Millions of documents stored in archives could provide scientists with the key to tracing the development of agriculture in the British Isles over the last 700 years, according to new research at the University of York and Trinity College Dublin.

But the crucial information the documents hold is not contained in their texts but the parchment on which it is written.

Researchers in Dublin and York used the latest scientific techniques to extract ancient DNA and protein from tiny samples of parchment from documents from the late 17th and late 18th centuries. The resulting information enabled them to establish the species type of animals from which the parchment was made.

It therefore gives scientists a potentially unrivalled resource to analyse the development of livestock husbandry across the centuries. The research is published in Philosophical Transactions of the Royal Society B.

Researchers in the Centre for Excellence in Mass Spectrometry at York extracted collagen (protein) from two tiny (2x2cm) samples of parchment provided by the University's Borthwick Institute for Archives. Scientists at Trinity College extracted DNA from the same parchment samples.

The first sample showed a strong affinity with northern Britain, specifically the region in which current black-faced breeds such as Swaledale, Rough Fell and Scottish Blackface are common. The second sample showed a closer affinity with the Midlands and southern Britain where the livestock Improvements of the later 18th century were most active.

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If other parchments show similar levels of endogenous DNA content, resulting DNA sequencing could provide insights into the breeding history of livestock particularly sheep breeding before, during and after the agricultural improvements of the 18th century that led to the emergence of regional breeds of sheep in Britain.

Professor Matthew Collins, of the Department of Archaeology at York, who heads the University's BioArCh research centre, said: "We believe the two specimens derive froman 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.

"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."

Professor of Population Genetics at Trinity College Dublin, Daniel Bradley, said: "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."

The research was funded by a grant from the European Research Council.

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Parchment a huge reservoir of DNA information

Before the mass production of paper, parchment was the major medium for legal documents and until the widespread adoption of typewriters, they were a clerk's preferred medium for many formal legal documents and records. Parchment has a number of properties that make it compelling material for DNA extraction and analysis.

Parchments are made from the skins of domestic animals, particularly livestock, and their manufacture results in robust artefacts, which can survive intact for many centuries. Secondly, they are abundant and because of their enduring legal value theyhave been carefully managed.

In the 20th century, this has included protecting them from both high temperatures and fluctuating humidity.

Thirdly, unlike bone remains, of which only a small percentage have been excavated, parchments are above ground, archived and in the case of legal documents, directly related to specific dates -- a level of resolution largely unachievable with any other historic DNA source. Even undated documents can be dated palaeographically to a resolution better and more cheaply than radiocarbon dating.