Field experiments find no evidence that chimpanzee nut cracking can be independently innovated

Cumulative culture has been claimed a hallmark of human evolution. Yet, the uniqueness of human culture is heavily debated. The zone of latent solutions hypothesis states that only humans have cultural forms that require form-copying social learning and are culture-dependent. Non-human ape cultural behaviours are considered 'latent solutions', which can be independently (re-)innovated. Others claim that chimpanzees, like humans, have cumulative culture. Here, we use field experiments at Seringbara (Nimba Mountains, Guinea) to test whether chimpanzee nut cracking can be individually (re-)innovated. We provided: (1) palm nuts and stones, (2) palm fruit bunch, (3) cracked palm nuts and (4) Coula nuts and stones. Chimpanzee parties visited (n = 35) and explored (n = 11) the experiments but no nut cracking occurred. In these experiments, chimpanzees did not individually (re-)innovate nut cracking under ecologically valid conditions. Our null results are consistent with the hypothesis that chimpanzee nut cracking is a product of social learning. ; © The Author(s), under exclusive licence to Springer Nature Limited 2022. Received 20 July 2021; Accepted 07 December 2021; Published 24 January 2022. We thank the DGERSIT and the IREB in Guinea for research authorization; research assistants, K. Doré, F. Doré, F. Zogbila, N. Doré, D. Zogbila, Y. Zogbila, C. Samy, N. Gbouomy and M. O'Reilly for help in the field; and R. Lavooij for technical support. We thank R. Wrangham and S. Koski for helpful comments on the manuscript. Research was supported by grants from the Lucie Burgers Foundation for Comparative Behaviour Research (the Netherlands), Gates Cambridge Trust (Cambridge, UK), Homerton College and Newnham College (Cambridge, UK) to K.K. and by MEXT (grant nos. 12002009, 16002001, 20002001, 24000001 and 16H06283) to T.M. The funders had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript. Data availability: The data for this study are included in Supplementary Table ...