Ancient DNA study of the populations of Flanders reveals the presence and fusion of two different groups in the early medieval coastal community of the North Sea

On 5.-8. centuries AD the Frankish state in Central Europe was ruled by the Merovingian dynasty, which gave its name to the entire era. During this period, extensive cultural and economic reorganization took place in the areas of present-day Belgian Flanders. However, what was the impact of the early medieval migrations on the people who lived or live in the region today has been unclear until now. Stefania Sasso, Kristiina Tambets, Maarten Larmuseau and Toomas Kivisild with their colleagues from the Institute of Genomics of the University of Tartu and KU Leuven University studied the origins and kinship ties of early medieval North Sea coastal inhabitants on the basis of DNA extracted from the teeth and skeletal remains of 30 ancient individuals buried in the late Merovingian burial site of Koksijde.

"Koksijde is one of the oldest sites in Flanders from the time after the fall of the Western Roman Empire, where uncremated human remains have been found, which can therefore be studied genetically," emphasized Toomas Kivisild, professor at the University of Tartu and KU Leuven.

The researchers compared the genomic data of the Koksijde individuals with the genomic data obtained from the remains of 18 individuals from one early and one late medieval burial sites in Flanders, in order to gain an overview of the population history of Flanders throughout the Middle Ages, and with the genomic data of today's inhabitants of the Netherlands and other European countries.

The results of the research indicate that Koksijde was not an elite burial place, and surprisingly it turned out that the community there was diverse and included two groups of different origins. The larger group was genetically similar to early medieval and present-day North Sea communities in England and Holland, i.e. Germanic in origin, and many members of the group were distantly related. No relatives were found among the members of the smaller group, and they probably included immigrants from among the descendants of the Gauls, one of the Celtic peoples who lived in the local interior. The remains of a mother and daughter were also found in the Koksijde burial place, whose genetic analysis showed that the two ancestry groups mixed with each other: the girl's mother came from the so-called Celtic ancestry group and the father from the Germanic ancestry group.

"It was interesting to learn that the two community groups also differed, for example, in characteristics related to pigmentation and the functioning of the enzyme that enables the digestion of milk sugar, which were due to their different ancestries rather than different adaptations to local environmental conditions," said Stefania Sasso, PhD student of the University of Tartu, bringing out one of the exciting aspects of the research.

"If it was initially thought that the members of this small early medieval community by the North Sea were closely related to each other through a family network, the research revealed quite the opposite - the community was diverse and consisted of two groups of different origins. This would not have been known without DNA analysis," said Kristiina Tambets, professor of archaeogenomics at the University of Tartu.

According to the authors, the research results indicate that early medieval population migrations have had a lasting impact on the formation of the Flemish population. The study results and abstract were published in the scientific journal PNAS. See also the KU Leuven news story.