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Norway than in the other clans. We expected some similarities, since the Viking ships would not
have distinguished between genetic clan when choosing their crews and there were plenty of
Oisins in Norway. When we took this into account it was clear that our initial estimates of Viking
ancestry had been a bit low. Some of the Northern Isle Oisins had almost certainly come with the
Vikings. Including them pushed our estimate of Viking ancestry in men from Shetland up to 42 per
cent. The proportion of Orkney men with a Norse Viking ancestry, which we estimated in the same
way, was slightly lower, at 37 per cent. But please do not concern yourself with exact proportions;
just take from this that the male Norse ancestry of Orkney and Shetland is substantial, but was
never complete.
I began our interpretation of the Northern Isles DNA with the Y-chromosome because of the
Vikings’ reputation, but I also wanted to see what the maternal DNA told us as well. At the time we
were analysing the DNA from the Northern Isles we had just completed a study with Agnar
Helgason, an Icelandic anthropologist, on the genetic ancestry of his native land where we had
asked a similar question about the paternal and maternal input. The histories of Iceland and of the
Northern Isles were quite different in that, when the Vikings began to settle Iceland from around AD
860, it was uninhabited. The few Irish monks who had settled there in the quest for a life of
contemplation sensibly left as soon as they saw the first sails on the horizon.
Over the next fifty years large numbers of Norse settlers arrived in Iceland, most from around
Bergen but some from Viking settlements in Britain. This was large-scale, planned immigration to a
land with no indigenous opposition and by the beginning of the tenth century there were 60,000
people living in Iceland. The population has grown to 250,000 today, but there has been no
recorded large-scale immigration since the original settlement. Agnar and I wanted to find out
whether this had been a predominantly male-driven settlement, with females brought in from
elsewhere, or whether roughly equal numbers of Norse men and women had arrived. There have
been persistent stories that Icelandic men raided the coasts of Scotland and Ireland for wives.
Agnar and I thought we could check these stories by comparing modern Icelandic Y-chromosomes
and mitochondrial DNA with the equivalent DNA from Scandinavia, Ireland and Scotland. By
going through the Icelanders’ DNA results one by one, we assigned their most likely origin from
comparison with British, Irish and Scandinavian samples.
We discovered that roughly two thirds of Icelandic Y-chromosomes were Scandinavian, while
the remaining third were from Ireland and Scotland. However, the origin of maternal DNA was
reversed, with only a third from Norway and two thirds from Ireland and Scotland. This confirmed
the stories that, while most of the men had settled in Iceland from Norway, they relied heavily on
women imported from Ireland and Scotland. It doesn’t necessarily mean they were taken there
against their will, as the results could not distinguish between settlers who had arrived straight
from Norway and the male descendants of Vikings who had spent a generation or two in Scotland.
Even so, it is hard to account for the Gaelic origins of a third of Icelandic Y-chromosomes without
contemplating that these men were taken to Iceland as slaves. The Iceland study gave us a very
interesting result, and also helped us to develop the way of assigning the Icelandic DNA to a Norse
or Gaelic/Pictish origin, which we then used for Orkney and Shetland and then, in modified form,
for the rest of the Isles.
When we tried the same treatment on the Northern Isles, expecting a similar result to what we
had found in Iceland, we were in for a major surprise. The maternal clans in Norway and in