Old Blue Eyes

Yesterday I watched the concluding episode of a fascinating two-part documentary series called The Burren: Heart of Stone, an extraordinary region of glaciated limestone klarst in County Clare. The landscape has a distinctly other-worldly look to it, yet humans have lived and farmed on it for at least 8,000 years.

Episode 1 was largely about the geology and ecology of the Burren which explained how the motion of glaciers across the area scraped away upper layers and revealed the limestone deposits formed by the bones and shells of ancient marine creatures who lived there tens of millions of years ago. The present-day Burren is windswept and rainy but is home to a rich ecosystem of plants, insects, birds and animals. Despite the heavy rainfall there are no rivers to be seen, but water flows underground through a complex network of tunnels and caves.

The first programme was interesting enough but Episode 2 was about the history of human habitation in the Burren, incorporating recent genetic discoveries, and that was absolutely fascinating.

The oldest population for which DNA sequencing has been possible were the mesolithic hunter- gatherers who lived in Ireland at least 8,000 years ago. Studies of the available remains show that these people had dark skin and blue eyes.

I only found out recently that the genetic mutation required for blue eyes arose in a single individual about 10,000 years ago; before that happened no humans had blue eyes. Having blue eyes myself, and in light of a recent discovery that I have a different mutation that arose more recently, I find that very intriguing.

Being hunter-gatherers these folk lived on the margins of the forests that covered most of Ireland, fishing and hunting animals as well as gathering nuts and berries. Their settlements were primarily impermanent affairs made of wood, so these people did not leave lasting impression on the landscape. Ireland probably couldn’t sustain a large population of these folk either, but the next people to arrive were the neolithic people who were the first farmers in Ireland. Their genetic profiles suggest they originated somewhere around modern-day Turkey and were also somewhat dark-skinned. They cleared the forests and set up permanent habitations involving stone structures, including the famous megalithic sites such as the tomb at Poulnabrone, which is at least 6,000 years old:

The Burren could have been popular with these people because, with its thin topsoil, it was much easier for them to get rid of the trees and start farming. They built stone walls to divide fields, and it is said that the walls which criss-cross the present-day Burren follow the line of these prehistoric structures.

Genetics reveal that these neolithic people and the mesolithic people intermingled and interbred, though the circumstances that led to this are of course unknown. It is hard to believe that a huge influx of people chopping down trees and clearing the land for farming would have caused no friction with the previous inhabitants. There may well have been violent struggles.

The neolithic culture survived and flourished in relative isolation until the arrival of Bronze Age settlers somewhere around 4000 years ago. These came originally from the Steppes of Russia, who took over many of the neolithic sites and adapted them for their own use before they were eventually abandoned. Evidence from the Burren suggests that the massive deforestation, combined with a climate downturn, led to catastrophic soil erosion; farming became impossible and the culture collapsed.

Incidentally, DNA studies of the Bronze Age people of Ireland are heavily mixed with neolithic genes but show no relic of the mesolithic population. Presumably these were diluted too much, as the neolithic culture sustained a much bigger population, probably around 200,000 in number.

All this was centuries before any Celtic people arrived in these shores, which was around 500 BC.

A fascinating programme, well worth watching if you can get to see it. There was a twist in the tail too: recent discoveries of apparent human activity on animal bones dated back to around 30,000 years ago, show evidence of a population of people in Ireland before the most recent Ice Age began.

Fascinating stuff!

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