Neolithic cultivation of water chestnuts (Trapa L.) at Tianluoshan (7000-6300 cal BP), Zhejiang Province, China

Abstract

Water chestnuts (Trapa) are frequently recovered at Neolithic sites along the Lower Yangtze River Valley and have been important components of the diets of prehistoric people. However, little systematic research has been conducted to determine their cultural and dietary importance. Excavations at the Tianluoshan site produced large quantities of well-preserved specimens, which provide an excellent collection for studying morphological changes with time. Using modern wild and domesticated water chestnuts (n = 447) as a reference, we find Neolithic samples (n = 481) at Tianluoshan are similar in shape but smaller in size compared to the domesticated species Trapa bispinosa. In particular, the Tianluoshan water chestnuts have bigger seeds than the wild species Trapa incisa. Further, water chestnuts diachronically increased in size at the Tianluoshan site with significant differences (one-way, ANOVA) observed for length (p = 7.85E-08), height (p = 3.19E-06), thickness (p = 1.2E-13), top diameter (p = 5.04E-08) and bottom diameter (p = 1.75E-05) between layers 7 (6700-6500 cal BP) and 6 (6500–6300 cal BP). These results suggest that water chestnuts were actively selected based on size (big), shape (full fruit, two round horns, wide base, etc.) and were an important non-cereal crop to the agricultural practices at the Tianluoshan site.

Genome sequencing and transcriptome analyses provide insights into the origin and domestication of water caltrop (Trapa spp., Lythraceae)

“…In particular, the Yangtze River Valley is likely the earliest centre of water caltrop domestication (Figures 3a, Figure S3). In fact, our genomic results are in line with recent archaeological findings (Guo et al, 2017), suggesting that the initiation of water caltrop domestication in China began c. 6300 (5600-13900) yr BP (Figure 4b; Table S12). The fruit remains of water caltrop discovered at the Tianluoshan site (Lower Yangtze Region; 6300-7000 yr BP, Guo et al, 2017) are smaller in size than the fruits of modern cultivars, but remarkably larger than those of extant wild accessions (Fig- ure 4c).…”

“…A total of 68 946 protein-coding genes were predicted by integrating results of three approaches, including protein-based homology searching, de novo gene prediction and transcriptome-based gene prediction (Table S7). Gene annotation was successfully performed on 96% of protein-coding genes by similarity search against six functional Figure 1 (a) Geographic locations of diploid and tetraploid T. natans as well as T. incisa sampled in this study; the enlarged photograph on the right shows fruit remains of water caltrop that preserved in storage pits at the Tianluoshan site (7000-5800 yr BP), an important settlement of the Neolithic Culture (Guo et al, 2017). (b) Differences in fruit morphology between diploid cultivated and wild Trapa natans (2x, AA), tetraploid T. natans (4x, AABB) and diploid T. incisa (2x, BB).…”

Why Rice Farmers Don’t Sail: Coastal Subsistence Traditions and Maritime Trends in Early China

“…Trapa water chestnuts may also have been under cultivation, as suggested by the domesticated morphology found at Tianluoshan and dating to ca. 7000 BP (Guo et al 2017). While some woodland resources are evident among the fruit and nut assemblages from this period, the predominance of rice, Trapa and Euryale highlight the importance of freshwater wetlands for subsistence resources.…”

Molecular and isotopic evidence for the processing of starchy plants in Early Neolithic pottery from China

“…Certainly, the organic data are consistent with degraded rice as a major component of many of the residues, however it is important to note the presence of other wild starchy plants present in the archaeobotanical assemblage, such as acorns, foxnuts and water chestnuts. These wild foods cannot be ruled out, particularly as these were important foodstuffs in their own right and are even considered to be ‘cultivated’ at this time 40 . Acorns in particular seem to be one of the staple foods at Tianluoshan especially in the earlier phases of the site.…”