Medieval genomes from eastern Iberia illuminate the role of Morisco mass deportations in dismantling a long-standing genetic bridge with North Africa

Abstract

This study investigates the demographic impact of Islamic influence on the Iberian Peninsula, focusing on gene flow and population structure in eastern Iberia from the early to late Medieval period through ancient DNA analysis. Our results reveal pre-Islamic Mediterranean-wide gene flow into Iberia, indicating a pan-Mediterranean homogenization during the Roman Empire. While North African ancestry appears sporadically in late antiquity genomes, it becomes more consolidated during the Islamic period. Notably, we identified one of the earliest Islamic burials in Spain, with evidence of high inbreeding, and for the first time, we demonstrate the persistence of North African ancestry in a Christian cemetery until the 17th century, along with signs of slave trafficking from the Maghreb. These findings emphasize the intricate relationship between political events and cultural shifts, such as the Expulsion of the Moriscos in 1609 CE, in shaping the genetic and cultural landscape of eastern Iberia.