http://news.bbc.co.uk/1/hi/sci/tech/2174437.stm
Modern Europeans can trace a great deal of their ancestry to Middle
or Near Eastern farmers who moved into the continent 10,000 years
ago.
The assessment comes from a new computer and genetics study which
has sought to understand how the new agrarian technologies were
introduced to the region.
It is clear from the work that it was not purely a spread of ideas -
but a mass movement of people who settled and mixed with the hunter
gatherers who dominated Europe at that time.
The new study is published in the journal Proceedings of the
National Academy of Sciences.
Genetic 'signature'
Anthropologists believe agriculture probably started in the Middle
East and then swept into Europe about 8,000 BC.
The debate has centred on whether the lifestyle changes at that time
represented simply an "invasion" of ideas and practices or were led
by a large immigrant population who mixed with the native people.
If the latter is correct, there should be a genetic "signature" left
in the modern gene pool.
Lounes Chikhi, from University College London (UCL), UK, and
colleagues looked for this marker by analysing mutations (errors) on
Y chromosomes, the bundles of DNA handed down from father to son.
Computer analysis
In particular, they studied rare mutations called unique event
polymorphisms (UEPs). These are not thought to have occurred more
than once in recent human history.
The presence of UEPs in different populations is likely to indicate
common ancestry rather than recurrent changes in gene structure.
The research team took the results of a previous study and subjected
them to a new computer-intensive technique. From this, the
scientists estimate that Middle Eastern farmers contributed about
50% of the analysed genes to the modern European population.
Contributions ranged from 15-30% in France and Germany, to 85-100%
in southeastern European countries such as Albania, Macedonia, and
Greece.
These figures are much larger than previous ones, suggesting that
the Middle Eastern contribution to European genetic heritage has
been underestimated.
Small and large
"Archaeologists have shown that farming moved from the Near East to
North West Europe... but we've never known how it happened," Dr
Chikhi told the BBC.
"We know that farming spread across Europe at approximately one
kilometre a year - or 20 km per generation."
The UCL researcher added: "All Europeans have hunter-gatherer genes,
but they also have Near East farmers' genes.
"There are clear differences between regions in Europe. For
instance, in Greece and the Balkans an individual has between 70-
100% of genes from Near East farmers, but in western France and
England as little as 10% of an individual's genes can come from the
Near East."