Bows and arrows, houses and kayaks are just a few examples of the highly optimized tools that humans have produced and used to colonize new environments1,2. Because there is much evidence that humans’ cognitive abilities are unparalleled3,4, many believe that such technologies resulted from our superior causal reasoning abilities5,6,7. However, others have stressed that the high dimensionality of human technologies makes them very difficult to understand causally8. Instead, they argue that optimized technologies emerge through the retention of small improvements across generations without requiring understanding of how these technologies work1,9. Here we show that a physical artefact becomes progressively optimized across generations of social learners in the absence of explicit causal understanding. Moreover, we find that the transmission of causal models across generations has no noticeable effect on the pace of cultural evolution. The reason is that participants do not spontaneously create multidimensional causal theories but, instead, mainly produce simplistic models related to a salient dimension. Finally, we show that the transmission of these inaccurate theories constrains learners’ exploration and has downstream effects on their understanding. These results indicate that complex technologies need not result from enhanced causal reasoning but, instead, can emerge from the accumulation of improvements made across generations.
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The data that support the findings of this study are available at https://osf.io/afwmr/.
Codes used in this paper are available at https://osf.io/afwmr/.
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We thank J. Clewett for valuable advice about the building of the wheel, F. Gosselin and A. Deymier for organizing the experimental sessions, and members of the Laboratory for Experimental Anthropology for helpful discussions during the development of the experimental protocol. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under Marie Sklodowska-Curie grant agreement number 748310. Support from the ANR-Labex Institute for Advanced Study in Toulouse is acknowledged. The funders had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript.
About this article
Nature Human Behaviour (2019)