Ylva Engström, Stockholm University (IMAGE) Stockholm University Caption Ylva Engström. Credit Eva Dahlin Usage Restrictions Creative Commons licence: Attribution-NonCommercial-NoDerivs CC BY-NC-ND 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.