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A team of researchers from the University of Huddersfield's Archaeogenetics Research Group has provided fresh insight into the genetic landscape of Spain.

The work, led by Ph.D. researcher Gonzalo Oteo-García, has revealed the huge impact of a major historic ethnic cleansing episode in the Iberian Peninsula through the study of ancient DNA from the region.

As part of the Research Group, led by Professor Martin Richards, Dr. Maria Pala and Dr. Ceiridwen Edwards, Dr. Oteo-García collaborated with archaeologists in Spain and geneticists at the Smurfit Institute of Genetics, University of Dublin, on the project. The work is in the journal Genome Biology.

The study explored how gene flow and population structure in eastern Iberia changed over time using ancient DNA. The aim was to better understand the demographic impact of North African influence on the Peninsula, from Roman to early modern times.

Their results pointed to gene flow from various Mediterranean regions into Iberia before the Islamic conquest and showed that North African ancestry was already present in genomes from the 4th to the 8th century prior to its consolidation during the Islamic period.

Most significantly, the North African ancestry persisted in a Christian cemetery in Valencia until the 17th century, after which point this ancestry greatly diminished. This corroborates historical evidence for the Expulsion of the Moriscos—Muslims who had been forcibly converted to Christianity—at the start of the 17th century.

The Expulsion was a massive ethnic cleansing episode, during which an estimated 300,000 Moriscos were expelled to North Africa. After this, little trace of North African ancestry remained in eastern Spain. Interestingly, though, North African ancestry is present in South America, carried by colonists who left before the time of the Expulsion.

The team collaborated with museums and archaeological collections all over the Valencian region in order to gather the bones they needed to carry out a comprehensive genomic analysis, which was conducted using the University of Huddersfield's ancient DNA lab facility.

Dr. Oteo-García, who is now a shared Marie Skłodowska-Curie Actions fellow between Sapienza University of Rome and the Center for Palaeogenetics at Stockholm University, commented, "We started this research with the mere academic interest of understanding the genetic makeup of the medieval population of eastern Iberia.

"However, as we started uncovering genetic evidence linking political upheavals and cultural shifts to the displacement of local populations who had inhabited this land for centuries as well as evidence of medieval slave trade, we realized the historical significance of our findings.

"As a researcher, these discoveries were both thrilling and sobering, given the sensitive nature of the topic. I hope our data will contribute to future archaeological and genetic studies. I also look forward to engaging with historians to further interpret the complexities of these results as I continue this line of work. There are still many gaps to fill."

Director of the University's Evolutionary Genomics Research Center, Professor Richards, leads the Archaeogenetics Research Group at the University. He commented, "This was a very thought-provoking piece of work which, unlike many Ph.D. projects, was essentially conceived and set up by Gonzalo himself while he was a student at Huddersfield."

The work at the University of Huddersfield was funded through a doctoral scholarship program in evolutionary genomics. This enabled the appointment of 15 Ph.D. students over a five-year period, allowing for the establishment of the Evolutionary Genomics Research Center at Huddersfield.

These included nine conducting ancient DNA analysis under the Archaeogenetics Research Group working on Anglo-Saxon England, the prehistory of Orkney and many other parts of Europe, pre-contact Canada, and cattle domestication, as well as this latest publication on the Iberian Peninsula.