On Thursday 19 September 1991 Erika and Helmut Simon, two experienced climbers from Nuremberg in Germany, were nearing the end of their walking holiday in the Italian Alps. The previous night they had made an unscheduled stop in a mountain hut, planning to walk down to their car the next morning. But it was such a brilliantly sunny day that they decided instead to spend the morning climbing the 3,516 metre Finailspitze. On their way back down to the hut to pick up their rucksacks they strayed from the marked path into a gully partly filled with melting ice. Sticking out of the ice was the naked body of a man.
Though macabre, such finds are not so unusual in the high Alps, and the Simons assumed that this was the body of a mountaineer who had fallen into a crevasse perhaps ten or twenty years previously. The following day the site was revisited by two other climbers, who were puzzled by the old-fashioned design of the ice-pick that was lying nearby. Judging by the equipment, this alpine accident went back a good many years. The police were contacted and, after checking the records of missing climbers, their first thought was that the body was probably that of Carlo Capsoni, a music professor from Verona who had disappeared in the area in 1941. Only days later did it begin to dawn on everybody that this was not a modern death at all. The tool found beside the body was nothing like a modern ice-pick. It was much more like a prehistoric axe. Also nearby was a container made from the bark of a birch tree. Slowly the realization sank in that this body was not tens or even hundreds but thousands of years old. This was now an archaeological find of international importance.
The withered and desiccated remains of the Iceman, as he soon came to be known, were taken to the Institute of Forensic Medicine in Innsbruck, Austria, where he was stored, frozen, while an international team of scientists was assembled to carry out a minute examination of this unique find. Since my research team in Oxford had been the first in the world to recover traces of DNA from ancient human bones, I was called in to see whether we could find any DNA in the Iceman. It was the irresistible opportunity to become involved in such thrilling discoveries that had persuaded me to veer away from my career as a regular medical geneticist into this completely new field of science, which some of my colleagues regarded as a bizarre and eccentric diversion of no conceivable use or consequence.
By now, carbon-dating – measuring the decay of minute traces of naturally radioactive carbon atoms within the remains – had confirmed the great antiquity of the Iceman, placing him between 5,000 and 5,350 years old. Even though this was much older than any human remains I had worked with before, I was very optimistic that there was a good chance of success, because the body had been deep frozen in ice away from the destructive forces of water and oxygen which, slowly but surely, destroy DNA. The material we had to work with had been put in a small screw-capped jar of the sort used for pathology specimens. It looked awfully unremarkable: a sort of grey mush. When Martin Richards, my research assistant at the time, and I opened the jar and started to pick through the contents with a pair of forceps, it seemed to be a mixture of skin and fragments of bone. Still, though it might not have been much to look at, there was no obvious sign that it had begun to decompose, and so we set to work with enthusiasm and optimism. Sure enough, back in the lab in Oxford, when we put the small fragments of bone through the extraction process that had succeeded with other ancient samples, we did find DNA, and plenty of it.
In due course we published our findings in Science, the leading US scientific journal. To be perfectly honest, the most remarkable thing about our results was not that we had got DNA out oi the body – by then this was a routine process – but that we had got exactly the same DNA sequence from the Iceman as an independent team from Munich. We had both shown that the DNA was clearly European by finding precisely the same sequence in DNA samples taken from living Europeans. You might think this was not much of a surprise, but there was a real possibility that the whole episode could have been a gigantic hoax, with a South American mummy helicoptered in and planted in the ice. The cold and intensely dry air of the Atacama desert of southern Peru and northern Chi le has preserved hundreds of complete bodies buried in shallow graves, and it would not have been hard for a determined hoaxer to get hold of one of them. The much damper conditions in Europe reduce a corpse to a skeleton very quickly, so if this was a hoax the body had to have come from somewhere else, probably South America. It may sound far-fetched; but elaborate tricks have been played before. Remember Piltdown Man. This infamous fossil had been ‘discovered’ in a gravel pit in Sussex, England, in 1912. It had an ape-like lower jaw attached to a much more human-looking skull, and was heralded as the long sought-after ‘missing link’ between humans and the great apes – gorillas, chimpanzees and orang-utans. Only in 1953 was it revealed to be a hoax, when radiocarbon analysis, the same technique that was later used to date the Iceman, proved beyond any doubt that the Piltdown skull was modern. The perpetrator, who has never been identified, had combined the lower jaw of an orang-utan with a human braincase and chemically stained them both to look much older than they really were. The long shadow cast by the Piltdown Man fraud lingers even to this day, so the idea that the Iceman might have been a hoax was very much at the front of everyone’s mind.
