This volume brings together contributions on the theme of tools from international specialists in various disciplines - anatomists, neurobiologists, prehistorians, ethnologists, and primatologists - at a symposium arranged by the Fyssen Foundation. Tools, whether of stone, wood, or metal, are a prolongation of the arm, but they acquire precision through the hand directed by the brain. A movement may have been identical from one another, in apes and in humans, in the past and in the present, but the resulting action varies according to the extended use of the tool. It is therefore necessary to understand the origin of tools, and also to be able to describe the techniques of cutting tools, and to imagine the possible uses of certain tools. Comparison of the techniques of chimpanzees with those of prehistoric Man and of twentieth-century Man has made it possible to appreciate the common aspects and to identify the differences. The transmission of ability, and of the understanding also called apprenticeship, has been studied in the various relevant societies: chimpanzees in their natural habitat and in captivity, hunter-gatherers, and workmen in prehistoric and in modern times.