Romanization of the Iberian Peninsula: Genetic Study Puts Germanic Migrations in Perspective

A peninsula at the heart of the Roman Empire

The Iberian Peninsula was one of Rome's first major conquests. Its position between the Atlantic and the Mediterranean, along with the wealth of its natural resources, made it a strategic territory for the Empire, which the Romans called Hispania.

As Roman power weakened, the arrival of the Alans, Vandals and Suebi in 409 opened a new period. After the fall of the Western Roman Empire, these Germanic groups founded kingdoms across Europe, including the Visigothic kingdom established on the peninsula in 507.

A method based on archaeogenomics

The study is presented as the first systematic, large-scale archaeogenomic analysis of this period. It combines genetic data extracted from ancient human remains with archaeological information, in order to place each individual within their historical context.

This approach goes beyond hypotheses based solely on written sources, which are often partial, to measure actual population movements. The authors stress the distinction between political, cultural and demographic change, three dimensions that do not necessarily coincide.

Romanization as a demographic transformation

According to the researchers, individuals dated from the 1st to the 4th century show a far greater diversity of ancestry than those of the relatively homogeneous Iron Age. Roman domination favored the arrival of people of eastern Mediterranean and North African ancestry.

Carles Lalueza-Fox, director of the Natural Science Museum of Barcelona and co-author of the study, emphasizes that Romanization was "also a major demographic transformation," linking local populations to human movements from across the Mediterranean.

Germanic migrations with limited demographic weight

From the 5th century onward, the researchers identify individuals of Central and Northern European ancestry, notably in funerary contexts associated with the new ruling groups. These contributions would represent between 12% and 22% depending on the region and social milieu.

For David Reich of Harvard University, the Iberian genetic history thus stands apart from other post-Roman regions of Europe, such as Britain or the Balkans, where migrations had a more marked demographic effect. The authors speak of migrations and new ancestries, but not of population replacement.

Family trajectories and mobile elites

The analyses identified two siblings buried about 725 kilometers apart: one in Mérida, the ancient Augusta Emerita, and the other at the Roman station of Ildum, in Castellón, on the via Augusta. Both had entirely Central European ancestry and were probably first-generation migrants.

The so-called "Suebic princesses," whose rich tombs had suggested a foreign origin, were found in one case to have local ancestry. This result suggests marriage alliances between Suebic elites and Hispano-Roman families, showing that group identity could be acquired through family and political ties.

A genetic history still being written

The populations of Late Antique Iberia were more heterogeneous than those of today, indicating that the gene pool continued to change in the Middle Ages, under Visigothic rule, during the Islamic conquests and with the expansion of Christian kingdoms.

The authors call for broader sampling, particularly in the north of the peninsula and in North Africa, and for more medieval and post-medieval genomes to link ancient inhabitants with present-day populations.