ethology(redirected from Animal learning)
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ethology,study of animal behavior based on the systematic observation, recording, and analysis of how animals function, with special attention to physiological, ecological, and evolutionary aspects. Laboratory or field experiments designed to test a proposed explanation must be rigorous, repeatable, and show the role of natural selection. At one time, an organism's actions were classified as either instinctive or learned behavior; the former included those actions, such as common reflexes, that are not influenced by the animal's previous experience; the latter comprised those actions, such as problem solving, that are dependent on earlier experiences. Current thinking emphasizes the complex interaction of environment and genetically determined responses, especially during early development. Among the early ethologists were Herbert Spencer, Charles Darwin, G. J. Romanes, and William James. Zoologists Konrad Lorenz and Nikolaas Tinbergen are widely considered to be the founders of modern ethology. In 1973 they and zoologist Karl von Frisch were awarded the Nobel Prize in Physiology or Medicine for their work in shaping the science of comparative animal behavior. See instinctinstinct,
term used generally to indicate an innate tendency to action, or pattern of behavior, elicited by specific stimuli and fulfilling vital needs of an organism. Examples of almost purely instinctive behavior are found in the behavior of many lower animals, in which
..... Click the link for more information. ; imprintingimprinting,
acquisition of behavior in many animal species, in which, at a critical period early in life, the animals form strong and lasting attachments. Imprinting is important for normal social development.
..... Click the link for more information. ; sociobiologysociobiology,
controversial field that studies how natural selection, previously used only to explain the evolution of physical characteristics, shapes behavior in animals and humans.
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The study of animal behavior. Modern ethology includes many different approaches, but the original emphasis, as expounded by Konrad Lorenz and Niko Tinbergen, was placed on the natural behavior of animals. This contrasted with the focus of comparative psychologists on behavior in artificial laboratory situations such as mazes and puzzle boxes. Ethologists view the naturalistic approach as crucial because it reveals the environmental and social circumstances in which the behavior originally evolved, and prepares the way for more realistically designed laboratory experiments. The approach goes back to the stress that Charles Darwin placed on hereditary contributions to behavior in all species, including humans. Viewing behavior as a product of evolutionary history has helped to elucidate many otherwise puzzling aspects of its biology and has paved the way for the new science of neuroethology, concerned with how the structure and functioning of the brain controls behavior and makes learning possible.
A central concept in classical ethology is that of the innate release mechanism. If a species has had a long history of experience with certain stimuli, especially those involving survival and reproduction, then to the extent that genes affect the ability to attend closely to such stimuli, natural selection leads to adaptations enhancing responsiveness to them. A common first step in the study of these adaptations was investigation of the development of responsiveness to such stimuli in infancy, focusing on situations that the ethologist knew to be especially relevant to survival. The term innate releasing mechanism, set forth by Tinbergen and Lorenz, eschews notions of innate mental imagery and has proved fertile in understanding how genes influence behavioral development, and in focusing attention of neuroethologists on inborn physiological mechanisms that permit learning while encouraging the infant to attend closely to very specific stimuli, the nature of which varies from species to species according to differences in ecology and social organization.
Modern research on the ethology of learning began when Lorenz discovered imprinting in geese. He found that if he led a flock of newly hatched goslings himself they became imprinted on him. When mature, they would court people as though confused about their own species identity. Learning occurred very rapidly and tended to be restricted to a short sensitive phase early in life. The learning is highly focused by genetically determined preferences both to follow a parent-object with particular appearance and emitting species-specific calls, and also to learn most quickly and accurately at a particular stage of development. The interplay between nature (genetic predisposition) and nurture (environmental influence) in learning is displayed especially clearly in imprinting, hence its special interest to biologists and psychiatrists. Indications are that it is not concerned so much with learning about species as with learning to recognize individual parents and kin, both to ensure mating with one's own kind and to avoid incestuous inbreeding.
There are many forms of imprinting. So-called filial imprinting, ensuring that ducklings and goslings follow only their parent, is distinct from sexual imprinting, affecting mate choice in adulthood; the sensitive phases for learning are different in each case. Imprinting-like processes also shape the development of food preferences and abilities to use the Sun and stars in navigation.
Unlike psychological studies of animal learning in the laboratory, which have tended to favor the “blank-slate” view of the brain's contribution to learning, ethology emphasizes the need to understand all aspects of the biology of a species under study before one can hope to understand how the animal learns to cope with the many complexities of individual existence and social living. Thus ethology may lead not only to an understanding of how natural behavior evolves, but also to new insights into how brains help organisms learn to cope with social and environmental problems confronting them as individuals. See Animal communication, Behavior genetics, Instinctive behavior
- a term used by J.S. MILL for the ‘science of character’, which he believed would become the basis of explanations within the moral sciences, using the inverse deductive method.
