The interplay between psychological predispositions and skill learning in the evolution of tool use

Tool use behaviours tend to be split into cases that appear to entail complex cognitive abilities and that are highly reliant on learning to be acquired (e.g. flexible tool use), and into others that seem to be more genetically canalized (e.g. stereotyped tool use). However recent evidences suggest that the differences between these forms of tool use are more nuanced than previously assumed, as in both cases tool use can entail some degree of both inborn predisposition and learning. Here, we particularly discuss the role played by intrinsic (e.g. not socially induced) motivation towards the manipulation of objects, in the emergence of flexible tool use. We highlight the importance of focussing on these psychological predispositions to understand the rarity of tool use among wild animals, as well as the higher proficiency in using tools that some species non-tool users express in captivity.