March 17, 2021   6 mins

The Welsh writer and historian Norman Davies reflects in his magisterial book The Isles: A History that what sets the Irish apart from the British, and in particular the English, is that they retained their mythology. By this, Davies alludes to the fact that the Irish became Christian gradually and through a process of local adoption, rather than as an external shock, cajoled by foreign missionaries or coerced by their ambitious monarch. When St Patrick converted the Irish — an event celebrated today by millions around the world — it was a remarkably peaceful transition that left the country’s ancient culture alive.

Due to the gradual nature of transformation, the pagan lore of Ireland was recorded by monks who saw their work as a way to preserve and continue the legacy of their own native culture. J. R. R. Tolkien famously created the world of the Lord of the Rings so that the Anglo-Saxons could have their own mythos. The Irish have no need of such creative endeavours, since the tales of Cú Chulainn and Fionn mac Cumhaill have wrapped within them the pathos of Túrin Turambar and Achilles. The Lebor Gabála Érenn, “Book of Invasions,” more than matches The Silmarillion.

These are enduring myths that have been preserved in Irish culture — but what if I told you that the legend and myth are rooted in reality? That the Irish oral tales preserved by monks in the 8th century AD are echoes of events from thousands of years in the past? Far afield from folklore and oral history, the new science of ancient DNA is putting concrete flesh and bones upon the veiled prehistory in which Irish myth is rooted.

The story goes back to the last Ice Age when Ireland was mostly covered in ice and, like Britain, uninhabited. As the ice sheets retreated 10,000 years ago, the island began to be recolonised by Mesolithic hunter-gatherers arriving from the continent, venturing into an empty landscape. These people had migrated out of southern Europe, following the fauna and flora north as the continent warmed up, and were related to people then found in Britain, France and Spain.

They looked strikingly different from today’s Europeans. Genetic analysis indicates that their skin was dark, as was their hair — but their eyes were likely blue. The genetic difference between these people and later Europeans is similar to that between modern Europeans and Chinese. This world of hunter-gatherers persisted for thousands of years, as small bands clung to the western edge of Europe, practising a lifestyle with roots in the deepest Palaeolithic, eating a protein-rich diet of horses, bison, aurochs and red deer.

All this ended with the arrival of farming. A generation ago there were roiling debates among archaeologists as to whether agriculture came to northern Europe through cultural diffusion or migration, a debate similar to that which had raged about whether the Anglo-Saxons had conquered Britain in large numbers. Ancient DNA has now definitively answered this question, and we know that the first farmers in Europe descended from Anatolian migrants who swept in from the Near East. They spread across the continent rapidly around five millennia before Christ, mixing only minimally with the native hunter-gatherers, who were thin on the ground and could offer little resistance; although hunter-gatherer peoples had healthier diets and probably lived longer, farming societies could feed vastly more people and so overwhelmed their neighbours.

These newcomers arrived in Ireland around 4500 BC, many thousands of years after they had established themselves in southern Europe. They brought with them their grains, sheep and cattle, but many of the elements of Irish agricultural life were already in place and had been for over 1,500 years, conditioned by the local ecology and climatic regime. Though the new people mixed with the native hunter-gatherers, their own language and culture came to dominate, while ancient DNA indicates that the hunter-gatherers were very small in number. There were simply many more of the newcomers.

What few Mesolithic hunter-gatherers there were retreated and were absorbed in the advancing human wave of farmers. For many generations the two groups would probably have been easy to distinguish: the newcomers were light-skinned and dark-eyed, while the hunter-gatherers were dark-skinned and light-eyed. Ancient DNA suggests dark-skinned people persisted long after the arrival of farmers in pockets and corners of the island, in more remote and mountainous regions of the country. Who knows if some of the Irish legends of different people and races did not emerge from these contacts?

