Stable isotopic investigations of modern and charred foxtail millet and the implications for environmental archaeological reconstruction in the western Chinese Loess Plateau

Stable isotopic analysis of carbon and nitrogen in human and faunal remains has been widely used to reconstruct prehistoric diets and environmental changes. Isotopic analysis of plant remains allows for a more extensive consideration of paleodiets and can potentially provide information about the environment in which the crops were grown. This paper reports the results of delta C-13 and delta N-15 analyses performed on modem and charred archaeological foxtail millet samples collected from the western part of the Chinese Loess Plateau. The delta C-13 mean value of modem samples is lower than that of ancient samples. There is a significant difference between grain and leaf delta N-15 values. These results challenge the standard assumption in isotope studies that the nitrogen isotope signals of the different part of plants consumed by humans and animals are the same. The 3-5 parts per thousand difference between human and animal delta N-15 values is always regarded as an indicator of whether human diets contained considerable animal protein. The difference between grain and leaf delta N-15 values makes this assumption problematic in a foxtail millet-dominated society. (C) 2015 University of Washington. Published by Elsevier Inc. All rights reserved.