An international research team led by JGU has analysed genomes from the period around the end of the Western Roman Empire. The study provides new insights into a time of profound change in Central Europe and has been published in the journal Nature.

Many of today's villages and towns in Central Europe trace their origins to settlements that emerged after the collapse of the Western Roman Empire, often on former Roman territory or in the immediate vicinity of the Limes, the former imperial frontier. Since the nineteenth century this period was often associated with the idea of large migrating groups of Germanic peoples. However, historical research has long since moved away from the concept of a unified Germanic identity and large-scale migration events. An international research team led by anthropologist and population geneticist Professor Dr. Joachim Burger from the Institute of Organismic and Molecular Evolution at Johannes Gutenberg University Mainz (JGU) has now analysed genomes of individuals from the former Roman frontier zone between 400 and 700 AD in southern Germany. Their results provide unexpectedly detailed insights into a period of major transformation. The findings have been published in the journal Nature.

The interdisciplinary study involved around sixty researchers from a range of European institutions, including JGU, the University of Tübingen, the University of Fribourg in Switzerland, the University of Freiburg in Germany, the Bavarian State Collections of Natural History, and several other institutions. The researchers come from fields such as population genetics, bioinformatics, anthropology, history and archaeology. The study focused on genomes from skeletal remains found in so called row grave cemeteries, burial sites that became widespread from the mid fifth century across northern Gaul, western and southern Germany, and as far as Hungary.

Two population groups in the Roman frontier region

In total the team analysed 258 genomes from present day Bavaria and Hesse and compared them with a reference dataset of around 2,900 ancient, early medieval and modern genomes from northern and southern Germany. The results show that even in the late Roman period, before the collapse of Roman rule, individuals were buried in cemeteries in what is now southern Germany whose genetic ancestry originated in northern Europe, for example at sites such as Altheim near Landshut and Büttelborn near Darmstadt. This is a surprising finding. At first glance it appears to confirm the established idea of a large-scale Germanic migration, but further analyses lead to a different interpretation.

According to Dr. Jens Blöcher, population geneticist at JGU and one of the two first authors of the study, people from northern regions had already moved south in small groups long before the end of the Western Roman Empire and had gradually adopted Roman ways of life. Many of them appear to have lived separately from the rest of the population, likely as agricultural workers, and tended to marry within their own groups, thereby maintaining the genetic signatures of their ancestry.

The other first author, Dr. Leonardo Vallini, also a population geneticist at JGU, adds that Roman administrative practices may have contributed to this separation. Land was often allocated to incoming groups under specific conditions, including restrictions on marriage, in order to manage integration and maintain control.

For the first time the research team also genetically characterised the population of a Roman military settlement. This population was highly diverse genetically, reflecting centuries of movement and exchange across Europe and even from Asia.

After the end of the Western Roman Empire the two population groups merged rapidly

Joachim Burger, senior author of the study, describes the period after around 470 AD as a turning point. With the collapse of Roman state structures insecurity increased and with it population mobility. People who had previously lived in cities or military settlements moved into rural areas, where they encountered groups with northern European ancestry. These groups formed new communities and began to bury their dead together in shared row grave cemeteries. Burger notes that there is continuity of population components from late antiquity, but also a clear process of merging between previously separated groups.

The old image of a large-scale Germanic migration is no longer supported

The new findings suggest a pattern of regional mobility and gradual integration. According to Professor Dr. Steffen Patzold, medieval historian at the University of Tübingen, the results – based on entirely new scientific data – confirm that the traditional view of large, coordinated migrations of Germanic peoples is inaccurate. Instead, the genomic data point to movements of smaller groups, families, or even individuals. Patzold emphasizes that the evidence indicates these movements were not mass migrations, but rather the result of smaller-scale relocations. The study was initiated jointly by Patzold together with his Tübingen colleagues, Professor Dr. Mischa Meier and Professor Dr. Sebastian Schmidt-Hofner.

The origins of European family structures

From the genomic data the researchers were able to reconstruct family relationships and show how new family structures emerged during this period of demographic change. According to Joachim Burger, the rapid formation of families across the two groups suggests a shared cultural framework, which he identifies as the late Roman cultural sphere. Long before the political end of the Roman Empire, both groups were already culturally connected through life within the imperial system.

The reconstructed family trees also provide detailed insights into household structures of the time. Households were mainly composed of nuclear families rather than extended clans. Marriages were monogamous, close kin marriages were avoided, and descent was traced through both maternal and paternal lines. According to Steffen Patzold, these patterns correspond closely to late antique written sources and demonstrate the lasting influence of late Roman social norms into the early medieval period.

Genetic foundations of southern Germany

From the seventh century onwards, these processes resulted in a population that is genetically very similar to that of present-day southern Germany. The northern ancestry component became increasingly prominent while both original groups contributed to the genetic structure of the region. According to Joachim Burger, this development shows how the upheavals of late antiquity gradually formed the basis of the population structure of central Europe that can still be observed today.

The study was funded by the German Research Foundation within the research group Migration and Mobility in Late Antiquity and the Early Middle Ages at the University of Tübingen and by the Swiss National Science Foundation. The collaboration included Johannes Gutenberg University Mainz, the University of Fribourg in Switzerland, the University of Freiburg in Germany, the Bavarian State Collections of Natural History, the Bavarian State Office for the Preservation of Monuments, the Hesse State Office for Monument Preservation, the Musée de l Homme and the French National Centre for Scientific Research in Paris, as well as additional partners in Germany, England, Spain, Italy, Austria, Serbia and Switzerland.