Blood of the Isles (2 page)

Wales Millennium Centre, Cardiff: © Photolibrary Wales; pupils at Moy School, Lahinch, County Clare: © Stephanie Maze/Corbis.

This is the very first book to be written about the genetic history of Britain and Ireland using DNA as its main source of information. It is the culmination of an ambition, almost a dream, that I first had ten years ago. Having successfully used DNA to solve several outstanding issues about the human past on a continental scale, I wanted to push the method to its limits and dissect the intimate genetic make-up of a smaller region. And where better to do this than in my own back yard, so to speak. My own country, one that I share with 60 million others and with an even greater number whose roots are here but who now live overseas. And what a land it is, full of myth and legend, brimming with archaeological treasures and set down in a rich treasury of historical documents.

For its new, scientific content,
Blood of the Isles
relies primarily on the results of a systematic DNA survey that I and my research team in Oxford University have undertaken over the last ten years, a survey involving more than
10,000 volunteers from every part of ‘the Isles’. The results, explained in the book, exceeded even my most optimistic expectations of the power of genetics to make a real contribution to our knowledge of a small region.

In
Blood of the Isles
, I approach the DNA evidence in the same way as others who write about the past using their different specialities – material artefacts, written documents, human remains and so on. The most important thing about the genetic evidence is that it is entirely independent of these other sources. It does not rely on them. However, to use genetics most effectively to fill in any picture of the past, it helps immensely to have this abundance of other evidence, and I use this resource throughout the book. Nevertheless, when you have read
Blood of the Isles
I hope you will agree that from now on genetics can take its proper place alongside history and archaeology as one of the principal lenses through which to view the past.

I have written two other books on DNA and human evolution:
The Seven Daughters of Eve
and
Adam’s Curse
. You may have read them, but I certainly do not assume that you have. You don’t need to in order to follow the story of
Blood of the Isles
perfectly well. However, there are some topics which are covered more extensively in the earlier books than they are here, but which to repeat here in full would be unnecessary.

I have deliberately avoided, as far as possible, putting technical data into the text. A little is absolutely essential, but too much soon disrupts the flow. For those readers who want to delve more deeply into the supporting scientific
evidence I have added an
Appendix
and, for real enthusiasts, I am publishing additional material on the website
www.bloodoftheisles.net
.

Finally, a word about the title. I use ‘the Isles’ rather than ‘Britain’ or ‘UK’, to avoid the pitfalls that follow from political boundaries much more recently drawn than the time depth covered by this book. Many in Ireland are not British and the Irish Republic is not part of the United Kingdom. But to leave them out would be absurd. Ours is a shared history. Throughout the book ‘Ireland’ includes Northern Ireland and ‘Britain’ embraces Scotland, Wales and England.

Some names have been changed to preserve confidentiality.

Everything was ready. I selected one of the diamond-tipped bits from the sterile rack and tightened it into the jaws of the high-speed drill. Turning the dial up to 500 revolutions a second, I looked carefully to see that the spinning drill was centralized in the chuck. There must not be any mistakes, especially today. In my left hand, I picked up the jaw bone and turned it so that the outer surface of the first molar tooth was facing me. I moved the jaw under the magnifier and brought the rotating drill to within a millimetre of the enamel surface of the tooth. The tooth that had never bitten into a pizza, nor crunched a piece of celery. The tooth that I was about to drill into was 12,000 years old. The last food this tooth had touched was the flesh of a reindeer or wild horse. It was the tooth of a young man, about twenty years old when he died. This man was a hunter, one of the first people to arrive in Britain since the end of the last Ice Age.

The skeleton of the young man had been dug out of the
limestone caves of Cheddar Gorge in Somerset in 1986. Ten years later, in the autumn of 1996, I had brought his lower jaw, with the beautifully preserved teeth still embedded, to my laboratory in Oxford. I was about to attempt to recover the DNA, the genetic essence, of its original owner, trapped in the dentine beneath the hard enamel which had encased and protected it for thousands of years. As the drill made contact with the enamel surface, I steadied my left arm on the lab bench and pressed the bit into the tooth. The whining pitch of the drill came down slightly as it cut into the enamel. This was a good sign. The enamel was not too soft. That would have been a sure sign of biological decay, which would have dashed any chance of finding intact DNA. Neither was the tooth granite-hard. That would have meant that all the organic remains, including the DNA, had literally turned to stone. The Cheddar tooth was somewhere in between, neither too soft, nor too hard.

After a few seconds, the drill had cut through the enamel layer and into the dentine which lay behind. I could feel the drop in pressure as the tip of the drill moved into the softer dentine, and heard its pitch rise as the speed increased. A second or two later, I caught the scent of burning – the same unforgettable smell that instantly recalled dread visits to the dentist and the fillings of a sweet-toothed youth. It was the smell of burning teeth. This was the unmistakable scent of vaporizing protein, and the moment I caught the smell of it coming from the ancient tooth my spirits rose. From that moment on, I was sure I would find his DNA, for if the protein which was being vaporized by the drill had survived for 12,000 years, then there was every chance
that his DNA would have done so too. Both are biological molecules subject to the same laws of age and decay.

