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Ancient parchment's secrets revealed through DNA

A history of agriculture is locked away in centuries worth of documents from the British Isles -- if you know how to find it.

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Sewn repair in Archbishop's Register 7 Greenfield, 1306 - 1311. By permission of The Borthwick Institute for Archives

Over the last 700 years, the history of agriculture in the British Isles is more or less known, through the use of record-keeping and physical evidence such as tree rings. However, no historical record will ever be utterly 100 percent complete and there is much that is unknown or unconfirmed.

Millions of documents stored around the British Isles could clarify -- even define -- the development of agriculture in the British Isles. Yet it is not what is written on the parchment that will provide the key -- it is what is hidden inside.

Parchment was used as a medium on to which to scribe documents and bind into books. The famous illuminated manuscripts, for example were written on vellum -- a particularly fine type of parchment. Its use was widespread -- seeing its apex in the Middle Ages. Yet this material was not made out of paper, instead, it was made from specially treated and stretched animal skins, such as cows, sheep and goats. Vellum was made from calfskin, and was considered the finest writing material available.

It is by using scientific techniques and equipment on this material that researchers from Trinity College Dublin and the University of York have been able to discover information -- by extracting and identifying the parchment's DNA.

"You can get DNA out of bones, but one of the problems with bones is that the DNA is not always terribly well preserved," Trinity College Dublin Professor of Population Genetics Daniel Bradley explained. "Now the thing about parchments is that parchments are precious materials, and as such, they've been kept in libraries or archives or scriptoria."

Studying the history of the domesticated animals from whose skin parchment is made amounts to a study about humans at the same time.

The test for this new technique were two 2x2cm scraps of parchment -- one from a late 17th century document, the other from a late 18th century document. Parchment is made up mostly of the protein collagen. Researchers from the Centre for Excellence in Mass Spectrometry at York extracted some of this collagen, as well as DNA, from the parchment samples.

The team then used ultra-high throughput sequencing to identify the DNA.

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Parchment manufacture marks in Archbishop's Register 41b Musgrave, 1853 - 1858. By permission of The Borthwick Institute for Archives

What they found was that the 17th century sample was consistent with northern Britain, where black-faced sheep breeds such as Swaledale, Rough Fell and Scottish Blackface are common; and the second sample was more in line with the Midlands and southern Britain, during the agricultural improvements of the late 18th century that led to the emergence of regional breeds.

"We believe the two specimens derive from an unimproved northern hill-sheep typical in Yorkshire in the 17th century, and from a sheep derived from the 'improved' flocks, such as those bred in the Midlands by Robert Bakewell, which were spreading through England in the 18th century," said University of York Professor of Archaeology Michael Collins.

"This pilot project suggests that parchments are an amazing resource and there are millions stored away in libraries, archives, solicitors' offices and private hands. They can give us significant data about the source animal and using them we can learn an enormous amount about the development of agriculture in the British Isles. We want to understand the history of agriculture in these islands over the last 1,000 years, and with this breath-taking resource, we can."

Other parchments could reveal much about livestock diversity in the country; when new breeds were introduced, for example, or changes in breeding techniques, or whether people had to introduce new animals in the wake of a disaster.

"Wool was essentially the oil of times gone by, so knowing how human change affected the genetics of sheep through the ages can tell us a huge amount about how agricultural practices evolved," Professor Bradley said.

The full study, "Paging through history: parchment as a reservoir of ancient DNA for next generation sequencing", can be found online in the journal Philosophical Transactions B.