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Ethology had the most impact from about 1940 to 1970, when it took the discipline of animal behavior by storm, earning Konrad Lorenz and Niko Tinbergen, with Karl von Frisch, a Nobel Prize in 1973. The underlying concepts were biological rather than psychological, derived from a Darwinian approach to naturally occurring animal behavior. Historically, the naturalistic aspect was crucial, with an emphasis lacking in psychology at the time. Although anticipated by American behaviorists, ethology came of age as a mature discipline in Europe. The proceedings of a 1949 conference in Cambridge, England, on physiological mechanisms in animal behavior presented a full exposition of the ideas of Lorenz, Tinbergen, and other participants in the emerging discipline (Lorenz 1950; see 1970, 1971 for collected works). Tinbergen's classical treatise on "The Study of Instinct" followed a year later (Tinbergen 1951). Ethology provided a comprehensive framework for studying the functions, evolution, and development of behavior and its physiological basis. Some insights were conceptual and others methodological. Four historically important aspects were the basic endogeneity of behavior, the concept of sign stimuli, the reinstatement of instincts, and the importance of cross-species comparisons.
Lorenz's medical training in Vienna exposed him to concepts of phylogeny emerging from comparative anatomy, but behavior was viewed as too amorphous to be amenable to the same kind of study. Encouraged by Berlin zoo director Oscar Heinroth, who was intimate with the behavior of scores of animals, Lorenz became convinced that comparative ethological studies could be as objective as anatomical investigations. Young animals of diverse species, raised under similar conditions, consistently develop distinctive behaviors, stable enough to yield insights into taxonomy and phylogeny. Many of the species-specific displays of captive ducks match those in the wild. The emphasis on comparative study, rendered more quantitative by Tinbergen and his students, was an important innovation, embodied in Lorenz's term "fixed action patterns." Although action patterns are not completely "fixed," any more than is morphology, careful scrutiny reveals consistent species and individual differences in modal action patterns. Descriptive studies of behavior took on new momentum, shifting focus somewhat from species comparisons to intraspecific variation, culminating more than a generation later in the quantitative sophistication of mating choice theory, and cladistic and other approaches to problems in phylogeny (Harvey and Pagel 1991).
A second innovation emphasized endogenous sources of motivation. The BEHAVIORISM of Watson (1924), given a more biological flavor by Schneirla and his colleagues, stressed the role of external forces in the control of behavior, perhaps initially as a healthy antidote to the indulgences of introspectionist psychology. Ethologists provided a refreshing reminder that without a genome you have no organism, and no instructions on how to respond to external stimuli or how to learn as a consequence of experience, countering such excesses as "psychology without heredity" (Kuo 1924). The notion of "instinct," eloquently championed by Darwin, had fallen into disrepute. Lorenz redressed this balance by stressing the importance of endogeneity, both in the motivational sense, manifest in the inherent rhythmicity of many behaviors, and in the ontogenetic sense, with certain patterns of behavior developing endogenously, only minimally perturbed or adjusted according to the vagaries of individual experience. The notion of strong internal forces driving behavior was then highly controversial. We now accept that the underlying neural circuitry of many behaviors includes neuronal pacemakers as key components. The theme of endogenous forces came to pervade research at the Institute for Behavioral Physiology established for Lorenz and codirector Eric von Holst by the Max Planck Gesellschaft in Bavaria in 1956, including pioneering studies of swimming rhythms, and later circadian and circannual behavioral cycles. Across the Atlantic, ethologically inspired insect physiologists Kenneth Roeder and Donald Wilson convincingly demonstrated the delicate interplay of exogenous and endogenous forces underlying locomotion and other behaviors (Roeder 1963; reviewed in detail in Gallistel 1980).
