Experimentally Heat Treated Silcrete Nodule (image) Arizona State University Share Print E-Mail Caption Evidence reported in the Aug. 14 issue of the journal Science shows that early humans living on the southern coast of Africa 72,000 years ago used a complex heat treatment process to manufacture blades and bifacial tools. Unheated silcrete (left) can show dramatic changes in color and texture after heating and flaking (right). An international team, including three researchers from the Institute of Human Origins at Arizona State University, note that silcrete is not found closer than 5 kilometers from their excavation at Pinnacle Point, Mossel Bay, South Africa, and that most pieces found are extensively flaked. Credit Photo by Kyle Brown/South African Coast Paleoclimate, Paleoenvironment, Paleoecology, Paleoanthropology Project (SACP4) Usage Restrictions with proper credit Share Print E-Mail 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.