Prior to 1963, classical ethological theory had surprisingly little to say about the development of behavior, in spite of the fact that Lorenz himself had published a landmark paper on the concept of imprinting in 1935. Tinbergen's (1951) book The Study of Instinct, for example, has only one short chapter on development, and only one paragraph on imprinting. Lehrman (1953), in his influential critique of ethological theory, pointed out this neglect of developmental questions, which subsequently led a number of ethological workers to consider problems of development. It is likely that it also led Tinbergen (1963), ten years later, to declare ontogeny as one of the four major problems of behavioral biology.

Tinbergen's discussion of ontogeny implies it to be the study of causal mechanisms: “I should like to characterize the phenomenon [i.e. ontogeny] as ‘change of behaviour machinery during development’. This is not, of course, the same as a change of behaviour during development;” (1963, p. 424). As Crews and Groothuis (2005, this volume) rightly point out, all of Tinbergen's “why” questions (i.e., causation, survival value, and evolution) can and should be asked of behavioral development. Nonetheless, in this chapter, we will concentrate on Tinbergen's original concern with the causal mechanisms of development, and only mention functional and evolutionary aspects briefly in the concluding section. We will also primarily consider studies using behavioral techniques.

By the mid 1960s, there was already a considerable body of research on the development of animal behavior.