Finding suggests modern history, not just prehistory, can leave a strong mark on a region’s genetic signature
Hold the history book presses. The Moorish invasion of Spain was never completely repelled, a new genetic analysis reveals.
As many as one in 10 men from Spain and Portugal still carry genetic evidence of North African ancestry, and nearly twice that number had Sephardic Jewish ancestors, reveals a study in the Dec. 12 American Journal of Human Genetics. Those results don’t fit with expectations from the historical record.
Sephardic Jews, who were likely in the Iberian Peninsula since Roman times, were supposed to all have fled the region in the wake of pogroms and persecutions between the early eighth and 14th centuries. In the late 15th century, 160,000 Spanish Jews (Sepharadh is the Hebrew word for Spain) were expelled and then settled in other parts of the Mediterranean.
Moors from northern Africa swept into Spain in 711, colonizing the peninsula and spreading Islam. But during the Spanish Inquisition, Spanish Muslims were driven out or forced to convert in a wave of religious intolerance.
But the new study, which analyzed Y chromosomes from 1,140 men from the Iberian Peninsula, shows that, even though large numbers of Sephardic Jews and Spanish Muslims left the peninsula, these groups also left behind descendents and a strong genetic presence.
Genetic studies of populations are often used to track movements of people from prehistoric times. But these results indicate that more modern events — religious persecution and conversion, modern migration and intermarriage — can shape human genetic landscapes more than previously suspected.
Certain groups have minor genetic variations that are characteristic. The researchers in this study used genetic markers found in North African populations, specifically Morocco and Algeria, to trace the North African contribution in the Iberian Peninsula. Sephardic Jewish genetic markers came from populations in Israel and Turkey.
Studies such as the new one “tell the true history of everyone’s ancestors and not just the history book lessons of kings and queens,” says James Wilson, a population geneticist at the University of Edinburgh in Scotland who was not involved in the study.
Wilson said he would have expected to find small but significant evidence of North African ancestry in southern Spain, where the Moorish reign lasted longest, but “to find it in the west defies my expectations,” he said. The researchers expected to find a gradient, with stronger ancestry in the south that would lessen farther north. In fact, they found a weaker North African presence in southern Spain.
Sephardic Jewish roots run deep in the peninsula, the researchers found. Nearly 20 percent of men in the study showed evidence of Sephardic Jewish ancestry.
“We think it might be an over estimate,” says Francesc Calafell, a human population geneticist at the Institute of Evolutionary Biology and Pompeu Fabra University in Barcelona, Spain. Calafell and Mark Jobling at the University of Leicester in England led the study.
The genetic makeup of Sephardic Jews is probably common to other Middle Eastern populations, such as the Phoenicians, that also settled the Iberian Peninsula, Calafell says. “In our study, that would have all fallen under the Jewish label.”
Still, the findings reflect how religious intolerance on the peninsula led to conversion of non-Christian groups and then integration into the larger Christian community, he says.
Adams, S.M., Bosch, E., et al. 2008. The Genetic Legacy of Religious Diversity and Intolerance: Paternal Lineages of Christians, Jews, and Muslims in the Iberian Peninsula American Journal of Human Genetics 83(Dec. 12)