Were European steppe bison migratory? ~(18)O,~(13)C and Sr intra-tooth isotopic variations applied to a palaeoethological reconstruction

摘要

This paper focuses on the palaeoethological study of steppe bison {Bison priscus), a Eurasiatic species that disappeared at the end of the Pleistocene. In the Southern steppe of Eastern Europe, this large bovid seems to have been a keystone species during the late Pleistocene, where it is omnipresent in archaeozoological assemblages and can constitute spectacular bone accumulations. Based on the principles of actualism, which assume that modern animal biology and their behavioural adaptations can be applied to the past, different models of bison palaeoethological reconstructions have been proposed to explain this important occurrence of bison in East European archaeological records. Considering the variability of extant bison behaviour, it appeared necessary to undertake a direct reconstruction of the behaviour of fossil bison, to assess how they were targeted. In order to reconstruct steppe bison ecology and habits stable isotope analyses were conducted of tooth enamel carbonate of 25 individuals from Amvrosievka, a Late Pleistocene (～ 18,500 BP) archaeological site complex from Eastern Ukraine. Intra- and inter-individual variations in the stable oxygen, carbon and strontium isotope composition of tooth enamel were analysed to reconstruct the feeding behaviour and seasonal movements of steppe bison. This is the first large scale multi-proxy study of its kind for a Pleistocene cohort. The results show that bison δ~(13)C values are wholly consistent with an exclusively C_3 plant diet, typical of steppe/grassland environments, with a likely consumption of lichen during the cold season. δ~(18)O, δ~(13)C and ~(87)Sr/~(86)Sr values are typical of sedentary bison herds, with limited inter-seasonal movement. These results challenge the previous assumption that Pleistocene bison of the East European steppe were migratory, demonstrating instead that they occupied limited ranges, with no long distance seasonal movement, and that they occasionally incorporated low nutrient foods in their diet. These new palaeobiological results confirm the ecological and behavioural plasticity of bison and have important implications for archaeologists studying hunter-gatherers since human acquisition strategies are directly related to the social, seasonal and spatial behaviour of prey species. This research demonstrates that direct reconstructions of the eco-ethology of fossil prey species are essential, therefore, before attempting to make inferences about the hunting tactics and subsistence strategies developed by Prehistoric hunters.