Spontaneous lithic percussion (IMAGE) PLOS Caption Loui (the juvenile male orangutan) using the core as an active element to vertically strike on the concrete floor of the testing room during the Flake Trading condition of Experiment 2. Credit Motes-Rodrigo et al., 2022, PLOS ONE, CC-BY 4.0 (https://creativecommons.org/licenses/by/4.0/) Usage Restrictions Credit must be given to the creator. License CC BY Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.