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Fortunately, all the other judges felt the same way. Which is how Dan Bradley and his team
from Trinity College Dublin got the green light – and the funds – to take charge of that central
aspect of the project. Dan had pioneered the use of DNA to find out how and when farm animals, in
particular cattle, had been domesticated. We had worked together a little on this when Jill Bailey,
one of the research students in my team, had been working on retrieving DNA from the bones of the
extinct ancestor of domesticated cattle, the fearsome aurochs. After getting her degree at Oxford,
Jill had spent a year in Dan’s lab in Dublin and I had been over a couple of times to give talks and
be an examiner for Dan’s graduate students. All of which is entirely irrelevant, except that it meant
that a highly experienced and competent geneticist, whom I knew and liked, would be covering the
same genetic ground in Ireland as I was already starting to do in the rest of the Isles. Which in turn
meant that I could concentrate on Scotland, Wales and England, knowing that Dan’s lab would
produce compatible genetic data from Ireland that could be integrated with the results of our Irish
customers at Oxford Ancestors and, eventually, all the data from the rest of the Isles. Which is
precisely what did happen and it is from this grand coalition of data that we begin our tour.
On my imaginary map, I moved all the Irish gene-coins across the Irish Sea and began to
distribute them according to their geographic origins. Each one of these was the end point of a
journey – the journey of a line of ancestors stretching through maternal and paternal threads way
back into the deep past. We know, from the archaeological records, that every one of these
ancestral journeys must have ended in Ireland within the last 9,000 years when the first Irish built
their timber-framed houses on the banks of the River Bann at Mount Sandel. Before that, as we
know, Ireland had been uninhabited since the Ice Age. Could it be that some of these DNA
fragments from today’s Irish men and women have actually been there all that time? How would we
know?
I began with the maternal DNA. I knew, from the identity of their clan mothers, when and where
all these journeys had begun. And from the locations on the map of Ireland, I also knew where
these journeys had ended. Well, not ended, because many of these genes will go on travelling the
world for millennia to come. To be more accurate, I knew where these immortal time travellers had
reached by the late twentieth century.
The longest journeys, in both time and distance, had been travelled by Ursula’s descendants.
Ursula herself had lived in Greece about 45,000 years ago, at the start of the Upper Palaeolithic,
and had shared the land with the far more ancient Neanderthals. We knew this date from counting
up all the mutational changes that had happened among her descendants and dividing this figure by
the mutation rate. As we have seen, among the seven principal clans in Europe there were far more
changes in the descendants of Ursula than in any of the others. That simple fact meant the clan of
Ursula was the oldest of the seven. We arrived at the age of the clan, and thus the time in the past
when Ursula herself lived, by factoring in a mutation rate of one change in every 20,000 years.
From thousands of DNA samples from all over Europe we knew that, on average, Ursulans have
2.25 mutations in their mitochondrial DNA compared to the DNA of Ursula herself. That puts the
age of the clan at 2.25 × 20,000 = 45,000 years.
We arrived at Ursula’s own location in Greece by looking to see where the clan today is both
the most frequent and at its most diverse. So long as there was good archaeological or climatic
evidence that the location was inhabited, or at least habitable, at the time, then that was where we
placed the matriarch. I realize from many letters that it is a frequent and understandable