This study systematically investigates the subsistence economy patterns of early human populations in Guangxi and the functional applications of stone tools, with a particular focus on Yahuai Cave in Long’an County. Employing an integrated methodological approach that combines chronological analysis, micro-botanical remains examination, and morphological studies, we conduct comprehensive research on both micro-plant remains and carbonized plant remains retrieved from the site. The AMS ¹⁴C dating results establish a chronological framework for Yahuai Cave, spanning approximately from 43,000 to 4,000 calibrated years before present, which can be clearly divided into four cultural phases.

Our phytolith analysis of stone artifacts provides significant insights into how early humans utilized different types of tools in various periods and their preferential selection of plant resources. Notably, carbonized grape seeds obtained through flotation have been taxonomically identified as Vitis bryoniaefolia, a wild grape species within the Vitis genus. The synthetic analysis of phytolith assemblages from both sediment samples and stone tool surfaces, combined with the study of macro-botanical remains, reveals a clear evolutionary trajectory of plant resource utilization strategies.

During Phases 1~2 (43,000~21,000 BP cal), the inhabitants adopted a diversified subsistence strategy involving both woody plants and Poaceae species. The phytolith record provides substantial evidence of the processing of various plant materials, including potential wild rice varieties, using stone implements. A significant transition in subsistence patterns becomes evident in Phase 3 (17,000~14,000 BP cal) and Phase 4 (4,000 BP cal). Our data indicate a marked shift towards greater reliance on herb species and climbing plant fruits. This change in dietary focus is reflected in both the micro-botanical remains and the functional analysis of stone tools, suggesting an adaptation to changing environmental conditions or the development of more specialized processing techniques.

The discovery of carbonized Vitis bryoniaefolia seeds represents the earliest direct evidence of wild grape utilization in the region, offering new insights into Paleolithic foraging behaviors. Moreover, the phytolith analysis of grinding stones and other processing tools reveals distinct use-wear patterns corresponding to different plant taxa, enabling the reconstruction of ancient food preparation methods.

Our findings make several important contributions to the understanding of pre-agricultural economies in southern China. First, we establish a detailed chronology of plant use patterns from the Late Pleistocene to the Middle Holocene periods. Second, we document the technological evolution of stone tools in relation to changing subsistence needs. Third, we provide a comprehensive record of wild plant exploitation strategies in Guangxi prior to the advent of agriculture. The micro-botanical evidence shows that early inhabitants developed sophisticated knowledge of local flora, selectively utilizing various plant resources according to availability and nutritional value. The presence of both woody plant and grass phytoliths in early phases suggests a broad-spectrum foraging strategy, while the later focus on Poaceae and vine fruits indicates a possible intensification of certain food resources.

This research not only fills critical gaps in our understanding of prehistoric subsistence patterns in subtropical China but also establishes a methodological framework for future studies of early human-plant interactions in similar ecological contexts.