The recovery of animal prey remains from archaeological sites provides a direct link to human hunting activity and serves as a valuable indicator of paleoenvironmental changes. In this study, we conducted carbon and nitrogen isotope analyses on mammalian bones from the Niupodong site in Guizhou Province to explore the mammalian paleoecological shifts across the first to the fourth cultural phases, with the aim of elucidating the chronological changes in human activities and paleoenvironments spanning from the Upper Paleolithic to Upper Neolithic.
Out of 92 mammalian bone specimens, collagen was successfully extracted from 80, with 72 yielding qualified isotopic data. The mean δ¹³C and δ¹⁵N values of various species including Cervus unicolor (sambar), Cervus nippon (sika deer), Muntiacus sp. (muntjac), Sus scrofa (wild boar), and Bubalus sp. (water buffalo) were −20.3‰±1.5‰ (n=72) and 4.9‰±0.9‰, indicating that these mammals mainly inhabited forest environments dominated by C₃ vegetation during the time of ancient human occupation at the Niupodong site. This indicates that these animals were primarily obtained through human hunting, with no apparent signs of domestication.
The range of mammalian δ¹³C values gradually expanded from Phase 1, potentially indicating an expansion of hunting areas due to increased demand for food resource after Phase 2. Cultural connotation changes were observed during the second and third phases, possibly suggesting advancements in hunting techniques. Coinciding with these cultural shifts, animal bones were highly fragmented at the Niupodong site during the first three phases but became less fragmented during Phase 4. The δ¹³C range of all the mammals, indicated by the standard deviations of the δ¹³C values, was narrower during Phase 4 compared to Phase 3, possibly due to the shrinkage of their hunting areas. The standard deviations of δ¹³C values for sambar specimens were relatively large in the first three periods, peaking in Phase 2 and decreasing to the smallest in Phase 4. This similar trend in data variations among sambar specimens may also reflect changes in hunting intensity.
Based on paleoenvironmental studies, Phase 1 of the Niupodong site, estimated to be approximately 15,000 BP, corresponds to the late glacial period. The second and third phases align roughly with the Holocene climatic optimum, characterized by a strong monsoon signal and a warm, humid climate, while Phase 4 corresponds to a weakening monsoon signal and a trend towards arid, cold conditions. In this study, the δ¹³C values of water buffalo specimens during the second and third phases were higher than those of Phase 4, exhibiting a C₄ signal during Phase 3. Since water buffalo are better indicators of paleoenvironmental conditions compared to cervids, which prefer inhibiting forests, the observed changes are likely associated with large-scale climate variations and shifts in vegetation. Moreover, isotopic data from other animals show minimal temporal changes. This suggests that despite significant paleoenvironmental and paleoclimatic fluctuations across the four cultural phases at the Niupodong site, early humans effectively utilize the animal resources in the surrounding forests, sustaining long-term survival in this region. However, given the gaps between different cultural phases at the Niupodong site, further researches are needed to explore the environmental characteristics of the surrounding areas in the absence of human activity and to determine whether human use of the cave is linked to environmental changes.