Genetic histories of individuals from multi-faith medieval Sicily

Abstract

Medieval Sicily, located at the intersection of Europe, North Africa and the Near East, experienced successive political and religious transitions under Byzantine, Aghlabid, Fatimid, Norman, and Swabian rule. While it is well established that these events led to multi-faith societies, the long-term genetic impact of regime change is unclear. To evaluate this potential impact, we applied ancient genomic analysis to 111 archaeological Sicilian individuals, leading to successful mitochondrial haplotype inferences for 67 individuals and genome-wide analyses for 32 individuals dated between the 5th and 15th centuries CE. In contrast to simple narratives of population replacement, the data indicate nuanced and unappreciated demographic shifts. Several individuals dating before the Islamic conquest of Sicily exhibit substantial North African ancestry, evidencing movement across the Mediterranean Sea before this conquest. Individuals buried in Islamic cemeteries during the 9th to 11th century were found to have diverse ancestries deriving from populations around the Mediterranean Basin, however, the same ancestry components are also found in earlier periods, limiting what can be inferred about intra-Mediterranean migrations in this dataset. Nonetheless, the Islamic period marks the appearance of individuals with distant ancestral origins, West Africa and Northern Europe. During the Norman period, Christian and Islamic burials show the same genetic diversity maintained for hundreds of years, however, by the late medieval period, the ancestry components shifted toward modern European populations. Altogether, the study demonstrates the value of examining recent periods with ancient DNA methodologies to better understand how culture, identity and mobility impacted demography in the past.