Evolution of prehistoric dryland agriculture in the arid and semi-arid transition zone in northern China.

Based on chronological and archaeobotanical studies of 15 Neolithic and Bronze Age sites from the northern Chinese Loess Plateau and southern Inner Mongolia-the agro-pastoral zone of China-we document changes in the agricultural system over time. The results show that wheat and rice were not the major crops of the ancient agricultural systems in these areas, since their remains are rarely recovered, and that millet cultivation was dominant. Millet agriculture increased substantially from 3000 BC-2000 BC, and foxtail millet evidently comprised a high proportion of the cultivated crop plants during this period. In addition, as the human population increased from the Yangshao to the Longshan periods, the length and width of common millet seeds increased by 20-30%. This demonstrates the co-evolution of both plants and the human population in the region. Overall, our results reveal a complex agricultural-gardening system based on the cultivation of common millet, foxtail millet, soybeans and fruit trees, indicating a high food diversity and selectivity of the human population.

Oldest directly dated remains of sheep in China.

The origins of domesticated sheep (Ovis sp.) in China remain unknown. Previous workers have speculated that sheep may have been present in China up to 7000 years ago, however many claims are based on associations with archaeological material rather than independent dates on sheep material. Here we present 7 radiocarbon dates on sheep bone from Inner Mongolia, Ningxia and Shaanxi provinces. DNA analysis on one of the bones confirms it is Ovis sp. The oldest ages are about 4700 to 4400 BCE and are thus the oldest objectively dated Ovis material in eastern Asia. The graphitisised bone collagen had δ(13)C values indicating some millet was represented in the diet. This probably indicates sheep were in a domestic setting where millet was grown. The younger samples had δ(13)C values indicating that even more millet was in the diet, and this was likely related to changes in foddering practices.

Diatom community response to climate variability over the past 37,000 years in the sub-tropics of the Southern Hemisphere.

Climate change is impacting global surface water resources, increasing the need for a deeper understanding of the interaction between climate and biological diversity. This is particularly the case in the Southern Hemisphere sub-tropics, where little information exists on the aquatic biota response to climate variations. Palaeolimnological techniques, in particular the use of diatoms, are well established and can significantly contribute to the understanding of climatic variability and the impacts that change in climate have on aquatic ecosystems. A sediment core from Lake McKenzie, Fraser Island (Australia), was used to investigate interactions between climate influences and aquatic ecosystems. This study utilises a combination of proxies including biological (diatom), geochemical and chronological techniques to investigate long-term aquatic changes within the perched-dune lake. A combination of (210)Pb and AMS (14)C dates showed that the retrieved sediment represented a history of ca. 37,000 cal.yBP. The sedimentation rate in Lake McKenzie is very low, ranging on average from 0.11 mm to 0.26 mm per year. A sediment hiatus was observed between ca. 18,300 and 14,000 cal.yBP suggesting a period of dry conditions at the site. The diatom record shows little variability over the period of record, with benthic, freshwater acidic tolerant species dominating. Relative abundance of planktonic species and geochemical results indicates a period of increased water depth and lake productivity in the early Holocene and a gradual decrease in effective precipitation throughout the Holocene. Results from this study not only support earlier work conducted on Fraser Island using pollen reconstructions but also demonstrate that diatom community diversity has been relatively consistent throughout the Holocene and late Pleistocene with only minor cyclical fluctuation evident. This record is consistent with the few other aquatic palaeoecological records from the Southern Hemisphere sub-tropics.