- the science of animal behaviour, especially where the findings of this study are intended to be extrapolated to the study of human behaviour. Ethology in this sense can be highly controversial, being objected to especially by those sociologists who emphasize the distinctiveness of human consciousness. See also SOCIOBIOLOGY.
one of the schools of study of animal behavior, chiefly concerned with analyzing the genetically determined (that is, hereditary and instinctive) components of behavior and its evolution. The term was first used in biology, in 1859, by the French zoologist E. Geoffroy Saint-Hilaire to define the study of the species-specific characteristics of animal behavior.
Development. The overall study of the behavior of animals in their natural environment has a long history. An enormous amount of descriptive material, as well as some experimental material, was collected in the works of 18th- and 19th-century natural scientists—for example, in the descriptions of the German scholar H. Reimarus and the French scientists G.-L. de Buffon and J. H. Fabre and in the experimental work of the French zoologist G. Cuvier. It was on the basis of such material that the category of instinctive behavior was singled out and clearly defined.
Ethology was directly influenced by the works of C. Darwin. The great number of facts he collected about the behavior of animals in their natural environment made it possible to distinguish the basic categories of behavior—namely, instinct, learning ability, and the elementary ability to reason. Darwin also showed that animals’ behavioral traits, like physical traits, are inherited and subject to change. Using instincts as an example, Darwin indicated the ways in which behavioral traits can evolve in the process of natural selection. The development of ethological notions was directly influenced by the research studies of various scientists (the Englishman D. Spaulding, the American C. O. Whitman, and the German O. Heinroth) who demonstrated experimentally that certain forms of behavior are of innate origin, are uniformly manifested, and are peculiar to certain species.
Ethology came into its own in the 1930’s as an independent scientific discipline, distinct from the physiological and psychological schools of behavioral investigation, such as zoopsychology and behaviorism. The acknowledged founders of ethology are the Austrian zoologist K. Lorenz and the Dutch zoologist N. Tinbergen. Lorenz’ theoretical works of 1931 to 1937 generalized the basic views of his predecessors—the Americans G. Whitman and W. Craig and the Germans J. von Uexküll and O. Heinroth—and of various scientists in other disciplines, such as the American scientists J. Loeb, H. Jennings, and W. MacDougall. The works of Lorenz, Tinbergen, and their followers (including the Dutch scientist G. Baerends and the Germans W. Wickler and P. Leuhausen) laid the foundations of the theory of instinctive behavior.
The ideas of classical ethology flourished and gained acceptance (chiefly in Europe) from the 1930’s to the late 1950’s. In the USA, ethological concepts at first met with rather strong opposition on the part of zoopsychologists and behaviorists. On the one hand, the further evolution of ethological views was influenced by the criticism of physiologists and psychologists; on the other hand, a new generation of ethologists was actively receptive to the advanced ideas of such sciences as ecology and neurophysiology. As a result, during the 1960’s and 1970’s the original ideas of the Lorenz-Tinbergen school tended to be transformed and synthesized into the positions of other behavioral and biological disciplines.
Ethology is gradually losing its status as an isolated discipline and is becoming part of the synthesized science of behavior now taking shape. Ethology developed out of field zoology (mainly ornithology) and evolutionary theory, and it is closely and increasingly associated with physiology, ecology, population genetics, and behavioral genetics. Its ties to experimental psychology are growing stronger as well.
Ethology’s traditional object of investigation is the behavior of animals in their natural surroundings. A complete description of species-specific animal behavior (using such objective recording methods as film, tape recording, and time studies) serves as the basis for compiling an “ethogram”—a list of individual behavioral acts characteristic of a given species. The ethograms of different species of animals are subjected to comparative analysis, and it is on such analysis that the study of the evolutionary aspects of their behavior is based. To this end ethologists utilize the entire range of species, from the invertebrates to the anthropoid apes. Some ethologists have started applying these methods to the study of human behavior.
In studying animal behavior in the context of the individual development of an organism, ethologists use laboratory methods as well. One such method consists of raising an animal in isolation from the influence of any external environmental factor. This method represented an essential stage in the study of behavioral ontogeny.
Of the various investigations of animal behavior undertaken in Russia since the late 19th century, some (for example, those of V. A. Vagner and A. N. Promptov) were close to ethology in their concepts and methods. Nevertheless, the views of the traditional school of ethology were not speedily accepted and developed in the USSR. The situation changed in the 1960’s, largely as a result of translations of books by foreign ethologists.
