Ancient DNA study finds Roman-era migration reshaped Iberia more than later arrivals

A study reported on 21 October found that movement during Roman rule changed the genetic makeup of the Iberian Peninsula more extensively than later migrations by the Suebi, Vandals, Alans and Visigoths. Researchers analysed 243 ancient genomes from 31 archaeological sites to trace population change between the first and eighth centuries AD, giving a measure of the groups’ demographic impact alongside their historical prominence.

The study, published in Cell, was led by the Institute of Evolutionary Biology in Barcelona, the Natural Sciences Museum of Barcelona, Harvard University and the University of the Basque Country. It compares ancestry across Roman rule and the centuries that followed through genetic evidence from ancient remains.

How Roman-era movement changed Iberian ancestry

“Romanization was not only a political, linguistic and cultural transformation,” said Carles Lalueza-Fox, director of the Natural Sciences Museum of Barcelona and a lead author, in the Max Planck Society account. Pablo Carrión, the study’s first author, said later migrations introduced new ancestry but had a much smaller demographic impact.

The later migrations’ smaller genetic footprint

The reported genetic contribution of the later groups ranged from 12% to 22%, depending on region and social context. The Max Planck Society account said mixing with local populations was gradual and did not radically alter Iberia’s genetic landscape. ARA reported that the contribution was concentrated largely among ruling elites, whose political prominence did not mean population-wide replacement.

ARA reported a much larger genetic contribution from post-Roman migrations in present-day England, at least 50%, and in the Balkans, between 40% and 60%. Those comparisons show how differently migration affected populations across regions after Roman rule.

The genetic analysis also identified two siblings of Central European ancestry buried at Mérida and Castelló, about 725 kilometres apart along the Roman road network. Their remains give the researchers an example of long-distance connections detectable in the ancient DNA record.

Lalueza-Fox told ARA that the researchers’ next challenge is to examine the genetic and social impact of Muslim-era presence. ARA said the planned work would draw on archaeological sites and remains spanning the eighth to sixteenth centuries across the Iberian Peninsula, the Balearic Islands and Portugal.