The four questions of ethology.

Ethology is the biological study of behaviour and concerns itself with questions about the causes, functions, evolution and development of aspects of behaviour. These different questions are illustrated with examples from the study of bird song. This subject has had most impact on understanding of developmental issues, showing the intricate interplay between genes and environment during ontogeny. Work on the evolution of song has involved comparison between closely related species to see how their songs have changed since separation, but also the shorter term cultural evolution that occurs when song is passed from one animal to another by learning. Studies of function, while fraught with difficulties, have revealed that song can have a variety of advantages. As far as causes are concerned, some impressive discoveries have recently been made on the neural basis of song. The need for such work to be complemented by studies of behaviour at the level of the whole animal is stressed, and studies of song sequencing are used to illustrate this.