Tool use and physical cognition in birds and mammals.

In the wild, chimpanzees are the most prolific and proficient tool users, yet their understanding of tools in the laboratory is surprisingly poor. Although this apparent lack of understanding might be interpreted as a reflection of a general failure of animals to appreciate 'folk physics', recent studies suggest that some non-tool using species perform rather well on such laboratory tasks. In some animals, tool use and manufacture may also engage aspects of planning, but some non-tool using species have also been shown to demonstrate prospective cognition. Consequently, we argue that habitual tool use is not a clear predictor of physical intelligence, for either instrumental tool tasks or tests of planning.