P. robustus (IMAGE) Washington University in St. Louis Caption The discovery of a remarkably well-preserved fossil from the extinct human species Paranthropus robustus suggests rapid evolution during a turbulent period of local climate change, resulting in anatomical changes that previously were attributed to sex. Credit Image courtesy Jesse Martin and David Strait Usage Restrictions For editorial purposes 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.