This is of interest in biological psychology for two reasons: the initiation of tool use marks an important point in the EVOLUTION of Homo sapiens (see HOMINID); and tool use by non-human animals is thought to reflect a degree of INTELLIGENCE. Tool use does not include behaviours shown by many animals in which specialized body adaptations are used in a quasi-tool like manner—many birds for example have beaks designed to achieve specific goals. Instead, tool use requires the operation of an object as an extension of one’s body in pursuit of a particular and immediate end.
Various PRIMATES have been observed to use tools in the laboratory (Wolfgang Köhler [1887–1967] observed laboratory chimpanzees using sticks to obtain otherwise unreachable food rewards) and in the wild. Chimpanzees use sticks and leaves in gathering food and, famously, macaques on Koshima island washed sand from sweet potatoes before eating them. The many examples of primate tool use have generated further appreciation of their intelligence, but it is clear that other animals can also use tools. For example, birds with their wings clipped have been shown to be able to move wooden blocks to use as steps in order to obtain food placed at an otherwise unreachable height.