There were a number of press enquiries following the publication of our scientific article about the Iceman, and I found myself explaining how we had proved his European credentials. Had it been a hoax, the DNA would have shown it. The closest matches would have been with South Americans and not with Europeans. But it was Lois Rogers from the Sunday Times who asked the crucial question.
‘You say you found exactly the same DNA in modern Europeans. Well, who are they?’ she enquired in a tone which told me she expected me to know the answer straight away.
‘What do you mean, who are they? They are from our collection of DNA samples from all over Europe.’
‘Yes, but who?’ persisted Lois.
‘I have no idea. We keep the identities of the donors on a separate file, and anyway, samples are always given on the basis of a strict undertaking of confidentiality.’
After Lois rang off, I switched on my computer just to see which samples matched up with the Iceman. LAB 2803 was one of them, and the series prefix ‘LAB’ meant it was either from someone working in the laboratory or from a visitor or friend. When I checked the number against the database containing the names of the volunteers, I could scarcely believe my luck. LAB 2803 was Marie Moseley, and LAB 2803 had exactly the same DNA as the Iceman. This could only mean one thing. Marie was a relative of the Iceman himself. For reasons which I shall explain in detail in later chapters, there had to be an unbroken genetic link between Marie and the Iceman’s mother, stretching back over five thousand years and faithfully recorded in the DNA.
Marie is an Irish friend, a management consultant from just outside Bournemouth in Dorset in southern England. Though not a scientist herself, she has an insatiable curiosity about genetics and had donated a couple of strands of her long red hair in the cause of science two years earlier. She is articulate, outgoing and very witty, and I was sure she could handle any publicity. When I rang to ask if she would mind if I gave her name to the Sunday Times she agreed at once, and the next edition carried a piece on her under the headline ‘Iceman’s relative found in Dorset’.
For a few weeks after that, Marie became an international celebrity. Of all the headlines that followed, I liked the one from the Irish Times best of all. Their reporter had asked Marie if she had been left anything by her celebrated predecessor. Shockingly, she revealed that she had not; so the story appeared as ‘Iceman leaves one of our own destitute in Bournemouth’.
One of the strangest and, at first, surprising things about this story, and the reason I tell it here, is that Marie began to feel something for the Iceman. She had seen pictures of him being shunted around from glacier to freezer to post-mortem room, poked and prodded, opened up, bits cut off. To her, he was no longer just the anonymous curiosity whose picture had appeared in the papers and on television. She had started to think of him as a real person and as a relative – which is exactly what he was.
I became fascinated by the sense of connection that Marie had felt between herself and the Iceman. It began to dawn on me that if Marie could be genetically linked to someone long dead, thousands of years before any records were kept, then so could everyone else. Perhaps we only needed to look around us, at people alive today, to unravel the mysteries of the past. Most of my archaeologist friends found this proposition completely foreign to them. They had been brought up to believe that one could understand the past only by studying the past; modern people were of no interest. Yet I was sure that if DNA was inherited intact for hundreds of generations over thousands of years, as I had shown by connecting Marie and the Iceman, then individuals alive today were as reliable a witness to past events as any bronze dagger or fragment of pottery.