Curiously, the closest modern people genetically to the Neolithic farmers of Ireland are the Sardinians. But this is not surprising considering that most of the ancestry of the first Irish farmers seems to have derived from the Cardial Culture of Spain (itself the product of a rapid expansion of farmers from the eastern Mediterranean). While the Mesolithic hunter-gatherers were dark-skinned but light-eyed, the farmers likely resembled many modern southern Europeans, with dark hair and eyes, and lighter skin. The contact between two such distinct groups, almost certainly speaking unintelligible languages, physically so different and practising contrasting lifestyles, almost certainly fed into later legends and myths.

The arrival of farmers in Ireland led to a transformation of the material culture. These Neolithic people were responsible for the construction of great stone megaliths, a practice that arose and spread along Europe’s Atlantic shores, seen with Stonehenge in Britain and the Carnac Stones of Brittany. They also built monuments such as the Newgrange passage tomb, one of the most ornate and beautiful pieces of prehistoric stonework in the world. These various stoneworks and tombs that litter the landscape of Ireland have shaped the Irish sense of their past, and loom large in legends of faeries and ancient peoples long lost and faded into the mists of time.

But the time of the Stone Age farmers ended in due course, and in 2500 BC the first of many waves of migrants swept west onto the island. Called the “Beaker Culture“, they were descendants of people who had left modern Germany, and earlier still had their origins on the Eurasian steppe. Genetically, the Beaker People resemble the modern-day inhabitants of the island and physically, too, these newcomers appeared rather like the fair-skinned and often fair-haired modern Irish. Though many of the traits now associated with the Irish, such as lactose tolerance, were not present in full, the roots of the genetic character of the modern people date to this period.

One hypothesis holds that it was the Beaker People who brought the Celtic languages, establishing the cultural patterns that persisted down to the Iron Age and contact with the Romans. If this is true, then the myths that were recorded by the Irish monks in the 7th and 8th centuries AD may date to the period of contact and conflict between the Neolithic tribes and the Beaker Culture. Could it be that the Tuatha De Danann, a mythologic race of supernatural beings mentioned in Irish legend, and vanquished by the ancestors of the Gaels, were actually the builders of the megaliths?

Recently, a group of Irish scientists has cataloged genetic remains from a host of locations across Neolithic Ireland. They discovered that a high-status man buried at Newgrange 5,000 years ago appeared to have been part of an important prehistoric dynasty, and was also the product of incest. The researchers point out that it is often a feature of highly-stratified Neolithic societies that royal families will practise incest, yet it is intriguing that the early historical Irish had legends of incest at the site of Newgrange, a story that must have survived thousands of years until Christianisation and literacy.

The local people in fact called the mound the “Hill of Sin”, and there were legends of incestuous activities between a ruler who built monuments and his sister in order to maintain the cycle of the sun. And so the existence of an individual who is quite inbred, and clearly of elite status, buried 3,000 years before these stories were written down is quite extraordinary.

Is it possible that Irish folklore was able to record an essentially truthful story over so many generations? The mythic legends of Ireland date to the time of Christ, over 2,000 years after the arrival of the Beaker Culture, and their likely conflict with the last of the Stone Age farmers who built the monuments they inherited. Preservation of such ancient motifs seems implausible. But note that Indian mythology preserves elements that are resonant with Greek myth, such as the divine twins — this, despite the two cultures being separated by thousands of years since their last common ancestor, suggesting a story that had been maintained for generation upon generation.

Davies, among other historians, highlights the Irish preservation of their mythic cycle as a matter of curiosity, and perhaps an edifying fact. But the detail and fidelity of the Irish in setting down their oral history may actually benefit future generations, as ancient DNA is telling us in exquisite detail the demographic processes by which the Irish people came to be the way they are. The true book of invasions is being written by unraveling DNA, and the existence of an oral record of the deep past may be essential for future scholars in understanding life in the islands before the Romans brought it into the light of history.

Razib Khan is a geneticist. He has written for The New York Times, India Today and Quillette, and runs two weblogs, Gene Expression and Brown Pundits. His newsletter is Razib Khan’s Unsupervised Learning