Surprise discovery about Roman Empire found in ancient DNA

Ancient DNA from the rise and fall of the Roman Empire reveals Italian ancestry had little detectable influence on Balkan Peninsula populations, despite the Empire’s cultural supremacy in the region.

Compelling research drawing on the triumvirate of genetics, archaeology and history uncovers new insights into the social and demographic history of the Roman Empire. One individual analysed was likely an adolescent who had travelled far and wide before dying on the frontier.

The Balkan Peninsula was a “historic crossroads” and crucial frontier in the Roman Empire linking 2000 kilometres of military and communication infrastructure stretching east-west from Mesopotama and Arabia to Britain, and north-south from the Rhine and Danube to the Sahara Desert.

“Rome’s cultural impact on the Middle Danube was deep, but our findings suggest that it was not accompanied by large-scale population movement from the metropole [modern day Italy],” the authors write.

Researchers from Europe and the United States analysed ancient DNA from 136 individuals excavated from 20 different sites and contexts across the Balkan Peninsula (present day Serbia and Croatia) combining their findings with archaeological and historical information, such as coins, jewellery and tools buried with individuals. 

The sites include Roman colonies, military fortresses and early medieval necropolises spanning the rise and fall of the Roman Empire.

“Despite the exceptional number of Roman colonies in the region and the large military presence along this frontier there is little ancestry contribution from populations long established in the Italian Peninsula,” the authors write. 

However, their new analysis reveals other patterns of migration.

During the high imperial period (1 – 250 Current Era, or CE), about half of the individuals analysed from Roman towns including Viminacium, Tragurium (Trogir), and Mursa (Osijek) appear to be direct descendants of Balkan Iron Age populations.

Meanwhile a third from the same period show evidence of ancestry from western Anatolia and Northern Levantine (eastern Mediterranean regions), suggesting an influx of people from the east of the Empire.

DNA analysis of individuals from the late Roman imperial period, 250 – 550 CE, suggests internal migration lessened during this period, except for sporadic migration from beyond the Empire.

A few individuals from this period have North or East African ancestry, which archaeological evidence suggests is consistent with sporadic long distance migration. 

One individual of East African ancestry was buried with an oil lamp depicting unusual eagle iconography, and isotopic analysis of his teeth suggest different dietary habits during childhood.

Publishing in Cell, the authors write: “he likely spent his early years elsewhere, possibly in East Africa, the land of his ancestors, and although we will never know his whole life story, whether as a soldier, slave, merchant, or migrant, it encompassed a long journey that ended with his death in adolescence on the northern frontiers of the Roman Empire.”

“In late antiquity, the region experienced numerous invading groups labelled by historical sources as Goths, Huns, Gepids, Avars, Heruls, Lombards,or Slavs,” the paper says. During this time, non-Romans were increasingly recruited into the Roman military.

The DNA evidence points to a stream of migrants coming into the region, particularly from the Northern/ Central Europe and the Pontic/ Kazakh Steppe, ancestry that vanishes in the DNA from later individuals.

After 700CE, during the post-Roman period, DNA from individuals approaches that of “present-day Eastern European Slavic-speaking populations”. 

But populations with Eastern European ancestry start appearing sporadically from the 2^nd or 3^rd centuries, later dominating the DNA data in the 7^th and 10^th centuries. According to the paper this offers “a remarkable illustration of how small-scale individual percolation into the dynamic economy of the Roman Empire may have pre-ceded larger-scale migration.”

The new revelations about demographic shifts during the Roman Empire are made possible by synthesising evidence from the fields of genetics, archaeology and history.

“Ancient DNA can give a lot of insight into historical periods, especially for regions where historical sources are scarce or when we don’t know whether sources are biased or not,” says population geneticist Iñigo Olalde of the University of the Basque Country, in Spain. “For example, most historical sources from the Balkans are written from the side of the Romans because the Slavic people didn’t write at that time.”