The spread of agriculture is an important topic of archaeological research, but relatively few studies address the drivers behind the spread of specific species empirically. Here we use published isotopic data to consider whether the millets spread from their putative domestication centre in the East to western Eurasia for use as a staple food. We show that the consumption of significant quantities of millet was both far more sporadic than the earliest appearance of millet might suggest and delayed. This is not to say that millet was not consumed, rather that any consumption was below the level of isotopic detectability, and thus millet cannot generally be considered a staple. Nevertheless, individuals who regularly consumed millet occur both as typical members of their population and as unusual individuals. The reasons for this pattern open up new questions about, and avenues of research into, the spread of agriculture.

Why move starchy cereals? A review of the isotopic evidence for prehistoric millet consumption across Eurasia

Prior to the introduction of wheat and barley from Central Asia during the Neolithic period, northern Chinese agricultural groups subsisted heavily on millet. Despite being the focus of many decades of intensive interest and research, the exact route(s), date(s), and mechanisms of the spread and adoption of wheat and barley into the existing well-established millet-based diet in northern China are still debated. As the majority of the important introduced crops are C3 plants, while the indigenous millet is C4, archaeologists can effectively identify the consumption of any introduced crops using stable carbon isotope analysis. Here we examine published stable isotope and dental caries data of human skeletal remains from 77 archaeological sites across northern and northwestern China. These sites date between 9000 to 1750 BP, encompassing the period from the beginning of agriculture to wheat's emergence as a staple crop in northern China. The aim of this study is to evaluate the implications of the spread and adoption of these crops in ancient China. Detailed analysis of human bone collagen δ13C values reveals an almost concurrent shift from a C4-based to a mixed C3/ C4- based subsistence economy across all regions at around 4500-4000 BP. This coincided with a global climatic event, Holocene Event 3 at 4200 BP, suggesting that the sudden change in subsistence economy across northern and northwestern China was likely related to climate change. Moreover, the substantially increased prevalence of dental caries from pre-to post-4000 BP indicates an increase in the consumption of cariogenic cereals during the later period. The results from this study have significant implications for understanding how the adoption of a staple crop can be indicative of large-scale environmental and socio-political changes in a region.

/pdf/stable-isotope-and-dental-caries-data-reveal-abrupt-changes-ntc9gg66ul.pdf

Stable isotope and dental caries data reveal abrupt changes in subsistence economy in ancient China in response to global climate change

We conducted a meta-analysis of published carbon and nitrogen isotope data from archaeological human skeletal remains (n = 2448) from 128 sites cross China in order to investigate broad spatial and temporal patterns in the formation of staple cuisines. Between 6000-5000 cal BC we found evidence for an already distinct north versus south divide in the use of main crop staples (namely millet vs. a broad spectrum of C3 plant based diet including rice) that became more pronounced between 5000-2000 cal BC. We infer that this pattern can be understood as a difference in the spectrum of subsistence activities employed in the Loess Plateau and the Yangtze-Huai regions, which can be partly explained by differences in environmental conditions. We argue that regional differentiation in dietary tradition are not driven by differences in the conventional "stages" of shifting modes of subsistence (hunting-foraging-pastoralism-farming), but rather by myriad subsistence choices that combined and discarded modes in a number of innovative ways over thousands of years. The introduction of wheat and barley from southwestern Asia after 2000 cal BC resulted in the development of an additional east to west gradient in the degree of incorporation of the different staple products into human diets. Wheat and barley were rapidly adopted as staple foods in the Continental Interior contra the very gradual pace of adoption of these western crops in the Loess Plateau. While environmental and social factors likely contributed to their slow adoption, we explored local cooking practice as a third explanation; wheat and barley may have been more readily folded into grinding-and-baking cooking traditions than into steaming-and-boiling traditions. Changes in these culinary practices may have begun in the female sector of society.

/pdf/the-prehistoric-roots-of-chinese-cuisines-mapping-staple-1t69hw3ch6.pdf

The prehistoric roots of Chinese cuisines: Mapping staple food systems of China, 6000 BC-220 AD

The Beiqian site located in Jimo city, Qingdao, a few kilometers from the modern coastline was excavated in 2007, 2009 and 2011. A large number of human bones from the early Dawenkou period were unearthed. Through C and N stable isotopic analysis, the food structure of the “Beiqian” ancestors was reconstructed and the influence of terrestrial and marine resources on their lifestyle was discussed. Based on the δ
 13C and δ
 15N stable isotopic values of human bone collagen, the analytical results obtained through a ternary mixed model reveal that the food sources of the Beiqian ancestors included about 44.1% marine species (probably shellfish and fish), 34.1% C4 plants (possibly millet), and 21.8% land animals. These results indicate that they lived mainly from fishing and farming, supplemented by hunting or poultry raising. Compared with other sites in the same period, the stable isotope results show that 5000–6000 years ago, the lifestyles of ancestors in the Yangtze River basin, Yellow River basin, Northern coastal area and inland area were very different. The ancestors from the Yangtze River basin focused on rice farming and fishing, whereas the ancestors in the Yellow River basin farmed millet and raised animals. Those in coastal areas relied mostly on farming and marine fishing.

