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not forget. So far we have only mentioned immigration into Ireland, by Anglo-Normans at first and
then through the plantations. But these are numerically dwarfed by the departures. Religious
intolerance and persecution from the sixteenth century onwards, closely coupled to land seizure,
drove many Catholic landowners abroad, mainly to France and Spain. Though doubtless traumatic
for them, these exiles did not really affect ordinary Irish agricultural workers, for whom life
continued much as before, though the land was under new ownership. However, in the nineteenth
century, Irish emigration on a large scale began in earnest.
In the first decades of the century, agricultural prices fell, estate rentals declined, investment in
the land was reduced to a trickle, and the rural population grew. Whatever the ultimate causes of
this cycle of economic decline, the effects on the rural poor were catastrophic. Reduced to almost
complete dependence on the potato as the staple crop, the countryside was decimated when the
crop was infested with the potato blight and rotted in the ground. During the Great Famine of the
mid 1840s, thousands died of starvation or of the infectious diseases which swept through the
malnourished population. Though many thousands died, thousands also made their escape. Ireland’s
mid-nineteenth-century population of 8 million began a steady decline that has only very recently
stabilized at 4.1 million in the Republic and 1.7 million in Ulster. The desparate diaspora of the
Irish saw massive immigration both to Britain and to the New World, especially the United States.
Today, there are far more ‘Irish’ genes abroad than there are in Ireland itself.
Though Ireland is not yet united into a single political state, the poverty and suffering which
suffuse all accounts of the history of the last centuries cannot be equated with Ireland today. The
economy is transformed. The bars and cafés of Dublin are as lively and as sophisticated as
anywhere in Europe. There is a tangible feeling of optimism in the air wherever you go. Though we
will have to wait to see how much of the turmoil of past centuries is remembered by the genes, I
suspect the main effect will be of emigration and the dispersal of Irish genes around the globe.
Now that the future of Ireland as an independent country is looking so good, this is the time to move
the sad centuries to one side and examine Ireland before the day when Henry II arrived to begin the
English occupation. That is where we must seek to interpret the patterns of the genes. What do we
know of these earlier times?
The appeal that Dermot MacMurrough made to Richard de Clare to come to his aid, the appeal
de Clare used as an excuse to invade, is a clear indication of the state of affairs in medieval Ireland
– the struggle for dominance of one minor king against another. It is so very typical of the middle
stage of evolution of any modern society and one that is only too visible in other parts of the world.
Except that in those places, like Afghanistan or unstable African countries, these men are not
dignified with the title ‘king’ but denigrated as ‘warlords’. In Ireland during the first millennium AD
there was a constant struggle for dominance between different minor kings. According to one
source, there may have been 150 of them at any one time, lending some credibility to the common
Irish boast that they are all descended from lines of Irish kings. This may be something we can test
as it could be visible in the Y-chromosome gene pool by what has come to be known as the
‘Genghis Khan effect’.
A few years ago, researchers from Oxford found a Y-chromosome that was very widespread
throughout Asia, more or less within the geographical limits of the Mongol Empire. Finding a
particular Y-chromosome with a specific fingerprint across such a wide area is highly unusual. Y-
chromosomes are generally much more localized. The explanation, which I think is the correct one,