Cutting edge stone tool complexity: Refining the cognitive demands for Acheulean handaxe productions using Petri net modelling

Stone tool technologies play a key role in reconstructing the evolution of hominin cognition. As the oldest, most lasting, and most extensively distributed form of material culture in the archaeological record, these tools offer significant insights into technological developments over vast timespans. Quantitative approaches are widely used to analyse these developments across technological complexity and efficiency. Within the study of cumulative cultural evolution, increasing efficiency and complexity were employed as quantitative hallmarks to contrast human material behaviour to that of other animals. Recently, Paige and Perreault (2024) examined lithic technological complexity by counting production techniques in toolmaking processes in the Palaeolithic. They suggest that complexity and efficiency increased considerably only after ~600 kya and argued for the onset of cumulative culture in the Middle Pleistocene. However, evidence of cumulative cultural evolution in non-human...Show moreStone tool technologies play a key role in reconstructing the evolution of hominin cognition. As the oldest, most lasting, and most extensively distributed form of material culture in the archaeological record, these tools offer significant insights into technological developments over vast timespans. Quantitative approaches are widely used to analyse these developments across technological complexity and efficiency. Within the study of cumulative cultural evolution, increasing efficiency and complexity were employed as quantitative hallmarks to contrast human material behaviour to that of other animals. Recently, Paige and Perreault (2024) examined lithic technological complexity by counting production techniques in toolmaking processes in the Palaeolithic. They suggest that complexity and efficiency increased considerably only after ~600 kya and argued for the onset of cumulative culture in the Middle Pleistocene. However, evidence of cumulative cultural evolution in non-human animals suggests that increasing efficiency and complexity alone cannot fully explain what makes human culture unique. To explore how quantitative approaches can elaborate upon the observations from Paige and Perreault, this study applies Petri nets, a computational modelling tool, to stone tool production. Petri nets allow multidimensional analysis of procedural complexity. Fajardo et al. (2023) introduced this method to archaeology by modelling birch tar adhesive production. Building on their work, this study tested whether Petri net complexity metrics could serve as a proxy for specific cognitive condition intrinsic to knapping. Two independently trained knappers produced seven experimental reductions: - Two early Acheulean handaxes with stone hammers, - Two late Acheulean handaxes with stone hammers, - Three late Acheulean handaxes with stone and antler hammers. Reductions were video-recorded and used to construct a Petri net model for each of the three Acheulean technologies. Three complexity metrics for the model’s structure were analysed (after Fajardo et al., 2023): 1. Interconnectedness of elements, 2. Number of paths through the model, and 3. Understandability of design patterns. These metrics were previously interpreted as implicated in cognitive demands such as attention, inhibitory control, and learnability. Efficiency was measured as: cutting edge to weight ratios for removals >2 cm. Key findings are: 1. Interconnectedness: the metric was marginally lower in early Acheulean than late Acheulean with stone hammers, but lowest in late Acheulean with stone and antler hammers. This implies lower demand on attention in the latter. 2. Number of paths: early Acheulean had fewer decision points than late Acheulean with stone hammers, and both had considerably fewer than stone and antler hammers. The additional hammer is implicated in and increased potential for errors from decision making, thus inducing uncertainty and requiring greater inhibition control. 3. Understandability: comprehension of early Acheulean design patterns took more effort than late Acheulean with stone hammers; the late Acheulean with dual hammers contained the least understandable patterns. 4. Efficiency: late Acheulean techniques produced more cutting edge relative to weight for removals >2 cm. For removals >3.5 cm, only reductions with both stone and antler hammers improved on this ratio. The results indicate that addition of antler hammers, which occurred in the Middle Pleistocene, resulted in the most pronounced change cognitive demands. Yet here, increases occurred solely for both uncertainty and difficulty in learnability. This specific shift draws a parallel to the open-ended quality of human cumulative culture proposed by Mesoudi and Thornton (2018). Future research would benefit from more specific interpretations of individual quantitative metrics to study technological change in the Middle Pleistocene in a more nuanced fashion.Show less

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Cutting edge stone tool complexity: Refining the cognitive demands for Acheulean handaxe productions using Petri net modelling