Volume Issue
Other issues in this volume:
Review Article
Time's arrow: the measurement and theory of archaeological time
Geoff Bailey
Department of Archaeology, University of York, UK
(Email: gb502@york.ac.uk)
Antiquity 80 no. 309 September 2006
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TOM HIGHAM, CHRISTOPHER BRONK RAMSEY & CLARE OWEN (ed.). Radiocarbon and Archaeology: Proceedings of the 4th Symposium, Oxford 2002 (Oxford University School of Archaeology Monograph 62). xi+ 348 pages, 140 figures, tables. 2004. Oxford: Oxford University School of Archaeology; 0-947816-65-8 paperback £35. |
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GAVIN LUCAS. The Archaeology of Time. x+150 pages, 20 figures, 2 tables. 2005. Abingdon: Routledge; 0-415-31198-5 paperback £12.99. |
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Radiocarbon dating, one of the great success stories of scientific innovation in the twentieth century, has come to be so taken for granted that few archaeologists would question the desirability of having more - and more accurate - dates. And, as dates have become more numerous and more accessible, the literature concerning the theory of temporal patterning in archaeological data, the sorts of temporal ordering presented by archaeological materials and dates, the kinds of explanations they facilitate or preclude, and what the durability of material culture and the vaster time scales involved might tell us about the wider human condition has grown apace (Bailey 2005). These two books deal respectively with time measurement and time concepts, and reading them together is a thought-provoking exercise. That there is almost no overlap between them is part of the provocation. The Radiocarbon volume offers a wide-ranging series of reports about the application of radiocarbon dating and technical issues of measurement, with almost no discussion of theoretical issues, while Lucas focuses on philosophy, theory and concepts, and scarcely at all on dating methods (offering a disarming apology in his preface for that omission).
Radiocarbon and archaeology
Radiocarbon and Archaeology, edited by members of the Oxford Radiocarbon Accelerator Unit, contains 33 papers. They divide broadly between those that are concerned with technical developments in improving the accuracy of radiocarbon dating or expanding the range of applications, and those that use radiocarbon dating to solve archaeological problems in an eclectic range of examples drawn from European and World Archaeology. Examples from the Americas are notably absent.
Two issues that have greatly modified interpretation of radiocarbon dates are examined at some length, namely calibration and the use of accelerator mass spectrometry (AMS) techniques. The use of tree ring sequences to measure variations in the production of 14C in the upper atmosphere is now well established and provides calibration back to 9908 cal BC with a degree of certainty, while annual growth increments in varved lake sediments and speleothems, and uranium series dating of coral terraces, now extend the calibration curve back to 50 000 years. The uncertainties introduced by calibration and the progressive divergence of radiocarbon years by 2000 years or more as one goes further back in time clearly have important implications for understanding the resolution of dates based on radiocarbon, the duration of archaeological phenomena, and the correlation of radiocarbon dates with other types of dating, especially historical chronologies. Yet, despite the considerable refinements of the past 30 years, few subsequent examples have matched the dramatic impact that Renfrew's first use of calibrated dates had on the interpretation of European prehistory (Renfrew 1973).
Many of the regional studies demonstrate the new opportunities offered by AMS for dating of tiny samples, for example in producing a chronology for cave paintings (Zoppi et al. on sites on Malakula in Vanuatu) or for organic tempers in potsherds (Youn et al. on the Korean Neolithic; Kuzmin et al. on the Amur Basin of the Russian Far East). Dates of about 14 000 radiocarbon years or 16 000 calibrated radiocarbon years for the latter confirm the large extent of Asian territory in which very early pottery using cultures were established, including China and Japan. Use of non-destructive plasma chemistry to remove microscopic amounts of carbon from the surface of organic artefacts expands the possibilities for dating individual artefacts (Steelman & Rowe), while AMS dates from resin coatings on potsherds compared to dates from associated charcoal from the Spirit Cave (Lampert et al.) add to the growing number of examples of contradictions between dated artefacts and their stratigraphic associations. The disagreements between two laboratories on the dating of rat bones as indicators of earliest human arrival in New Zealand (papers by Beavan Atfield, and by Higham et al.) offer a sobering commentary on the potential for contamination of dated materials and the problems involved in determining the reliability of controversial dates.
