The provided text offers a comprehensive overview of the invention and evolution of chipped stone tools (打製石器), arguing that this technological revolution fundamentally shaped human development. It explains that stone tool use dates back much further than previously thought―at least 3.3 million years ago (Lomekwi 3)―predating the genus Homo and challenging the traditional link between tool use and Homo habilis. The text chronicles the progression of this technology through three main phases: the initial primitive tools (3.3–2.6 Ma), the Oldowan culture (2.6–1.7 Ma), and the Acheulean culture (1.7–0.2 Ma), highlighting the highly sophisticated and symmetrical hand-axes of the Acheulean period. Furthermore, the sources explore the profound impacts of this technology across multiple domains, including its necessity for adapting to climate change and expanding grassland environments, its role in improving food processing (especially meat and bone marrow) and enhancing hunting and defense capabilities, and its influence on social organization (e.g., division of labor and hierarchical formation). Ultimately, the use of stone tools is presented as a crucial evolutionary factor that drove the development of the human brain, cognitive abilities, and physical adaptations like hand structure.