Friday, August 26, 2016
Ireland's Mideast origins for our hunter-gathering genes
Now is the time to find big, ripe, juicy blackberries, fresh and unwormed. Picture: Damien Enright
I wonder were the bones found in a cave in Co Mayo earlier this month those of hunter-gatherers, or are they that old? Once the archaeologist have dated them, the geneticists might decide to DNA analyse them, and find their genetic history. Who knows what information about the journey of mankind to this sacred isle such bones might reveal.
In 2015, study of the remains of a woman who died 5,200 years ago in Co Down revealed that she was of Middle Eastern extraction. She would have been a member of a group of Stone Age farmers, our forbearers, themselves descendants of the first agriculturists in the fertile crescent of the Tigris and Euphrates rivers that flow into the Persian Gulf. She had black hair and brown eyes, typical of Middle Eastern people. Middle Eastern DNA —perhaps Syrian? — is in our blood.
The first cereals were grown in Syria 9,000 years ago; the first hybrid trees in Jordan, 2,000 years earlier. Her ancestors arrived in Ireland, bringing with them cereals, livestock and pottery, and the colourful, edible snail we find everywhere, but often close to the sea.
The banded snail, Capaea nemoralis, most likely arrived in Ireland with Mesolithic migrants moving west. Evidence of its presence begins 8,000 years ago, and there is a continuous fossil record from that time. Its DNA matches that of banded snails found only in the Pyrenees, on the route Mesolithic migrants would probably have taken to Ireland. They may have carried them as a fresh food source.
In tandem with the study of this Stone Age woman’s remains, the Trinity College/ Queen’s University team studied the DNA of three men buried on Rathlin Island, Co Antrim 1,000 to 1,500 years after she died.
Using a technique called whole- genome analysis to ‘read’ not only the unique characteristics of individuals but to compare the DNA from all four bodies, the scientific teams aimed to arrive at a broader understanding of migration and settlement.
The three men in Rathlin lived in the Bronze Age and were descendants of peoples that originated in the Pontic Steppe in southern Russia, the Baltic States, Poland and Central Europe. That we have some of their DNA sequences is beyond doubt.
They carried a distinctive genetic disorder called haemochromatosis, a hereditary variant which causes the body to store too much iron in the liver, heart and pancreas. The variant is evident in almost all Irish DNA, so universal that it has been called the Celtic disease.
They also carried the gene that allows adults to digest milk —useful in the largely dairy-product economy that Ireland has become. Many other races become intolerant to milk after infancy. They were more like the Irish of today. Their eyes were often blue; their antecedents, the farmers, had brown eyes. Their language may even reflect an early form of our national language.
Early newcomers did not compete with those already on the land but became Irish themselves.
These northern Europeans brought the Bronze Age — bronze ploughshares, metal tools and craftsmanship in gold. By the time of their arrival, the farmers would already have subsumed, or integrated with, the hunter-gatherer population that preceded them.
So, the ‘Irish’ moved from hunting-gathering, to farming, to a metal age culture.
The human story is a narrative of movement and migration, and an exchange of genes and cultures that over-ride border controls.
After the Bronze Age came the Iron Age and the legendary Celts, with their flowing hair and flowing robes. They began their migration out of Central Europe in 1,000BC, possibly under some pressure from the Roman Empire, and began to reach Ireland from about 600BC onward. Before long, the old Bronze Age culture was supplanted but, of course, farming never stopped.
Another migration, another step forward, added DNA and, possibly, hybrid vigour. With the Celts, we became more technologically, artistically and linguistically sophisticated.
What these lately-discovered Co Mayo bones will tell us is not known. Perhaps their owners were Stone Age farmers, Bronze Age metal workers, bardic Celts or perhaps they lived in the ancient days of picking berries and hunting giant elk, or knocking trees and creating arable land, like the Ceide Fields in Mayo, 6,000 years old.