83459348539

is that this is the Y-chromosome of the first Mongol emperor, Genghis Khan, who lived in the first
half of the thirteenth century. Not only is the Y-chromosome fingerprint geographically dispersed, it
is also very common. In Mongolia, for example, 8 per cent of men have inherited the Genghis
chromosome. If you compute the number of men who carry this Y-chromosome throughout Asia,
and occasionally on other continents, then it comes to a staggering 16 million. Even a cursory
glance at Genghis Khan’s methods in warfare is enough to understand the genetic mechanism. On
conquering an enemy’s territory he would kill all the men, then systematically inseminate all the
good-looking women – he left his commanders strict instructions on that point. When he died, the
custom of patrilineal inheritance ensured that his empire was distributed among his sons, and their
sons. Thus his Y-chromosome increased with each generation of male descendants, who inherited
not only a portion of his wealth but also, presumably, his attitude to women. Though we have no
historical records of men with quite such sexual predominance in the Isles, the confusion of minor
kings is just the sort of condition where one might expect to discover the Genghis effect.
It was not all chaos in Ireland. Some kings managed to exert sufficient authority to stake a claim
to the title of High King and to be installed at the sacred site of Tara, about 20 miles north of
Dublin. Though none of the High Kings ever managed complete dominance over the whole island,
some had a very good try and this may well be reflected in an Irish Genghis Khan effect. While
such behaviour may rearrange the genes of Ireland, or anywhere else in the Isles for that matter, it
is however only a rearrangement. While the Genghis effect will mean that one, or a few, Y-
chromosomes may prosper at the expense of others, no amount of Khan-like behaviour can actually
create new Y-chromosomes. And it has no effect whatsoever on the maternal lineages, traced by
mitochondrial DNA. These will persist whatever the kings get up to.
Peering further back into the Irish past, what can we see that needs to be taken into account?
Though it was Ireland’s misfortune to be occupied by the English for so long, it entirely avoided
being conquered by the Romans, which large swathes of Britain did not. Ireland was very lucky to
escape. The Roman historian Tacitus, in his account of the campaigns of his father-in-law Agricola,
tells how the great general seriously contemplated an invasion. In his fifth year of campaigning in
Britain, in AD 88, Agricola brought his army and his ships to Galloway in south-east Scotland, only
20 miles across the sea from Ireland. Such were the inaccuracies in the geography of the day that
Agricola believed that Ireland was midway between Britain and the Roman province of Spain. So
he could see the tactical advantages of including Ireland within the Empire. He had received
favourable reports about the character and way of life of the inhabitants and of the soil and climate.
To a Roman they did not differ much from the British, whom he had successfully subdued during the
previous five years. Tacitus wrote that he often heard Agricola say that Ireland could be conquered,
and held, with a single legion supported by a modest force of auxiliaries. Agricola even took the
precaution of befriending a minor Irish king who had been exiled in case the opportunity to use him
should arise. In the end he decided against an invasion. Tacitus does not say why and we can only
guess. But that he had serious intent is certain.
One negative consequence of this lucky escape was that there are no written histories of Ireland
from the Roman period. Not until the arrival of early Christians in the fifth century AD, and of St
Patrick in particular, did written accounts, however unreliable, begin to appear. St Patrick himself
is credited with the authorship of the earliest documents in Irish history, written in Latin: the
Confessions, which defines and defends his mission, and one other, a short letter excommunicating