The magic of the founding effect: The history of the gypsy people.
One of the most genetically interesting populations of the continent European are the gypsies, also called romans, because of their history demographic Currently the European gypsies are about ten million people who are distributed in dispersed groups throughout the continent, although They are mostly found in the Balkans and the Iberian Peninsula. The linguistic and physical anthropology suggest that the origin of the gypsy places in the Indian subcontinent, although the cultural features and the bases Genetics are not always transmitted together. For this reason, the data genetic data have allowed us to refine a lot when it comes to finding out the story of the Roma people.
Studies conducted during the last decade of genomes uniparental (the Y chromosome and mitochondrial DNA) in gypsy groups They show a mixture of European lineages with lineages that are only found in the Indian subcontinent, which supports what is observed with linguistic data and anthropological. In addition, the diversity of these lineages (European and Indian) is quite reduced, which suggests that the current gypsies come from a small number of individuals of Indian origin with a genetic introgression European However, single-parent lineages represent a small fraction of our whole genome and, in order to refine the demographic history of the gypsies, we had to analyze thousands of genome variants of several Roma groups. In a work appeared in December 2012 in the magazine Current Biology (Mendizabal et al., 2012) analyzed almost one million genetic variants in different individuals of various gypsy groups and the We compare with other European, Indian and Near Eastern populations. He analysis of the observed genetic diversity allowed us to conclude that the origin of European gypsies is located in north-west India and from that Instead a small number of individuals left the region some 1,500 years. The diaspora of this small group meant a drastic reduction of the genetic diversity (50% of what we observed in India) due to a Strong founder effect.
After a rapid migration through the Middle East, with very little genetic mixing with the populations that were found during this crossing, the ancestors of the gypsies arrived on the European continent and They settled in the Balkans. The genetic data suggest that this population initial fragmented into smaller groups (more founding effects) than They began to disperse around the European continent about 900 years ago. During This dispersion, the ancestors of gypsies from India mixed with different European groups, and it's because of this mix that Today's Gypsies have genetic variants typical of India and Europe. In any case, this genetic mixture has not been uniform in all Gypsy groups: our analyzes show that the Roma populations of the Balkans have fewer typically European variants than populations Gypsies from the Iberian Peninsula, that is to say, after dispersion in Europe, Iberian gypsies were more mixed with neighboring populations than gypsies Balkan We have even been able to establish that this mixture with populations non-Roma in the Balkan groups has been quite recent, as the European chromosomal fragments found in these gypsy groups are unusually long, which suggests that chromosomal recombination (a genomic process that makes the matched chromosomes cross over their information) has not had time to act massively.
In short, the genetic data have allowed us to decipher some aspects of the demographic history, of social relations between groups gypsies and refine hypotheses raised by other disciplines such as linguistics or anthropology.
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