The interpretation of responses to external situations not as driven from without but as interactions between changing environments and purposively changing organismal states was not unique to ethology. A generation previously, in an essay on "appetites and aversions as constituents of instincts," the American ethologist Wallace Craig (1918) clarified the issues of uniformity and plasticity with a distinction made previously by Sherrington, and later by Lorenz, between appetitive (i.e., proceptive) behavior, endogenously motivated and variable, and consummatory behavior, externally triggered and more stereotyped. Craig was a student of Charles Otis Whitman, whose 1898 Woods Hole lectures on animal behavior anticipated other aspects of ethological thinking. But Craig's message fell on deaf ears, appreciated by few psychologists, and apparently known to Lorenz only after his career was well launched. He may also have been unaware of Craig's assertion that aggression is less endogenously driven than most behaviors (Craig 1928). Lorenz's controversial 1966 book "On Aggression," presented the contrary case, that there are strong endogenous wellsprings for agonistic behavior. Few of the many critics of Lorenz's position acknowledged Craig's thoughtful counterargument (see also Heiligenberg and Kramer 1972).
Until the postwar years, American biologists and psychologists alike were curiously unresponsive to efforts within their ranks to instate ethologically styled concepts. A prophetic paper by one of its most respected pioneers, titled "Experimental analysis of instinctive behavior" (LASHLEY 1938; see Beach et al. 1960), anticipated some developments in ethology but had much less impact than his work on cortical memory mechanisms. Lashley's preoccupation with endogenous motivational forces was evident in his arguments with Pavlovian theorists who reduced all behavioral and psychological activity to chains of conditioned reflexes. There had also been limited appreciation of the case made a generation previously by Lashley's teacher, Jennings (1906), for the existence, even in single-celled organisms, of complex, sometimes purposive, endogenously driven behaviors. His suggestion that equivalent observations in higher organisms would suffice to encourage cognitive theorizing may have helped to spur his later colleague Watson (1924) to put an end to subjective, introspective psychologizing. Instead, Watson shifted the emphasis to observable behaviors and Pavlovian reflexes, thus launching behaviorism. But what began as a worthy effort to reintroduce objectivity into comparative psychology hardened into dogma, and the importance of endogenous factors was again forgotten until reinstated by Beach and other students of Lashley, increasingly preoccupied with physiological psychology as an emerging discipline (Beach et al. 1960). The notion of instinct met a similar fate, swept aside by the appeals of pragmatism. In developmental studies, American comparative psychologists grappling with the nature/nurture problem lost sight of the need to balance environmental influences with contributions of the genome, a primary emphasis in ethology.
Environmental factors were not neglected by ethologists. Tinbergen and his students, more experimentally oriented than Lorenz, focused on key components of complex situations to which animals actually respond (collected in Tinbergen 1971, 1973). Many of these "sign stimuli," or "social releasers," often a small fraction of the total that the animal can perceive, were communicative signals (see ANIMAL COMMUNICATION). Physiological mechanisms were inferred for filtering incoming stimuli, apparently operating at birth in many young organisms, such as the nestling birds that Tinbergen studied. Lorenz posited central "innate release mechanisms" with properties varying according to genetically encoded instructions. The determination of ethologists to reinstate concepts of innateness led to the sometimes legitimate criticism that they caricatured young animals as completely preprogrammed automata (Lehrman 1953). It became clear later that even young organisms with well-defined innate responsiveness, such as herring gulls, display great developmental plasticity, quickly acquiring new information about their parents and other aspects of life around them. But they do so by learning processes that are canalized by innate predispositions, insuring a certain range of trajectories for development, whether behavioral or neurological (Hailman 1967; Waddington 1966; Rauschecker and Marler 1987).
