Ontogeny of behavior, the development of behavior within the individual, was the fourth pillar of Tinbergen's 1963 treatise that marks the new synthesis of modern ethology. It was his contribution to Huxley's (1914, 1923) “three major problems of biology,” namely causation, survival value, and evolution. Here he recognized that, while development had long been a subject of study by embryologists, for behaviorists it had become “a field in which there is a real clash of opinion.” The controversy reflected the different approaches practiced by students of behavior in Western Europe and North America.

The European approach was strongly influenced by Lorenz, one of the founding fathers of Ethology. Lorenz is perhaps best known for his discovery of sexual imprinting, namely that the young of precocial birds would, if presented during a certain window of time following hatching, follow any conspicuous stimuli as if it was their mother, despite the fact that the stimulus did not have the slightest similarity with a conspecific, and that this attachment even transformed in adulthood to sexual preferences for that stimulus. This, and the development of species-specific motor patterns, led him to the proposition that the development of certain behaviors is pre-programmed by genes and independent of experience. This view was rejected vigorously by behavioral scientists in North America, most notably Hebb (1953), Lehrman (1953), and Beach and Jaynes (1954).