Unlocking the Past Read online

  In memory of my mother

  from whom I learnt to look more closely at things

  Copyright © 2001, 2016 by Martin Jones

  All rights reserved. No part of this book may be reproduced in any manner without the express written consent of the publisher, except in the case of brief excerpts in critical reviews or articles. All inquiries should be addressed to Arcade Publishing, 307 West 36th Street, 11th Floor, New York, NY 10018.

  First North American edition 2002

  First published in 2001 by Allen Lane, The Penguin Press, England

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  10 9 8 7 6 5 4 3 2 1

  Maps illustrated by Vicki Herring

  Print ISBN: 978-1-62872-447-9

  Ebook ISBN: 978-1-62872-479-0

  Printed in the United States of America

  contents

  acknowledgements (2001)

  foreword (2016)

  1 a different kind of past

  2 the quest for ancient DNA

  3 our curious cousins

  4 final traces of life

  5 gaining control

  6 ending the chase

  7 great journeys

  8 beyond DNA

  9 friends and relations

  10 enemies within

  11 the hunt goes on

  references

  index

  acknowledgements (2001)

  The initial encouragement to write this book arose during lunch in a Greek restaurant in Cambridge. Not only do I warmly thank my lunching companion, Graeme Barker, for setting me off on a most stimulating project, but also for coming up with a suitable title between servings of meze. This was in the summer of 1998, shortly after the completion of the Natural Environmental Research Council’s Ancient Biomolecules Initiative, which it had been my privilege to chair. The Initiative brought together around fifty researchers within seventeen projects scattered around the country, all doing pioneering work in a very novel field of applied science. Interaction with that dedicated group of people provided me with the experience and insight upon which I have constantly drawn to write this book, and my sincere thanks go to them all. I extend that thanks to everyone involved in the Initiative, the International Steering Panel, the contributors to the annual Cambridge workshops, and to the staff at NERC.

  Ancient biomolecule research has been going on not only in the UK, but right across the world, from America to Japan and New Zealand. Many of those international colleagues and teams I have had the privilege to meet; others I have contacted only through email. Without exception, all have been generous and forthcoming with advice and ideas, and everywhere the enthusiasm for being part of a new scientific departure shines through. Particular thanks for dealing with specific queries and supplying information in advance of publication go to Dan Bradley (Dublin), Jane Buikstra (Albuquerque), Jacques Connan (Pau), Bill Hauswirth (Florida), Rika Kaestle (Yale), Andy Merri-wether (Michigan), Svante Pääbo (Leipzig), Franco Rollo (Camarino), Yo-Ichiro Sato (Shizuoka), Anne Stone (Albuquerque), and Mark Stoneking (Leipzig).

  For help with Oliver Hunt’s cover illustration, thanks go to Joan Oates and Helen McDonald. The text itself benefited from a critical reading in sections by a number of colleagues. My thanks for this invaluable assistance go to Robin Allaby, Dan Bradley, Terry Brown, Matthew Collins, Geoff Eglinton, Richard Evershed, Peter Forster, Terry Hopkinson, Chris Howe, Matt Hurles, Miranda Kadwell, Adrian Lister, Svante Pääbo, Franco Rollo, Charlie Shaw, Andrew Smith, Helen Stanley, and Mark Stoneking. Thanks also to Janet Tyrrell for her scrupulous copy-editing, and to my editor Stefan McGrath and my agent Clare Alexander for their intelligent engagement, support, and critical encouragement throughout the project from its inception. The text would have been a much inferior thing without them.

  The least tangible contributions can also be among the more important ones. Over several years in labs, conference halls, pubs, and private homes, conversations and debates with a number of colleagues have been invaluable in shaping the ideas that unfold in this book. The list of such colleagues is too long to reproduce here, but I do want to mention in this context the unstinting encouragement of Lucy Walker, and my numerous conversations with Geoff Eglinton, Terry and Keri Brown, and Robin Allaby. All these have guided and nurtured my own thoughts and ideas.

  foreword (2016)

  Writing about a newly emerging field was an exciting thing to do. This was not just because a number of the findings were so novel, unimagined even. It was also because a number of the key practitioners were exploring how to situate themselves within an ill-defined landscape of research and discovery. Several of those individuals, who are now distinguished professors, were at that time graduate students, turning up to conferences at which all the key players found themselves in a single room. Egyptologists were rubbing shoulders with protein chemists; cancer researchers were taking issue with analysts of insects in amber. In retrospect, we can remember moments during these gatherings when the new field was tipped one way or another. Those were interesting times.

  Fifteen years may not seem a very long time, but the human past provides us with many examples of timeless, established traditions emerging with surprising rapidity from shaky beginnings. Fifteen years since the publication of The Molecule Hunt, there are research centres across the globe with impressive laboratories and large research groups. Such Journals as Science, Nature, and PNAS continue to chart the milestones in their progress, and molecular studies are well embedded in archaeology courses at several levels. Our whole idea of being human and the human past has become difficult to narrate without the new findings at their heart.

