Many stories from the Middle Ages never reached the present. A new study suggests the loss was far greater than scholars once thought. Researchers estimate that up to 60% of medieval literary works and more than 95% of the manuscripts that once carried them have disappeared over time.
Old French chivalric narratives around Europe (years 1100–1500). Credit: Camps, J.-B., Randon-Furling, J., & Godreau, U., PNAS Nexus (2026)
The study, published in PNAS Nexus, looked at chivalric tales written from the 12th century onward. These include famous works like the Song of Roland, along with many stories whose names are now forgotten. The team combined computer models with data from about 2,000 medieval manuscripts copied across four centuries.
Before the printing press, every book had to be copied by hand. Each new copy introduced small changes, whether through mistakes, edits, or deliberate additions. Over generations of copying, these changes spread through families of manuscripts. Scholars use those shared changes to build family trees, known as stemmata, which show how surviving copies are linked.
Those family trees tell only part of the story. They leave out every manuscript and every work that vanished without leaving descendants. To fill that gap, the researchers built computer simulations based on ideas from complexity science. The models tested how different rates of copying and destruction affected the survival of texts over hundreds of years.
The eight phases of the Song of Roland in one picture; illustration by Simon Marmion from an illuminated manuscript of the Grandes Chroniques de France (15th century), currently preserved in the Hermitage Museum in Saint Petersburg, Russia. Public domain
The results matched patterns already seen in real manuscript collections. They also reproduced a long-debated feature of manuscript family trees, where some branches grow while many others end quickly.
One finding stood out. A text faced its greatest risk during the first years after people wrote it. If only a few copies existed, the chances of complete loss rose sharply. A work needed enough early copies to survive fires, wars, decay, or simple neglect.
The study also suggests the original version of many famous works no longer exists. Every surviving manuscript likely comes from a later branch of the text’s family tree. For works such as the Song of Roland, the earliest form of the story has almost certainly disappeared forever.
Random events also shaped what survived. Large disasters, including the Black Death, likely wiped out many manuscripts in a short time. Chance, along with human decisions about which books deserved copying, played a major part in shaping today’s literary record.
The researchers say the same approach reaches beyond medieval romances. Similar models could help estimate losses in Classical literature, legal records, scientific writings, and religious texts. By combining historical evidence with computer simulations, the study offers a clearer picture of how written culture changed through time and why so much of humanity’s literary past has vanished.
Publication: Camps, J.-B., Randon-Furling, J., & Godreau, U. (2026). On the transmission of texts: Written cultures as complex systems. PNAS Nexus, 5(7), pgag207. doi:10.1093/pnasnexus/pgag207