Natural processes can turn stones like these chert balls, found in a field in Oman, into sharp flakesMichelle R. Bebber and Metin I. ErenWhen ancient humans first invented stone tools, they may have been trying to emulate naturally formed sharp stones, meaning they would not have needed a huge leap of inspiration.What our hypothesis does is, it really turns the origin of technology entirely on its head, says Metin Eren at Kent State University in Ohio. Instead of imagining a sharp tool and then figuring out