It seemed to me absolutely essential to widen my research to cover modern people. Only when much more was known about the DNA of living people could I hope to put the results from human fossils into any sort of context. So I set out to discover as much as possible about the DNA in present-day Europeans and people from many other parts of the world, knowing that whatever I found would have been delivered to us direct from their ancestors. The past is within us all.
My research over the intervening decade has shown that almost everyone living in Europe can trace an unbroken genetic link, of the same kind that connects Marie to the Iceman, way back into the remote past, to one of only seven women. These seven women are the direct maternal ancestors of virtually all 650 million modern Europeans. As soon as I gave them names – Ursula, Xenia, Helena, Velda, Tara, Katrine and Jasmine – they suddenly came to life. This book tells how I came to such an incredible conclusion and what is known about the lives of these seven women.
I know that I am a descendant of Tara, and I want to know about her and her life. I feel I have something in common with her, more so than I do with the others. By ways which I will explain, I was able to estimate how long ago, and approximately where, all seven women had lived. I reckoned that Tara lived in northern Italy about 17,000 years ago. Europe was in the grip of the last Ice Age, and the only parts of the continent where human life was possible were in the far south. Then, the Tuscan hills were a very different place. No vines grew; no bougainvillaea decorated the farmhouses. The hillsides were thickly forested with pine and birch. The streams held small trout and crayfish, which helped Tara to raise her family and held the pangs of hunger at bay when the menfolk failed to kill a deer or wild boar. As the Ice Age loosened its grip, Tara’s children moved round the coast into France and joined the great band of hunters who followed the big game across the tundra that was northern Europe. Eventually, Tara’s children walked across the dry land that was to become the English Channel and moved right across to Ireland, from whose ancient Celtic kingdom the clan of Tara takes its name.
Soon after the conclusions of my research were published, news of these seven ancestral mothers began to appear in newspapers and on television all round the world. Writers and picture editors used their imagination in finding contemporary analogues: Brigitte Bardot became the reincarnation of Helena; Maria Callas was Ursula; the model Yasmin le Bon was linked, naturally, with Jasmine; Jennifer Lopez became Velda. So many people rang us to find out which one they were related to that we had to set up a website to handle the hundreds of enquiries. We had stumbled across something very fundamental; something we were only just beginning to understand.
This book tells the story behind these discoveries and their implications for us all, not just in Europe but all over the world. It is a story of our common heritage and our shared forebears. It takes us from the Balkans in the First World War to the far islands of the South Pacific. It takes us from the present time back to the beginnings of agriculture and beyond, to our ancestors who hunted with the Neanderthals. Amazingly, we all carry this history in our genes, patterns of DNA that have come down to us virtually unchanged from our distant ancestors – ancestors who are no longer just an abstract entity but real people who lived in conditions very different from those we enjoy today, who survived them and brought up their children. Our genes were there. They have come down to us over the millennia. They have travelled over land and sea, through mountain and forest. All of us, from the most powerful to the weakest, from the fabulously wealthy to the miserably poor, carry in our cells the survivors of these fantastic journeys – our genes. We should be very proud of them.
My part in this story begins at the Institute of Molecular Medicine in Oxford, where I am a professor of genetics. The Institute is part of Oxford University, though geographically and temperamentally removed from the arcane world of the college cloisters. It is full of doctors and scientists who are working away applying the new technologies of genetics and molecular biology to the field of medicine. There are immunologists trying to make a vaccine against AIDS, oncologists working out how to kill tumours by cutting off their blood supply, haematologists striving to cure the inherited anaemias which disable or kill millions each year in the developing world, microbiologists unravelling the secrets of meningitis and many others. It is an exciting place to work. I am based at the Institute because I used to work on inherited diseases of the skeleton, in particular on a horrible condition called osteogenesis imperfecta, better known as brittle bone disease. Babies born with the most severe form of this disease sometimes have bones so weak that when they take their first breath, all the ribs fracture and they suffocate and die. We were researching the cause of this tragic disease and had traced it to tiny changes in the genes for collagen. Collagen is the most important and abundant protein in bones and it supports them in much the same way as steel rods strengthen reinforced concrete. It made sense that if collagen failed because of a fault in the gene, the bones would break. The research involved finding out a lot about the way collagen and its genes varied in the general population – and it was through this work that, in 1986, I came to meet Robert Hedges.
