Michael F. Hammer, University of Arizona (image) University of Arizona Caption This is University of Arizona's Michael F. Hammer with an ancient hominid fossil. Credit M. F. Hammer Usage Restrictions This visual may only be used in conjunction with reporting/posting of this news release. Image/video credit must be included. 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.