In May 2006, Tim Stinson traveled to England to visit libraries in London, Oxford and Cambridge. At the time, he was editing a 14th-century poem for his doctorate at the University of Virginia in Charlottesville, and after months of poring over grainy microfilm copies, he couldn’t wait to get his hands on an original. On a visit to the Bodleian Libraries in Oxford – a place so magical that scenes from the Harry Potter films were filmed there – he was finally handed one of the manuscripts he had traveled all this way to see. But he found himself so fascinated by the physical book that the text it contained became secondary.
The volume was about six centuries old, bound in worn brown leather and composed of 266 yellowed sheets of carefully crafted parchment. It bore the marks of heavy use: light stains marked the pages and the edges were worn from repeated handling.
“It had its own biography, its own deep history. It looked like an archaeological site between the covers,” recalls Stinson, now a medievalist at North Carolina State University in Raleigh. “The parchment even had a vague animal smell, although pleasant.”
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Stinson wondered whether DNA might survive in the animal skins used to make the book’s pages, and whether that DNA might offer new ways to date and contextualize manuscripts beyond the conventional markers of handwriting and dialect. His brother, a biologist, said it was theoretically possible, but warned that the technological hurdles were daunting. The technologies needed – next-generation sequencing methods and associated computational tools to decipher the data – were still in their infancy. Even if effective techniques existed, conservators were unlikely to allow destructive sampling of irreplaceable cultural objects.
Nearly two decades later, this curiosity has helped give rise to a new field. The development of non-destructive sampling methods, along with advances in genomics and proteomics, have made it possible to extract biological information from ancient scrolls without visibly damaging them. The emerging discipline – known as biocodicology – combines molecular biology with codicology, the study of books as material objects.
The findings are transforming the way researchers understand human history. By analyzing the scroll, researchers discover evidence of trade networks, animal husbandry, medical and ritual practices, climate change, epidemics and floods.
In doing so, they discovered that ancient scrolls preserve more than just words.
A biological archive
In medieval times, parchment was the dominant writing material in Europe, used for everything from legal documents to sacred texts. It was made by soaking animal hides in lime, stretching them over frames, and scraping them finely as they dried. Even after hundreds of years, the parchment bears subtle traces of this process: follicular patterns on the hair side, smoother textures on the flesh side, and variations that experienced scholars can read almost intuitively. Its durability has long made medieval manuscripts prized historical objects.
In a 2009 article, Stinson argued that the parchment manuscripts represented an annual record of animal life and human-animal interactions spanning a millennium. Why, he asked, have zooarchaeologists focused on digging for bones when a vast, precisely dated wildlife archive has sat on library shelves for centuries?
The idea caught the attention of Matthew Collins, a biomolecular archaeologist based jointly at the University of Copenhagen and the University of Cambridge, UK. Collins had developed a technique known as zooarchaeology mass spectrometry (ZooMS) to identify animal species from old bones. ZooMS works by analyzing fragments of type I collagen, the predominant structural protein in skin, teeth and bones. Species-specific variations in collagen produce distinctive molecular “fingerprints” when measured in a mass spectrometer.
Collins recalls an excavation project in Scotland for which his team analyzed more than 1,000 bone fragments. After three years, they could confidently identify only 29 individual animals. “It was a really disappointing project,” he says. When he realized that parchment was made from a similar material, rich in collagen – and that manuscripts commonly announced when and where they were made – Collins was eager to explore its scientific potential.
Without a trace
Sarah Fiddyment was completing a PhD in cardiovascular proteomics at the University of Zaragoza in Spain when a chance conference on the application of scientific techniques to cultural heritage inspired her to pursue a postdoc with Collins. Collins asked him to develop a method of identifying animal species on parchment. Fiddyment planned to obtain samples by shaving a thin strip off the edge of the manuscript. But when she arrived at the Borthwick Institute for Archives in York, UK, the conservators refused to let her approach their documents with a knife. “I was indeed faced with a two-year project that was not going to come to fruition. »
This impasse reflects a long-standing divide between the sciences and the humanities – what the British novelist and physicist CP Snow called the two-culture problem. Scientists are accustomed to drilling into fossil cores or cutting off feathers, while scholars generally consider even the smallest wound on a medieval page anathema. Any method of sampling biological material contained in parchment would therefore have to clear an unusually high bar: its effects would have to be effectively invisible, even under a microscope.