The importance of innately guided learning, well illustrated by song learning in birds, was the special province of British ethologist William Homan Thorpe (1956). More than Lorenz or Tinbergen, Thorpe prepared the way for the emergence of COGNITIVE ETHOLOGY (Griffin 1976). He was the first to formalize criteria for different types of learning, some very basic, others with clear cognitive implications. His thoughtful scholarship emphasized the importance of internalized processing in perception and the purposiveness of behavior. The interplay of nature and nurture is most evident in "imprinting," the developmental process for which Lorenz is best known. During imprinting, young of some organisms learn to recognize and bond with their parents, or parent surrogates, and others like them, by processes destined to become favored paradigms for investigating the neural basis of memory formation (Horn 1985). Imprinting occurs most rapidly during sensitive periods, as experience interacts with innate preferences for visual and auditory stimuli that capture attention and initiate the imprinting process. That these early experiences sometimes influence later social and sexual preferences, with varying degrees of reversibility, attracted special attention in psychiatry and the social sciences (Bowlby 1969, 1973; Hinde 1982). There are parallels with song learning in birds and with human speech acquisition, where the choice of what to learn is guided by generalized innate preferences, resulting ultimately in specific learned vocal traditions (Marler 1991; Pinker 1994). The interplay of inheritance and experience that canalizes the development of many behaviors is epitomized by the apparently paradoxical term "instincts to learn" (Gould and Marler 1987). More than any other, the concept of instinctively guided learning captures the essence of what was uniquely distinctive about classical ethology, still providing a valued heuristic framework for contemporary research on behavioral ontogeny (see EVOLUTIONARY PSYCHOLOGY).
Beach, F. A., D. O. Hebb, C. T. Morgan, and H. W. Nissen. (1960). The Neuropsychology of Lashley: Selected Papers of K. S. Lashley. New York: McGraw-Hill.
Bowlby, J. (1969, 1973). Attachment and Loss. Vols. 1 and 2. London: Hogarth Press.
Craig, W. (1918). Appetites and aversions as constituents of instincts. Biological Bulletin 34:91-107.
Craig, W. (1928). Why do animals fight? International Journal of Ethics 31:264-278.
Gallistel, C. R. (1980). The Organization of Action: A New Synthesis. Hillsdale, NJ: Erlbaum.
Gould, J. L., and P. Marler. (1987). Learning by instinct. Scientific American 256(1):62-73.
Griffin, D. R. (1976). The Question of Animal Awareness: Evolutionary Continuity of Mental Experience. New York: Rocke feller University Press.
Hailman, J. P. (1967). The ontogeny of an instinct. Behavior 15:1-142.
Harvey, P. H., and M. D. Pagel. (1991). The Comparative Method in Evolutionary Biology. Oxford: Oxford University Press.
Heiligenberg, W., and U. Kramer. (1972). Aggressiveness as a function of external stimulation. Journal of Comparative Physiology 77:332-340.
Hinde, R. A. (1982). Ethology: Its Nature and Relations with Other Sciences. New York: Oxford University Press.
Horn, B. (1985). Memory, Imprinting and the Brain. Oxford: Clarendon Press.
Jennings, H. S. (1906). Behavior of the Lower Organisms. Bloomington: Indiana University Press. (reprint, 1962.)
Kuo, Z. Y. (1924). A psychology without heredity. Psychology Review 31:427-448.
Lashley, K. S. (1938). Experimental analysis of instinctive behavior. Psychological Review 45:445-471.
Lehrman, D. S. (1953). A critique of Konrad Lorenz's theory of instinctive behavior. Quarterly Review of Biology 28:337-363.
Lorenz, K. Z. (1950). The comparative method in studying innate behaviour patterns. Symposia of the Society for Experimental Biology No. IV. Cambridge: Cambridge University Press, 221-268
Lorenz, K. Z. (1966). On Aggression. New York: Harcourt, Brace and World.
Lorenz, K. Z. (1970, 1971). Studies in Animal and Human Behavior, vols. 1 and 2. Cambridge, MA: Harvard University Press.
Marler, P. (1991). The instinct to learn. In S. Carey and R. Gelman, Eds., The Epigenesis of Mind: Essays on Biology and Cognition. Hillsdale, NJ: Erlbaum, pp. 37-66.
Pinker S. (1994). The Language Instinct. New York: William Morrow.
