Plants and people from the Early Neolithic to Shang periods in North China

Plants and people from the Early Neolithic to Shang periods in North China
Gyoung-Ah Lee*, Gary W. Crawford†,‡, Li Liu*, and Xingcan Chen§
+Author Affiliations

*Archaeology Program, La Trobe University, Victoria 3086, Australia;
†Department of Anthropology, University of Toronto Mississauga, Mississauga, ON, Canada L5L 1C6; and
§Chinese Academy of Social Science, Beijing 100710, China
Communicated by Bruce D. Smith, Smithsonian Institution, Washington, DC, November 11, 2006 (received for review August 15, 2006)

An assemblage of charred plant remains collected from 26 sites in the Yiluo valley of North China as part of an archaeological survey spans the period from the sixth millennium to 1300 calibrated calendrical years (cal) B.C. The plant remains document a long sequence of crops, weeds, and other plants in the country. The results also demonstrate the effectiveness of sediment sampling as part of an archaeological survey. Ten accelerator mass spectrometer (AMS) radiocarbon dates on crop remains inform an assessment of the sequence of agricultural development in the region. Foxtail millet (Setaria italica subsp. italica) was grown during the Early Neolithic period and was the principal crop for at least four millennia. Broomcorn millet (Panicum miliaceum) was significantly less important throughout the sequence. Rice (Oryza sativa) was introduced by 3000 cal B.C. but apparently was not an important local crop. Wheat became a significant crop between 1600 and 1300 cal B.C. The weed flora diversified through time and were dominated by annual grasses, some of which were probably fodder for domesticated animals. The North China farming tradition that emphasized dry crops (millets, wheat, and legumes) with some rice appears to have been established at the latest by the Early Shang (Erligang; 1600–1300 B.C.) period

Early Neolithic.

Peiligang sites here are small, and cultural deposits are thin, so their representation in our sample is low. Nevertheless, foxtail millet is part of the plant assemblage at Wuluoxipo and Fudian E, in contrast to the Early Neolithic occupations at Xinglonggou in Inner Mongolia and Yuezhuang in Shandong, where broomcorn millet predominates. Weeds are represented only at Wuluoxipo by probable green foxtail grass. Both broomcorn and foxtail millet are reported from the Peiligang site (6), so the absence of broomcorn millet from the small sample in the Yiluo valley late Peiligang is not necessarily evidence of its absence. The two flotation samples, because they contain millet and annual weeds, are qualitatively similar to the rest of the Yiluo survey samples, although they are among the lowest in density of all of the samples. The low density is suggestive of less-intensive food production, but this suggestion needs to be tested by more comprehensive sampling.

Middle Neolithic

Millets are the main crop remains during the Yiluo valley Late Yangshao. Weedy annuals are also quite common. Seed densities are higher at Late Yangshao sites than in the Early Neolithic (Fig. 3), suggesting a greater intensity of crop production and land disturbance by 3500–3000 B.C. Rice phytoliths have been identified at the Yulinzhuang site, situated on the tableland near the Shengshui River (3). Charred rice is in samples that are part of the ongoing analysis of samples from the excavation phase of the Zhaocheng site (Table 1). Subsistence may have been enhanced with the introduction of rice either as a trade item or as a locally grown crop. A possible soybean is in the Zhaocheng sample, but the plant appears to have no more significance there than at other sites in the region. Climatic amelioration and fertile, stable lowlands probably contributed to the success of intensifying agricultural production with two types of millets and possibly rice and soybean being grown. By this time, a two-tiered settlement hierarchy had appeared in the region with the rise of the large center at Zhaocheng (2) in addition to a number of small sites. The other Late Yangshao occupations sampled are the comparatively small ones. The samples, one or two pits from each site, are far too few to provide a comprehensive assessment of hierarchical specialization here. In fact, the evidence for such specialization from the perspective of the plant remains is weak.

Late Neolithic.

Foxtail millet is still the dominant crop during the Longshan. Broomcorn millet density is higher in both the Early and Late Longshan period compared with other periods. Three sites have relatively dense representation of this millet, the highest for all sampled periods (Table 1). Rice is present at Huizui, and an AMS date on the rice (SNU04416) confirms its Late Longshan association in the Yiluo region (Fig. 2). Rice phytoliths have been found in pit samples at Nanshi and Luokou NE, but charred grains have not been found at either location (3). The majority of weedy grasses appear to be millet-tribe grasses (Paniceae) and exhibit far greater morphological variation than do the grasses from earlier periods. Some specimens may be Panicoideae rather than Paniceae. The mannagrass-type seeds are more common than in preceding periods, suggesting that, if the specimens are mannagrass, aquatic habitats are increasing in local significance. Anthropogenic habitats were far more extensive in the Longshan period, and people may have encouraged the grasses, possibly for fodder. Indeed, the Late Longshan Huizui occupation has significant evidence of livestock, primarily pig, but also cattle, sheep, and goat.