Collins recalls this tense moment in the Borthwick archives as a turning point. “‘No’ is a very powerful word for scientists,” he said, “because it kind of makes you think.” Fiddyment spent a month at the archives observing the conservators. She noticed that they regularly cleaned the parchment with large white erasers, the kind that adorn many elementary school desks. So she asked if she could have the eraser crumbs. “These little fragments that you generate and blow away, those are the pieces that I collected, and we found that it worked wonderfully.”
The crumbs, which they later called “erdu” for gum dust, turned out to be molecular gold. When a polyvinyl chloride eraser is pushed across parchment, static electricity lifts microscopic particles from the surface, including collagen and traces of DNA. Fiddyment analyzed the crumbs it collected using a version of the ZooMS protocol it called eZooMS.
Fiddyment tested its approach on 13th-century “pocket Bibles,” whose paper-thin pages were long thought to come from the skins of animals such as squirrels and rabbits. His analysis showed the opposite. Parchment was made from the usual materials: calf, goat or sheep skins. This discovery does not highlight the use of unusual materials, but rather the fact that it involves extraordinary craftsmanship.
But other studies have raised more questions than answers. Stinson remembers the first book he worked on with Fiddyment and Collins: a 12th-century glossy copy of the Gospel of St. Luke. To his trained eye, the manuscript appeared to be made entirely of calfskin. “When the results came in, everyone was blown away,” he says. Tests revealed a voluntary alternation between calfskin and sheepskin. Goat skin was also present, but only immediately after the parable of the prodigal son, which includes the only mention in the text of a kid goat. “Now it could be a coincidence, we don’t know,” Stinson says. “But this book is profoundly weird.”
Reading residuals
Although effective, the method is laborious. This involves rubbing the same piece of parchment until enough crumbs accumulate to fill the bottom of a microcentrifuge tube. At the Duke University Rare Book Library in Durham, North Carolina, Stinson spent days sampling a single volume. “Honestly,” he said, “it’s like tennis elbow after two days of this.”
While searching for less punitive alternatives, Stinson teamed up with colleague Kelly Meiklejohn, a forensic pathologist whose experience includes a postdoctoral stint at the FBI laboratory in Quantico, Virginia. There, she developed methods to identify toxic plants and fungi that had been used as potential biological weapons. These were often in powder form and lacked obvious identifying signs.
The team tried a range of non-destructive methods on old manuscripts purchased online. Some ideas were quickly dismissed: the dull edge of a butter knife, forensic fiber-lifting tools used at crime scenes, and even gecko tape, which has microscopic bumps that allow it to adhere to surfaces without the use of chemical adhesives. Although technically non-destructive, the tape remained stuck to laboratory clamps and tubes and contained traces of cow DNA, presumably from the manufacturing process.
Ultimately, the researchers focused on two nondestructive approaches: erasers and soft cytology brushes, the disposable tools used for cervical screening tests. Comparisons showed that brushes were easier to use and recovered DNA as effectively as erasers.
The DNA extracted from the parchment is usually fragmented into tiny pieces and present in quantities too small to be detected using standard tests. But “we do it on every sample,” Meiklejohn says, because his lab uses a forensic-style workflow designed for this type of genetic material.
His team converts the DNA into sequencing libraries and uses a technique known as capture hybridization to extract animal sequences of interest. Magnetic RNA “baits,” designed to match the mitochondrial genomes of species commonly used in parchment, bind to the target DNA even when the sequences differ by up to 20% from modern genomic references. The enriched material is then sequenced and mapped against a panel of 16 reference genomes, including those of humans, dogs, pigs and various deer species.
On a computer screen, the results appear as a dense, staggered stack of brightly colored horizontal bars – short stretches of ancient DNA aligning imperfectly but convincingly with modern references. In repeated testing, results obtained with the brush method matched known species identifications and often exceeded expectations.
However, this approach has its logistical quirks. When Meiklejohn struggled to find the right cytology brushes before a planned research trip to the UK, she used the opportune moment during her annual gynecological exam to ask where they were purchased. The clinic offered to provide him with a few bags, but another supplier eventually managed to come through.
Beyond species
Working with Duke, the team applied its brush cytology technique to documents spanning a wide range of time and space, sampling parchments spanning the eighth to twentieth centuries and from Europe, North Africa, and the Middle East. The results, which have not yet been published, are based on 351 samples taken from 91 manuscripts. Researchers identified the source species in 58% of cases. Most of the samples came from sheep, followed by cattle and goats, with just one curious sample indicating pigskin. They found that species choice mainly followed regional patterns; for example, sheep were the main species used in England and goats in Mediterranean regions.
