The Foundations of Ethology: The Principal Ideas and Discoveries in Animal Behavior

Lorenz argues that the fixed motor pattern—a centrally coordinated, endogenously generated movement sequence—is the fundamental unit of ethological analysis. These patterns are evolutionarily conserved and can be classified by homology, just as anatomical structures are. The book rejects behaviorist reductionism, which treats behavior as chains of reflexes assembled by conditioning, and it rejects the view that learning is a unitary process. Lorenz instead insists that adaptive modification operates within genetically determined constraints, and that ethology must ground itself in neurophysiology, embryology, and Gestalt psychology rather than in a general theory of learning.

King Solomon’s Ring (1952) presented ethology through vivid naturalistic anecdotes aimed at general readers. The Foundations of Ethology (1978/1981) is a systematic theoretical monograph. It defends ethology’s conceptual apparatus against two decades of criticism, restates the innate/acquired distinction, revises the psycho-hydraulic model of motivation in response to critics like Robert Hinde, and engages neurophysiological evidence from Erich von Holst, Kenneth Roeder, and W. R. Hess. The tone is defensive and retrospective rather than exploratory. As one contemporary reviewer put it, Lorenz is “far too concerned with defending his concepts against later criticism” for the book to function as a neutral textbook.

Lorenz argues that learning is not a general capacity but a set of distinct processes that evolved independently. He borrows the concept of an “open program” from Ernst Mayr: a genetically determined structure that provides a finite set of options, within which the organism selects the most adaptive response under given circumstances. This allows Lorenz to acknowledge behavioral plasticity without abandoning genetic determinism. He distinguishes learning processes involving “feedback reporting success” (stimulus selection, response selection) from those that do not (Pavlovian conditioning, imprinting, habituation). This framework was his attempt to reconcile ethology with evidence of learning while preserving the primacy of innate structure.

Reviews were mixed. A Nature review criticized the book as “awkwardly antediluvian,” arguing Lorenz could have written it thirty years earlier and that it defended outdated positions against modern motivation research. A review in The American Journal of Psychology found the book “somewhat poorly organized” and noted that much material was taken verbatim from earlier papers, giving it the character of memoirs rather than a definitive text. Both reviews, however, acknowledged the force of Lorenz’s systematic presentation of the ethological approach. The reviewer in The American Journal of Psychology concluded that the book’s value lay “not in the evidence it presents for a conclusive understanding of animal behavior, but in stating forcefully the power of the ethological approach”.

In the revised model, the innate releasing mechanism is no longer represented as the outlet valve of a reservoir. Instead, Lorenz locates the IRM in the stream of fluid entering the reservoir alongside endogenously produced excitation. The discharge valve is operated solely by the accumulated action-specific potential and the valve’s built-in properties, such as inertia. He also adds “unspecific sources of stimulation” that contribute to charging the system, though he considers them minor. These revisions responded to criticisms from Robert Hinde and others that the original hydraulic model was too rigid and failed to account for motivational dynamics. Lorenz presents the updated model as a defense of the core insight—endogenous production of action-specific potential—rather than a wholesale abandonment.

Both men treat fixed action patterns as basic units, but their models emphasize different aspects. Tinbergen’s hierarchical diagrams depict information flow and the organization of instinct at multiple levels, making his model easier to relate to neural circuits. Lorenz’s model focuses on the dynamics of action-specific potential and the inertia of excitation, using a hydraulic analogy. As MIT course materials note, Tinbergen’s model “depicts hierarchical organization” but “fails as a descriptive model of the inertia phenomenon,” while Lorenz’s model deals with inertia but is harder to map onto neurophysiology. The two models are complementary rather than rival: Lorenz acknowledged Tinbergen’s hierarchy as a framework for integration while insisting on the centrality of endogenous motivation.