FARMERS from the Middle East carried civilisation with them into Europe, 10,000 years ago. A genetic analysis reveals that modern inhabitants of Paris, Athens and Berlin share an average of 50 per cent of their genes with people from Baghdad, Tehran, Ankara and Damascus.
That means farmers must have emigrated en masse from the Middle East into Europe, mingling and interbreeding with the hunter-gatherers of the day. It also helps settle the long-running debate about whether immigrants brought agriculture directly to Europe or if the idea simply spread west by word of mouth.
The development of agriculture is considered to have been one of the most important steps leading to modern civilisation. Archaeologists have shown that agriculture moved north-west through Europe at about one kilometre a year, based on the dating of clay pots and other tools.
Advertisement
But how this happened has been less clear. In the 1970s, scientists first proposed that farmers must have moved west, as certain genetic traits such as eye colour seem to follow the archaeological sweep across Europe. But later studies favoured the idea of a slow cultural exchange of ideas.
Two years ago, for instance, a study examining 22 genetic markers on the Y chromosome of over 1000 men suggested that fewer than a quarter of modern European genes come from Middle Eastern stock, implying very little mixing between the populations.
But now Loun猫s Chikhi from University College London and his team say that this analysis was too simplistic. Using a different statistical model to look at the same data, they found that Middle Eastern farmers contributed at least half of the genes of modern Europeans, ranging from 85 to 100 per cent in Greece to only 15 to 30 per cent in France (Proceedings of the National Academy of Sciences, doi: 10.1073/pnas.162158799). That indicates farmers moved en masse across Europe.
Chikhi鈥檚 method is the first that can tell whether genetic similarities are caused by populations mixing or simple genetic drift. Surprisingly, they found that people in Sardinia look genetically similar to their Greek neighbours only by chance. Sardinians are almost purely descended from local hunter-gatherers, whereas Greek people can trace most of their ancestry back to the Middle East, a finding that agrees with most archaeological theories.