Some of the USSR’s scientific centers are engaged in ethological investigations based on a synthesis of ecological-physiological and physiological-genetic methods. At the A. N. Severtsov Institute of Evolutionary Morphology and Animal Ecology, the aim of various research studies on the behavior of mammals and birds is to identify distinctive ontogenetic features, the structure of biocenoses, and the mechanisms of communication—especially acoustic and chemical ones (for example, in V. E. Sokolov’s investigations). Research at the University of Moscow includes studies of the structure of biocenoses and of acoustic signals (such as the investigations of N. P. Naumov) as well as the study of elementary reasoning activities in animals (L. V. Krushinskii).
Research on the genetics of animal behavior is centered in the University of Leningrad and the I. P. Pavlov Institute of Physiology (including the work initiated by M. E. Lobashov) as well as in the Institute of Cytology and Genetics of the Siberian Division of the Academy of Sciences of the USSR (for example, studies by D. K. Beliaev). Investigations of animal behavior are carried out at a number of other institutions, including natural preserves.
Basic traditional tenets. The conception developed by ethologists was based on the distinctive features that were observed in the ontogenetic development of certain types of behavior. Some of these appear as a fixed stereotypical sequence of actions, usually characterizing all the individuals of a given species and constituting a behavioral pattern—a set of actions performed at a particular stage of ontogenetic development without having been specifically learned. Such behavior patterns were called by Lorenz innate instinctive movements, or coordinated hereditary actions.
Many instinctive actions are elicited only in response to certain stimuli, called “triggering” stimuli, or “releasers.” Without any previous individual experience, an animal recognizes such stimuli at their very first appearance; for example, the red spot on the belly of the male stickleback elicits aggressive reactions on the part of other males of the same species. The mechanism through which a movement is executed in response to the corresponding triggering stimulus has been called the “innate releasing mechanism.”
A special group of stimuli are those whose recognition requires a specific type of learning, called imprinting. In any given case, a stimulus will be effective for an adult animal only if it has been presented to that animal during a particular “sensitive” period in its early postnatal development. It was subsequently demonstrated that such “sensitive” periods are characteristic for certain types of learning—for example, the development of a particular birdsong.
The study of triggering stimuli and imprinting played an important part in our understanding of the mechanisms of animal communication. It was shown that to a great extent animal communication is a function of triggering stimuli—namely, certain peculiarities of external appearance and coloration, characteristic ritual body movements, or species-specific acoustic signals that elicit the corresponding reactions in other individuals without any previous learning.
These ideas were reflected in the hypothesis proposed by Lorenz and later worked out in detail by Tinbergen concerning the internal mechanisms of instinctive behavior; according to this hypothesis, various internal and external factors (such as hormones and temperature) act on the corresponding nerve centers to produce an accumulation of “action energy,” or action potential, that is specific to each drive (for example, hunger or thirst). The buildup of such energy over a certain level leads to the phase of investigative behavior, which is characterized by the great variety of the actions performed by a given individual as well as by different members of the same species.
The investigative phase consists of an active search for the stimuli that will satisfy the animal’s drive. Once the appropriate stimuli are found, the innate releasing mechanism is activated, and the action is completed. In the case of a high buildup of action potential, the concluding action may occur “spontaneously”—that is, without any triggering stimulus. This second phase is species-specific; it is characterized by uniformity of execution and is to a large extent genetically conditioned. It includes what is known as innate instinctive behavior, or hereditary coordination. The Lorenz-Tinbergen hypothesis as a whole has become largely obsolete, although its formulation and testing served to establish the connection between ethology and physiology.
The identification of the category of innate instinctive behavior made it possible to use comparative methods in the study of animal behavior and to shift to the investigation of its evolutionary aspects. It was possible to estimate the degree of phylogenetic kinship and to determine the position of individual species in the classification system by using findings about the presence or absence of common traits in different types of animals (that is, in members of different groups as classified in animal systematics). For example, no morphological trait so clearly distinguishes members of the order Columbiformes as does their sucking motion when drinking.
Comparative studies also contributed to the development of ideas about the evolution of different kinds of behavior, about the adaptive significance of specific types of behavior, and about the factors that gave rise to such specific behavior in the course of evolution. The Tinbergen school of ethology made an important contribution to the study of the evolutionry aspects of animal behavior. As a consequence of such research, ethologists were able to describe the effects of the law of natural selection on behavioral traits.
Comparisons of the instinctive behavior of members of closely related species, together with the study of intraspecies variations in behavior, laid the foundation for the study of the role of behavior in microevolutionary processes. Lorenz was one of the first to compare the behavior of different members of the Anatidae family. Protracted investigation of the role of behavior in population differentiation showed that behavior affects group composition and, by the same token, influences the fate of the genotypic changes that occur in the population. This proves that behavior is a major factor in microevolution.