A 13th-century Greek New Testament features a tantalizing near-match with the red deer (Cervus elaphus hippelaphus), but the signal fell just below the threshold required for definitive identification.
During a visit to Duke, I joined Stinson as he collected additional samples of this mysterious manuscript. In a quiet reading room, Andrew Armacost, curator of rare book collections, had arranged several volumes of medieval manuscripts along a long table, under bright, even light. The book’s pages were dense with elegant writing in black and red ink – some bound in dark, cracked leather, others reduced to simple, orphaned sheets. As we watched, Stinson donned gloves, set a timer, and gently swept a brush in slow circles over a blank spot of parchment for a minute before snapping the brush head into a tube.
Arma Costs has had to refuse requests for destructive sampling from otherwise promising projects, unwilling to see even an inch cut from the collection. He is excited to see non-destructive methods take hold and curious to know what they might reveal. “We have always thought about [parchments] as textual resources,” he says, “but perhaps they also have many other stories to tell. »
An expanding field
These stories are beginning to come to light. Today, scientists can determine the sex of source animals, classify specific breeds and detect pathogens. For example, researchers have detected clavate in many parchment samples. Because the virus evolves slowly – about one mutation every two years – scientists can use phylogenetic analyzes to date a given strain over a period of about 50 years.
Biocodicology can also allow scientists to reconstruct how ancient manuscripts were handled and the environments in which they circulated.
Salt, for example, was essential to the production of medieval parchment. Since various regions rely on distinct types of salt, salt-loving — or halophilic — bacteria left on the skin can serve as geographic signatures.9. Even insect damage tells a story. “Bookworms” are actually the larvae of various furniture beetles that burrow into the bindings of medieval books. The exit holes and DNA left behind by the larvae reveal where the insects – and the books – existed. Remarkably, the distribution of these beetles closely follows the geographic boundaries of the Protestant Reformation. “We call them Protestant and Catholic beetles,” says Stinson.
Non-destructive methods can also reveal practices rarely documented in texts. Fiddyment used eZooMS to sample the residue of a medieval birth belt, a religious talisman worn to protect women during pregnancy and childbirth. In a belt from the end of the 15th century, she found traces of cervicovaginal fluid as well as traces of goat’s milk, eggs, honey and various species of plants, ingredients taken from medieval childbirth recipes. “It was the first kind of direct evidence,” Fiddyment says, “that people actually wore it.”
Some scientists even use biocodicology in climate science. To reconstruct historical precipitation patterns, Collins’ group developed a solvent-based aspiration technique to extract lipids from ancient parchment. Oxygen isotopes preserved in lipids record past precipitation and temperature levels, allowing researchers to detect global climate events such as the “year without a summer” of 1816, which followed the 1815 volcanic eruption of Mount Tambora in Indonesia. Taken on a large scale, Collins suggests, parchment could rival tree rings as a climate record.
The future
But the ability to address such broad questions varies widely. While U.S. researchers have faced significant funding losses, Europe has committed more than €20 million ($23 million) to biocodicology through European Research Council initiatives such as Beasts to Craft and CODICUM. Collins says some funding agencies enjoy pushing technologies to their limits, in part because methods developed for ancient manuscripts can have broader applications to modern problems such as food safety, medicine and forensics.
Stinson lost his grant from the US National Endowment for the Arts, but he managed to make another research trip to the UK last June with funding from his university. This time he visited the Norfolk Record Office in Norwich, where he collected 100 brush samples from the historic manor court rolls. The volume of biological material available was staggering: the archives contained 1.7 million parchment items, far more than he could hope to sample in his lifetime. “It’s just one county,” he said. The UK National Archives in London “has miles and miles” of shelves of scrolls. “We’re talking about a massive, massive wildlife archive. No one has ever designed it that way.”
At the Norfolk office, Stinson was given a badge that allowed him to roam freely around the premises, with the stern warning that if an alarm was triggered, he would have only moments to leave before the fire suppression system sucked all the oxygen from the room.
He doesn’t need to remind him to be careful. These ancient objects are valuable not only because of the text on their pages, but also because of the biological stories they contain, waiting to be read.
This article is reproduced with permission and has been published for the first time April 7, 2026.