Researchers have used ancient DNA to identify a brother and sister buried 725 kilometers apart in Roman Spain roughly 1,600 years ago, Arkeonews reported on Oct. 22.
The siblings were among 243 people from 31 archaeological sites whose genetic data helped researchers trace migration into the Iberian Peninsula. Their graves represent the greatest geographical separation yet documented between first-degree relatives in the ancient DNA record, according to the study.
The brother was buried at the Los Blanes cemetery in Augusta Emerita, now Mérida in western Spain. His remains date to between A.D. 364 and 535. His sister’s burial at Hostalot-Ildum, a roadside complex along the Via Augusta in northeastern Spain, dates to between A.D. 257 and 409.
Both had ancestry closely associated with Central and Northern European populations. The researchers suggested they may have been first-generation migrants to Hispania, the Roman name for the peninsula.
The woman’s grave contained a glass vessel and two gold pins associated with traditions from the Danube and Black Sea regions. The pins resemble objects found at Los Blanes, providing an archaeological connection between the distant burial sites as well as a genetic one.
The researchers suggested that she may have died while traveling south and that her brother continued toward Augusta Emerita. They couldn’t establish whether the pair traveled together. They estimated that the journey between the burial sites would have taken about 24 days on foot or 14 days on horseback.
The wider study, led by Pablo Carrión and colleagues and published in Cell, compared the newly generated data with previously published ancient genomes to examine population changes between approximately A.D. 100 and 800. It found that migration under Roman rule changed Iberia’s ancestry more extensively than the Germanic migrations that followed.
In one analysis of 66 Roman-period people, 55 had ancestry associated with the Eastern Mediterranean. The researchers found particularly close connections to populations resembling those of Roman and Byzantine western Anatolia, including areas around Ephesus, Pergamon and Smyrna.
North African ancestry was also widespread, especially in southern and central Iberia. Researchers detected it in 33 of 34 Roman-period people examined from southeastern sites. The findings point to population changes accompanying the peninsula’s connections across the Mediterranean through trade, military activity and imperial administration.
At Cortijo Coracho, an early Christian cemetery near Lucena, the team reconstructed a family network spanning four generations. The community included ancestry associated with local Iberian, Eastern Mediterranean and North African populations. Genetic evidence alone cannot establish how Christianity traveled between those places.
The later arrival of Suebi, Vandals, Alans and Visigoths brought further migration. Researchers detected Central and Northern European-related ancestry in 53 of 164 people from the migration period, particularly at sites with Germanic material culture and higher-status burials.
But the broader Hispano-Roman population largely persisted, with evidence of intermarriage between newcomers and established communities. The researchers contrasted that continuity with earlier genetic findings of more extensive population changes in Britain after Roman rule.
The authors identified gaps in the evidence for northern Iberia, the Iron Age and the Roman Republican period, limiting how fully they could reconstruct the peninsula’s demographic history.