King Sverre Sigurdsson had a tumultuous reign. He came to power in Norway in the 12th century and, according to a legendary saga, launched an unorthodox attack on his enemies in 1197. He attacked Sverresborg Castle, raiding and burning the stronghold. During all this, he poisoned the water supply by throwing a body into the water well.

That was the legend — and now, researchers have managed to confirm that legend.

“This is the first time that a person described in these historical texts has actually been found,” says Professor Michael D. Martin of the Norwegian University of Science and Technology’s University Museum in Trondheim, Norway. “There are a lot of these medieval and ancient remains all around Europe, and they’re increasingly being studied using genomic methods.”

Sagas from the medieval era, like the Norse sagas, are a fascinating mix of fact and fiction. They weave together real historical events, larger-than-life characters and mythic embellishments. The problem is, you never really know what’s fact and what’s fiction.

The Sverris Saga, written in the 12th century, is one of the few remaining accounts of King Sverre Sigurdsson’s ascent to power. It portrays King Sverre as a formidable and at times ruthless leader The saga refers to Sverre’s followers as “Birkebeiners” and his primary adversaries as “Baglers”. These two factions’ allegiances were deeply rooted in Norway’s political and religious tensions. Sverre’s army, consisting largely of commoners from central Norway, clashed with the Baglers, who were backed by the church and southern nobles.

This “Well man” — the person supposedly thrown into the well — was a historic mystery. He was a buried secret that remained undisturbed for centuries until excavations in 1938 started uncovering parts of the castle. Finally, more extensive digs in 2016 unearthed a partial skeleton beneath layers of stone.

Radiocarbon dating confirmed that the body is around 900 years old, and previous studies suggested it was a man aged 30-40 years old. Through advanced DNA analysis, the team sequenced the Well man’s genome, piecing together several bits of information as to who this person was.

The genetic markers of the Well man

For starters, the Well-man’s physical traits, reconstructed through genetic markers, offer a glimpse into what he might have looked like. Using DNA-prediction models, researchers believe he likely had blue eyes and light-colored hair, both common traits in modern Scandinavian populations.

The researchers also tested the Well man’s DNA for signs of infectious disease. Ancient skeletons are valuable sources of information about past epidemics. DNA from pathogens like Yersinia pestis (plague) can sometimes be detected in the teeth or bones of old skeletons. In this case, no significant pathogens were found. However, researchers noted that DNA degradation or contamination could have affected this outcome.

The Well man’s southern Norwegian ancestry makes him a likely member of the Baglers. This genetic link corroborates the saga’s narrative and demonstrates how DNA can serve as an independent line of historical evidence, confirming even something like a 900-year-old saga.

“We can corroborate what actually happened in a more neutral way,” says Dr. Martin Rene Ellegaard of the Norwegian University of Science and Technology.

DNA evidence in history

Researchers extracted DNA from the Well man’s tooth, which had been preserved in relatively good condition due to the burial environment. The tiny DNA fragments were then pieced together and compared with both modern and ancient DNA samples from Scandinavia and the British Isles.

The researchers were only able to draw so many conclusions thanks to a large amount of reference data from the genomes of modern-day Norwegians made available through different projects. But there was also a trade-off. To avoid contamination, the tooth was ground into a powder, which means the sample can no longer be used for further tests.

 “It was a compromise between removing surface contamination of the people who have touched the tooth and then removing some of the possible pathogens … there are lots of ethical considerations,” says Ellegaard. “We need to consider what kind of tests we’re doing now because it will limit what we can do in the future.”

For historians and archaeologists, this type of science-based independent verification of historical texts is invaluable. Ancient DNA offers a rare chance to test historical narratives that were often written centuries after the events they describe. In the case of Sverris Saga, the discovery of the Well man’s skeleton provided the perfect opportunity to cross-reference written history with biological data.

Ancient DNA research continues to grow, opening new doors to understanding the people and societies that once thrived across Europe and beyond. By using similar methods, scientists now hope to reconstruct the genetic history of more regions and possibly link genetic data with other historical events, from migrations to epidemics.

The study was published in iScience.