  So what can be gained by returning to a text assembled fifteen years ago? It goes without saying that if each and every one of the findings still held true today, then the field would have stagnated, and the prediction in the text that it would do otherwise have proven false. It is quite interesting to reflect on the findings that have held true, but it is certainly the case that much has changed, and some findings have essentially been reversed.

  Could the text be fundamentally rewritten to bring it forward to the present? Probably not—at least not in the same voice. As a field moves to maturity, a different sort of voice becomes relevant to relay the ‘facts’, the ‘knowns’, and an associated canon of scientific procedures. Indeed, a number of such texts have been excellently written, leaving the human process of actually doing science as something of a given. That is a perfectly appropriate voice for a field that has moved significantly beyond its birth pains.

  I would be equally unhappy to leave the text as it is, as one author’s perception of the state of field at a particular moment in time, a moment that now has very clearly passed. Instead I have chosen to attach ‘afterwords’ to each of the original chapters, briefly reflecting upon how some of the key issues and arguments within each chapter have been sustained, modified, turned on their head, or in some cases a combination of all these. We are no longer in the situation where the players can find themselves together in a single room, so I am at a greater distance from several of the key practitioners, knowing them only from their published papers, rather than the coffee room and bar, conference presentations and grant applications. It is, of course, a more detached and impersonal academic community, but by no
means devoid of its personalities and its intrigue. In my brief afterwords, many of those themes will remain in the subtext.

  In assembling the additional text, I owe enormous gratitude to Dr. Mim Bower. As one of the scientists, her research career has grown in the context of molecular archaeology, and she has herself published widely on the archaeogenetics of the horse. Mim has gone through the original text, making detailed suggestions of connections with subsequent publications. That has provided a landscape in which my own reflections on how things have moved forwarded are more securely grounded. I am also grateful to my colleague Harriet Hunt for her critical thoughts and suggestions on my new text, and to Vicki Herring, for furnishing each chapter with an expertly drafted map. I also want to thank my agent Claire Alexander of Aitken Alexander Associates, and my editor Joseph Sverchek of Skyhorse Publishing, for persuading me that a return to the text would be an interesting and worthwhile project. I have benefited greatly from that return and subsequent reflection, and I very much hope that my readers do as well.

  Martin Jones

  1

  a different kind of past

  first encounters with archaeology

  A visit to a museum is quite different from actually digging up the past. In a museum, conserved objects are seen behind glass, neatly arranged and labelled in their controlled environment of scholarly explanations and humidity meters. An archaeological dig is something else. Here, the past is dirty, sticky, tactile, and quite often smelly. All this came as some surprise with my first taste of archaeology in the field, three decades ago. I had somehow imagined there would be a great deal of brushing, sifting and so forth, with one of those museum objects very occasionally emerging from the dust. In reality, what our ancestors have left beneath the ground is much more varied and challenging than that.

  Rather than brushing and sifting, my introduction to field archaeology involved much wielding of picks. We pushed enormous battered wheelbarrows and hurled shovel-loads of earth as the sludge from a rather wet Somerset field found its way into our boots. Along with that moist sensation came surprise at the sheer quantity and variety of things emerging out of the ground. As our spades penetrated the turf of a slight mound in the middle of this field, our finds trays quickly filled, but not only with the kinds of objects seen behind museum glass. True, there were fragments of the elaborately decorated Glastonbury Ware pottery, its dark burnished surface adorned with the kind of swirling designs we associate with Celtic art forms across Europe. It was an unusual sensation to have been the first to hold such an artefact for over 2,000 years. But there were also large numbers of discarded animal bones, not so often seen in archaeological displays, some broken up for the soup bowl and glue pot, others elegantly fashioned into the weaving equipment of the ancient village dwellers. One day one of the diggers found another trace of their everyday lives, a broken pot spilling over with small black pellets. On closer inspection these pellets proved to be cereal grains, blackened by charring. We gathered around to peer down on the curiosity, before it was taken away to be entered into the record books of that delightful antiquarian category ‘small finds’, which is the archaeologist’s repository for coins, beads, oddments, and anything that falls outside the most familiar categories.

  As we dug down, the range of surviving materials increased. By the time the adjacent turf-line was at the level of our waists, that range had broadened dramatically. The grey clays we had been removing gave way to something very different. This blackened peat below was full of all the things that had decayed from the sediments above. Our trowels teased their way through, to reveal leaves, nuts, and vast quantities of wood. As pieces of the freshly exposed peat were pulled apart, branches of birch buried for over two millennia revealed their silvery, flaky bark. Blades of grass could be seen that still seemed to be green, as if the chlorophyll within them had remained intact. Now that they had been exposed to the air, that green coloration quickly changed to brown, just as a host of other processes of breakdown and decay set in. That exposed peat was soon peppered with insect holes, as burrowing soil animals responded with enthusiasm to the opening of the larder door. Waterlogged and sealed off from the air, the organic peats had been protected from the foraging of these creatures. We archaeologists had taken that protection away and now the limbo in which these fragments of life had been suspended would soon come to an end. In the case of the wood, this change took place before our eyes. When first exposed, the wood fragments within the peat seemed solid enough. Their surface features and patterned grain were clear to see, the main distinction from modern wood being their darkened colour. Once lifted and exposed on the grassy verge beside our trench, these pieces began to shrink as the water within them evaporated. They would twist and crack, and their surfaces would become flaky. Their solidity had been an illusion, only maintained while they remained within their enclosed and waterlogged refuge.

