Sanger Institute - Crusader Y chromosomes in Lebanon


Uploaded by sangerinstitute on 17.11.2009

Transcript:
The Y chromosome is carried by men and not women
And amazingly all Y chromosomes can trace back to a single man
Who would have lived maybe 100,000 years ago and almost certainly in Africa
And now, with genetics, we have the means to trace the history of all of those Y chromosomes and link them together
And also link them to other events that we know about in history
So we trace Y chromosome lineages: sometimes these tell us things about individuals
And sometimes even we can guess the names of those individuals, like a study of Genghis Khan we did some time ago
But other times it tells us more general things about the populations and where a population might have come from
This study was focussing on Lebanon, and Lebanon is an amazing crossroads
It was visited by just about everyone we've heard about in history: by the Romans, the Greeks, the Egyptians
And then more recently by several migrations that were of particular interest to us:
The Arab expansion, the Crusaders and the Ottoman expansion
We sampled over 900 men from Lebanon. Then we typed their Y chromosomes with almost 70 genetic markers
We could compare with the sources of these historical migrations that we know about:
Western Europe, the Arabian Peninsula or Turkey
And search to see if we could find any evidence that would link the Lebanese to those places
To our surprise and delight, we did find evidence for two of the three known migrations
The first one, around 1,400 years ago, was the Muslim expansion from the Arabian Peninsula
And we found a Y chromosome type in Lebanese Muslims introduced by that
And then the second migration from western Europe, with the Crusaders
Introduced a different Y chromosome type into Lebanese Christians
And this was particularly striking because this type of Y chromosome was otherwise found only in the far west of Europe
We didn't find any evidence for the migration from Turkey
We think there are probably two reasons for that
One is that Turkey is quite close to Lebanon, so the [genetic] differences are rather small
The other is that the people from Turkey may just not have left children in Lebanon
We know that Lebanon was visited by other people like the Romans, the Greeks and the Egyptians
We also know that it was the source of the Phoenician people who expanded 2,000 or 3,000 years ago
So by doing wider regional studies we can look for those influences
Our knowledge of history is very limited to a few centres like Europe, China and India
So I think there are wonderful opportunities to expand into a more global analysis.