associate professor in UCD’s School of Agriculture and Food Science, supervised the work, which drew in more than 30 institutions. The team pulled viral DNA out of the pages themselves, then compared what it found with modern virus sequences and with older material from the Bronze Age.

Reading a manuscript as a veterinary record

Sheeppox is deadly in the plain sense: it spreads quickly through a flock, can kill a high share of animals, especially young ones, and cuts wool, meat and milk output, as the Helmholtz Institute for One Health summary of the study describes it. Because parchment is made from animal skin, it can hold traces of infections the animal carried when it died. The researchers treated each page as a small sample of a medieval herd.

Several manuscripts carried sheeppox DNA on multiple pages, which suggests infected animals supplied some of the skins. The York Gospels was one; another was the Corpus Glossary at Corpus Christi College, Cambridge, one of the earliest English dictionaries. Daly said in a Technology Networks piece that parchment making has been considered a vanishing craft, but researchers are beginning to see how much of the past it retained.

The virus also turned up on calfskin and goatskin. Sheeppox mainly infects sheep, so the authors weigh two readings: a rare infection of other livestock, or contamination while the skins were being made into parchment.

The project reads like a roster of disciplines. The author list runs to 36 names and includes geneticists, historians, virologists, protein chemists and conservators. Trinity College Dublin, the University of Leicester, Cambridge University, the University of Copenhagen, Paris 1 Panthéon-Sorbonne and the Helmholtz Institute for One Health took part, with funding from Taighde Éireann-Research Ireland and the European Research Council. L’Hôte said recording ancient pathogen DNA has changed how historians understand infectious disease in the past, and the parchment results extend that to livestock, whose losses shaped wool, meat and milk supplies in medieval economies.

Bronze Age teeth and the 3,700-year timeline

The oldest sheeppox traces came from a different material. Sheep teeth from Bronze Age pastoralist settlements on the Eurasian steppe held viral DNA, pushing the disease’s documented presence back more than 3,700 years. Archaeology Magazine’s account counts 21 new ancient sheeppox genomes spanning roughly 1700 BCE to the Early Modern period.

Comparing those genomes with modern sequences, the team estimated that the sheeppox, goatpox and lumpy skin disease lineages split from one another between about 11,500 and 3,700 years ago. The authors link that window to livestock domestication and the movement of sheep from the steppe into Europe.

Those 21 genomes fill the long middle of the timeline: the Bronze Age teeth anchor the oldest end, and the manuscripts supply sequences from the centuries when parchment was the standard writing surface in Britain and on the continent. Sheeppox is not the only poxvirus in the picture, because the same lineage split produced goatpox and lumpy skin disease viruses.

Stability is the other finding. Unlike smallpox, the sheeppox genome changed little over the last several thousand years, L’Hôte said. The authors suggest that earlier genetic changes, before the span they sampled, may have been what let the virus become a sheep pathogen in the first place.

A paper’s dates, a preprint, and a live outbreak

The research appeared in Science Advances, volume 12, issue 36, in early September, according to the Helmholtz summary, which is dated Sept. 8 and names Sébastien Calvignac-Spencer of the Helmholtz Institute for One Health as supervisor of the evolutionary analyses. Calvignac-Spencer said the better researchers understand past changes and their consequences, the better prepared people are. The ScienceDaily page, posted Nov. 11, cites an earlier bioRxiv preprint with DOI 10.64898/2026.02.23.707469, so the same work has circulated in two forms, and the reported span varies between 3,500 and 3,700 years depending on the passage.

The subject is not purely historical. The Microbiologist’s report and ScienceDaily’s posting both note an ongoing sheeppox outbreak in Greece, where L’Hôte says it is causing significant economic damage. The journal paper is registered under DOI 10.1126/sciadv.aeh3571.

What the pages cannot yet settle is whether the calfskin and goatskin hits are real cross-species infections or workshop contamination. The authors flag both possibilities without choosing, and the York Gospels results alone do not say which flocks supplied its skins.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.