Irish DNA: What is the Genetic History of Ireland?

What is the genetic history of Ireland and what is the genetic make-up of the modern Irish population? Now the Irish word for island is Eire, which is thought to derive from Eru, who is the goddess of the Tuath Dé Danann in Irish mythology. Although the etymology of the word Eru is disputed, it could ultimately descend from a Proto-Indo-European term meaning fertile land or abundant land. What we do know is that Irish is an Indo-European But what about Ireland's genetic history? Well this is what Ireland would have looked like around 20,000 years ago during the last ice age. Now once the ice melted, the ancient genetic history of Ireland is similar to other Western European countries. It was a fusion of three main sources, firstly Western hunter-gatherers that started moving back into the land we call Ireland today after the ice had melted, then there was early European farmers that moved in that were originally from around Anatolia, and then the third component is this steppe ancestry that is connected to the Pontic-Caspian steppe and also the Yamnaya culture. A really interesting study that looked at the early genetics of Ireland is worth noting in a little detail. It was published in PNAS in 2015 and it analysed one Neolithic woman that lived around 5,000 years ago, just over 3,000 BC, and was found near modern Belfast, and three Bronze Age men from Rathlin Island, which sits just north of Ireland, and who lived between 2,000 and 1,500 BC. If we start with the Neolithic female, she mainly had Near Eastern ancestry but she also had a little Western hunter-gatherer ancestry as well, which makes sense as early farmers mixed with hunter-gatherers as they moved across Europe. The authors also found she had some connections to ancient Spain as opposed to central Europe, as she shared high levels of genetic drift with early and middle Neolithic samples from Spain rather than those from Germany, supporting a link between the early farming cultures of Atlantic Europe. As far as haplogroups and what she looked like, she belonged to the mitochondrial haplogroup HVO and probably had a dark hair shade and brown eyes. Now what about the three Bronze Age men in this study? Well, they were indicative of this massive wave of steppe ancestry that swept across Europe during the Bronze Age. And this study found that many of the central attributes of the Irish genome were formed around this time 4,000 years ago. All three men showed substantial steppe genetic heritage, indicating that the European population upheavals of the third millennium manifested all the way from southern Siberia to the Western Ocean. They went on to give an estimate of around 32% Yamnaya ancestry in these Bronze Age individuals. They also note that the vector for the spread of this Yamnaya or steppe ancestry may have been This period was associated with the appearance of copper mines which were followed by bronze tool making, wepary and gold working, with distinct food vessel pottery succeeding from the earlier beakers. The way people were buried also changed around this time. It is marked by the end of the large passage graves of Neolithic Ireland in favour of single burials and small wedge tombs. The authors also go on to note that this genetic transformation in ancient Ireland during the Bronze Age opens the possibility of accompanying language change as well, perhaps the first introduction of the Indo-European language ancestral to Irish. They go on to note that this assertion gains some support by the relative lack of affinity of non-Indo-European speakers, i.e. the Basque people, to the ancient Bronze Age genomes. As far as what these men could have looked like, this study found that each individual had at least one copy of the haplotype associated with blue eye colour in the which basically means that the Bale Beakers could have made blue eyes a bit more common amongst the population when they came into Ireland. As we know that the early European farmers had darker eyes and darker hair, even the western hunter-gatherers did have blue eyes. But what haplogroups did these ancient individuals belong to? Well, on the maternal side, the mitochondrial side, two of the men belonged to U5, and one had the mitochondrial haplogroup J2B1A. As far as why DNA haplogroups, all three men belonged to variations of R1B. And if you're an Irish male watching this, there is a good chance you share this haplogroup, as we'll see later. This study also notes that there is an ancient genetic affinity between the Irish, Scottish and Welsh, and to a lesser extent the English, which is mainly due to the influence of the Anglo-Saxons, suggesting a degree of continuity stretching over 4,000 years at the Insular Celtic Age of Europe. Now before we move on to look at a few interesting points that this study found, and in Ireland's more modern genetic history, I would like to quickly thank the sponsor of today's video, Mantasleep. Now these videos take a lot of time and energy to make. That's why getting a good night's sleep is essential. That's where Mantasleep comes in. 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Please click the top link in the video description below to find out more information, and use the code HISTORY at checkout to get 10% off your order. Thanks to Mantasleep for sponsoring this video, and now on with the rest of the video. Now another interesting point I will note from this study is that they found the presence of certain genotypes associated with a genetic disease called Haemochromatosis, also known as the Celtic disease, in these Bronze Age individuals. This is an inherited condition where iron levels in the body slowly build up over many years, and today it is most common in countries where lots of people have a Celtic background, such as in Ireland, Scotland and Wales according to the NHS. This study thus shows that this disease has ancient origins in Ireland, and probably in these other two countries as well. Another finding from this study was that these Bronze Age individuals had the genetic coding for lactose tolerance, and there is an increasing body of evidence