Cueva de El Portalón (Atapuerca) (IMAGE) Uppsala University Caption El Portalón cave in the Sierra de Atapuerca (northern Spain) contains four millennia of biomolecular prehistory. Credit Courtesy of Eneko Iriarte (Universidad de Burgos) Usage Restrictions May only be published in connection to reports about the research by Valdiosera et al. 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.