A section on high resolution dating provides some interesting examples of dates obtained by dendrochronology (Slusarenko et al. and Hajdas et al.), but highlights the limitations of such opportunities to timber artefacts that can be tied in to a radiocarbon-dated tree ring sequence.
Overall, this volume provides a wide-ranging view of developments and applications in dating methods. Sixty years on from the first use of the radiocarbon technique, we have vastly more radiocarbon dates, and much earlier dates for some prehistoric developments; and yet, the new techniques have, if anything, multiplied the uncertainties, or at any rate made more explicit the margins of uncertainty inherent in the radiocarbon method. Studies of diffusion processes over large territories, which depend less on the accuracy of individual dates than on coherent patterns of relative date differences, are clearly well served by current techniques. There is also an implicit recognition that some problems are more easily solved within the current limits of accuracy than others. Perhaps more interesting is the growing number of examples that bear on our understanding of how archaeological deposits are formed. Individually dated objects found side by side in the same stratigraphic layer turn out to be separated by thousands of years; successive layers in a stratigraphic sequence turn out to have dates that are essentially indistinguishable, while high precision dates are possible for some timber objects, but that leaves open the problem of how they are to be correlated with other less precisely dated objects. These hint at theoretical issues yet to be explored.
The archaeology of time
The Archaeology of Time is about perceptions of time, both those of past people and how we might identify them from the material record, and the perceptions or preconceptions of archaeologists and their influence on the practice of archaeology. The book is informed by an explicit conviction, which should command wide agreement, that collection of dates, like any other form of data gathering, is meaningless without some reference to the problems they are intended to solve or some awareness of the assumptions and theories involved in their investigation.
The opening chapter ('Beyond Chronology') provides the core of the argument, which rests on a distinction between 'chronological time' and 'real time'. Chronological time is the objective time of scientific measurement, a universal framework that emphasises time as succession, as a unilinear sequence of events. In contrast, real time emphasises time as duration, time as flow rather than as sequence, which corresponds more closely to time as we experience it subjectively, and can thus result in many different temporalities and narratives. This distinction is reinforced by an excursion into the philosophical literature, with an emphasis on McTaggart's distinction between the A series - time as duration or tense, flowing from past to present to future (or real time in Lucas's terms), and the B series - time as a succession of moments that stand in a before/after relationship to each other (chronological time), and on Husserl's ideas about echo or retention. McTaggart was an idealist philosopher who concluded that time does not exist, while Husserl is better known as the founder of phenomenology, suggesting that Lucas's sympathies lie with those who view time 'as a mysterious illusion of the intellect', to use the words of Whitrow (1980: 375), as opposed to those who consider time to be 'an essential feature of the universe'.
Chapter 2 elaborates on the varying ways in which time is used in archaeological interpretation. The analysis of changes in the meanings of objects through time is highlighted as a way of escaping the paradoxes of time and embracing time both as subjective duration and as objective sequence. Chapter 3 looks at the way in which the attitudes of past societies to time can be inferred from their material culture, while Chapter 4 develops the idea of object biographies by looking in detail at the life and times of a Roman jar from the moment of its manufacture in the second century AD to its current resting place in an archaeological store room. Chapter 5, subtitled somewhat enigmatically as 'forgetting the past' takes off into a wide-ranging if rather obscure discussion about salvage and amnesia, which I suspect many readers who do not share the author's postmodernist stance will find quite incomprehensible.