  None of this curious decay caused great waves back in the 1960s when that Somerset dig was underway. The main business of archaeology lay beyond those flaking timber fragments on the grassy verge, a place in which another set of transformations was busily taking place. The excavated finds were being washed and marked. Toothbrushes and nailbrushes were scrubbing away in bowls of cold, murky water. The task was to remove all those things that separated the dig from the museum–the dirt, the peat, the stickiness and the smell–in order that the object we had unearthed might one day inhabit a neat museum drawer, if not a plinth within a humidity-controlled cabinet.

  Since the 1960s, our perception as archaeologists of what we are digging up has changed. It has become clear that what we left behind in those peaty sediments, on the earthy surfaces we scrubbed from the pots, from the bones and organic objects, and even the partially decomposed materials we can smell, may be rich in intimate clues about past lives. We would no longer reduce what lay beneath that shallow mound in a Somerset field to an assortment of cleaned pottery fragments and other durable, easily visible objects. Bit by bit, other data were gathered and analysed as part of the archaeological routine. First came the more stable biological materials, the animal bones, and then those charred cereal grains. Then methods were refined for conserving and gleaning information out of all that waterlogged wood and the other debris within the peat. Most recently of all, it has become clear that the reason any of that organic material survives at all is because even the molecules of which it is built retain a remarkable trace of its fragile and intricate structure for thousands, even millions, of years. Those molecules can be hunted down and analysed in their own right, and have a considerable story of their own to tell.

  disciplines in flux

  The great changes that have happened in archaeology, in the time that has elapsed since I first got my socks wet in a Somerset field, have not taken place in isolation. A perennial human curiosity as to what traces of the past might linger on has been an important driver of those changes, but not the only one. The things we wish to know about the past have also changed. Our queries have drawn us more and more towards organic traces, and then to the molecular information within them. Back in the days of my first dig, the question in an archaeologist’s mind as he or she pondered the trays of washed and marked pottery was how those durable artefacts fitted into some grand scheme of European prehistory. The swirling patterns we had found incised on those pot fragments bore some resemblance to patterns found on metal swords and mirrors recovered from prehistoric graves in mainland Europe. Arrows could be drawn across the map to link the two, implicitly tracking a distant cultural journey, a movement from mainland Europe to the British Isles, bringing with it a package of cultural ideas and practices, encapsulated in a series of elegant swirls on the side of a pot.

  By such reasoning, sites such as this contributed a few pieces to a vast and intricate three-dimensional jigsaw puzzle of Europe, two dimensions of space and one of time, all knitted together by arrows across the map, linking common attributes and design features in the durable remains recove
red by excavation. These, it was assumed, traced the paths of a network of cultural journeys, migrations and invasions by which prehistory could be both narrated and explained. In this way, a line could be traced back from the swirling designs on our particular pots, in use in that Somerset lake village a little over 2,000 years ago, to similar swirling patterns on metalwork recovered from the shores of Lake Neuchatel in Switzerland, at a site called La Tene.

  Stories of this kind had two weaknesses. Just around the corner was a scientific method of dating, already tried and tested but not yet a routine tool of archaeological excavation. Radiocarbon chronology was in the process of severing and disposing of a number of those arrows. It was becoming clear that migrations and invasions could not be, and were not, the only sources of change in prehistoric society. To tally with the rigid scientific chronology now emerging, archaeologists were forced to look more seriously at the possibility of indigenous change within existing communities, rather than simply drawing arrows between poorly dated objects. This is where the second weakness came in. To examine indigenous change, we really needed to know what life was like, and we did not in fact know a great deal about the ordinary lives of those who used the elegantly decorated pots that had been at the centre of archaeological attention. Such durable artefacts had dominated the whole process of inquiry. The site report would eventually reproduce page after page of illustrations of them. The potter’s workplace and the stone-worker’s floor were among the few features of a reconstruction drawing that would have any detail–the people, their clothes, their dwellings and their farms dissolving into a semi-impressionistic swirl in the background.

  A few years after that excavation, David Clarke at Cambridge attempted to shift focus and to make some sense of the people who actually lived and farmed on the late prehistoric villages of which our excavation had revealed a part. Those same prehistoric villages, the ‘lake villages’ of Glastonbury and Meare, had been excavated earlier in the century by Arthur Bulleid and George Gray, and a series of weighty tomes had been produced, cataloguing and describing their earlier excavations in great detail. Clarke combed through this data, searching for patterns in space and structure and in the distribution of different kinds of artefacts across them. In the new account he assembled, the emphasis shifted right away from sequence and pottery styles to talk of huts, workshops, granaries and stables. The village had family groups and a place in the landscape. He speculated upon the farming activities in the fields around. The settlement was coming alive, and at the same time, one of Clarke’s Cambridge colleagues was beginning to look more closely at the remains of living things from that ancient landscape.