Population density, intensified intergroup conflict, and social stratification all increased during the Longshan in the Huanghe basin. The Late Longshan marked a significant increase in the number of sites compared with the preceding Early Longshan, when there was a significant drop in settlement numbers, perhaps representing a local depopulation. Hierarchically organized societies were well established by this time. Agricultural intensification evidenced by expansion of anthropogenic habitats and higher densities of crops correlates with these developments. Broad interregional interaction such as trade in the Yiluo region is evidenced for the first time. To what extent plants were traded is a question for further research. For example, rice may have been a product brought to the region from the south and east. Increasing land instability and climate deterioration during the third millennium B.C. did not deter agricultural intensification (9). The deterioration clearly did not go beyond the tolerances of productive agriculture.

Erlitou Period.

The trends noted for the earlier periods continue. Rice is more prevalent in the samples, although it is still rare and restricted to the large sites, particularly Shaochai. The large Erlitou-period sites also have higher weed diversity, but this may well be a factor of the larger sample size from this period. Preliminary animal-bone analysis at Huizui indicates the continuing importance of livestock. Pigs are dominant, followed by cattle, sheep/goats, and dogs. Many of the weeds are potential animal fodder as they may have been earlier in the valley. Stable isotope analyses at the Yangshao period Xipo site in western Henan provide evidence that pigs and dogs consumed substantial quantities of C4 plants, probably domesticated millet and green foxtail grass (21). Settlement number and size increased significantly during the Erlitou period, and the first major urban center emerged at the Erlitou site (3). Settlement nucleation appears in the survey area for the first time. Shaochai is a large regional administration center, subsidiary to Erlitou (3). The rest of the settlements dating to this period consist of large, medium, and small sites. Small sites have no evidence of craft specialization (2), so they were probably agricultural villages.

Erligang (Early Shang) Period.

Erligang samples are not as numerous as those from the preceding Erlitou period because of a significant reduction in population in the Yiluo valley. Most Erligang period sites are small because the primary urban center moved from Erlitou to Yanshi and subsequently ≈60 km east to Zhengzhou (2). Nevertheless, four sites have substantial plant remains. Foxtail millet still outnumbers other crops, but wheat has the second-highest representation next to foxtail millet at this time (Table 1). The Erligang association of wheat is confirmed by an AMS date (Fig. 2). Beefsteak plant, a potential domesticate for seasoning, oil, and possibly leafy greens, first appears in the flotation record at this time (SI Fig. 15). Rice constitutes a negligible proportion of the grain at the Shangzhuang and Tianposhuiku sites.

Discussion
Conducting flotation during the survey stage of this project has proven to be an effective heuristic device as well as a method for developing basic knowledge of subsistence through time in a narrowly defined region, the Yiluo valley. Interpretations and limitations of the data must be contextualized in terms of sample size and type. In particular, plants that people rarely used are likely not represented in the flotation samples, so, for example, the initial appearance of introduced crops such as wheat and rice may not be resolvable yet. Two crops, hemp (C. sativa) and canola or rapeseed (B. rapa) reported from a few Neolithic sites in North China have not been found in the Yiluo sequence. Foxtail millet was an important crop, whereas broomcorn millet was a minor, secondary crop throughout the sequence. Broomcorn millet was probably an important insurance food in case of drought. We need to assess whether the Early Neolithic predominance of broomcorn over foxtail millet at Xinglonggou and Yuezhuang ca. 6000 cal B.C. is a regional phenomenon or whether broomcorn millet was domesticated earlier than foxtail millet. No occupations contemporary with these sites are known in the Yiluo valley. However, we suspect that the predominance of foxtail millet relative to broomcorn millet was established by the Late Peiligang/Early Yangshao. Rice was not domesticated in the Huanghe valley but was apparently used in the Yiluo region by Late Yangshao times as evidenced at Zhaocheng. Rice has occasionally been reported from other Yangshao contexts in North China, but none of these specimens has been AMS-dated. Its Yangshao association is feasible because it was as far north as Yuezhuang in Shandong by 6000–5800 cal B.C. AMS dates on rice clearly associate the crop with Longshan occupations at both Huizui in this study and the Liangchengzhen site in Shandong (9). If rice was a valuable commodity, it may have been consumed primarily by the elite lineages living at the largest towns that so far are the only sites with rice in the Yiluo region. However, large sites with rice are situated in the lowlands close to wetlands where rice could have been grown productively, so rice may have been a resource available mainly in these locales. More extensive sampling will help answer such questions related to the distribution and importance of rice in the region.