Robert runs the carbon-dating laboratory for archaeological samples in Oxford. He had been thinking about ways of getting more information from the bones that passed through his lab, aside from just dating them by the radiocarbon method. Collagen is the main protein not only in living bones but also in dead ones, and it is the carbon in the surviving collagen that is used to date them. Robert wondered if there was any genetic information in these surviving fragments of ancient collagen, so he and I put together a research proposal to study them. Collagen, being a protein, is made of units called amino-acids, arranged in a particular sequence. As we shall see in the next chapter, the sequence of amino-acids in collagen, and all other proteins for that matter, is dictated by the DNA sequence of their genes. We hoped to discover the DNA sequence of the ancient collagen genes indirectly by determining the order of amino-acids in the fragments of protein that survived in Robert’s old bones. We advertised for research assistants several times but got no response at all. We would have expected a flood of applications for a regular genetics post, and put this zero interest down to the unusual nature of the project. Disappointingly few scientists want to venture from the mainstream field of research at an early stage of their careers. For us, this lack of a recruit meant we had to put back the start of the project by a year. Although very frustrating at the time, the delay proved to be a blessing in disguise – because, before the project got going, news came in of a new invention. A US scientist in California called Kary Mullis had dreamed up a way of amplifying tiny amounts of DNA – under perfect conditions, as little as a single molecule – in a test tube.
One warm Friday night in 1983 Mullis was driving along Highway 101 by the ocean; according to his account of events, ‘the night was saturated with moisture and the scent of flowering buckeye’. As he drove, he was talking to his girlfriend, seated beside him, about some of the ideas he had been pondering to do with his work at a local biotech company. Like everyone else in the genetic engineering business, he was making copies of DNA in test rubes. This was a slow process because the molecules had to be copied one at a time. DNA is like a long piece of string, and the copying started at one end and finished at the other. Then it started at the beginning again and you got another copy. He was talking out loud about this and suddenly realized that if, instead of starting the copying at one end only, you started at both ends you would start what would effectively be a sustainable chain reaction. You would no longer just be making copies of the original but copies of copies, doubling the number at every cycle. Now, instead of two copies after two cycles and three copies after three cycles, you would double up after each cycle, producing two, four, eight, sixteen, thirty-two, sixty-four copies in six cycles instead of one, two, three, four, five and six. After twenty cycles you would have not just twenty copies but a million. It was a real ‘Eureka’ moment. He turned to his girlfriend to get her reaction. She had fallen asleep.
This invention, for which Kary Mullis rightly won the Nobel Prize for Chemistry in 1993, genuinely revolutionized the practice of genetics. It meant that you could now get an unlimited amount of DNA to work on from even the tiniest piece of tissue. A single hair or even a single cell was now all that was needed to produce as much DNA as you could ever want. The impact of Mullis’s brainwave on our bone project was simply that I decided to forget about working on the collagen protein, which would have been horrendously difficult, and use the newly invented chain reaction to amplify what, if anything, was left of the DNA in the ancient bones. If it worked, then we would get vastly more information from the DNA than we would ever have got from the collagen. We would be going directly for the DNA sequence itself, rather than inferring it from the amino-acids. Much more importantly, we would be able to study any gene, not just the ones that controlled collagen.
At last we got an answer to our advertisement for a research assistant, and Erika Hagelberg joined the team. We were obviously not going to get anyone with previous experience in working with ancient DNA, because it had never been done before, but Erika’s degree in biochemistry, combined with research posts in homoeopathy and in the history of medicine, reflected a combination of a solid scientific training and the catholic interests which suited the project. Besides, she was the only applicant. Now we needed some very old bones.
