Preliminary Discussion Of Neolithic Water Chestnut(Trapa) Remains From The Tianluoshan Site,China

Water chestnuts(Trapa L.)are frequently found at Neolithic sites along the Middle and Lower Valleys of the Yangtze River,and are believed to have been important components of the diets of prehistoric people.However,little systematic research has been conducted on water chestnuts to determine their cultural as well as dietary importance.Excavations at the Tianluoshan site produced large quantities of well-preserved specimens,and these provide an excellent collection with which to study changes in morphological features and domestication with time.Using modern water chestnuts(wild and domesticated)(n=447)as a reference,we find that Neolithic water chestnuts(n = 481)at Tianluoshan are similar in shape but smaller in size compared to the domesticated species Trapa bispinosa Roxb.In particular,the Tianluoshan water chestnuts are found to have bigger seeds than the wild species,Trapa incisa Sieb.and Zucca.Furthermore,water chestnuts are found to diachronically increase in size at the Tianluoshan site with significant differences(one-way,ANOVA)observed for length(p = 7.85E-08),height(p = 3.19E-06)and other indexes between layers 7(ca.6700-6500 B.P.)and 6(ca.6500-6300 B.P.).These results suggests that water chestnuts were actively selected based on size(big),and shape(full fruit,two round horns,wide base,etca.).Besides,simulated drying experiment has been applied to modern domestic water chestnuts from Yuyao City(n=15).The shrink rate is then used on Tianluoshan water chestnuts from layers 8,5 and 4,which are preserved in the air-dry way(n=238).The revised values show the possibility that Tianluoshan human had obtained comparatively high techniques of water chestnut cultivation in layer 8.In addition,as illustrated by the soil investigation of layer 8 to 3(sum volume:4600 ml),the relationship between rice and water chestnut is probably better depicted by 'complement' than 'inverse correlation'.Furthermore,the carbon and nitrogen stable isotope ratio analysis reveals the distinction between water chestnuts in layer 8 and the subsequent ones in terms of techniques or micro environment.Apart from this,water chestnuts remained stable technically and environmentally during layer 7 to 5.Above all,water chestnuts were an important non-cereal crop to the agricultural practices at the Tianluoshan site,and its role is long-term irreplaceable in the diet of Tianluoshan inhabitants.