The Smithsonian team found small stone points (above) made of non-local obsidian at their Middle Stone Age sites. The team also found larger, unshaped pieces of the sharp-edged volcanic stone at Olorgesailie, which has no obsidian source of its own. The diverse chemical composition of the artifacts matches that of a wide range of obsidian sources in multiple directions 15 to 55 miles away, suggesting exchange networks were in place to move significant quantities of the valuable stone across the ancient landscape. The National Museums of Kenya loaned the materials pictured above to conduct the analyses published in Science.
Photo courtesy Human Origins Program, Smithsonian