News came in during 1988 of an excavation going on in Abingdon, a few miles south of Oxford. A new supermarket was going up and the mechanical diggers had ploughed into a medieval cemetery. The local archaeology service had been given two months to excavate the site before the developers moved back in, so when Erika and I arrived, it was buzzing with activity. It was a hot and brilliantly sunny day and dozens of field assistants, stripped down to the bare essentials, were dotted all round the site scraping at the earth with trowels, rummaging around in deep pits or wading through water-filled trenches. Several skeletons lay half-exposed, encrusted with orange-brown earth, criss-crossed by strings which marked out a reference grid. As we gazed down at them, our prospects didn’t look at all promising. Having worked with DNA for several years, I was trained to treat it with respect. DNA samples were always stored frozen at 70° below zero, and whenever you took DNA out of the freezer you were taught always to keep it in an ice bucket. If you forgot about it and the ice thawed then you had to throw the DNA out because, so everyone assumed, it would have degraded and been destroyed. No-one imagined it would last for more than a few minutes on the laboratory bench at room temperature, let alone buried underground for hundreds or even thousands of years.
Nevertheless, it was worth a try. We were allowed to take three thigh bones from the excavation away with us. Back in the lab we had to make two decisions: how to get the DNA out, and what section of DNA to choose for the amplification reaction. The first was easy enough. We knew that if there were any DNA left at all it would probably be bound up with a bone mineral called hydroxyapatite. This form of calcium had been used in the past to absorb DNA during the purification process, so it seemed quite likely that the DNA would be stuck to the hydroxyapatite in the old bones. If that was the case, we had to think of a way of disengaging the DNA from the calcium.
We cut out small segments of bone with a hacksaw, froze them in liquid nitrogen, smashed them up into a powder, then soaked the powder in a chemical which slowly took out the calcium over several days. Fortunately, when all the calcium had been removed, there was still something left at the bottom of the tube – a sort of grey sludge. We guessed this was the remnants of the collagen and other proteins, bits of cells, maybe some fat – and, we hoped, a few molecules of DNA. We decided to get rid of the protein using an enzyme. Enzymes are the catalysts of biology, making things happen much more quickly than they otherwise would. We chose an enzyme which digests protein, rather like the ones in a biological washing powder which get rid of blood and other stains for the same reason. Then we got rid of the fat with chloroform. We cleaned what was left with phenol, a revolting liquid which is the base for carbolic soap. Even though phenol and chloroform are both brutal chemicals, we knew they did not harm DNA. What remained was a teaspoonful of pale brown fluid which, theoretically at least, should contain the DNA – if there was any. There would be at best only a few molecules, so we had to use the new DNA amplification reaction to boost the yield before we could carry out the next steps.
The essence of the amplification reaction is to adapt the system for copying DNA that cells use. Into the tube go the raw materials for DNA construction. First in is another enzyme, this time one used for copying DNA; it is called a polymerase and gives the reaction its scientific name – the polymerase chain reaction or PCR for short. Next, a couple of short DNA fragments are added to direct the polymerase enzyme to the segment of the original DNA that is to be amplified and ignore everything else. Finally, the raw materials – the nucleotide bases – for building new DNA molecules go into the mix along with a few ingredients, like magnesium, to help things along. Plus, of course, the stuff you want to amplify – in our case, an extract of the Abingdon bone containing, we hoped, a few molecules of very old DNA.
Then we had to decide which gene to amplify. Because we knew there wasn’t going to be much, if any, DNA left in the bone extract we decided to maximize our chances by choosing something called mitochondrial DNA. We chose mitochondrial DNA for the simple reason that cells have upwards of a hundred times more of it than any other gene. As we will see, mitochondrial DNA turns out to have special properties which make it absolutely ideal for reconstructing the past; but in the first instance, we chose it as our target simply because there was so much more of it than any other type of DNA. If there was any DNA at all left in the Abingdon bones, then our best chance of finding it was by targeting mitochondrial DNA.
