The genetic distinctiveness of the Irish race

Emmeline Hill:

Men with Gaelic surnames coming from the west of Ireland are descendants of the oldest inhabitants of Europe. In a recent study, scientists at Trinity College, Dublin, created a new genetic map of the people of Ireland. By comparing this map to European genetic maps they have shown that the Irish are one of the last remnants of the pre-Neolithic hunters and gatherers who were living throughout Europe over 10,000 years ago, before the invention of agriculture. The Irish really ARE different.

Surnames in Ireland have been passed from father to son for almost 1,000 years. The surname system in Ireland is thought to exist as one of the oldest applications of the hereditary surname system in the world. In Ireland this system was not introduced but rather it is thought that toponymics (names derived from place names) and nicknames were adopted. For example, the name O'Callaghan comes from the Irish O'Ceallachain, a diminutive of ceallach, which was taken to mean 'frequenter of churches.'

Traditionally, newly married women have taken up residence in the homeland of their husband, meaning that family names have remained in the area of the particular clans or septs for generations. Surnames, except in the infrequent case of non-paternity, are therefore an indication of family history, and on a larger scale, of population history.

In developing the new genetic map, the scientists studied the DNA of 221 men from all over the country. The DNA was separated into groups of people with names coming from the same area. For example, names that originated in Ulster, such as Gallagher and O'Reilly, were grouped together. Names from Munster (e.g. Hogan, Meagher, Ryan); Leinster (e.g. Conlan, Phelan, Rafter); and Connaught (e.g. Conway, Flynn, McHugh, Ruane) were all grouped accordingly and were considered to be Gaelic Irish. Also names of English (e.g. Harrison, Hill, Jacob, Moore) Scottish (e.g. Hamilton, Johnston, Knox), Norman (e.g. Barry, Bryan, MacNicholas) and Norse (e.g. Doyle) descent were grouped separately. These were considered to be non-Gaelic Irish. By separating the DNA as such, they could study the genes that were present in a particular region of Ireland over 1,000 years ago, when the surname system was adopted.

In Issue 88 of INSIDE IRELAND, the article "Who are we? - It's in the Genes" outlined the basic science behind genetic studies of populations. Each cell in our body contains a signature of our past. Modern technology allows us to look directly at the amount of variation in the genes in these cells. Variation accumulates over time through a random process of mutation. Mutations occur at a constant rate. Therefore, the more different two people are genetically, the longer they have been separated.

Using modern technologies to look at the differences between genes in the different peoples of Ireland, the scientists in Trinity College studied the genes on the Y chromosome. The Y chromosome is the male-specific sex chromosome that is passed from father to son in the same way that surnames are passed from father to son.

By performing a number of genetic tests the scientists were able to identify a particular genetic pattern in the Y chromosome of the Irish. An ancient genetic marker, known as haplogroup 1, was found in most Irish men. Scientists think that most of the population of Western Europe carried this gene over 10,000 years ago. Over time however, through the movement and mixing of peoples, this gene was diluted. Now it is found in relatively fewer people throughout Europe.

The greatest movement and migration of peoples in Europe has been the movement of farmers from the south-east of the continent after the invention of agriculture about 10,000 years ago. The farmers moved with their new technologies north-west into Europe, probably displacing the local hunter-gatherer populations that were living there at the time. In this way the haplogroup 1 genes in Europe were diluted, the farmers introducing new and different genes.

This resulted in the formation of a gradient of haplogroup 1 genes throughout the continent, the lowest frequency of these ancient genes being found in Turkey, and the highest frequency in Ireland, with intermediate frequencies in continental populations. In Ireland 78.1% of all men have the haplogroup 1 gene.

In Ireland men with Gaelic names have higher frequencies of this ancient marker than men with non-Gaelic names. For example, men in Ireland with surnames of English origin have 62% haplogroup 1 genes; men with Scottish names have 52.9% and men with Norman and Norse names have 83%. In Leinster, 73.3% of men with Gaelic surnames have this gene, in Munster, 94.6% and in Ulster 81.1%.

The most striking finding was that in Connaught, the westernmost point of Europe, almost all men (98.3%) carry this particular gene. This means that the people of Connaught have been relatively isolated, genetically, from the movements of people that shaped the genetic makeup of the rest of the continent. By comparison, in the east of the country there has been a lot more mixing of genes coming from foreign sources.

The prevalence of ancient genes in Ireland suggests that the Irish have largely maintained their pre-Neolithic genetic heritage. There has been little genetic influence from outside the country since the first people came to Ireland almost 9,000 years ago.

By looking at the amount of variation (the number of mutations that have accumulated over time) in the haplogroup 1 genes of these men it was possible for the scientists to estimate a date for the origin of the bulk of these genes in the country. They estimated that most of the genetic variation in Ireland has accumulated over the past 4,200 years following a rapid growth of the population at this time. This is the time of the Early Bronze Age in Ireland.

The Early Bronze Age in Ireland, among other things, saw the appearance of megalithic tombs. Newgrange in Co. Meath is the best known example. The scale and magnanimity of these structures suggest that the creators belonged to a large, highly socially evolved society.

The scientists have shown most of the genes present in Ireland today came from the people who were living at the time of Newgrange. These people were the descendants of the ancient hunter-gatherers of Europe.

Research paper:

Y-chromosome variation and Irish origins