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Tuesday, December 29, 2015
Til 5000 B.C. The Irish Genome Had Mid-Eastern Roots; Then Immigration By E. European Celts
A reconstruction of an ancient Irish woman. Her genes tell us she had black hair and brown eyes.
Ancient Irish genome reveals a massive migration from the east
Rachel Feltman, Washington Post
Just over 5,000 years ago, there lived an Irish farmer with black hair and dark eyes. Her DNA spoke of ancestors mostly Middle Eastern in origin, and she would have looked more like a southern European woman than a red-haired Irish lass.
But just 1,000 years later, her world was full of blue eyed easterners. This quick transition to Ireland as we know it, genetically speaking, is likely due to a massive migration that occurred sometime during those 1,000 years. The evidence comes from a study published Monday in the Proceedings of the National Academy of Sciences, where geneticists from Trinity College Dublin and archaeologists from Queen's University Belfast sequenced the genomes of four ancient citizens of Ireland to unlock the secrets of their origins.
Ireland is particularly interesting to geneticists, because it seems like a place where many ancient peoples may have converged. For starters, the pre-historic residents there showed a smooth transition from hunting and gathering to farming, and then from stone to metal working. It's likely that changes like these were driven by newcomers with new ideas, but we can't assume that the original inhabitants of Ireland didn't just come up with these life changes on their own.
But even the genes of the modern Irish hint at a melting-pot past. They have some of the highest levels of certain genetic mutations, including the one that allows adult humans to tolerate dairy. Several mutations that promote dangerous illnesses, like haemochromatosis (excessive iron retention) andcystic fibrosis are also more prevalent than they are elsewhere in the global population.
Study author Dan Bradley, professor of population genetics at Trinity College Dublin, explained that recent technological and methodological advances in ancient DNA analysis allowed his team to produce full genomes for the four skeletons used in their research. They were surprised to see how different the Neolithic woman, who was found in Belfast in 1855 and lived over 5,000 years ago, was from the three male skeletons analyzed, who were found off of Rathlin Island in 2006. With just 1,000 years separating them, their genomes shouldn't have looked so strikingly different - which suggests that some major migration really must have occurred.
The Irish woman's remains. (Daniel Bradley, Trinity College Dublin)
"It was a surprise to see several genetic elements typical of the modern Irish genome, both of interesting genes but also of more anonymous DNA fragments, appearing in the Bronze Age specimens," Bradley said of the more recent skeletons. "These genomes when taken as a whole are more like modern Irish, Scottish and Welsh - insular Celtic populations. This suggested some large degree of establishment of the genetics of these populations 4,000 years ago."
The Bronze Age men even had the genetic mutation for haemochromatosis, which is now so common in Irish populations that it's sometimes called a Celtic disease.
The differences between these men and the ancient farming woman speak of a "profound migratory episode" in the 1,000 years between their lifetimes, Bradley said. Based on the men's DNA, the researchers suspect that their ancestors may have come to Ireland from the Pontic Steppe - the area of Eastern Europe that sits over the Black Sea, including what's now the Ukraine.
For now, this probable migration is still quite mysterious. We know it must have occurred sometime between about 5,000 years ago and 4,000 years ago, but scientists will have to sequence the genomes of more skeletal remains from before, during and after that period to confirm just how and when the migration took place.
The Irish are descended from early Middle East farmers and from bronze metalworkers on the steppes around the Black Sea, scientists have found.
Genome sequencing and DNA analysis of the remains of people living 5000 years ago in what is now Ireland uncovered the origins of its population.
By sequencing the first genomes from Irish people of different eras, scientists found unequivocal evidence of mass migration into Ireland.
These genetic influxes brought cultural change such as moving to settled farmsteads, bronze metalworking - and may have been the origin of western Celtic language.
Geneticists from Trinity College, Dublin, and archaeologists from Queen's University Belfast studied the genome of a woman farmer who lived 5200 years ago near what is now Belfast.
They also carried out DNA analysis of three men on Rathlin Island from 4000 years ago in the Bronze Age after metalworking began.
The early farmer's ancestry originated ultimately in the Middle East, where agriculture started. She had black hair and brown eyes - like current south Europeans.
The Bronze Age male genomes are different again with one-third of their ancestry from the Pontic Steppe. They had the most common Irish Y chromosome type, the blue eye gene variant.
Dan Bradley, Trinity professor of population genetics, said: "There was a great wave of genome change that swept into Europe from above the Black Sea into Bronze Age Europe. It washed all the way to the shores of its most westerly island."
The study was published in the journal Proceedings of the National Academy of Sciences of the USA.