So, into the reaction went all the ingredients necessary for amplifying mitochondrial DNA, plus a few drops of the precious bone extract. To get the reaction to fire in the tube you need to boil it, cool it, warm it up for a couple of minutes; then boil it again, cool it, warm it up… and go on repeating this cycle at least twenty times. Modern genetics laboratories are full of machines for doing this reaction automatically. But not then. Back in the 1980s the only machine on the market cost a fortune, and there was no money for one in our budget. The only way to do the reaction was to sit with a stop-watch in front of three water baths, one boiling, one cold and one warm, and move the test tube by hand from one bath to the next every three minutes. Then do it again. And again. For three and a half hours. I only tried it once. The reaction didn’t work and I was bored stiff. There had to be a better way. What about using an electric kettle? I spent the next three weeks with wires, timers, thermostats, relays, copper tubing, a washing-machine valve and my kettle from home. In the end I had a device that did all the right things. It boiled. It cooled (very fast) when the washing-machine valve opened and let cold tap-water into the coils of copper tubing. And it warmed up. And it worked.
We could see that the machine (christened the ‘Genesmaid’, after the tea-making device people of a certain age regard as an essential bedroom accessory) had managed to get the amplification reaction to work not only with a control experiment using modern DNA but also, very faintly, with the Abingdon bone extract. By comparing its sequence to those published in scientific papers, it didn’t take us long to prove that the DNA was genuinely human. We had done it. Here, in front of our very eyes, was the DNA of someone who had died hundreds of years ago. It was DNA resurrected, literally, from the grave.
Now, looking back, it is hard for me to believe that the research set in motion by the recovery of DNA from those crumbling bones in the Abingdon cemetery, the bones which looked so unpromising when I first saw them half-buried in the earth, should lead over the following years to such profound conclusions about the history and soul of our species. As my story unfolds you will see that, like most scientific research, this was not a seamless progression towards a well-defined goal. It was more like a series of short hops, each driven as much by opportunity, personal relationships, financial necessity and even physical injury as by any rational strategy. There was no set path towards the discovery of the Seven Daughters of Eve. The research just moved a little bit at a time, mostly forwards, towards the next dimly visible goal, informed by what had gone before but ignorant of what lay ahead.
At the time, though our result was a great triumph, strangely enough it didn’t feel like it. I think Erika and I were too heavily involved in the details to appreciate the significance of what we had achieved. Besides, by then we were not getting on at all well. Tension had been building for weeks because, for some reason, Erika and I did not seem to be working together effectively. Only much later did I start to realize what our breakthrough could mean, not only for science but for popular history as well. That would come later; at the moment we had more pressing claims on our attention. 1 had heard on the grapevine that other research teams were also looking for DNA in old bones. This meant we had to get our work published with maximum speed, otherwise there was a real danger that we would be scooped. What counts in science is not being the first to do an experiment but being the first to publish the results. If someone else published even a day before we did, then they would claim the prize. Fortunately, the editor of the scientific journal Nature was persuaded to rush our paper into print in record time, and it was published just before Christmas 1989.
I was quite unprepared for what happened next. Although my previous research on brittle bone disease had occasionally been covered in the local papers and even once or twice in the nationals, it could not be said that any new result had sparked off a media frenzy. So it was a new experience when I got into work next day to find the phone constantly ringing with press enquiries. A few years previously I had actually spent three months in London as a reporter for ITN, which runs the television news service for the main commercial terrestrial channels in the UK. This venture was part of a well-intentioned fellowship scheme run by the Royal Society, designed to bridge the gap between science and the media. I was attracted to it by the generous expenses with which I hoped to pay off my bank overdraft. In fact, I ended up owing more money than I had to start with, not least because of the amount of time I spent in bars and restaurants with the well-heeled professionals. One night, for instance, I was precocious enough to offer to buy a drink for one well-known presenter. ‘Thanks, dear boy, I’ll have a bottle of Bollinger,’ came the great man’s answer. What could I do but comply? Still, though a financial disaster of major proportions, those few months taught me many things about the news media, including the way to trim my replies to reporters’ questions down to the simple sentences I knew they wanted.