As soon as I smelled the burning, I pulled across the suction line. This was a device rather like a miniature vacuum cleaner which I had rigged up for collecting the powdered dentine into a sterile test tube. With this in place, I began to drill out the dentine, carefully moving the bit up and down inside the tooth, pulling back as soon as I felt it touch the hard enamel on the other side. All the time the vacuum line was transferring the creamy white powder into the test tube and collecting it in a small pile at the bottom. Within a few minutes, I had completely excavated the inside of the tooth. In the test tube lay precisely 208 milligrams of dentine powder from the Old Stone Age.

Within two weeks, and in ways that we will cover later, I had recovered enough DNA from the Cheddar tooth to read the genetic fingerprint of its original owner – a young man whose pattern of life was so utterly different from our own that it is hard to imagine any possible connection between him and ourselves. And yet the fragment of his DNA that I had recovered from his tooth is exactly the same in every detail as that of thousands of people living in the Isles today. His descendants are with us still – and you may well be one of them.

It is now almost ten years since the day I drilled into the Cheddar tooth, but the moment is still vivid in my memory. It was not the first time I had attempted to recover DNA from ancient skeletons, but it was the most scary. This was a priceless and irreplaceable specimen. But what was I, a trained geneticist, doing drilling into the tooth in the first
place? I had spent the early part of my career researching the causes of inherited diseases, mainly those affecting the skeleton – hence the location of my laboratory in Oxford’s Institute of Molecular Medicine. This research had led to the discovery of the genes involved in giving strength to bones – the genes which coded for bone collagen – and to the mutations in the collagen genes which caused these often devastating diseases.

It was only a chance introduction to an archaeologist, Robert Hedges, who runs the carbon-dating lab in Oxford, that got me involved in the human past at all. Robert wanted to see if he could get more from the bone samples coming to his laboratory for carbon-dating than merely finding out how old they were. Carbon-dating relies on counting the tiny number of radioactive carbon atoms that lie in the collagen of ancient organic remains. As these atoms decay with time, the fewer there are, the older the sample. Robert got in touch, having heard about my research on the genetics of bone collagen, and we started to plan what we might be able to do with these old bones. To cut a long story short, within two years we had worked out a way of recovering DNA from human and animal bones that were hundreds or even thousands of years old.

Being the first laboratory in the world to do this, we were well placed to receive exciting samples from all over the world. Over the years we have had bits of Neanderthals; Oetzi, the famous Iceman from the Alps; various claimants to being Anastasia, the last of the Romanovs; a selection of dead poets and statesmen; not to mention the odd piece of Yeti skin. To put the DNA results
from this eclectic collection into some form of context, I began a programme of collecting DNA samples from living people. For instance, although it was wonderful to be able to get DNA from the 5,000-year-old Iceman, and that became a story in itself, it only became really interesting when his DNA could be compared, and indeed matched, with someone living today. The whereabouts of his modern descendants told us something about the movement of people throughout Europe during the five millennia since his death.

Sometimes the DNA from modern people can solve long-standing riddles that had proved to be intractable by any other means. The outstanding example of this was the research on the origin of the Polynesians. These are the people who live on the far-flung islands of the Pacific. All the islands, from Hawaii in the north to Easter Island in the east and New Zealand in the far south, had been settled by Polynesians well before the time Europeans began to explore the Pacific Ocean in the early part of the sixteenth century. But where had the Polynesians come from? Was it from Asia, as the bulk of the evidence from language, domestic animals and crops suggested? Or had they arrived in the other direction from America, as the legendary Norwegian anthropologist Thor Heyerdahl believed? Like many schoolboys, I had been captivated by Heyerdahl’s adventures on the balsa raft
Kon-Tiki
, on which he drifted from Peru to the Tuamotu islands, not far from Tahiti, to prove his point. So it was with a tinge of regret that, in 1995, I published the genetic data which proved conclusively that Heyerdahl was wrong. The Polynesians had
come from Asia, not America. This slight regret at having disproved a boyhood hero was more than compensated by the proof that the Polynesians must have explored the Pacific intentionally, driving their canoes into wind and current eastwards across the vast ocean, rather than lazily drifting with the prevailing elements from South America. The ancestors of today’s Polynesians were without doubt the greatest maritime explorers the world has ever known.

The proof of their true origins came from the DNA of modern Polynesians that I had collected from dozens of Pacific islands. From the detailed genetic fingerprints of the islanders I was able to trace the route that their resolute ancestors had taken through the island chains of South-east Asia and out into the vast Pacific Ocean. In ways that I will explain later, I could follow the genetic threads that had percolated through the generations and reconstruct the 3,000-year-old journeys of these astonishing navigators.

It was because I was attempting to reproduce this first success in the much more difficult arena of Europe that I found myself drilling into the Cheddar tooth. My colleagues and I had followed the same procedure that had yielded such compelling results in Polynesia. We had collected almost 1,000 DNA samples from all over Europe and, again in ways I will later explain, come to a conclusion about the origin of modern Europeans. That conclusion was, in a nutshell, that the ancestors of most native Europeans were hunter-gatherers and not, as was commonly believed at the time, farmers who had spread into Europe from the Middle East about 8,500 years ago. To say that our conclusion caused a stir is an understatement.
There followed several years of fierce debate between ourselves and the proponents of the agricultural-ancestry theory, and the experiment with the Cheddar tooth was one of our efforts to prove our case. The idea behind it was that, if we could show that a very old human fossil, a genuine hunter-gatherer who lived well before farming arrived, had pretty much the same DNA as people living today, that would strengthen our side of the argument.