The secret hidden in these ancient manuscripts isn’t written in ink

Parchment is made from animal skin and was used for thousands of years across Europe, the Middle East, and parts of Africa. It served as the material for many kinds of written records, including legal documents and maps. Because the skins retain biological material, parchment can preserve genetic clues alongside the words written on its surface.

"Because they are made from animal skins, it is often possible to extract genetic information from parchments," says Tim Stinson, corresponding author of a paper on this research and an associate professor of English at North Carolina State University. "That genetic information, in turn, offers us a window into the past, answering questions about things such as when and where a manuscript was made."

DNA Preserved in Ancient Parchment

The genetic information could reveal much more than the origins of individual documents. Since parchment was widely used for centuries, DNA recovered from it may help researchers investigate how domesticated animals changed over time, how different breeds emerged, and what diseases affected livestock.

"Because parchments have been in use for so long, and often record detailed historical information, the genetic information they contain can also shed light on the evolution of domesticated farm species, how breeds developed over time, livestock diseases and so on," says Matthew Breen, co-author of the paper and the Oscar J. Fletcher Distinguished Professor of Comparative Oncology Genetics in NC State's College of Veterinary Medicine.

Until now, one major obstacle has been access. Libraries, museums, and other institutions have understandable concerns about allowing researchers to take samples from rare and culturally important manuscripts if doing so might cause permanent damage.

"This paper is particularly important because one of the biggest challenges for this emerging field of genetic analysis has been gaining access to historic parchments, due to concerns that collecting samples would damage these culturally significant artifacts," says Stinson. "Our work shows that we can collect samples without harming the parchments, which is a big step forward."

Testing 91 Historic Manuscripts

To demonstrate the approach, the researchers collected cellular samples from 91 manuscripts housed in the Rubenstein Library at Duke University. The documents came from locations ranging from England to Ethiopia and were produced between the late eighth and early 20th centuries.

The sampling method is surprisingly simple. Researchers gently rub the parchment with a dry cytology brush, the same type of brush used for Pap smears. The brush picks up cellular material while leaving the historic document intact.

"Cytology brushes can be used when dry and do an excellent job of harvesting cellular material without damaging the integrity of the artifact being sampled," says Breen.

After collecting the cells, the team removes the material from the brushes and uses forensic-level, next-generation sequencing technologies to isolate and amplify genetic sequences.

"We're essentially using state-of-the-art technologies and genetic analytical techniques to get new, empirical information regarding historical cultural and agricultural practices," says Stinson.

A New Source of Historical Evidence

The ability to recover substantial genetic information without damaging the parchment could make institutions more comfortable allowing researchers to study valuable manuscripts.

"We've shown that we're able to extract a tremendous amount of new information from these parchments without harming them," says Breen. "This will hopefully engender trust with those organizations that are responsible for preserving these historic documents."

Researchers believe historic parchment represents a largely unexplored source of information that could connect genetics with questions traditionally studied by historians, archaeologists, and other scholars.

"We're excited about the potential of this field and are seeking funding that will allow us to explore that potential," says Stinson. "We've demonstrated that this is a vast, untapped source of historical information, and we want to continue this pioneering work."

"We have a remarkable opportunity here," says Breen. "It is essentially a whole new field, bringing together a truly interdisciplinary range of expertise spanning fields from genetics to medieval history."

The paper, "Adventures in the Animal Archive: New Techniques for the Genetic Analysis of Parchment Manuscripts," is published open access in the journal Manuscript Studies. The paper was co-authored by Melissa Scheible, a research associate at NC State; Rachael Thomas, a senior research scholar at NC State; Benjamin Callahan, an associate professor of population health and pathobiology at NC State; Nicholas Wagner, a postdoctoral research associate at Duke University; and Kelly Meiklejohn, an associate professor in forensic science at Western Sydney University.