Carla Possamai_29 (IMAGE) University of Wisconsin-Madison Caption A group of northern muriquis sit together in a tree. The peaceful egalitarian structure of northern muriquis groups makes them different from many other groups of primates which tend to see more violence. Credit Carla Possamai Usage Restrictions None License Original content 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.