that the ability to digest milk is associated with the Yamnaya culture and steppe ancestry. But what about Ireland's more modern genetic history, from the Celts to the Vikings to the plantations? Well let's start with the Celts. During the Iron Age Celtic culture flourished in Ireland, but it's not really clear whether this was a cultural adoption or through a migration of people from continental Europe that came into Ireland. But a really interesting study published in Nature in 2017 had some interesting insights. The study analysed Irish DNA mapped to Ireland genetically, and one finding is that there is some Northwest French ancestry in Ireland. So this is potentially a signal from the ancient Celts, but some of you may be saying that it could be from the Normans. Well the authors directly addressed this, explicitly stating that considering the links from Northwest France to other Celtic populations, we do not interpret this as a Norman signal. So this Northwest French ancestry could be a legacy of the ancient Celts, as we know Gaul, which was around the territory of modern France, was the home of Celtic civilisation. We do know as well that there was a migration of people from around ancient France into ancient England and Wales just before the onset of the Iron Age, and perhaps this migration also reached Ireland, but this study did not look at Ireland unfortunately, and more research is definitely needed into this topic. What is more clear however, is that the Vikings had a profound impact on the genetics of Ireland. Viking raids on Ireland began in the 8th century AD, and then progressed from there, and they went on to establish various fortified bases, including in Dublin, which was home to a significant Viking slave market. This study that looked at the Irish DNA atlas found that there is a significant Norwegian signal in Ireland, with this Norse signal shared across Ireland and not limited to regions of Norse settlement, such as Limerick, Waterford, Wexford and Dublin. They estimated that some regions within Ireland could have up to 20% Norwegian ancestry, which is pretty sizeable. In fact, a study found that the level of Norwegian ancestry in Ireland was second only to Orkney when they compared Ireland's DNA to other regions in these isles, and we know that Orkney has a major Viking and Norwegian signal, helped by the fact that it was actually part of Norway for a period. But what genetic impact did the Normans leave, with the Anglo-Norman invasion of Ireland taking place in the 12th century? Well, as I've already touched on, there is this signal from northwest France in different samples across Ireland, although this seems to be from ancient Celtic groups. The Normans seem to have left a very limited genetic impact on Ireland, which is actually similar in England, there's a very limited genetic impact of the Normans on England as well. Yet there was another episode that had a significant genetic impact on Ireland, this time during the 16th and 17th centuries. During this period there was an increase in Scottish and English ancestry. And this is probably related to the plantations, when the crown confiscated Irish land and moved mainly Protestants into these areas from England and Scotland. This gene flow from Scotland could have been confounded by earlier migrations as well, including the settling of the Scottish Gallaglass mercenary dynasties from the late 13th to the early 14th centuries, and perhaps the hiring throughout the 16th century of large numbers of Scottish red shank mercenaries. And on the subject of the links between Scotland and Ireland, the western part of Scotland around Argyll, or the coast of the Gales, has a greater genetic affinity with Ireland than other parts of Scotland. This is hardly a surprise given the links between these areas historically, including through the Gaelic kingdom of Dalriada of course. But what about Ireland's modern genetic makeup, and what haplogroups are common the population today? Well, let's begin by looking at the genetic structure of Ireland as a whole. This study on the Irish DNA Atlas found that the Irish population can be divided into ten distinct geographically stratified genetic clusters, seven of Gaelic-Irish ancestry and three of shared Irish-British ancestry, with this last component concentrated in the north, which makes sense. The Gaelic-Irish clusters also showed the lowest ancestry proportions of German clusters, which in turn are thought to reflect Germanic-Saxon influence, which again makes sense historically. As far as the historical genetic structure of Ireland, this study found that Ireland in general is geographically stratified and surprisingly faithful to the historical boundaries of Irish provinces and kingdoms. But what about haplogroups? Well, haplogroup R1b is the dominant haplogroup amongst Irish males, reaching a frequency of almost 80%. As we saw earlier, the Balebeakers probably brought this haplogroup into Ireland around 4,000 years ago, which is quite remarkable the lasting impact these people had. To be more specific, Rl21 is the dominant sub-clad of R1b within Ireland, and this haplogroup is associated with insular Celts in general. Another haplogroup found at lower levels in Ireland is I1, and this is associated with Scandinavia and is probably a legacy of the Vikings in Ireland in many respects, but it is also associated with Germanic peoples. So for some in the Irish-British clusters, this could potentially be a legacy of the Anglo-Saxons by way of this English ancestry. Other haplogroups found at low levels include I2 and R1a. On the maternal side, H is the most common mitochondrial haplogroup in Ireland, similar to many other parts of Western Europe. Variations of the mitochondrial haplogroup U are also found at reasonable levels, including U5 for instance. T giant care also among the other mitochondrial haplogroups found in Ireland. So as we've seen, Ireland has a rich genetic history, from the Bell Beakers to the Vikings. But what is the genetic history of a land just to the east of Ireland, England? To find out, please click here. 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