Authors: Bryan Sykes
Copyright Â© 2001 by Bryan Sykes
All rights reserved
For information about permission to reproduce selections from this book, write to Permissions, W. W. Norton & Company, Inc., 500 Fifth Avenue, New York, NY 10110
Library of Congress Cataloging-in-Publication Data
The seven daughters of Eve / Bryan Sykes.â1st American ed.
1. Human population genetics. 2. Human evolution. 3 WomenâAnthropometry. 4. Evolutionary genetics. I. Title.
GN289 .S94 2001
W. W. Norton & Company, Inc., 500 Fifth Avenue, New York, N.Y. 10110
W. W. Norton & Company Ltd., Castle House, 75/76 Wells Street, London W1T 3QT
To my mother
This book owes many things to many people. Do not imagine for a moment that everything reported here as coming from my laboratory is exclusively my own work. Modern science relies on teamwork and I have been fortunate to have had some very talented people in my research group over the years. In different ways they have all helped in creating this story. In particular I want to thank Martin Richards, Vincent Macaulay, Kate Bendall, Kate Smalley, Jill Bailey, Isabelle Coulson, Eileen Hickey, Emilce Vega, Catherine Irven, Linda Ferguson, Andrew Lieboff, Jacob Low-Beer and Chris Tomkins. In Oxford I must also thank Robert Hedges from the Radiocarbon Accelerator Unit for getting me started on all this, William James, Fellow of most Oxford colleges in his time, for his inspired suggestions along the way and, in London, Chris Stringer of the Natural History Museum for allowing me to drill holes into the fossils in his care. I am very grateful to Clive Gamble for his tutorials on the ancient world. I must also pay particular thanks to Professor Sir David Weatherall for not only tolerating but actually encouraging the performance of such exotic and seemingly pointless research in his Institute of Molecular Medicine in Oxford.
You may also gain the impression that my research group is the only one in the world doing this sort of work. It certainly is not and none of what I describe would have been possible without the pioneering work of, among many others, Luca Cavalli-Sforza, Alberto Piazza, Walter Bodmer, the late Allan Wilson, Svante Paabo, Mark Stoneking, Rebecca Cann, Douglas Wallace, Antonio Torroni, Mark Jobling and Peter Underhill. As you will see, we do not all necessarily agree with one another all of the time; but without them, and many others like them, mine would have been a much harder, and far duller journey.
Four people in particular have helped to bring this story into print. The quiet professionalism of my editor, Sally Gaminara, and the infectious enthusiasm of my agent, Luigi Bonomi, have kept me going. Add to that the thoroughness of Gillian Bromley, my copy editor, and the patience of Julie Sheppard, who typed up my scribbled notes, and few authors could have had more assistance.
I am indebted to the thousands of volunteers who, by giving me their DNA samples, have allowed me to peer into the secrets of their genetic past. Without them there would be no story to tell. Some names have been changed to protect anonymity. I particularly want to thank the government and people of Rarotonga in the Cook Islands for being exceptionally helpful, and Malcolm Laxton-Blinkhorn for his outstanding hospitality during my stays on this delightful island. And lastly, thanks to Janis, Jay, Sue and my son Richard, though only an embryo at the time, for coming with me.
THE SEVEN DAUGHTERS OF EVE
Where do I come from?
How often have you asked yourself that question? We may know our parents, even our grandparents; not far beyond that, for most of us the trail begins to disappear into the mist. But each of us carries a message from our ancestors in every cell of our body. It is in our DNA, the genetic material that is handed down from generation to generation. Within the DNA is written not only our histories as individuals but the whole history of the human race. With the aid of recent advances in genetic technology, this history is now being revealed. We are at last able to begin to decipher the messages from the past. Our DNA does not fade like an ancient parchment; it does not rust in the ground like the sword of a warrior long dead. It is not eroded by wind or rain, nor reduced to ruin by fire and earthquake. It is the traveller from an antique land who lives within us all.
This book is about the history of the world as revealed by genetics. It shows how the history of our species,
, is recorded in the genes that trace our ancestry back into the deep past, way beyond the reach of written records or stone inscriptions. These genes tell a story which begins over a hundred thousand years ago and whose latest chapters are hidden within the cells of every one of us.
It is also my own story. As a practising scientist, I am very lucky to have been around at the right time and able to take an active part in this wonderful journey into the past that modern genetics now permits. I have found DNA in skeletons thousands of years old and seen exactly the same genes in my own friends. And I have discovered that, to my astonishment, we are all connected through our mothers to only a handful of women living tens of thousands of years ago.
In the pages that follow, I will take you through the excitement and the frustrations of the front-line research that lies behind these discoveries. Here you will see what really happens in a genetics laboratory. Like any walk of life, science has its ups and downs, its heroes and its villains.
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 â measuring the decay of minute traces of naturally radioactive carbon atoms within the remains â 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
, the leading US scientific journal. To be perfectly honest, the most remarkable thing about our results was not that we had got DNA out of the body â by then this was a routine process â 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 Chile 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 âdiscovered' 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 âmissing link' between humans and the great apes â 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
who asked the crucial question.
âYou 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.
âWhat do you mean, who are they? They are from our collection of DNA samples from all over Europe.'
âYes, but who?' persisted Lois.
âI 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 âLAB' 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
she agreed at once, and the next edition carried a piece on her under the headline âIceman'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
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 âIceman 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 â 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 â Ursula, Xenia, Helena, Velda, Tara, Katrine and Jasmine â 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 â 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 â 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
, 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 â and it was through this work that, in 1986, I came to meet Robert Hedges.