Long before musty old paper volumes and Google Book Search, most tomes in medieval Europe were written on animal skins—a practice which might now hold the key to tracing their origins.

Timothy Stinson, an associate English professor at North Carolina State University in Raleigh, has started using DNA testing to track the history and age of medieval manuscripts. His goal: to create a DNA database from the books with known publication dates and places (such as calendars and histories) in an effort to use the genetic information gleaned from them as a baseline to date those manuscripts whose backgrounds are unknown.

"There are these tantalizing hints that this would work for parchment," he says of the DNA testing, "but no one was really using it." He says that in addition to tracing the roots of written documents, genetic clues may help piece together manuscripts that were separated over time.

Thousands of fragile manuscripts still survive from the Middle Ages (roughly 400 to 1500 CE), a time when most of Europe's population was illiterate, and monks transcribed nearly all of the books that circulated around the continent. Until recently, scholars relied on visual analysis (such as handwriting samples) to trace the origin of most ancient texts. But Stinson says that more precise genetic analyses are possible because the preferred "paper" of the day was thin parchment made from the skin of local cattle, sheep or goats. "DNA offers much more specific information, but no one's mapped it yet," he says.

Stinson and his team tested five pages from a 15th-century French manuscript and found genetic material from at least two different cows. "If you can do this to a 2,000-year-old mummy," Stinson says, "you can do this to a book from the 15th century."

DNA testing has previously been used to study Greek manuscripts as well as the Dead Sea Scrolls. Nikos Poulakakis, an assistant professor of biology at the University of Crete in Greece who conducted some of that research, says he's eagerly awaiting the results of the U.S. study. He notes that in addition to revealing important information about old manuscripts and library collections, the genetic material may also shed light on ancient trade routes and even domestic animal herds of the time.

Medieval manuscripts often were written on pages made from the skins of as many as 100 different animals, according to Stinson. But scholars speculate that, at least until the mid-15th century, most books were made from local herd animals, which could make tracing their point of origin fairly reliable.

Tom Gilbert, a geneticist at the University of York in England, points out, however, that, "working with material from domestic animals is tricky." Many animals within a herd may be closely related—or even identical twins—and parchments may have been treated with other animal products, either during creation or previous conservation, which could confuse results. Stinson will present his findings later this month at the Bibliographical Society of America in New York City.