A page from the York Gospels. Eraser rubbings left over from cleaning the pages of this manuscript revealed the ancient genomes of the animals used to produce the parchment. (Image: York Minster)
Innovative methods of utilising ancient protein and DNA analysis have revealed new information about medieval parchment and the animals from which they are made.
A group of researchers from Trinity College Dublin and the University of York have taken eraser rubbings – left over from the cleaning of medieval manuscripts – and extracted DNA and proteins from the waste. This method means that parts of the manuscript no longer need to be removed for destructive testing.
The group recently used this technique to analyse the pages of the York Gospels, an Anglo-Saxon book (c.1000 AD) containing the four Gospels of the New Testament, a letter from King Cnut, and land ownership documents, with interesting results.
Protein analysis was able to determine that most of the pages of the original Gospels were made from calfskin, whereas the later additions to the codex were made of sheepskin, possibly indicating spatial or temporal shifts in parchment production. The DNA analysis revealed that four out of the five sampled pages were made from female animals. It was also able to confirm which pages of the Gospels were most frequently handled by the higher presence of degraded human DNA.
This new technique could have major implications in terms of conservation. In the course of the study, it was discovered that many of the pages from the York Gospels contained the Saccharopolyspora bacteria, a genus that has been flagged as possibly causing measles-like spotting on parchment – which if not accounted for, can lead to degradation of the parchment.
It is hoped that future work using this method could potentially map medieval animal distribution and disease – periods when one type of animal skin may have been exchanged for another due to changing animal husbandry practices or short supply.
A preprint on these findings was recently released at bioRxiv, and can be read for free at: https://www.biorxiv.org/content/biorxiv/early/2017/07/24/146324.full.pdf. The Gospels are part of an exhibition in the undercroft of York Minister, which is open to the public. More information can be found at: www.yorkminster.org/visit-york-minster/minster-treasures/.
This article will appear in CA 333.