Identification of the category of instinctive actions as basic units of behavior made it possible to examine the question of the genotypic foundations of behavior as well as the combination and interrelation of the influence of the environment and the influence of the genotype in the development of individual behavioral traits. The concept of “innateness” was used in ethology to designate behavioral responses that are completely determined by genotypic factors and whose development is not contingent on any special learning or training, as opposed to traits that are “acquired” in the process of development under the influence of specific factors in the external environment. The behavioral response as a whole was viewed by ethologists as a very complex interweaving of innate and acquired components.
Present status and problems. The principal schools of thought in which traditional ethological views are still of paramount importance are comparative ethology and the field of study known as socioethology—the latter being concerned with the ways in which biocenoses are organized and with animals’ communication methods. Scientists engaged in such studies are particularly interested in animal population dynamics, in the various factors controlling the development, structure, and number of groupings of individuals in different species, in the evolution of biocenotic methods of organization, and in the evolutionary succession and interrelation of biocenoses.
A contemporary current in ethology is the study of human behavior (as represented by Tinbergen, by the German I. Eibl-Eibesfeldt, and by J. Crook of Great Britain), such research being a direct continuation and development of Darwin’s ideas; the study of the biological foundations of human behavior was based on Darwin’s work The Expression of the Emotions in Man and Animals. What modern ethologists are chiefly concerned with is the objective recording and accurate description of certain instinctive human actions and certain human reactions to biologically significant stimuli by means of ethological methods and approaches that have been successfully tested in the study of animal behavior. Such studies represent an important stage in the development of evolutionary ideas, inasmuch as they help destroy the idealist notion of a barrier separating man, as a biological species, from animals.
The development of ethological research has great import for many aspects of human activity. For example, the growing influence of anthropogenic factors on the environment makes it imperative to undertake in-depth studies of the behavior of animals in their natural habitat, aiming at the conservation, restoration, and rational utilization of fauna. Knowledge of animal behavior is also very important in various branches of agriculture. As demonstrated in studies by the Soviet scientist D. K. Beliaev and his co-workers, the breeding of fur-bearing animals for behavioral traits can also greatly affect various traits that are economically significant. Detailed studies of the group behavior of agricultural animals are particularly important for the introduction of industrial methods in the maintenance and breeding of such animals.
Increasingly important, too, is the study of the mechanisms of animal behavior—for example, in medicine, cybernetics, and bionics, as well as in practical application.
Organizations, congresses, and journals. Ethologists’ activities are coordinated by the International Ethological Committee. International ethological conferences are held every four years. The 14th such conference was held in the USA in 1973; the 15th, in the Federal Republic of Germany in 1977. Two all-Union conferences on animal behavior were held in the USSR—in 1973 and 1977.
The principal journals that publish ethological findings are the international journals Behaviour (Leyden, since 1947), Biology of Behaviour (Paris, since 1976), and Behavioral Ecology and Sociobiology (Berlin, since 1976), as well as the journals Zeitschrift für Tierpsychologie (Berlin-Hamburg, since 1937), Animal Behaviour (London, since 1953), and Animal Behaviour Abstracts (London, since 1973).
In the USSR, articles on ethology are published in Zoolo-gicheskii zhurnal, Ekologiia, Zhurnal obshchei biologii, and Bul-leten Moskovskogo obshchestva ispytatelei prirody (Bulletin of the Moscow Society of Naturalists).
REFERENCESPanov, E. N. Etologiia—ee istoki, stanovlenie i mesto v issledovanii povedeniia. Moscow, 1975.
Krushinskii, L. V. Biologicheskie osnovy rassudochnoi deiatel’nosti. Moscow, 1977.
Tinbergen, N. Povedenie zhivomykh. Moscow, 1969. (Translated from English.)
Lorenz, K. Z. Kol’tso tsaria Solomona. 1970. (Translated from English.)
Hinde, R. A. Povedenie zhivotnykh. Moscow, 1975. (Translated from English.)
Jaynes, J. “The Historical Origins of ‘Ethology’ and ‘Comparative Psychology.’” Animal Behaviour, 1969, vol. 17, no. 4.
Function and Evolution of Behaviour. Edited by P. H. Klopfer and J. P. Hailman. Reading, Mass., 1972.
Lorenz, K. Über tierisches und menschliches Verhalten, vols. 1–2. Munich, 1973–74.
L. V. KRUSHINSKII and Z. A. ZORINA