Playing Chimps (image) Max-Planck-Gesellschaft Caption Playtime! While motherless chimpanzees engaged in social play more frequently than chimps that were reared by their mothers, it more often led to aggression. Credit Max Planck Institute for Psycholinguistics, Nijmegen Usage Restrictions None 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.