Paleolithic Human Exploitation of Plant Foods During the Last Glacial Maximum in North China

Paleolithic human exploitation of plant foods during the last glacial maximum in North China Li Liua,1, Sheahan Bestelb, Jinming Shic, Yanhua Songd, and Xingcan Chenb aDepartment of East Asian Languages and Cultures, Stanford Archaeology Center, Stanford University, Stanford, CA 94305; bInstitute of Archaeology, Chinese Academy of Social Sciences, Beijing 100710, China; cShanxi Museum, Taiyuan 030024, China; and dDepartment of Archaeology, Shanxi University, Taiyuan 030006, China Edited by Dolores R. Piperno, Smithsonian National Museum of Natural History and Smithsonian Tropical Research Institute, Fairfax, Washington DC, and approved February 11, 2013 (received for review October 18, 2012) Three grinding stones from Shizitan Locality 14 (ca. 23,000–19,500 Vigna beans, Dioscorea opposita yam, and Trichosanthes kirilowii calendar years before present) in the middle Yellow River region snakegourd roots. were subjected to usewear and residue analyses to investigate Sites and Environmental Contexts human adaptation during the last glacial maximum (LGM) period, when resources were generally scarce and plant foods may have S14 (110°32′40″ E, 36°02′11″ N; 655 ± 5 m in altitude) is among become increasingly important in the human diet. The results show a series of more than 50 late Paleolithic localities (ca. 25,000– that these tools were used to process various plants, including Triti- 9,000 cal. B.P.), referred to as the Shizitan site cluster, distrib- ceae and Paniceae grasses, Vigna beans, Dioscorea opposita yam, uted along the Qingshui River, a tributary of the Yellow River in southern Shanxi (Fig. 1). All of these localities are characterized and Trichosanthes kirilowii snakegourd roots. Tubers were impor- fl tant food resources for Paleolithic hunter–gatherers, and Paniceae primarily by small aked tools and a microlithic technology, with no pottery, dwelling structures, human burials, or storage facili- grasses were exploited about 12,000 y before their domestication. – The long tradition of intensive exploitation of certain types of flora ties found, suggesting that the occupants were mobile hunter gatherers (7–9, 11). The long time span of human occupation helped Paleolithic people understand the properties of these plants, with abundant material remains provides a wealth of data for including their medicinal uses, and eventually led to the plants’ do- study of the transition from the late Paleolithic to the early mestication. This study sheds light on the deep history of the broad Neolithic in the middle Yellow River valley. ANTHROPOLOGY spectrum subsistence strategy characteristic of late Pleistocene north Excavations at S14 in 2000, 2003, and 2005 revealed three China before the origins of agriculture in this region. continuous cultural strata (II, III, and IV) within a depth of 50– 100 cm in an area of 25 m2, dating to a time period of ca. 23,000– ancient starch | late Paleolithic China | plant processing | 18,000 cal. B.P. (Table S1). Material remains uncovered include usewear analysis | stone tool function 1,643 lithic artifacts and 2,776 animal bone fragments, in addi- tion to 17 ash and burnt surface areas (fireplaces). Several t has long been argued that foragers at the end of the Pleis- grinding tools (slabs) have been found near fireplaces in all strata Itocene broadened their resource base to encompass a wide (refs. 8 and 9; ref. 12, p. 20), and three of them (all made of array of plant and animal foods and that this “broad spectrum sandstone), analyzed here (Fig. 1), were uncovered from Strata revolution” entailed the transition to farming (1). New studies III and IV (ca. 23,000–19,500 cal. B.P.). have shown that human exploitation of an extensive range of The site is situated in a mountainous region with a temperate plant foods can be traced back to much earlier dates in late climate and a diversity of flora resources today. Pollen data ob- Paleolithic times in southwest Asia, suggesting a long history of tained from Shizitan suggest that vegetation coverage in the re- intensive foraging for plants before domestication (2). gion was dominated by grasses from 35,100–9,400 B.P. (dating by Usewear traces and plant residues on grinding stones can thermoluminescence analysis) (13). During the last glacial maxi- provide crucial information for understanding the plant-foraging mum (LGM), the climate was dry and cold, featuring a steppe strategies of ancient people. By applying these methods, several environment. During the period of ca. 18,500–13,200 cal. B.P., this projects have shown evidence of widespread plant use, including region experienced the last deglaciation, characterized by a mild wild cereals and tubers, by late Paleolithic populations in many and arid or semiarid steppe environment with a small amount of areas of the world, dating to a period between ca. 30,000 and 23,000 deciduous and broadleaf species. This episode was then followed by y ago, including the Near East (3), Europe (4), and Australia (5). adryandcoldperioddatingto13,200–13,000 