Ecology of Tool Use in Wild Chimpanzees: Toward Reconstruction of Early Hominid Evolution

Abstract

The emergence and evolution ofhuman technology is a central issue in evolution- ary anthropology. To date,most evidence has come from stone artifacts found to- gether with hominid fossils (e.g.,Leakey 1971). The oldestknown stone tools manu- factured byhominids date back to about 2.5 million years ago (Semawet al. 1997). According to recent molecular studies,however,the human lineage diverged from the chimpanzee-bonobo lineage about 6million years ago (e.g.,Sibleyand Ahlquist 1984). It follows that we have no evidence of tool use by early hominids from the period 6-2.5 million years ago, more than half of hominid history. Should we assume that they did not use tools? The answer is probably no. Because organic matter such as sticks and leaves is the material most likely to have been used by early hominids for tools, any artifacts would quickly have decomposed and are unlikely to have been fossilized. Many textbooks end their discussion simply by saying that early hominids must have used tools to the same extent as modern chimpanzees. However,chimpanzees' tool use has been regarded as opportunistic, and is thought to have only a trivial effect on their subsistence (e.g.,Mann 1972)