Complexity in animal behaviour: towards common ground.

The ambiguity of the term 'complex' in studies of animal behaviour and cognition can lead to theoretical and methodological disputes, as there seems to be little common ground regarding the features thought to introduce complexity. Based on examples not only in human and nonhuman primates but also in some species of birds, we explore three dimensions of complexity: motor precision, coordination, and anticipatory planning. We argue that it is necessary to identify which dimensions are present in each study to formulate and explore relevant questions in behavioural sciences, especially with an evolutionary perspective. [ABSTRACT FROM AUTHOR]