cal. B.P. before an- In China, the earliest grinding stones have been uncovered other era of improved climatic conditions (ref. 12, p. 167). from several Paleolithic site clusters distributed on the Loess Results Plateau region along the middle Yellow River valley. These include Longwangchan in Shaanxi (6) and Shizitan and Xiachuan We collected usewear and residue samples from three grinding in Shanxi (7–9), dating to ca. 25,000–9000 calendar years before stones (GS1, GS2, GS3), which were kept in the Shanxi Museum present (cal. B.P.). A study of usewear traces and starch residues after excavation. To compare used tools with unused natural stone, on grinding stones from Locality 9 (S9 hereafter) in the Shizitan we also took samples from a sandstone rock (SS1) in a noncultural site cluster (ca. 12,700–11,600 cal. B.P.) has demonstrated that deposit near the site (Table S2). people used these tools to process various plant foods, including grasses, tubers, acorns, and legumes (10). Among the grass starch Usewear Analysis. Polyvinyl siloxane (hereafter PVS or peel) was granules uncovered at this site, some from Panicoideae may have applied to the Shizitan grinding stones to provide portable and been the wild ancestors of domesticated millets (Panicum mil- iaceum and Setaria italica ssp. italica). Therefore, it is important to investigate the use of plants in an earlier period in this region, Author contributions: L.L. and X.C. designed research; L.L., S.B., J.S., Y.S., and X.C. per- to trace possible continuity in a putative plant procurement formed research; L.L. and S.B. analyzed data; and L.L. and S.B. wrote the paper. strategy that may have eventually led to domestication. In this The authors declare no conflict of interest. study, we demonstrate usewear patterns and residues on three This article is a PNAS Direct Submission. grinding stones (ca. 23,000–19,500 cal. B.P.) excavated from 1To whom correspondence should be addressed. E-mail: [email protected]. Locality 14 (S14 hereafter) in the Shizitan site cluster (9), which This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10. disclosed the exploitation of Triticeae and Paniceae grasses, 1073/pnas.1217864110/-/DCSupplemental. www.pnas.org/cgi/doi/10.1073/pnas.1217864110 PNAS Early Edition | 1of6 Downloaded by guest on September 30, 2021 A 110° 30' 110° 40' PVS peels were taken from the used surface. The microscopic surface is rather flat with a few polished areas, and striations are Jixian China Dongchengxiang rare. On peel one (P1), some crystal grains show medium-level polish without striations, and on P2, small areas of shallow striations with U-shaped cross-sections (sleeks) are present (Fig. 2, 4 Yellow River Qingshui River and 5). Compared with the references in our experimental studies, Shizihe Xijiaotou the polish is similar to that from tuber grinding, and the striations S29 Qianxialing S9 resemble traces from large seed processing, such as with beans S1 S14 Jingmen (Fig. S1, 4). Dahuling modern village modern town Summary. Shizitan site Three slabs examined all show usewear traces, which 36 Baishansixiang 2 km clearly differentiate them from unused stone surfaces (Fig. 2, 6). B These slabs were apparently used to process various plant foods, GS1 GS2 GS3 such as seeds, tubers, and nuts. To understand exactly what plants were involved here, we have to rely on residue analysis. 2 P2 P2 2 Residue Analysis. P1 1 Ten residue samples were extracted from the 1 1 P1 three tools either by applying a small amount of distilled water to P1 P3 the tool and then extracting the sample with a pipette or by re- 10 cm 10 cm 10 cm moving sediment adhering to the tool surface (21, 22). Phytolith remains on the S14 grinding implements were minimal PVS sampling location starch sampling location and mostly not diagnostic (Supporting Information and Table S4). Grass husk phytoliths were not recovered, suggesting that these Fig. 1. Site location and artifacts analyzed. (A) Major localities of the Shi- grinding stones were probably not used to dehusk cereals. Charcoal zitan site cluster in Jixian, Shanxi. (B) Grinding stones analyzed and sampling and/or burnt phytoliths were present on all three tools, perhaps locations on the tools. reflecting the location of the implements near fireplaces or food processing areas. durable records for microscopic analysis. Previous research, us- ing PVS on usewear patterns from grinding stones in China (10, 14, 15) and other parts of the world (16–19) established valuable reference data for the study of ancient tools. In recent years, we have also conducted a series of experimental studies on grinding stones (20) to produce references for processing seeds, tubers, nuts, wooden objects, minerals, shells, and stone implements. Based on these studies, the analytical variables examined in the current project include: stage of polish development (low, medium, high), polish reticulation pattern, polish topography, striations (furrow, sleek, fine), pitting and pecking, and surface microtopography (Table S3).

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