After a morning of fielding enquiries about our scientific paper, I was beginning to feel a little bored with explaining in one sentence what DNA was, etc. etc. By the time the science correspondent of the Observer rang, this ennui had got the better of me. Having gone through the standard questions, he asked what could be done now that DNA could be recovered from archaeological remains. I replied that one possibility was that we might be able to tell whether or not the Neanderthals had become extinct. A perfectly reasonable reply and, as it turned out, a correct forecast. Then I slipped in: ‘Of course we will also be able to solve questions that have puzzled scholars for centuries – like whether Rameses II was a man or a woman.’ As far as I know, not a single scholar has ever entertained this possibility for a second. No-one has ever had the slightest doubt that the great pharaoh was a man. And yet, on the following Sunday, underneath his likeness, I read the caption ‘KingQueen Rameses II’.
Many years later I had the good fortune to be invited to the opening of the new Egyptology gallery in the British Museum in London. At dinner that evening in the magnificent Egyptian Sculpture Gallery, my place was set directly opposite the huge granite statue of Rameses. He was looking down right at me with his unnervingly benign and omniscient gaze. I knew at once that he had heard about my joke at his expense, and that I was going to be in big trouble in the afterlife.
One of the most difficult things about getting ancient DNA out of old bones is that, unless you are extremely careful, you end up amplifying modern DNA, including your own, instead of the fossil’s. Even when it is present, the old DNA is pretty shattered. Chemical changes, mostly brought about by oxygen, slowly change the structure of the DNA so that it starts breaking down into smaller and smaller fragments. If even the tiniest speck of modern DNA gets into the reaction then the polymerase copying enzymes, which don’t realize that you are trying to amplify the worn out little scraps of ancient DNA, concentrate their efforts on the pristine modern stuff and, not knowing any better, produce millions of copies of that instead. So it looks as though the reaction has been a great success. You put a drop of ancient bone extract in at the beginning and get masses of DNA out at the end. Only when you analyse it further do you realize that it’s your own DNA, not that from the fossil at all.
Although we were fairly sure this hadn’t happened with the Abingdon bone, we thought one way of checking would be by getting DNA from old animal rather than old human bones. It would then be very easy to tell whether we had amplified animal DNA – the real thing – or human DNA, which would have to be a contaminant. The best source of sufficiently old animal bones we could think of was the wreck of the Mary Rose. This magnificent galleon had sunk during an engagement with a French invasion fleet off Portsmouth in 1545. Very few of the crew survived. For over four hundred years the wreck lay in the mud under 14 metres of water until it was raised in 1982 and put on display in a museum in Portsmouth harbour, where it is still being drenched with a solution of water and anti-freeze to prevent its timbers from buckling. As well as the skeletons of the unfortunate crew, hundreds of animal and fish bones were recovered from the wreck. The ship had been full of supplies when it sank, and among these were sides of beef and pork and barrels of salted cod. We persuaded the museum curator to let us have a pig rib to try. Because it had spent most of its life (after death, that is) buried in the oxygen-free ooze at the bottom of the Solent, the rib was in very good condition and we managed to get lots of DNA from it without much trouble. We analysed it – and there was no doubt at all that it was from a pig and not a human.
The point of telling you all this is not to take you through our experiments one by one, but to explain the reaction when the result was published. More phone calls and more headlines – of which my favourite is from the Independent on Sunday: ‘Pig brings home the bacon for DNA’. This was going to be fun.
