Early Neolithic Chronological Relationships of Cyprus and South-West Asia: Legacy Dates and Research Design

After a century of research into the earlier stages of the Neolithic of south-west Asia (c. 10th–7th mil cal BC) the agenda is shifting from one focused on farming, to one tracing a range of cultural processes, often happening over extended periods of time, among which the development of agriculture was just one facet. Yet, as the synthetic arguments grow in complexity, so does the need for improved chronologies; it is difficult to make arguments relying on the pacing of cultural changes if we cannot determine whether the changes in question took place over a single generation or over several centuries. This report summarizes some of the more general findings of the first five months of a one-year CBRL fellowship project that evaluates the existing ¹⁴C data sets and the chronologies that can be built upon them. The project focuses on Cyprus, but also includes a substantial grab sample of mainland sites. The work entails an audit of individual samples in terms of their contextual and technical reliability and, information allowing, construction of Bayesian site models. While the audit and the modelling for the most part highlight chronological ambiguities, in the long term such observations aid the development of more efficient dating programmes and better chronologies.

Kalavasos—Tenta and sample pre-treatment

One of the most important parts of the radiocarbon dating process is suitable sample pre-treatment. Such procedures are essential to the removal of contaminants from ¹⁴C samples and hence fundamental to obtaining meaningful results. The typical pre-treatment for carbonized plant remains (which constitute the bulk of the samples from the Neolithic) is acid-alkali-acid (AAA). AAA consists of an acid wash that removes acid-soluble contaminants (such as carbonates) and an alkali wash that removes alkali-soluble contaminants (such as acids formed during the decomposition of plant matter). As alkali can draw down atmospheric carbon dioxide, the protocol is completed by a final acid wash that neutralizes the alkali and thus prevents contamination with atmospheric CO₂. While almost all modern labs follow this pre-treatment for carbonized plant remains, there are differences in the kinds of acids and alkali used, their concentrations, and the temperatures at which washes are undertaken as well as the pre-treatment times.

One drastic example of just how important pre-treatment protocols are, comes from Kalavasos-Tenta, a site on Cyprus, excavated by Ian Todd in the 1970s, where some samples were subject to the full AAA method and others only underwent a single acid wash. In the instances where multiple samples dated the same contexts, major differences emerged between the AAA and acid-only pre-treated material (Fig. 1). When combined with the sampling of features much later than the main occupation of the site mixed with pre-conceptions regarding the islands’ prehistory when the site was first published, the under-pre-treated determinations led to the placing of Tenta in the 7th millennium BC, which may be over 1000 years after the majority of archaeological activity ceased.

Fig. 1. Comparison of the radiocarbon dates from the same context associated with the abandonment of Structure 5 at Kalavasos-Tenta. Sample P-2548 (black fill) underwent complete acid-alkali-acid pretreatment, while sample P-2551 (grey fill) underwent acid-only pre-treatment. Data from the first volume of the site report, edited by Ian Todd and published in 1987.

While such drastic cases are rare in more recent dating programmes, there is a possibility that in atypical geological conditions different approaches to the detail of pre-treatment methods will lead to different results (for example too weak an acid stage might fail to dissolve carbonate crystals). In some ways, these cases may be more difficult than the example of Tenta, as they will lead to subtle incongruities between the radiocarbon determinations and the stratigraphy. These in turn might cause ambiguities as to whether the apparent contradictions emerge from sample pre-treatment protocols or emerge from taphonomy and site formation processes. Therefore, it is important that details of the pre-treatment protocol are appended to new radiocarbon date publications.

Asprokremnos, Klimonas and dating resource allocation

The longevity of many of the south-west Asian Neolithic sites means that in numerous instances excavators are faced with difficult resource allocation choices. While some projects will have substantial dating components with hundreds of ¹⁴C determinations (for example Tell Sabi Abyad), it is far more common for excavators to be able to afford less than 20 ¹⁴C samples. This triggers a strategic question; are the limited resources better invested if the sampling focuses on a particular feature or group of features, or is attempting a generalized site chronology more reasonable?

The potential value of concentrating resources is illustrated by two Cypriot PPNA sites, Ayios Tychonas- Klimonas (excavated under the direction of J. D. Vigne) and Agia Varvara-Asprokremnos (excavated under the joint direction of Stuart Manning and Carole McCartney).At both sites,asmallnumberofsamples(sixatAsprokremnosand11at Klimonas) were focused on specific features (at Asprokremnos this was a midden and at Klimonas abandonment and reconstruction of a structure on the same location). Due to this this concentration, the Bayesian models for both sites deliver precision of just over a century, even after taking the possibility of an old wood effect into account, thus placing the activity at these locations in the very specific context of the final stages of the Pre-Pottery Neolithic A. Nevertheless, the value of such concentration is always relative to the archaeological questions asked and, at times, it might be more reasonable to disperse the dating resources to attain a better overview of the overall site chronology. For example, at neither Klimonas, nor Asprokremnos can we make justified judgements as to the duration of activity at the site based on the ¹⁴C determinations published to date, nor do we have an overall picture of when these settlements began or ended. This, and similar case studies, demonstrate the importance of the relationship between the radiocarbon sampling strategies and the viability of archaeological questions.

Conclusion

The first five months of the project provide grounds for cautious optimism. While high-precision chronologies of the kind necessary to make some of the more ambitious theoretical propositions viable are some way off, our ability to produce them is improving. Sites such as Asprokremnos and Klimonas demonstrate that features with good integrity exist and that, by targeting them within broader problem-oriented dating programmes, we might be able to attain a good degree of chronological control on our understanding of specific archaeological events. Furthermore, even on sites where the dating evidence is sparse, or consists of determinations that are problematic, be it on contextual or technical basis, there is often enough information to guide the development of follow- up programmes. Further improvement is needed in publication standards to allow a more critical understanding of the various chronologies (a good set of guidelines is provided by Andrew Millard in Radiocarbon 56.2).

As for the remainder of this current project, the plan is to finalize a set of regional and local chronologies. In places such as the Middle Euphrates, or the system of valleys running from Wadi Fidan to the Greater Petra Area, there are by now numerous excavated and published sites with multiple radiocarbon determinations. It should be possible to attain at least a glance of how settlement in these areas emerged in real time, and thus make a contribution to breaching the gap between analysis at the level of individual sites and discussion on regional and supra-regional scales. Furthermore, there are a number of key sites, such as Mureybet or ‘Ain Ghazal, which are fundamental to our discussion of various transformations in the Neolithic, but whose large radiocarbon assays are as yet unexplored. It may well be that by auditing these determinations and modelling them into site chronologies, our understanding of the larger cultural shifts, such as the emergence of the Pre-Pottery Neolithic B, will become enriched. It is through such research in these and related directions that the current project aims to define the key chronological ambiguities of the earlier Neolithic, and thus contribute to their resolution.