The genetic legacy of the Crusades can be seen today in the chromosomes of Lebanese Christian men, according to new research that shows many have a European ancestry.

A disproportionate number of the Middle Eastern country’s Christian men carry a Y chromosome that is clearly of Western European origin, which scientists believe was carried to the region by Crusaders and pilgrims between the 11th and 13th centuries.

This genetic signature is more often seen among Christians, and more rarely in Lebanon’s Muslim or Druze communities. The Y chromosomes of many Muslim men trace their ancestry to earlier migrations from the Arabian Peninsula, as Islam spread during the 7th and 8th centuries.

The findings, from a study of 926 Lebanese men, show how human movements that are known from historical records can be detected in modern DNA. They suggest that both Christian and Muslim communities in Lebanon owe their origins, at least in part, to different founding events, which may have influenced the development of different religious traditions. All three of the main Lebanese ethnic groups, however, still share many more genetic similarities than they have differences, the study found.

Pierre Zalloua, of the Lebanese American University in Beirut, who led the study with Chris Tyler-Smith, of the Wellcome Trust Sanger Institute near Cambridge, said: “This is the most careful and comprehensive study of these populations ever undertaken, and it’s revealed new insights into the complex history of my country.”

The research, which is published in the American Journal of Human Genetics, focused on the male Y chromosome, which can be used to chart patrilineal descent. While women have two X chromosomes, men have one X and one Y, and the Y is always inherited from their fathers. As it is never paired with a partner, it escapes a process called recombination that shuffles the code of every other chromosome in each new individual. Like a surname, it is thus usually transmitted intact in the male line from generation to generation, altered only by rare spontaneous mutations.

These mutations can be used to identify categories of Y chromosome, known as haplogroups. Men from the same haplogroup must have shared a common male ancestor in the past.

The study, funded by the National Geographic Society’s Genographic Project , found that 10 per cent of Lebanese Christian men belong to a Y haplogroup known as R1b, which is of Western European origin. Just 6 per cent of nonChristians had this kind of Y chromosome.

This indicates that more Christians than non-Christians have at least one male ancestor from Western Europe, and fits with the region’s history. More than 250,000 men from England, France, and what are now Germany and Italy travelled to the Levant during the four Crusades between 1095 and 1204, and thousands stayed to build and to garrison castles.

A more detailed look at Christians from the R1b haplogroup narrowed down the geographical origins of their Crusader ancestors. One in five had a sub-type known as WES, which is specific to Western Europe – particularly Germany, the Low Countries and Burgundy, northern Italy, Spain and the British Isles. These regions also provided the bulk of the Crusader armies.

A different Y chromosome haplogroup, J*, was found to be present in 25 per cent of Muslim men, compared with 15 per cent of Christians and Druze. This haplogroup is of Arabian origin, and probably reached Lebanon during the Islamic expansions of the 7th and 8th centuries.

The scientists found the Druze have a higher number of men belonging to haplogroup E3b, which is of Middle Eastern and North African origin.

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