The religious conversions of Jews and Muslims have had a profound impact on the population of the Iberian Peninsula


 Elena Bosch and Francesc Calafell, researchers of the Evolutional Biology Unit of the Department of Experimental and Health Sciences (CEXS) of the UPF have participated in this study, together with the University of Leicester (United Kingdom) with the support of the Wellcome Trust. The results of the study were published on 5 th December in the American Journal of Human Genetics, and show that current genetic patterns appear to be influenced by religious conversions of Jews and Muslims by our ancestors.

According to Elena Bosch, "By studying the Y chromosome we have been able to quantify the North African contribution to the current peninsular and Balearic populations in a very detailed way. An unexpected result is that we have found greater North African influence in the west (for example León) than in the east of the Peninsula (for example Granada), which could reflect the massive deportations of Moriscos from Granada to Castille that took place in the 16 th century".   The study shows that religious conversions and the subsequent marriages between people of different lineage had a relevant impact on modern populations both in Spain, especially in the Balearic Islands, and in Portugal.  

To reach these conclusions, the researchers have analysed a wide sample of Y chromosomes - present only in men and passed on from fathers to sons - in the current population of the Iberian Peninsula. The result has been a very high proportion of genetic characteristics attributable to Sephardic Jewish ancestors (19.8%) and to populations originating from North Africa (10.6%). This fact would be explained by the complex recent history of the Iberian Peninsula which entailed, for long periods of time, the cohabitation of very different peoples with different religious filiations: Christians, Jews and Muslims, who also had different geographical origins and certain unique cultural and religious features.

However, the most surprising finding of this study is the high proportion of Sephardic Jewish ascendance which does not fit in with historical records. Likewise, the particular genetic characteristics of North African populations found in the current population do not match the expected geographical distribution of Muslim colonization of the Peninsula in 711 or their withdrawal in the 15 th century. This fact can only be explained by a high level of religious conversion, whether voluntary or forced by historical and social episodes of religious intolerance which ultimately led to the integration of their descendants who have reached the present day.

Other recent studies carried out by the Evolutional Biology Unit

 The previous issue of the American Journal of Human Genetics published the results of a recent study in which members of the Evolutional Biology Unit of the UPF-CEXS also participated.

This study is part of the research being carried out as part of the Genographics project, for which Jaume Bertranpetit and David Comas, researchers of the Evolutional Biology Unit, are the co-ordinators for Europe. In this study, the team of researchers studied the genetic footprints of the Phoenician expansion along the Mediterranean, between the years 2000 and 3000 B.C. in the current population, based on a study of the Y chromosome. The relevant unique feature of this study is that it has developed a specific methodology, applicable to any historically documented expansion of populations, that permits the comparison of populations that have been in contact with others that have not.

The Evolutional Biology Unit of the UPF CEXS, headed by Professor Jaume Bertranpetit, seeks understanding of the genomic diversity in humans and other species such as primates. The study of different genomic regions aims to discover the mechanisms that operate in the variation and the possible implications for the phenotype differences existing between individuals and populations and also at species level. In a more applied sphere, a number of projects seek to understand the biological bases of diseases from a genetic epidemiology perspective.

Works of reference:

Adams, SM; Bosch, E; Balaresque, PL; Lee, AC; Arroyo, E; López-Parra, AM; Aler, M; Grifo, MSG; Brion, M; Carracedo, A; Lavinha, J; Martínez-Jarreta, B; Quintana-Murci, Ll ; Picornell, A; Ramon, M; Skorecki, K; Behar, D; Calafell, F; Jobling, MA., " The genetic legacy of religious diversity and intolerance: paternal lineages of Christians, Jews and Muslims in the Iberian Peninsula",  American Journal of Human Genetics, 84.

Pierre A. Zalloua, Daniel E. Platt, Mirvat El Sibai, Jade Khalife, Nadine Makhoul, Marc Haber, Yali Xue, Hassan Izaabel, Elena Bosch, Susan M. Adams, Eduardo Arroyo, Ana María López-Parra, Mercedes Aler, Antònia Picornell, Misericordia Ramon, Mark A. Jobling, David Comas, Jaume Bertranpetit, R. Spencer Wells, Chris Tyler-Smith and The Genographic Consortium, " Identifying Genetic Traces of Historical Expansions: Phoenician Footprints in the Mediterranean", American Journal of Human Genetics, 83, 633-642.

Last updated 10-12-2008
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