https://link.springer.com/content/pdf/10.1007%2Fs11434-012-5029-y.pdf

Reconstructing the food structure of ancient coastal inhabitants from Beiqian village: Stable isotopic analysis of fossil human bone

https://cdr.lib.unc.edu/downloads/76537173h

Bioarchaeology of Adaptation to Climate Change in Ancient Northwest China

In this research,carbon and nitrogen stable isotopes in human bones dating from the Spring and Autumn periods were analyzed from the Sunjianantou site,Fengxiang,Shaanxi Province.All samples were well preserved and could be clearly used as dietary indicators.During these periods,the ancient Qin peoples' diet mainly relied on C4 plants and some meat,based on the comprehensive analysis of δ~13C and δ~15N values.From this analysis,we suggest that the substance strategy was a mixture of agriculture and herding.According to the comparative analysis of δ~13C and δ~15N values,the human as funerary objects probably represent concubines or attendants whose diet was similar to their owners.Obviously the diet of Qin ancestors was stable from Spring and Autumn period through to the Warring States period,and any change in the proportions of C4 and value of δ~15N were related to the historical transition of the society.

Carbon and Nitrogen Stable Isotopic Analysis on Human Bones from the Qin Tomb of Sunjianantou Site,Fengxiang,Shaanxi Province

The plasticity improvement of cold-deformed metal by electric pulse treatment (EPT) is generally attributed to the promotion of recovery or recrystallization. This paper found that EPT improves the plasticity of the cold-deformed 6111 aluminium alloy more than heat treatment when the induced microstructure recovery is similar. The reduction of inner micro-pores is another mechanism for EPT to improve the plasticity of the alloy besides the recovery factor. The confinement effect of the fixed electrodes is another main reason for EPT to reduce the micro-pores in the alloy besides the existing micro mechanisms. 

Another Reason for Plasticity Enhancement of Cold-deformed Aluminium Alloy Induced by Electric Pulse treatment

The relationship between the producer and the consumer is important in grassland ecosystems. Most producer-consumer models only consider food quantity and focus on the above ground part of producers in producer-consumer interactions, while food quality and the below ground part of the producer can be an important factor in these models. We developed a stoichiometric producer-consumer model, where the producer represents a primary production in terrestrial plant with above ground and below ground parts subject to stoichiometric constraints of carbon and phosphorus. The analysis shows that the dynamic behavior of the model is richer than that of the traditional producer-consumer models. The solution curves of the model can be used to explain the paradox of enrichment and reflect the rapid growth of the vegetation. Our findings help understand and interpret the relationship between the producer and the consumer in grassland ecosystems and provide guidance for ecosystem management on maintaining ecological equilibrium.

Dynamics of a Stoichiometric Regrowth-Consumer Model

In this study, we performed electric pulse treatment (EPT) on the cold-rolled pure copper sheets. And the effects of the current density of EPT on the microstructure and mechanical properties of the cold-rolled pure copper sheets were investigated. It has been found that the change in the current density of EPT has a remarkable influence on the surface temperature, microstructure, strength, plasticity and microhardness of the samples. Compared with the untreated sample, the elongation after fracture increased by about 3.2 times at a current density of 200 A mm−2, whereas the ultimate tensile strength decreased by only 38.0%. Microstructures indicate that the electric pulse can induce rapid recrystallization in cold-rolled pure copper sheets within a short time, while reducing the dislocation density, weakening the rolling textures and increasing microstructure uniformity, thereby improving the plasticity of the material. Therefore, the present research has the potential to provide an effective alternative way to the traditional heat treatment of copper sheets and strips.

https://iopscience.iop.org/article/10.1088/2053-1591/ace02d/pdf

Ling Xue

Papers

Carbon and Nitrogen Stable Isotopic Analysis on Human Bones from the Qin Tomb of Sunjianantou Site,Fengxiang,Shaanxi Province

Another Reason for Plasticity Enhancement of Cold-deformed Aluminium Alloy Induced by Electric Pulse treatment

Dynamics of a Stoichiometric Regrowth-Consumer Model

An eco-friendly electric pulse treatment process for improving the microstructure and properties of cold-rolled pure copper sheet