[LCM Articles] Crusaders 'left genetic legacy'

[Abdallah Jabbour]

*http://news.bbc.co.uk/2/hi/science/nature/7316281.stm

* By Paul Rincon
 Science reporter, BBC News
*
Scientists have detected the faint genetic traces left by medieval crusaders
in the Middle East.*

The team says it found a particular DNA signature which recently appeared in
Lebanon and is probably linked to the crusades.

The finding comes from the Genographic Project, a major effort to track
human migrations through DNA.

Details of the research have been published in the American Journal of Human
Genetics.

The researchers found that some Christian men in Lebanon carry a DNA
signature hailing from Western Europe.

Four crusades came through Lebanon between the 11th and 13th Centuries - the
first, second, third and sixth. The bulk of the crusader armies came from
England, France, Germany and Italy; many of the men stayed to build castles
and settlements, mixing with the local populations.

The scientists also found that Lebanese Muslim men were more likely than
Christians to carry a particular genetic signature. But this one is linked
to expansions from the Arabian Peninsula which brought Islam to the area in
the 7th and 8th Centuries.

But they emphasise that the differences between the two communities are
minor, and that Christians and Muslim Arabs in Lebanon overwhelmingly share
a common heritage.

*Genetic 'surname'*

The legacy of the Muslim expansion has been demonstrated in other studies
which looked at the genetics of Middle Eastern and North African
populations. But signs of recent European migration to the region are more
unusual.

The study focused on the Y, or male, chromosome, a package of genetic
material carried only by men that is passed down from father to son more or
less unchanged, just like a surname.

But over many generations, the chromosome accumulates small changes, or
copying errors, in its DNA sequence.

These can be used to classify male chromosomes into different groups (called
haplogroups) which, to some extent, reflect a person's geographical
ancestry.

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.

A genetic signature on the male chromosome called WES1, which is usually
only found in west European populations, was found among the Lebanese men
included in the study.

*Science and history*

"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.

"The goal of the study was to put some science to the history of this
country - which is very rich," said Pierre Zalloua, a co-author on the
paper, from the Lebanese American University in Beirut.

He added: "To have these great civilisations - with the Islamic expansion
and the migration from Europe - coming to Lebanon, leaving not only their
genes but also some of their culture and way of life, it can only make us
feel richer."

The Genographic Project was launched by National Geographic in 2005 to help
piece together a picture of how the Earth was populated.

The consortium has sold 250,000 DNA test kits and regional centres have
taken samples of genetic material from 31,000 indigeous people.
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