Evolution of stone tool culture. Chimpanzees make use of cobbles to break nuts, but they do not modify them. Homo habilis was one of the earliest hominin species that intentionally modified cobbles to manufacture the crude, Mode One choppers. Homo habilis was only able to break out large flakes from a cobble; its voluntarily control of its mental template was quite crude. Homo erectus, on the other hand, was able to break off much smaller flakes and produce the fine, symmetrical, Mode Two handaxes; therefore, Homo erectus was most likely capable of finer voluntary control of its mental template. (Ape reproductions as photographed by the author at the evolution exhibit the Valladoki Science Museum, Spain.)