The edge is already there: Experimental insights into the origins of stone tool technology

• Natural edges may have served as precursors to manufactured sharp edges. • Free-hand percussion required incremental technical advancements to emerge. • Early stone tool making may have required instruction or guidance. The origins of stone tool technology remain a subject of ongoing debate. To investigate the early stages of this technological evolution, we conducted an experiment examining how naïve contemporary humans approached the task of cutting rope in a quasi-realistic setting where natural materials—such as boulders, cobbles, nodules, and seashells —were readily available. The study began with the assumption that participants would devise ways to create sharp-edged tools. However, the results revealed a consistent tendency to rely on naturally occurring sharp edges. These findings support the notion that early hominins may have initially exploited such naturally available edges before progressing to deliberate tool manufacture. When participants were explicitly instructed to produce sharp edges, they employed techniques of bipolar, throwing, and anvil percussion; none attempted freehand percussion. This observation reinforces the idea that freehand flaking required incremental technical advancements before it could emerge as part of early lithic technology.