Chimpanzee cracking a nut with stones (IMAGE) University of Zurich Caption Chimpanzee cracking a nut with stones Credit Kathelijne Koops, UZH Usage Restrictions No restrictions. License Public Domain 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.