The team analysed the Y chromosomes of 926 Lebanese males and found that patterns of male genetic variation in Lebanon fell more along religious lines than along geographical lines.As I predicted, the finding of similarity between Christian and Muslim Lebanese in the older National Geographic story on Wells' and Zalloua's work was premature, based on their common possession of Y-haplogroup J, because it did not look at downstream markers which differentiate between Christians and Muslims. As I observed based on the work of Capelli et al., it is the overrepresentation of Y-haplogroup J*(xJ2), which comprises almost entirely of J1 chromosomes that is the mark of the Arab descent of Muslim Lebanese.
A genetic signature on the male chromosome called WES1, which is usually only found in European populations, was found among the Lebanese men included in the study.
"It seems to have come in from Europe and is found mostly in the Christian population," said Dr Spencer Wells, director of the Genographic Project.
"This is odd because typically we don't see this sort of stratification by religion when we are looking at the relative proportions of these lineages - and particularly immigration events."
He told BBC News: "Looking at the same data set, we saw a similar enrichment of lineages coming in from the Arabian Peninsula in the Muslim population which we didn't see [as often] in the Christian population."
Lebanese Muslim men were found to have high frequencies of a Y chromosome grouping known as J1. This is typical of populations originating from the Arabian Peninsula, who were involved in the Muslim expansion.
I will post the abstract of this study and any further comments when I see it.
UPDATE: The Genographic project has its own page on this research, as well as a link to the paper (pdf).
Y-Chromosomal Diversity in Lebanon Is Structured by Recent Historical Events
Pierre A. Zalloua et al.
Lebanon is an eastern Mediterranean country inhabited by approximately four million people with a wide variety of ethnicities and religions, including Muslim, Christian, and Druze. In the present study, 926 Lebanese men were typed with Y-chromosomal SNP and STR markers, and unusually, male genetic variation within Lebanon was found to be more strongly structured by religious affiliation than by geography.We therefore tested the hypothesis that migrations within historical times could have contributed to this situation. Y-haplogroup J*(xJ2) was more frequent in the putative Muslim source region (the Arabian Peninsula) than in Lebanon, and it was also more frequent in Lebanese Muslims than in Lebanese non-Muslims. Conversely, haplogroup R1b was more frequent in the putative Christian source region (western Europe) than in Lebanon and was also more frequent in Lebanese Christians than in Lebanese non-
Christians. The most common R1b STR-haplotype in Lebanese Christians was otherwise highly specific for western Europe and was unlikely to have reached its current frequency in Lebanese Christians without admixture.We therefore suggest that the Islamic expansion from the Arabian Peninsula beginning in the seventh century CE introduced lineages typical of this area into those who subsequently became Lebanese Muslims, whereas the Crusader activity in the 11th-13th centuries CE introduced western European lineages into Lebanese Christians.