About 1.7 million years ago in Africa, Homo erectus, an ancestor of modern humans, started using large hand axes and cleavers. This know-how spread to Asia and Europe and remained cutting-edge technology for well over a million years. Eventually, however, it gave way to the Middle Stone Age, which featured smaller and more sophisticated blades and spearheads... In the 1990s... archaeologists dated a Middle Stone Age site in Ethiopia called Gademotta to 235,000 years ago -- implying that the technology had been maturing for a while before the arrival of modern humans... Kapthurin in Kenya, was more reliably dated in...