The Romani represent the largest minority group in Europe consisting of approximately 11 million people. That means the size of the Romani population rivals that of several European countries, including Greece, Portugal and Belgium, the researchers say.

"We were interested in exploring the population history of European Romani because they constitute an important fraction of the European population, but their marginalized situation in many countries also seems to have affected their visibility in scientific studies," said David Comas of the Institut de Biologia Evolutiva and Universitat Pompeu Fabra in Spain.

The Romani people lack written historical records on their origins and dispersal. To fill in the gaps in the new study, Comas together with Manfred Kayser from the Erasmus University Rotterdam in the Netherlands and their international European colleagues gathered genome-wide data from 13 Romani groups collected across Europe to confirm an Indian origin for European Romani, consistent with earlier linguistic studies.

The genome-wide evidence specified the geographic origin towards the north or northwestern parts of India and provided a date of origin of about 1,500 year ago. While the Middle East and Caucasus regions are known to have had an influence on Romani language, the researchers saw limited evidence for shared ancestry between the European Romani and those who live in those regions of the world today.

Once in Europe, Romani people began settling in various areas and the authors show that the Romani spread across Europe likely occurred via the Balkan region about 900 years ago.

 "From a genome-wide perspective, Romani people share a common and unique history that consists of two elements: the roots in northwestern India and the admixture with non-Romani Europeans accumulating with different magnitudes during the Out-of-India migration across Europe," Kayser said. "Our study clearly illustrates that understanding the Romani's genetic legacy is necessary to complete the genetic characterization of Europeans as a whole with implications for various fields, from human evolution to the health sciences."

Reference article: Mendizábal et al. Reconstructing the population history european roman from genome-wide data. Current biology (2012), in press; DOI http://dx.doi.org/10.1016/j.cub.2012.10.039