Archaeological surface in Boker Tachtit (IMAGE) Proceedings of the National Academy of Sciences Caption Archaeological surface in Boker Tachtit with stone tools dated to 47-44 thousand years ago. Credit Image credit: Elisabetta Boaretto and Omry Barzilai. Usage Restrictions None 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.