The earliest evidence of tool-use by human ancestors has been found in Ethiopia.
Animal bones with cut marks on them indicating they were sliced by stone tools have been dated to between 3.2-3.5 million years ago. The earliest stone tools ever found are 2.5 million years old. Not only does this finding push the date of tool use first appearing back by 800,000 years, but it also means that tools were used by ancestors in the genus Australopithecus. It was previously thought that only creatures belonging to the genus Homo, such as our own species, Homo sapiens, used tools. But if this evidence is accurate it means that Australopithecines, which are the evolutionary predecessors of Homo, used tools as well.
No stone tools have actually been found; the conclusion is inferred from cut marks in bone. Nevertheless, the results give a tantalizing, if speculative, insight into hominid evolution.