<b><a href="http://news.bbc.co.uk/2/hi/science/nature/7316281.stm">http://news.bbc.co.uk/2/hi/science/nature/7316281.stm</a><br><br></b><span class="byl">
By Paul Rincon
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Science reporter, BBC News</span><br><b><br>Scientists have detected the faint genetic traces left by medieval crusaders in the Middle East.</b>
<p>
The team says it found a particular DNA signature which recently appeared in Lebanon and is probably linked to the crusades.
</p><p>
The finding comes from the Genographic Project, a major effort to track human migrations through DNA.
</p><p>
Details of the research have been published in the American Journal of Human Genetics.
</p><p>
The researchers found that some Christian men in Lebanon carry a DNA signature hailing from Western Europe.
</p><p>
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.
</p><p>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.
</p><p>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.
</p><p>
<b>Genetic 'surname'</b>
</p><p>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.
</p><p>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. <br></p><p>
But over many generations, the chromosome accumulates small changes, or copying errors, in its DNA sequence.
</p><p>
These can be used to classify male chromosomes into different groups
(called haplogroups) which, to some extent, reflect a person's
geographical ancestry.
</p><p>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.
</p><p>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.
</p><p>
<b>Science and history</b>
</p><p>"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.
</p><p>"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." </p><p>
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."
</p><p>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. </p><p>
"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.
</p><p>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."
</p><p>The Genographic Project was launched by National Geographic in
2005 to help piece together a picture of how the Earth was populated.
</p><p>The consortium has sold 250,000 DNA test kits and regional
centres have taken samples of genetic material from 31,000 indigeous
people.
</p>