Adze-shaped tools are chipped stone tools that emerged during the late Upper Paleolithic period in North China and continued to be used into the early Neolithic in the northern forest-steppe ecotone area. A significant number of adze-shaped tools have been discovered in both survey collections and excavated sites in the distributional zone (the border between Hebei and Inner Mongolia) of the Yumin Culture (8600-7000 BP cal). This study examines the technical characteristics of these tools through morphological observation, feature measurement, analysis of manufacturing process and reduction sequence, as well as experimental replication to reconstruct the chaîne opératoire. The goal of this research is to reconstruct the production process of adze-shaped tools, investigate their technical design, and explore their cultural adaptation in the Yumin Culture.
Our analysis reveals that these tools are steep-edged and end- cutting tools that vary in length from 50 to 90 mm, width from 30 to 45 mm, and thickness from 1/2 to 1/4 of the width. They have an end-cutting angle ranging from 55° to 75° and weigh less than 100 g. They could be divided into flat edge types with unifacial flaking and bulge edge types with bifacial flaking, each with different strategies in raw material preparation, shaping technology, and manufacturing processes. The production of these tools had a high degree of flexibility in the chaîne opératoire due to the application of bifacial skills, which reflects a technological adaptation to the risk environment in the Neolithic forest-steppe ecotone area.
Transition from the Paleolithic to the Neolithic led to the complete replacement of chipped stone tools by polished stone tools as settlement mobility decreased and demand for durable stone tools increased. Adze-shaped tools emerged during this transition, but the process was not linear. In the Yumin Culture, both chipped and ground tools including microlithic tools, were used. The chipped adze-shaped tool technology, along with other coexisting stone tool technologies, reflects a specific adaptation to a semi-mobile lifestyle based on the technological organization and cultural-ecological adaptation theory. This adaptation intensified the utilization of steppe and forest edge resources that maintained a seasonal and mobile way of life. The diversified technological organization strategy of stone tools may also reflect adaptation resilience to resources in this ecotone environment and division of labor within the society.