The most common Irish Y chromosome type, the blue eye gene variant. Photo / Ben Fraser
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.