The Neolithic Transition and European Population History-A Response
Steele, James, Gkiasta, Marina, Shennan, Stephen, Antiquity
We thank Crombe and Van Strydonck for their comments on our earlier paper (Gkiasta et al. 2003). They kindly draw attention to recent surveys of radiocarbon data from Belgium, most of which were published subsequent to our own work, which was carried out in 1999. Even at the time we were under no illusion that our compilation was complete: "It became clear in the course of the project that, despite the large sums of money which have been spent over the years on radiocarbon dating in Europe, the state of public availability of the dates, their context and associations and details which enable users to judge the reliability of dates is in general very poor. Thus, no claim is made that the database is in any sense complete" (Gkiasta et al. 2003: 48). It would probably also be as well to correct the impression that the dates we used were mainly derived from Gob (1990). Over half those finally included were extracted from the University of Lyon Banadora database; the remainder came from a wide range of other sources. The new dates from Belgium may well sited new light on the chronology of the transition in that region. New discoveries frequently do cause old interpretations to be modified or revised; we look forward to their analysis and demonstration of the implications of the new data to which they refer.
A number of methodological issues are raised by Crombe and Van Strydonck relating to sample selection and the accurate dating of cultural phases on archaeological sites. Our own data-set does indeed contain predominantly charcoal samples, and most of the radiocarbon determinations were indeed derived using the conventional methods. We found some indication in the Neolithic sample that the charcoal dates tended to be slightly older than the brute dates within sites and phases (Russell 2002: 28), and it is certainly possible that this may reflect an 'old wood' problem. There are also, however, well-documented problems in bone pretreatment, which can lead to the opposite effect--an artificial reduction in the age of a dated bone sample, due to incomplete removal of organic contaminants (e.g. Hedges & Van Klinken 1992).
The observations that fine resolution can be achieved by AMS dating of remains of short-lived plant organisms that were demonstrably part of diet, and that plant food remains give more reliable dates for occupation episodes than unstratified charcoal in highly bioturbated open-air sites, seem to us to be no more than common sense. Detailed sample-by-sample evaluation of integrity and contextual association is, in many circumstances, essential if the research question is to be properly addressed. In our own case, since completion of the initial survey contained in the Gkiasta et al. database, some members of our group (Sue Colledge, James Conolly and Stephen Shennan) have been concentrating on close analysis of archaeobotanical data relevant to tracking the early diffusion of plant domesticates in the Near East and Europe (for first results see Colledge et al., in press). However, it is not clear how significant this is for trend lines fitted to data from hundreds of sites dispersed at the continental scale, that is to say, whether there is a systematic spatial gradient in the magnitude and direction of the dating errors, or just increased 'noise' that is randomly distributed in space. The former would be a problem for our analyses, the latter less so.
Although we therefore accept the broad relevance of Crombe and Van Strydonck's commentary, and admire their rigour in calling for a moratorium on any chronological arguments other than those based on AMS dating of seed and nut remains, we feel that there is still merit in investigating the broad overview. We were concerned to see how well more recent data corroborated the broad picture of the chronology of the Neolithic transition in Europe that had been depicted by earlier scholars. As we also indicated, the research context for this was provided by recent work in archaeo-genetics (e. …