Radiocarbon Evidence for the Pace of the M-/L-PPNB Transition in 8th Millennium BC Southwest Asia

Abstract

Abstract:The transition from the Middle to Late Pre-Pottery Neolithic B (PPNB) happened throughout southwest Asia in the mid-8th millennium cal BC. It entailed the abandonment of a number of sites, rapid growth of others, as well as the widespread of morphologically domestic caprines. What remains an unknown is how rapid these processes were in real time. Over the period when the transition was taking place, the calibration curve has two shallow sections divided by a sudden drop, which for many of the older dates creates an illusion of a sudden cultural break around 7600-7500 cal BC. Yet a more detailed study presented in this paper suggests that the transition event could have been spread over a more extended period of time. This, however, is still far from certain due to risks of old wood effects and complexities of site formation. Keywords: Legacy dates, Pre-Pottery Neolithic, Bayesian analysisThe tempo of cultural transformations is fundamental to understanding their nature and thus identifying factors that caused (pre)history to follow the specific path it took. When rapid changes take place, corresponding major causal factors, such as abrupt climate change (Childe 1936;Weninger et al. 2009), or a socio-political upheaval (Gebel 2004), have to be invoked and explored. Slower rates of change often imply greater continuity (Harding 2004) and the study of the transitions in question becomes one of tracing the connections in the processes involved. These are basic considerations, but they show that understanding change in prehistory often requires specific chronological resolution and that in turn leads to specific requirements of 14 C chronologies. This paper discusses whether these requirements are fulfilled for the transition from the Middle to Late Pre-Pottery Neolithic B (M-and L-PPNB), which took place in south-west Asia in the eighth millennium BC. The aim is to look beyond the apparent abruptness of the transition, induced by the shape of the calibration curve, and evaluate whether it is possible to derive good temporal estimates for some of its associated processes. The discussion takes place from a 14 C perspective and makes no assertions as to how the transition might appear from the perspective of other markers, such as lithic technologies. Archaeological background to the M-/L-PPNB transition and effects of the calibration curveThe Neolithic of south-west Asia (mid-tenth to the sixth millennium cal BC) was a period when a number of earlier practices persisted, such as the wide-ranging exchange networks ( Figure 1). Hence the chronological variability on either side of 7500 cal BC was hidden and an impression of an abrupt transition emerged in the 14 C record. While the interpretation in terms of sudden change might be correct, its radiocarbon basis is an artifact of the radiocarbon calibration curve. Assessing the abruptness of the M-/L-PPNB transition: methodologyWith the development of the calibration curve for the eighth millennium cal BC, the increasing number and precision of 14 C determinatio...