Paleoanthropologists once considered making tools to be one of the defining characteristics of being human–along with a big brain, language, and upright walking. But they had to rethink the concept of "man the toolmaker" in recent decades as they spotted wild chimpanzees pounding
nuts open with stone hammers, fishing for termites and ants with sticks, and extracting honey with brushes made of sticks. Skeptics countered that tool-wielding chimpanzees were just imitating humans living in the same forests.
A new study bolsters the idea that chimps came up with the tools themselves. Researchers working in Africa's Côte D'Ivoire (Ivory Coast) have discovered stone hammers made 4300 years ago that appear to be the handiwork of chimpanzees, not humans. The ancient age of the tools shows that they were made by chimpanzees because "we know this was happening when no farmers were around–it predates farming in the area by 2000 years," says lead author Julio Mercader, a Paleolithic archaeologist at the University of Calgary in Canada.
