Stone Age Chimps?

A team led by archaeologist Julio Mercader of the University of Calgary in Alberta reports that a layer estimated at 4,300 years old has yielded evidence chimpanzees, as well as humans, figured out the stone tool business a long time ago. While tool use by modern chimps is well established, the almost-nonexistent chimpanzee fossil record has given us no clues about when the apes learned this skill. Now diggings in the African nation of Ivory Coast indicate nuts favored by chimps were cracked open with rocks in an area that shows no sign of human habitation.