The modern European gene pool was formed when three ancient populations mixed within the last 7,000 years, Nature journal reports.

Blue-eyed, swarthy hunters mingled with brown-eyed, pale skinned farmers as the latter swept into Europe from the Near East.

But another, mysterious population with Siberian affinities also contributed to the genetic landscape of the continent.

The findings are based on analysis of genomes from nine ancient Europeans.

Agriculture originated in the Near East – in modern Syria, Iraq and Israel – before expanding into Europe around 7,500 years ago.

Multiple lines of evidence suggested this new way of life was spread by a wave of migrants, who interbred with the indigenous European hunter-gatherers they encountered on the way.

But assumptions about European origins were based largely on the genetic patterns of living people. The science of analysing genomic DNA from ancient bones has put some of the prevailing theories to the test, throwing up a few surprises.

Genomic DNA contains the biochemical instructions for building a human, and resides within the nuclei of our cells.

In the new paper, Prof David Reich from the Harvard Medical School and colleagues studied the genomes of seven hunter-gatherers from Scandinavia, one hunter whose remains were found in a cave in Luxembourg and an early farmer from Stuttgart, Germany.

The hunters arrived in Europe thousands of years before the advent of agriculture, hunkered down in southern refuges during the Ice Age and then expanded during a period called the Mesolithic, after the ice sheets had retreated from central and northern Europe.

Their genetic profile is not a good match for any modern group of people, suggesting they were caught up in the farming wave of advance.

However, their genes live on in modern Europeans, to a greater extent in the north-east than in the south.

The early farmer genome showed a completely different pattern, however. Her genetic profile was a good match for modern people in Sardinia, and was rather different from the indigenous hunters.

But, puzzlingly, while the early farmers share genetic similarities with Near Eastern people at a global level, they are significantly different in other ways. Prof Reich suggests that more recent migrations in the farmers’ “homeland” may have diluted their genetic signal in that region today.

Prof Reich explained: “The only way we’ll be able to prove this is by getting ancient DNA samples along the potential trail from the Near East to Europe… and seeing if they genetically match these predictions or if they’re different.

“Maybe they’re different – that would be extremely interesting.”

Source: BBCNews Read and see more

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