Chromosomes and castles: Research reveals Crusaders’ legacy in Lebanon
27 March 2008
The communities living in Lebanon are genetically very similar, but now researchers have uncovered subtle genetic differences between communities, which - they think - reflect migrations into Lebanon that occurred hundreds of years ago. Among the findings of the international study is that some Lebanese Christian men carry genetic signatures usually found in Europe, which suggests that the legacy of invading Crusaders included Y chromosomes as well as castles.
A global team of scientists - led by Dr Pierre Zalloua of the Lebanese American University, Beirut and Dr Chris Tyler-Smith of the Wellcome Trust Sanger Institute, Cambridge, UK - analysed the Y chromosomes of over 900 men from the Christian, Muslim and Druze communities of Lebanon. Y chromosomes are passed down almost unchanged from father to son. As such, they are a ‘genetic surname’ that can be studied to reveal information about a male’s ancestors.
While Lebanese communities carry broadly similar genetic markers, the researchers found subtle but distinct genetic differences between different groups. For example, a genetic signature called WES1 was present in 2 per cent of Lebanese Christian men but was completely absent from Lebanese Muslim men and all the surrounding countries. This signature is otherwise found only in Western European populations, and its presence in Lebanese men is thought to be a consequence of the Crusades, which began almost a thousand years ago.
Lebanese Muslim men were more likely than Lebanese Christian men to carry a genetic signature that is typical of the population involved in the Muslim expansion of the 7th and 8th centuries.
This research is part of the Genographic Project, a study that aims to use DNA samples from people around the world to map historical patterns of human migration and answer other anthropological questions.
Image: The ruins of the Crusader castle in Byblos, Lebanon; http://commons.wikimedia.org/wiki/Image:ByblosCrusaderCastle1.jpg
References
Zalloua, P et al. Y-chromosomal diversity in Lebanon is structured by recent historical events. Am J Hum Genet 2008 [in press].