Shift in subsistence crop dominance from broomcorn millet to foxtail millet around 5500 BP in the western Loess Plateau

Abstract

Broomcorn and foxtail millet were the most important crops in northern China during the Neolithic period. Although the significance of broomcorn millet in human subsistence exceeded that of foxtail millet during the early Neolithic, this pattern was reversed by the end of Neolithic period. However, the process underlying this shift remains unclear. The recent excavation of the Gedachuan (GDC) in Zhangjiachuan county has revealed an abundance of relics including millet crop remains from relatively continuous strata of the Yangshao and Qijia cultures, and therefore provides a unique opportunity to examine how and when foxtail millet replaced broomcorn millet as the dominant crop in the western Loess Plateau during the Neolithic period. In this study, we identify 1,738 and 2,686 broomcorn and foxtail millet remains, respectively, from 74 flotation samples, accounting for 38.81% and 59.98% of total plant remains, respectively. Compared with 23 direct dates of carbonized crop grains in GDC, we propose that the weight of foxtail millet in plant subsistence of GDC first exceeded that of broomcorn millet as early as ∼5,500 BP, filling an important gap in the archaeobotanical record from the western Loess Plateau. Further comparative analysis of multidisciplinary data suggests the shift in significance of these two millet crops during the late Neolithic may have been triggered by variations in human settlement intensity and climate change in the western Loess Plateau. The results of this study also suggest that the Banpo Phase of Yangshao Culture survived in the western Loess Plateau as late as ∼5,600 BP.

Keywords: Gedachuan site; archaeobotanical analysis; late Neolithic; millet; radiocarbon dating; subsistence strategy..

FIGURE 1

The distribution of survey and excavation sites in the WLP from 8,000 BP to 4,000 BP. (A) The distribution of survey and excavation sites in the WLP. (B) The distribution of Gedachuan site and its adjacent Zhuanglang county survey sites.

FIGURE 2

Excavation site of ring trench settlement and representative pottery of various cultural periods. (A) ring trench settlement. (B–D) pottery of the Banpo Phase of Yangshao Culture. (E) Painted pottery of the Maodigou Phase of Yangshao Culture. (F) Painted pottery of the Late Yangshao Culture. (G) Pottery of the Qijia Culture.

FIGURE 3

Photographs of charred crop remains unearthed from different periods at the Gedachuan site. (A–C) Banpo Phase. (D–F) Miaodigou Phase. (G–I) Qijia Culture. (A,B,D,E,G) Broomcorn millet. (C,F,H,I) Foxtail millet. (Scalebar: 1 mm).

FIGURE 4

The chronology of different prehistoric cultures based on the Bayesian model at the Gedachuan site.

FIGURE 5

Proportion of crop remains from different periods at the Gedachuan site (in red) and the Zhuanglang survey sites (in black). Black font represents the survey sites with identified crop remains data from Li (2018). n represents the number of identified crop remains.

FIGURE 6

Comparison of human activity intensity, climate change and millet ratio in the WLP from 9,000–4,000 BP. (A) δ¹³C record of a single plant in Hongyuan peat bog (Hong et al., 2003). (B) Northern Hemisphere (30°∼90°N) temperature record (Marcott et al., 2013). (C) Reconstructed precipitation based on fossil pollen at Tianchi Lake (Zhao et al., 2010). (D) Stalagmite δ¹⁸O record at Wuya Cave (Tan et al., 2020). (E) Proportions of broomcorn millet and foxtail millet in the WLP between 9,000–4,000 BP at different periods. (F) Absolute number proportions of foxtail millet to broomcorn millet identified from sites dated between 9,000–4,000 BP in the WLP. (G) The Summed Probability Distribution (SPD) of averaged dates of bins (The line chart) and the dated site number (The column chart) in the WLP.