The transition of human subsistence strategies in relation to climate change during the Bronze Age in the West Liao River Basin, Northeast China

Abstract

Despite the proposed climate–human connection in the West Liao River Basin during the Bronze Age, the question of how climate change could have affected the subsistence strategies, and consequently, the cultural transformation from the Lower Xiajiadian to the Upper Xiajiadian periods, has never been systematically explored. Based on radiocarbon dating and the analysis of plant remains recovered by flotation, as well as the spatial distribution of archaeological sites, this study investigates the subsistence strategies of ancient people and their influence on cultural development in the West Liao River Basin during the Lower Xiajiadian (3900–3400 cal. yr BP) and Upper Xiajiadian periods (3000–2500 cal. yr BP). Carbonized seeds collected from 13 archaeological sites reveal that people engaged in millet-based agriculture in this area throughout the Bronze Age. Favorable climate during the Holocene Optimum promoted millet farming among the Lower Xiajiadian Culture. The end of the Holocene Optimum and its associated climate deterioration led to agricultural shrinkage in the Upper Xiajiadian period, which is revealed by the reduced amount of carbonized millet seeds and the ratio between foxtail millet and broomcorn millet. Climate deterioration led to diverse subsistence strategies, resulting in the dispersal of human settlements and the differentiation of the spatial distributions of different groups. People with millet-based subsistence strategies retreated southward, while people with animal husbandry and hunting-based subsistence strategies migrated westward. The above findings may offer insights in comprehending how climate deterioration could have affected the multi-facets of human societies in the West Liao River Basin, which is a climatically sensitive region, in Chinese prehistory.

Ancient genomes from northern China suggest links between subsistence changes and human migration

“…3b and Supplementary Table 7). A previous archeological study suggests that the Lower to Upper Xiajiadian transition was associated with a climatic change to a drier environment less favorable to millet farming and led to southward population migrations within the WLR region 20 . Our results highlight the other side of the process: climate change made a pastoral economy more favorable and may have led to an influx of people already practicing it.…”

“…For example, paleobotanical and isotopic evidence suggest that the contribution of millets to the diet of the WLR people steadily increased from the Xinglongwa to Hongshan to Lower Xiajiadian (2200-1600 BCE) cultures 18 , but was partially replaced by nomadic pastoralism in the subsequent Upper Xiajiadian culture (1000-600 BCE). Although many archeologists associated this subsistence switch with a response to the climate change 19,20 , it remains to be investigated whether substantial human migrations mediated these changes. The WLR region adjoins the Amur River (AR) region to the northeast, in which people continued to rely on hunting, fishing, and animal husbandry combined with some cultivation of millet, barley, and legumes into the historic era 21,22 .…”

Climate change stimulated agricultural innovation and exchange across Asia

“…BP? In the Liao River Basin, the numbers of millet remains present in archaeological sites decrease following 3000 BP and major changes in settlement distribution are seen during the Upper Xiajiadian period ( 30 ). On the southeastern Tibetan Plateau (SETP), the impacts of this cooling episode appear to have been catastrophic: Many sites in the region appear to have been abandoned during this period of time.…”

On the linkage between hydrology and society—learning from history about two-way interactions for sustainable development

“…This is counter-intuitive, as increasing scarcity is expected to negatively influence the development of a basin. For example, climate variability in late Holocene led to changes in subsistence strategy and outmigration in the West Liao River Basin, Northeast China (Jia et al 2016). The Maya collapse has also often being attributed to the onset of a mega-drought that led to up to 40% reduction in water availability (Medina-Elizalde and Rohling 2012).…”