Irish ancestors came to the island from the Middle East, where agriculture was invented, according to a study led by geneticists from Trinity College Dublin and archaeologists from Queen’s University Belfast, which was published in the Proceedings of the National Academy of Sciences. The paper authors discovered evidence of mass migration from the east by sequencing the genomes of four ancient Irish.
The genome comprises three billion paired DND “letters” and contains the genetic information of an organism. Researchers sequenced that material of a woman who lived 5,200 years ago in the Neolithic period and three 4,000-year-old men who lived in the Bronze Age.
The ancient female was a farmer with black hair and dark eyes, so her ancestors probably came from the Middle East. On the other hand, the genome of the three 4,000-year-old male skeletons appeared to be significantly different from the Neolithic woman, since a third of their ancestry came form ancient sources in the Pontic Steppe. Genetically, the men are similar to modern Irish, Scottish and Welsh.
Researchers were amazed at the striking difference between the male who were found off of Rathlin Island in 2006 and the female skeleton that was discovered in Belfast in 1855. After about 1,000 years of the female’s death, almost everyone in Ireland had blue eyes, which is why scientists believe there was a massive migration during those 1,000 years.
“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,” said lead author Dan Bradley from Trinity College Dublin, referring to the male 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.”
Ireland happens to be a country were many ancient peoples may have gathered, since it has the world’s highest frequencies of genetic variants that code for the ability to drink milk into adulthood, known as lactase persistence, and some genetic diseases such as haemochromatosis, which is excessive iron retention. Scientists found the haemochromatosis mutation in one of the Rathlin men, which gives a hint that the disorder was established by the Bronze Age. The female skeleton carried another variant, which is related to an increased risk of the disease.
Bradley pointed out that the male individuals were not exactly like modern groups and that further research is needed to better understand the way Irish diversity developed in Celtic populations.