Archaeobotanical and palaeoecological assessment of three freshwater shell middens dating to the early Holocene, Yongjiang River, Guangxi, southern China

Abstract

There have been few studies of plant utilization in southern China, especially for the period before the introduction of rice farming to Guangxi. The results of archaeobotanical and palaeoecological assessments of three freshwater shell middens - Baozitou, Shichuantou and Nabeizui - in Nanning City, Guangxi, provide significant data on pre-agricultural subsistence status in southern China. Multiple archaeobotanical methods were applied in this study, including the analyses of macrobotanical remains, archaeological parenchyma, microcharcoal, starch grains, and phytoliths, as well as radiocarbon dating.

Two AMS radiocarbon dating programs have refined the chronology of freshwater shell middens in the Yongjiang River Basin. The studied shell middens were all used during the early Holocene between c. 10,100-9000 cal BP. Each shell midden was used for a maximum of 390 years to 1110 years, although probably for much shorter occupation periods. The periods of use for the three sites show significant overlaps.

Phytolith and microcharcoal results indicate that palaeoecological trends present in different ways at each site during the period of the occupation. Baozitou and Shichuantou share more similarities in the transformation of the local environment, whereas Nabeizui exhibits opposite trends to the other sites. In addition to the inconsistencies in the palaeoecological trends, each site exhibits a similar period during which palm phytoliths are present. The similar occurrence of palms during a discrete period of occupation at each site is suggestive of human-directed resource intensification of palms in the landscape.

The starch grains from the three shell midden sites can be classified into four major types, including Fagaceae, Poacea, USOs and unknown taxa (may include some nuts). The relative abundance of species reflects the diversity of tool-processed food and the diversity of food structure of the subsistence strategy of shell midden people. In terms of the artefacts, most of the starch grains come from three artefacts, and each site has one artefact with relatively rich starch grains. The extracted starch grains from the Nabeizui grinding stone suggest it is a multifunctional tool for processing multiple types of edible plant materials.

The diversity of macrobotanical remains is relatively rich, indicating that the shell midden people exploited and utilised a variety of food resources (e.g. nuts, USOs, grass seeds and fruits). The discovery of carbonised food remains also suggests that humans learned to process and cook starchy foods. Many carbonised parenchyma fragments were found in the macrobotanical remains. Some parenchyma fragments can be identified as bulb and Lotus root (Nelumbo nucifera).

The archaeobotanical findings in this study indicate that the groups who used and created the freshwater midden sites were engaged in broad-spectrum plant exploitation during the early Holocene. Based on the macro- and micro-botanical remains analysis, shell midden people exploited and consumed a variety of plant resources, such as palm (Arecaceae), various nuts (e.g. Canarium and acorn) and multiple USOs (e.g. lotus root, Nelumbo nucifera). Such findings are consistent with broad-spectrum plant exploitation prior to the adoption of agriculture in a range of other wet tropical and subtropical regions. There is no evidence that to suggest that the groups occupying the shell middens practiced cultivation or agriculture.

According to the palaeoecological data, coupled with available archaeological findings for shell midden sites in this region, communities in the Yongjiang River Basin during the early Holocene adopted a logistical strategy to obtain resources in the landscape. The shell midden communities did not live at a specific site year-round, but they did reside and utilise the midden site for an extended period within each year and such a connection was maintained over an extended timeframe. Show more