The proteomic and isotopic analysis of parchment and their application to post-medieval sheep husbandry in Britain

The archives and libraries of Europe are full of dead animals. As the primary medium for writing for over 1000-years, tens of millions of durable parchment skins were manufactured, many of which survive to this day. While a few are illuminated Gospels or Royal Charters, the vast majority are mundane legal deeds concerning the ownership or right over property. When viewed simply as a textual resource, they are often considered to be of limited historic value and risk being deaccessioned or refused by archives. However, as a physical object they are an extraordinary high-resolution zooarchaeological and molecular archive, through which centuries of craft, trade and animal husbandry can be explored.

To explore the use of parchment as an isotopic resource, sheep, goat, pig and calfskin parchment was manufactured, identifying an impact from production on the measured values in fresh skin. The isotopic relationship between skin and bone was explored though paired samples to aid the integration of parchment results with bone collagen data; and a freeranging diet study undertaken on a modern flock of sheep to examine the isotopic spacing between diet, bone, skin and parchment. These results were used to interpret data from 663 British legal deeds dating from the 12th to 20th century. Species identification via peptide mass fingerprinting indicted an almost exclusive use of sheepskin parchment throughout the medieval and post-medieval period. δ13C and δ15N isotope analysis revealed information on the use of domestic and potentially imported skins, as well as a likely preference for the skins of young lambs. Insight was also provided into the increasing geographical range livestock and skins moved across Britain facilitated by transport developments.