Stone tool shaping without direct cultural transmission

While environment and biology play important roles, the complexity and variability of human life today depends in many ways on special cultural processes. Terminologies differ, but the key insight is that these processes are required to enable and to produce copies of behavior or artifacts that otherwise lie fully or partly beyond individual reach. Such “know-how copying” has proven rare in the animal kingdom, and is nearly or fully absent in contemporary apes, suggesting an evolution in hominins. It has been claimed that the earliest widely accepted instances of shaped stone artifacts – handaxes, which appear with the Acheulean (c. 1.9–1.6 Mya) – must have required know-how copying. The argument holds that the knowledge of how to shape (shaping know-how) handaxes is beyond individual reach in principle. If true, handaxes would be a valid marker for the presence of know-how copying. We tested this specific claim in two complementary studies using the “puppet method,” a new methodology that experimentally disentangles knapping know-how and shaping know-how. Knapping-naïve “puppeteers” were tasked with replicating target shapes by directing the flake removals of an expert “puppet” knapper, who was not shown the target shapes. As a validation of the puppet method, we first tested if knapping-naïve puppeteers could shape glass blanks into novel, non-archaeological shapes (Arbitrary Shape Study). Two types of analyses, a sorting task and geometric morphometric analyses, confirmed that they could. We then tested whether knapping-naïve puppeteers could replicate an Acheulean handaxe target shape in stone by directing the puppet knapper (Handaxe Study). Three expert lithic archaeologists independently classified the outcomes and confirmed that naïve participants successfully created handaxe shapes. Across both studies, our findings indicate that not all shaping know-how requires direct access to cultural models, and this also holds true for handaxe shaping per se . This conclusion aligns with recent calls for a reorientation in the search for the origins of know-how copying in the hominin lineage. • The novel puppet method disentangles knowledge of how to knap from how to shape stone. • This method can test whether knapping-naïve individuals can learn how to shape stone. • Naïve humans learned how to shape novel arbitrary shapes and handaxe shapes. • Handaxes per se cannot pinpoint a necessity for copying model's shaping know-how.