Hadza Cooperation Fieldwork 1 (IMAGE) University of Pennsylvania Caption University of Pennsylvania psychologist Coren Apicella (left) spent time between 2010 and 2016 with the Hadza in Tanzania, one of the world's last remaining hunter-gatherer populations, studying how cooperation evolves. Credit Eduardo Azevedo Usage Restrictions None License Licensed 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.