Palaeoenvironmental conditions of the Palaeolithic-Neolithic transition in the Fergana Valley (Central Asia) - New data inferred from fossil molluscs in Obishir-V rockshelter (Kyrgyzstan)

摘要

In the Fergana Valley and the surrounding territories, the number of archaeological sites increased during the Early Holocene. The coincidence of this cultural event, represented by the Obishirian archaeological unit with the onset of the Holocene, suggests that this growing intensity of human activity was driven by climate change, in particular warming and/or wetting. To test this hypothesis, we used fossil terrestrial molluscs from Obishir-V, the eponymic Obishirian site in southern Kyrgyzstan, as a proxy of palaeoenvironmental conditions. We studied preObishirian loess-like deposits from the final Pleistocene and the Early-Middle Holocene sequence of Obishirianbearing deposits. We analysed taxonomic composition of the mollusc assemblages and used it to infer palaeoecological characteristics, namely preferences in temperature and humidity as well as in differing habitats. Our results showed that the palaeolandscapes and the vegetation during the accumulation of the studied deposits remained almost unchanged. The mollusc assemblages reveal constant dry and warm climatic conditions and stable steppe-like vegetation. Our observations of rather stable climatic conditions in the Fergana Valley during the Pleistocene-Holocene turnover suggests that climate was only a minor driver of the rapid demographic change in Central Asia during those times. Some other factors beyond the changes of humidity must have played an important role. On the basis of our data derived from fossil mollusc assemblages at Obishir-V, we propose to consider the hypothesis that the factor responsible for the intense human occupation of the Fergana Valley during the Early Holocene had not an environmental, but rather a cultural background, such as the neolithization process, such as introduction of domestic livestock.