Rita Peyroteo Stjerna (IMAGE) Uppsala University Caption Researcher Rita Peyroteo Stjerna at the National Museum of Archaeology, Lisbon, working with the Mesolithic skeletons excavated in the 1950s-1960s at the Sado Valley, Portugal. Credit José Paulo Ruas Usage Restrictions to accompany this specific study 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.