Earliest domestication of common millet (Panicum miliaceum) in East Asia extended to 10,000 years ago

Abstract

The origin of millet from Neolithic China has generally been accepted, but it remains unknown whether common millet (Panicum miliaceum) or foxtail millet (Setaria italica) was the first species domesticated. Nor do we know the timing of their domestication and their routes of dispersal. Here, we report the discovery of husk phytoliths and biomolecular components identifiable solely as common millet from newly excavated storage pits at the Neolithic Cishan site, China, dated to between ca. 10,300 and ca. 8,700 calibrated years before present (cal yr BP). After ca. 8,700 cal yr BP, the grain crops began to contain a small quantity of foxtail millet. Our research reveals that the common millet was the earliest dry farming crop in East Asia, which is probably attributed to its excellent resistance to drought.

Fig. 1.

Locality map. (A) Map showing the location of Cishan and other important Early Neolithic millet agricultural sites in the semiarid region of northeastern China. (B) The Cishan site is located on a terrace of the Ming River (Inset). A detailed plan of the west area of Cishan site excavated in 1976–1978, showing the outlines of the serried storage pits and the 5 newly excavated storage pits, CS-I to CS-V (numbers in brackets), in an area to the northwest of the earlier excavation is presented. (C) A photograph of the newly excavated storage pit CS-V, found on the cliff of the northern terrace. (D) Close-up photograph of the loose layer of grain crop remains in storage pit CS-III found in situ in the loess layer.

Fig. 2.

Scanning microscopic interferometer photographs. (A and B) Phytoliths from CS-I storage pit (A), compared with modern η-I type husk phytoliths from P. miliaceum (B). (C and D) Phytoliths from CS-II storage pit (C), compared with modern η-II type husk phytoliths from P. miliaceum (D). (E and F) Phytoliths from BWG (E), compared with modern η-III type husk phytoliths from P. miliaceum (F). (G and H) Phytoliths from CS-II storage pit (G), compared with modern Ω-II type husk phytoliths from S. italica (H). (I) Bivariate biplot showing coordinates of the 3,303 measurements from epidermal long cells of P. miliaceum and 2,774 measurements from those of S. italica, plotted along axis W (width of endings interdigitation of dendriform epidermal long cells) and axis R (ratios of W to undulations amplitude of dendriform epidermal long cells), and their classification into 2 groups corresponding to 2 species (P. miliaceum and S. italica) (13). Also plotted are the fossil samples of husk phytoliths from CS-I-V and BWG, interpreted to be of P. miliaceum origin, dated between ca. 10,300 and ca. 7,500 yr BP. The CS-II, V, and BWG samples contained 0.4–2.83% Ω-type husk phytoliths, interpreted to be of S. italica origin, dated to less than ca. 8,700 yr BP.

Fig. 3.

Carbon-14 dates and chronology-corrected dates of samples excavated at Cishan site. Lab no: GZ, Laboratory of Peking University Accelerator Mass Spectrometry and Key Laboratory of Isotope Geochronology and Geochemistry, Guangzhou, Chinese Academy of Sciences; CNL, Radiocarbon Laboratory of the Institute of Geology and Geophysics, Chinese Academy of Sciences; ZK, Laboratory of the Institute of Cultural Relics of the Chinese Bureau of Cultural Relics (8). Red box, calendar 68% range, by CalPal, University of Cologne Radiocarbon Calibration Program Package (www.calpal.de/). G, grain crops; C, charcoal.

Fig. 4.

Percentage diagram of 4 phytolith types in CS-I, showing 3 prominent layers of lemma and palea phytoliths from common millets alternating with 3 layers of mixed common millet glumes, reed, and panicoid types. Three radiocarbon dates were obtained from the grain crops. Ages shown are dendro-corrected calendar years BP. Minor age reversal is attributed to the intrusion of roots from the modern grasses growing on the cliff foot face.

Fig. 5.

Total ion chromatogram of extracted aromatic hydrocarbons and ethers from common millet (A), foxtail millet (B), and grain crops from BWG and CS-V-03 (C). Peaks labeled 1, 2, 3, 4, and 5 correspond to PTME-1 [M⁺ 440, m/z, 425, 393, 257, 218, 204, 189, 161, 135, 109 (100%), 95, 69] (Fig. S3A), PTME-2 [miliacin, olean-18-en-3β-ol ME, M⁺ 440, m/z, 425, 393, 257, 218, 204, 189 (100%), 177, 161, 135, 109, 95, 69], PTME-3 [M⁺ 440, m/z, 425, 397 (100%), 365, 261, 229, 218, 204, 189, 175, 161, 135] (Fig. S3B), PTME-4 [α-amyrin ME, urs-12-en-3β-ol ME, M⁺ 440, m/z, 393, 259, 218 (100%), 203, 189, 161, 135, 109, 95] (Fig. S3C), and PTME-5 [M⁺ 440, m/z, 425, 408, 393, 257, 221, 203, 189 (100%), 147, 135, 121, 109, 95] (Fig. S3D), respectively. Mass spectra of PTME-2 (miliacin, olean-18-en-3β-ol ME) are presented in D.