Rauschecker, J, and P. Marler, Eds. (1987). Imprinting and Cortical Plasticity. New York: Wiley.
Roeder, K. D. (1963). Nerve Cells and Insect Behavior. Cambridge, MA: Harvard University Press.
Thorpe, W. H. (1956). Learning and Instinct in Animals. Cambridge, MA: Harvard University Press.
Tinbergen, N. (1951). The Study of Instinct. Oxford: Clarendon Press.
Tinbergen, N. (1971, 1973). The Animal in its World: Explorations of an Ethologist, vols. 1 and 2. Cambridge, MA: Harvard University Press.
Waddington, C. H. (1966). Principles of Development and Differentiation. New York: Macmillan.
Watson, J. B. (1924). Behaviorism. Chicago: University of Chicago Press.
Alcock, J. (1997). Animal Behavior: An Evolutionary Approach. Sunderland, MA: Sinauer Associates Inc.
Baerends, G. P. (1988). Ethology. In R. C. Atkinson, R. J. Herrnstein, G. Lindzey, and R. D. Luce, Eds., Stevens' Handbook of Experimental Psychology, vol. 1: Perception and Motivation. New York: Wiley, pp. 765-830.
Barlow, G. W. (1977). Modal action patterns. In T. A. Sebeok, Ed., How Animals Communicate. Bloomington: University of Indiana Press.
Bateson, P. P. G. (1966). The characteristics and context of imprinting. Biological Reviews 41:177-220.
Bateson, P. P. G. (1978). Early experience and sexual preferences. In J. B. Hutchison, Ed., Biological Determinants of Sexual Behavior. New York: Wiley, pp. 29-53.
von Cranach, M., K. Foppa, W. Lepenies, and D. Ploog, Eds. (1979). Human Ethology. Cambridge: Cambridge University Press.
Eibl-Eibesfeldt, I. (1975). Ethology: The Biology of Behavior. New York: Holt, Rinehart and Winston.
Gottlieb, G. (1979). Comparative psychology and ethology. In E. Hearst, Ed., The First Century of Experimental Psychology. Hillsdale, NJ: Erlbaum.
Gould, J. L., and P. Marler. (1987). Learning by instinct. Scientific American 256(1):62-73.
Grillner, S., and P. Wallen. (1985). Central pattern generators for locomotion with special reference to vertebrates. Annual Review of Neuroscience 8:233-261.
Hess, E. H. (1973). Imprinting: Early Experience and the Developmental Psychobiology of Attachment. New York: Van Nostrand.
Hinde, R. A. (1960). Energy models of motivation. Sym. Soc. Exp. Biol. 14:199-213.
Hinde, R. A. (1970). Animal Behavior: A Synthesis of Ethology and Comparative Psychology. 2nd ed. New York: McGraw-Hill.
von Holst, E. (1973). The Behavioral Physiology of Animals and Man. Selected Papers of Eric von Holst. Coral Gables, FL: University of Miami Press.
Maier, N. R. F., and T. C. Schneirla. (1935). Principles of Animal Psychology. New York: McGraw-Hill.
Marler, P. (1985). Ethology of communicative behavior. In H. I. Kaplan and B. J. Sadock, Eds., Comprehensive Textbook of Psychiatry, vol. 1. Baltimore/London: Williams and Wilkins, pp. 237-246.
Marler, P. R., and W. J. Hamilton III. (1966). Mechanisms of Animal Behavior. New York: Wiley.
Schleidt, W. M. (1962). Die historische Entwicklung der Begriffe "Angeborenes auslösendes Schema": und "Angeborener Auslösemechanismus". Z. Tierpsychol. 19:697-722.
Seligman, M. E. P., and J. L. Hager, Eds. (1972). Biological Boundaries of Learning. New York: Appleton-Century Crofts.
Thorpe, W. H. (1961). Bird Song. Cambridge: Cambridge University Press.
Copyright © 1999 Massachusetts Institute of Technology