To Bayes or not to Bayes? The limitations Bayesian modelling as demonstrated at Aceramic Neolithic Canhasan III and Neolithic/Chalcolithic Canhasan I in Turkey

In the brave new world of easily accessible software, and with increasing pressure from journals to apply Bayesian approaches to all radiocarbon sequences, it is easy to fall into the trap of generating junk chronological models of limited worth, especially when dealing with legacy samples from unpublished sites. In this seminar I will discuss the experience of attempting to develop revised settlement chronologies for the Aceramic Neolithic settlement of Canhasan III and the Neolithic/Chalcolithic settlement of Canhasan I, located to the south of World Heritage Catalhoyuk on Turkey’s Konya Plain. A combination of new AMS dates and a revised settlement sequence by the Late David French, excavator of both sites, provided the basis for chronological revision. An initial Bayesian model for Canhasan III made too many assumptions about the source material and was abandoned for an approach based on kernel density estimates and analysis of sample distribution. The latter provided strong evidence to demonstrate that Canhasan III was abandoned by the end of the 8th millennium BC, overlapping with the foundation of Catalhoyuk East. Interestingly, the abandonment correlates with a widespread abandonment of the Konya Plain at this time. A Bayesian model was successful for Canhasan I and indicates occupation as part of a new phase of settlement into previously abandoned locales at the end of the 7th millennium BC. The new chronology makes sense of the material culture record and indicates broadly synchronous patterns of settlement agglomeration and dispersal across the Konya Plain. The significance of these changes will be discussed along with the lessons learnt about chronological modelling approaches.

Andy Fairbairn is an archaeobotanist and archaeologist interested in ancient agriculture, foraging practice and past anthropogenic landscape change. He has worked in Turkey since 1999, publishing research on past farming practice and economic change in a range of sites including Neolithic Çatalhöyük East, Pınarbaşı and Canhasan III and Boncuklu, where he is the project co-director, as well as Bronze Age, Iron Age and Medieval occupations at Kaman Kalehöyük, Büklükale, Yassihöyük, Kültepe and Kinet Höyük. Andy studied at the Institute of Archaeology in London before working at The Museum of London, Cambridge University, The Australian National University and has been at UQ since 2006, where now Head of Discipline for Archaeology in the School of Social Science. He has published research on sites in the UK, central Europe, Jordan, Papua New Guinea and Australia and is Associate Editor for the journal Vegetation History and Archaeobotany.