Lucas's classification of time ideas is ingenious and provocative, and the problem he poses of reconciling the distinction between sequence and duration is ever-present in archaeological thinking, and in the most basic practices of archaeology such as the interpretation of stratigraphy. However, the contrast he draws between two broadly opposed approaches to time in archaeology is over-simplified. In Lucas's opinion, archaeologists who use dating schemes, such as those supplied by radiocarbon dating, are bound to engage in explanations couched in terms of 'chronological' time, and thus to subscribe to an unilinear, progressive, 'totalising' view of history, imposing a western scientific colonialism that denies other views of the past and minimises the subjective experience of time. This is over-exaggerated and confuses chronology as a framework of reference with chronology as a particular type of explanation. The one does not necessarily lead to the other any more than the use of modern maps to travel around a foreign country imposes a western scientific conception of space on the people who live there. The universal chronological framework of radiocarbon dating makes possible a comparative prehistory, as Grahame Clark (1961) clearly advocated over forty years ago, but that is not the same thing as a universal totalising history. On the contrary, the framework offered by scientific dating methods has helped to undermine 'western' and 'colonial' visions of the past by restoring to previously marginal peoples and places in the world a sense of their own history.
Lucas has interesting things to say about palimpsests ‹ in his words 'the traces of multiple, overlapping activities over variable periods of time and the variable erasing of earlier traces' (p. 37). He emphasises the perceptual dimension of this concept, that is the ways in which different people bring different meanings to the material world around them, but does not engage with the physical dimension of palimpsests, the loss of evidence and loss of resolution that inevitably occur when one moves beyond the study of a single object. While recognising the problem of differences in chronological resolution in Chapter 4, he sidesteps the issue by concentrating on the biography of an individual object, a type of study that neatly spares the analyst from grappling with the problematic and all-pervasive issue of contemporaneity. He is critical of time perspectivism, a term that I defined 25 years ago, which he sees as an example of 'chronological' interpretation, but plays down the central point of that concept, which draws attention to the differences of resolution that come with different scales of observation. Lucas insists that one can find real time events anywhere in the archaeological record, even in the Lower Palaeolithic, citing the manufacture of a handaxe and the Boxgrove horse-butchery site as examples. However, whether Palaeolithic 'living floors' are single events, rather than palimpsests incorporating unrelated episodes of deposition, is a contentious matter. As for the handaxe, one would not get far in its interpretation without comparing it to other examples, at which point one has to recognise that any two or more handaxes, even if found in the same deposit, may be separated by thousands of years (cf. Stern 1993).
Lucas's book is an important if flawed book, full of interesting ideas and examples, which raises issues that are fundamental to archaeological practice, and I recommend it to any archaeologist interested in time and especially to those who think that issues of time can be ignored. Lucas admits that he is offering a partial view, and there is much that is missing. The book certainly does not provide a full discussion of chronology and change, in spite of the publisher's claims to the contrary, and there is no reference to the earth sciences, where many archaeologists have sought common ground in addressing issues of time and temporality. On the other hand, Lucas is particularly good on the temporality of material culture and the anthropology of time. It is perhaps significant that his best examples are historical and ethnographic ones. Whether all this amounts to an archaeology of time, let alone the archaeology of time, remains debatable.
If there is a single message to be extracted from reading these books together, it is that there is still a large area of unexplored territory between the development of dating methods on the one side, and archaeological interpretations of temporality on the other. Dating specialists need to engage more fully with the theoretical implications of the novel and often counter-intuitive empirical patterns that their methods reveal, archaeological practitioners need to ask themselves why they want more dates or more accurate ones, and archaeological theorists need to take more seriously the problems and opportunities posed by application of scientific dating methods. When that happens, then, perhaps, it may be possible to talk about an archaeology of time. These books provide suggestive indications of how the field of study might develop, but the hard work of producing a distinctively archaeological conception of time and temporality as opposed to conceptions borrowed from neighbouring intellectual disciplines, whether they deal with the much shorter time ranges and higher resolution of the recent past or with non-human phenomena on the vaster time scales of geological time, has scarcely begun.
References
BAILEY, G. Concepts of Time, in C. Renfrew & P. Bahn (ed.) Archaeology: the key concepts 26873. London: Routledge.
CLARK, G. 1961. World prehistory: an outline. Cambridge: Cambridge University Press.
STERN, N. 1993. The structure of the Lower Pleistocene archaeological record. Current Anthropology 34: 20125.
WHITROW, G.J. 1980. The natural philosophy of time. Second edition. Oxford: Oxford University Press.
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