First published in 1976, this volume is a collection of essays by some of the most prominent and active ethologists. It is organized into four sections: motivation and perception, function and evolution, development, and human social relationships. The first three sections reflect the four questions which are basic to ethology: what were the immediate causes of a behaviour pattern; what is its biological function; how did it evolve; and how did it develop in the individual? The last section involves questions of all four types. The sections are introduced and linked by editorials and the book concludes with an important statement on asking the right questions. The essays are forward looking and identify areas of importance for the study of behaviour. The volume is a source of formative ideas for students, their teachers and research workers in a wide variety of disciplines in the biological psychological and social sciences.