A new study uses a sophisticated genetic strategy to reveal new roads past an apparent dead end in the historical record of a distinctive civilization that dominated the Mediterranean Sea during the first millennium BC. The research from National Geographic and IBM's Genographic Project, published by Cell Press in the November 14th issue of the American Journal of Human Genetics, describes a methodology that may prove to be useful for discovering previously undetected signals left by migrations for any historically documented expansion.
Although extensive documentation by writers and archeologists has provided detailed insight into the origins and early expansion of the Phoenician people, their genetic contributions to the current population are unknown. "The Phoenicians were the dominant traders in the Mediterranean Sea two to three thousand years ago, and expanded from their homeland in the Levant to establish colonies and trading posts throughout the Mediterranean, but then disappeared from history. We wished to identify their male genetic traces in modern populations," explains senior study author Dr. Chris Tyler-Smith from The Wellcome Trust Sanger Institute.
Drs. Zalloua, Platt, Tyler-Smith and colleagues developed a strategy to identify a genetic pattern associated not with an overall geographical gradient, but with the specific historical expansion of the Phoenician people. They chose Phoenician-influenced sites based on well-documented historical records and collected new Y chromosomal data from 1330 men in these sites as well as comparative data from the literature. "We chose the Y chromosome because its male-specificity means that it would have been carried by the predominantly male Phoenician traders, and is high level of geographical differentiation provides the best chance of recognizing colonization events," offers Dr. Tyler-Smith. The researchers developed an analytical strategy to distinguish between lineages linked with Phoenicians and those associated with geographically similar but historically distinct events.
This technique allowed them to identify weak but systematic genetic signatures shared by the Phoenician sites that could not be explained by chance or by other expansions. Specifically, the Phoenician signature contributed at least 6% to the modern Phoenician-influenced populations that were examined. "Our work underscores the effectiveness of Y-chromosomal variability when combined with appropriate computational analysis for studying complex patterns of human migration, and the utility of wide geographical sampling using a uniform marker set. This method is applicable to any type of genetic information from which descent could be inferred," concludes Dr. Tyler-Smith.
The researchers include Pierre A. Zalloua, The Lebanese American University, Beirut, Lebanon, Harvard School of Public Health, Boston, MA; Daniel E. Platt, Bioinformatics and Pattern Discovery, IBM Thomas J. Watson Research Centre, Yorktown Heights, NY; Mirvat El Sibai, The Lebanese American University, Beirut, Lebanon; Jade Khalife, The Lebanese American University, Beirut, Lebanon Nadine Makhoul, The Lebanese American University, Beirut, Lebanon; Marc Haber, The Lebanese American University, Beirut, LebanonYali Xue, The Wellcome Trust Sanger Institute, Cambridge, UK; Hassan Izaabel, Laboratoire de Biologie Cellulaire & Génétique Moléculaire (LBCGM), Université Ibn Zohr, Agadir, Maroc; Elena Bosch, Universitat Pompeu Fabra, Barcelona, Spain; Susan M. Adams, University of Leicester, University Road, Leicester, UK; Eduardo Arroyo, Universidad Complutense de Madrid, Ciudad Universitaria, Madrid, Spain; Ana María López-Parra, Universidad Complutense de Madrid, Ciudad Universitaria, Madrid, Spain; Mercedes Aler, Universidad de Valencia, Valencia, Spain; Antònia Picornell, Institut Universitari d'Investigació en Ciències de la Salut i Departament Biologia, Universitat de les Illes Balears, Palma de Mallorca, Spain; Misericordia Ramon, Institut Universitari d'Investigació en Ciències de la Salut i Departament Biologia, Universitat de les Illes Balears, Palma de Mallorca, Spain; Mark A. Jobling, University of Leicester, University Road, Leicester, UK; David Comas, Universitat Pompeu Fabra, Barcelona, Spain; Jaume Bertranpetit, Universitat Pompeu Fabra, Barcelona, Spain; R. Spencer Wells, The Genographic Project, National Geographic Society, Washington, DC; Chris Tyler-Smith, The Wellcome Trust Sanger Institute, Cambridge, UK; and The Genographic Consortium, The Genographic Project, National Geographic Society, Washington, DC.