Wheat, the only crop in the Yiluo samples not native to East Asia, appears during the Erligang (Early Shang) period and was probably a significant crop by then. It is a rare component of Longshan period crop assemblages in Shandong (9) and elsewhere, so we surmise that it was grown in the Yiluo region during the Longshan period as well. More sampling should resolve this issue. Soybean is also a minor component of the Yiluo plant remains from Longshan times onward. Soybean domestication is an unresolved problem, with historic and archaeological data hinting that it was present from the Xia period (equivalent to the Erlitou period) and domesticated by the Zhou period. Where it was domesticated, or whether there were multiple domestications, are unanswered questions. Beefsteak plant, a potential cultigen, is rare but was also present by Erligang times. There is a limited record of this plant for the Late Neolithic period elsewhere (9). A wide range of annual weeds consistent with agricultural land disturbance and possibly fodder for domesticated animals is a component of all assemblages in the region.

Differences in site function and/or taphonomy are suggested by the contrast in seed densities between small and large sites. The highest seed densities are found at small sites, particularly from the Late Yangshao and later periods from which we have substantial samples. Crops are found in higher densities in small sites, but small Late Longshan and Erlitou sites have higher proportions and densities of crops than do larger sites. In contrast, all other artifact classes are common in the larger sites, indicating that craft production and administration occurred only in large settlements. Future research will examine this issue closely by broader sampling of a variety of contexts, particularly to test the possibility that some form of redistributive system that moved products from specialized production centers has a long history in the region. The archaeological record indicates, in fact, that social complexity was well developed by Late Yangshao times in the Yiluo valley (3). Site functions were apparently becoming specialized by the Late Yangshao; smaller settlements may have functioned mainly for agricultural production. Future research will assess whether crops were a component of the redistributive system. However, crops were probably produced as well as consumed at the large sites. Late Longshan agriculture at the large and complex Liangchengzhen and Shantaisi sites to the east have a wide variety of plant remains that vary in composition depending on their context. The same situation likely holds true in the Yiluo valley. The Yiluo plant remains are generally similar to those from both Shantaisi and Liangchengzhen with respect to both weeds and crops, suggesting that food production throughout North China shared many features. Another similarity lies in the limited evidence for the use of nuts and fleshy fruits. These and other questions pertaining to the relationship between plants and people in the Yiluo valley will be more adequately tested in the excavation phase of the project.

Materials and Methods
The Yiluo team systematically surveyed 219 km2 of alluvial plains and loess terraces (Fig. 1) (3). Sediment samples were collected from each site. Assemblages of plant remains tend to vary by context, so every reasonable effort was made to minimize the impact of contextual variation on this stage of the study by sampling the same type of context at each site. Sites are often buried 0.5–2 m below the surface, but pit features visible in vertical cuts of the loess terraces enabled the collection of samples from pits representing domestic contexts (SI Fig. 16). Pit fill normally represents secondary deposition (i.e., infill of general sediment and refuse resulting from a variety of activities by the site occupants). Thus, such samples are ideal for intersite comparisons of a general nature. Samples were collected from one to seven pits at each site depending on the number that was visible. To some extent, the soil volume collected is proportional to the number and complexity of sites in each period (Fig. 4). Individual sample volumes are proportional to the size of each pit and range from 3 to 14 liters of sediment. The relatively small sample from each site limits interpretations to discussions of fundamental similarities and differences among the assemblages. One variable that is affected by the sample size is the number of plant taxa recovered. The number of taxa in the samples exhibits a positive correlation with sample volume (Fig. 6), so small samples tend to contain fewer plant taxa and few or no examples of plants that are rare in the collection as a whole. Details of the flotation process are available elsewhere (22), and sample processing procedures are described in SI Text.

I always associated China with rice. It’s interesting that it wasn’t their first crop. Domesticated rice first appears in Korea about 13,000 years ago. From my previous entry, it seems to have a genetic origin in the Yangzte river area. It’s quite possible that the original domestication site is underwater, as large areas of South East Asia are underwater, mostly the fertlile lowland areas wher rice would have grown, which would have put the Yangtze river delta quite close to Korea