Oxford today

DR STEPHEN LESLIE
28 What makes the British?
POBI map of UK, created by Dr Stephen
Leslie, showing the genetic clustering of
individuals: big variations are at the periphery
taken from volunteers living in rural areas
where all four grandparents had been
born in the same area. This ensured that
the samples were more likely to be locally
representative. Effectively, the data gave
an accurate picture of the genetic makeup
of rural Britain in around 1880, before
the wide-scale population movements of
the 20th century or, more recently,
immigration from other countries.
“In order to really understand the British
population genetically, you can’t just go
into the high street and look for someone
who says they are British. You need to
be more specifi c about where you look,”
says Bodmer.
Another vital point was the team’s
ability to measure a large amount of
genetic material from each sample. More
than 670,000 positions in the genome
of each individual were measured and
evaluated by Donnelly and his team in
order to produce a precise picture of that
person’s genetic make-up. Sophisticated
statistical techniques were then applied
to sift and analyse the relevant data from
this vast body of information.
The volunteer samples were analysed
for ways in which their DNA was similar
to each others’. They were then grouped
according to their genetic similarities.
The fi nal results were then laid on top
of a map of the British Isles… with
astounding results.
“It is simply not the case that we have
seen what we expected to see,” says
Robinson. “I feel we’ve produced
something which is of major signifi cance
and will stimulate much debate.”
“Broadly speaking, people look very
similar to each other at the DNA level
from one end of the UK to the other,
so the differences we found were subtle
but nonetheless real,” says Donnelly.
“However, we were struck by how clear the
patterns of regional differences were, by
how people had stayed in their geographic
regions. Clearly, in some areas there had
been quite a bit of isolation and relatively
little intermarriage over the years.”
When the data was fi rst split, into two
groups, it was the inhabitants of Orkney
who were most different from the rest of
the British Isles.
The researchers continued to break
down the data, using increasingly fi ne
distinctions between the samples. Wales
broke away, then Cornwall and Devon; the
Welsh borders separated from Wales, and
Northern Ireland formed a group with
north western Scotland; Northern
England also split away.
By the fi nal analysis, there were 17
cluster groups (see map) with north and
south Wales showing two very separate
clusters. There were also two distinct
groups in the Orkney Islands. But by
far the biggest homogeneous region was
a large swathe of southern and central
England (pictured in red on the map).
The researchers then compared their
PoBI results with DNA data from 7,000
people in Europe to try to trace the
ancestry of the British DNA.
It was clear that the Orkney islanders
had Norwegian ancestors, while the red
central and southern English cluster had
the largest Belgian, Danish and German
contribution (relating to the Anglo-Saxon
invasion and perhaps later supplemented
in places by the Vikings). The Cornish
and Welsh had more similarity with the
modern French, while people in Northern
Ireland and Western Scotland have
substantial common Irish ancestry.
“We can see clear signs of certain
patterns which are present in the DNA
of samples from all over the British Isles
– this means that they are likely to be
very old, and is what we have termed the
ancient British DNA,” says Donnelly.
Researchers agree that the DNA evidence
fi ts the known colonisation patterns of
early settlers to the British Isles after the
Ice Age between 9,600 and 8,000 BC. The
fi rst settlers made their way across to the
warming tundra that was then the British
Isles from North-West Europe via the land
bridge that still attached the UK to the
area that is now the Low Countries.
Others came by boat from the Atlantic
coast of France to the western side of
England and Wales and Ireland. This
is clearly refl ected in the similarities to
French and probably Belgian DNA in
southern and central England, and the
increased level of western French DNA
in Cornwall and Wales. So our ancient
British DNA has deep roots on the
continent – and particularly in France.
For the large section of the population
living in the red section of southern and
central England, their DNA contained
substantial contributions from both the
ancient British and the Anglo-Saxons.
It is this that has led the researchers to
conclude that although the Romano-
British people were certainly overwhelmed
by a large infl ux of Anglo-Saxons, they
were not annihilated by them, but
married and mixed with the newcomers.
Equally it’s clear from the PoBI results
that both the Roman and Norman
invasions left relatively little genetic trace
in Britain, being restricted to a relatively
small number of elite rulers.
“One of the most rewarding aspects
of this project has been the way that
academics from different departments
of the university – geneticists, statisticians
and archaeologists – have collaborated
and pooled their expertise,” says Robinson.
But the researchers are far from resting
on their laurels. Bodmer and Donnelly
are now involved in a new project to
understand exactly how our genes control
the make-up of our facial features. Could
this, for instance, lead to police giving out
descriptions of wanted individuals based
on DNA samples from crime scenes?
“It’s possible, in the very distant future,
I suppose,” says Donnelly, “but we’re really
a very long way from that at the moment.”
Meanwhile, back in the archaeology
department, there are plans to compare
the modern PoBI fi ndings with ancient
DNA samples from skeletal remains in
Anglo-Saxon graveyards. “I believe that
this will back up our interpretations…
but if it doesn’t, well, that’s how progress
is made,” says Robinson.
And there’s also much more work to
be done in understanding the DNA
make-up of European populations and
to extend the PoBI research to southern
Ireland. One thing’s for sure, however:
and that’s that after the conclusions of this
project are fi nally published, many areas
of academic research will never be the
same again.
Judith Keeling is a freelance writer and editor contributing to
a wide range of national newspapers and magazines. She is
editor of Oxfordpeople, an interactive community website.