Wellcome Sanger Institute uncovers secrets of Crusades by sequencing DNA of 13th-century skeletons
The work of geneticists has given new insight into our understanding of 13th-century Crusaders.
Scientists at the Wellcome Sanger Institute have unravelled the secrets of nine skeletons found in a burial pit in Sidon, Lebanon, by analysing ancient DNA extracted from them.
Their findings confirm that the warriors travelled from western Europe to the near East, where they mixed, had children with local people and recruited them to their religious cause.
Dr Chris Tyler-Smith, from the Wellcome Sanger Institute, said: “Historical documents tell us the names of the nobility who led the Crusades, but the identities of the soldiers remained a mystery.
“Genomics gives an unprecedented view of the past and shows the Crusaders originated from western Europe and recruited local people of the near East to join them in battle. The Crusaders and near Easterners lived, fought and died side by side.”
During the Crusades, a series of religious wars fought between 1095 and 1291, the Christian invaders attempted to claim the near East.
Archaeologists recently uncovered 25 skeletons from the 13th century of men who had died violently in battle. They had suffered blunt force injuries to their skulls and other bones, and their bodies were disposed of in the pit and burned. Clues such as European shoe buckles, a coin and carbon-14 dating analysis prompted archaeologists to believe the human remains were Crusaders.
They also found an isolated skull nearby. It has been suggested that the head may have been thrown into the opposition’s camp to spread disease and damage morale.
Scientists at the Sanger Institute worked with the archaeologists at the excavation site to transfer the bones of the nine skeletons from Lebanon to the laboratory at Hinxton.
DNA extraction experts then took small portions of the 800-year-old DNA from the temporal bone in the skulls for sequencing – particularly challenging tasks, as the bodies had been burned and buried in a warm and humid climate, where DNA degrades quickly.
An ultra-sterile working environment was established to prevent contamination of the samples with their own DNA, which would have rendered them useless.
Sanger Institute scientists were then able to carry out the first whole-genome sequences of the DNA from the skeletons. The work relied on recent advances in DNA extraction and sequencing technology.
The study – reported in American Journal of Human Genetics – confirmed that the skeletons were indeed those of Crusaders.
Three individuals were Europeans of diverse origins, including Spain and Sardinia, four were near Easterners recruited to the cause and two had mixed genetic ancestry, which suggests they were the descendants of mixed relationships between Crusaders and near Easterners.
But the genetic influence of the Crusaders in the region was short-lived.
By sequencing the DNA of people living in Lebanon some 2,000 years ago, long before the Crusades, the researchers have shown that today’s Lebanese population is genetically similar to the Roman Lebanese. This suggests the Crusades had no lasting impact on the genetic make-up of the people of Lebanon.
Dr Marc Haber, from the Sanger Institute, said: “The Crusaders travelled to the near East and had relationships with the local people, with their sons later joining to fight their cause. However, after the fighting had finished, the mixed generation married into the local population and the genetic traces of the Crusaders were quickly lost.”
The work is an indication of how advances in genetics can help us to reinterpret or better understand history.
Dr Claude Doumet-Serhal, director of the Sidon excavation site in Lebanon, said: “I was thrilled to discover the genetic identities of the people who lived in the near East during the Crusades. Only five years ago, studies like this would not have been possible.
“The uniting of archaeologists and geneticists creates an incredible opportunity to interpret significant events throughout history.”