It is distinguished by its balanced treatment of both the underlying mechanisms and evolutionary causes of behaviour, and stresses the utility of evolutionary theory in unifying the different behavioural disciplines. Important concepts are explained by reference to key illustrative studies, which are described in sufficient detail to help students appreciate the role of the scientific process in producing research discoveries. Examples are drawn evenly from studies of invertebrates and vertebrates, and are supported by nearly 1300 reference citations. The writing style is clear: beginning students should have no difficulty following the material, despite the strong conceptual orientation of the text.