SCHNEIRLA, THEODORE CHRISTIAN

(b. Bay City, Michigan, 23 July 1902; d. New York, New York, 20 August 1968), comparative psychology, ethology, instinct, learning, epigenesis, ants.

Schneirla was a comparative psychologist who made important empirical and theoretical contributions to the study of animal behavior. His research focused on the behavior of army ants. He was a critic of both behaviorist learning theory and ethological instinct theory, arguing for the necessity of an epigenetic approach to behavioral development, which emphasizes the joint action of genetic and environmental influences, and an appreciation of differences in the levels of organization to be found in the animal kingdom.

Career T. C. Schneirla grew up in a farming community in Michigan, near Saginaw Bay. He attended public schools, and then the University of Michigan in Ann Arbor. He was musically inclined, playing trumpet in the university band, and maintaining active engagement with music throughout his life. He also became adept at typing and shorthand, a skill he later put to good use as a means of making field notes of behavioral observations.

Schneirla completed his BS degree in 1924, and an MS in psychology the following year. He stayed on at Michigan as a graduate student, working on the behavior of ants under the guidance of John F. Shepard. Thus began the interest that remained the main subject of his research for the rest of his life. In 1926 he married a fellow student, Leone Warner, with whom he fathered two children. The couple spent the summer of 1927 in Oklahoma, where Schneirla had a university teaching job. In 1928 they moved to New York University (NYU), where Schneirla finished his PhD thesis: “Learning and Orientation in Ants.”

He taught at NYU for the next three years, and then got a National Research Council fellowship, which enabled him to spend a year working with Karl Lashley in Chicago. There also he began a close friendship with Norman Maier, which eventuated in their writing a book together: Principles of Animal Psychology(1935). This text presented a radical approach for its time in that it took the whole animal kingdom, from protozoa to people, as its province, and emphasized how behavioral capacities relate to body design (e.g., symmetry) and the kinds of sensory, neural, and motor equipment possessed. It remains a classic of the animal behavior literature. In 1932 Schneirla returned to NYU, where he continued as a member of the psychology faculty for the rest of his life. In 1932 Schneirla went on a field trip to study ants in the wild on Barro Colorado Island in Panama. This was the first of many such travels to Panama, Mexico, and the southwest United States.

In 1943 Frank Beach, curator of the Department of Animal Behavior at the American Museum of Natural History, invited Schneirla to join him as associate curator. When Beach moved to a professorship at Yale four years later, Schneirla replaced him as curator. However, he continued at NYU as an adjunct professor, teaching courses in comparative psychology, behavioral development, and thinking.

From early on in his career Schneirla involved himself with issues of public concern. For instance he campaigned for support of the government side during the Spanish Civil War and sought to organize relief for out-of-work psychologists during the Depression years of the thirties, activity contributing to the establishment of the Society for the Psychological Study of Social Issues.

For more than twenty years Schneirla suffered from unremitting ringing in the ears (tinnitus), and had to cope with other disabling contingencies. Nevertheless, he maintained a high level of productivity, both in research and theoretical writing. He also influenced the field of comparative psychology through his teaching, doctoral supervision, and collaborative involvement. Among those he taught or worked with were Lester Aronson, Herbert Birch, Daniel Lehrman, Jay Rosenblatt, William Tavolga, Ethel Tobach, Howard Topoff, and Gerald Turkewitz. One of his last accomplishments was the creation and design of the Behavioral Alcove in the Hall of Invertebrates at the museum.

Research Unlike many of the animal psychologists of his day, Schneirla can be said to have been truly comparative. His interests ranged over the whole animal kingdom. He also contrasted with the “rat runners” in choosing to concentrate his research efforts on an invertebrate: the army ant Eciton burchelli. Of this work a survey of ant biology had this to say: “it was T. C. Schneirla … who, by conducting patient studies over virtually his entire career, first unravelled the complex behavior of … Eciton. His results were confirmed and greatly extended in rich studies conducted by C. W. Rettenmeyer” (Hölldobler and Wilson, 1990, p. 573).

These ants live in groups consisting of between 150,000 and 750,000 individuals of different castes. The “armies” alternate between “statary” and “nomadic” phases. During the statary phase the ants form temporary nests or “bivouacs” by having numerous of their number construct an outer shell with their own linked bodies to contain and shelter the single fertile queen and her brood. Every six weeks or so, during the statary phase, the queen lays upwards of 100,000 eggs, which are tended by sterile female worker ants. Hatching of the eggs initiates the nomadic phase, when raiding parties fan out from the colony in search of prey that they can overwhelm by their numbers. The brood and queen are transported as the rest of the colony trails after the host of hunters. Pupation of the larvae, and hence lowering of the food requirements, returns the colony to quiescence.

Schneirla showed how this cycle depends upon an intricate system of reciprocal influences between colony members and the brood, which transcends the limited cognitive capacities of any individual ant, or any simple conception of their collective sum: “The cyclic pattern … is self re-aroused in a feedback fashion, the product of a reciprocal relationship between queen and colony functions, not of a timing mechanism endogenous to the queen” (Schneirla, 1957, p. 129). Nevertheless he eschewed the vague anthropomorphic or supraorganismic explanations of his predecessors. He painstakingly charted a nested hierarchy of feedback loops acting homeostatically to adjust microcli-mate within a bivouac, and dynamically to meet mounting nutritional needs by launching the hunting frenzy (Schneirla, 1940, 1957, 1971).

Alongside this involvement with cyclicity in the lives of army ants, Schneirla maintained the interest in ant learning that he had inherited from Shepard. For instance he compared the performances of ants and rats when presented with mazes of comparable difficulty. He was able to show that the two species deal with the task quite differently, in accordance with the differences in the kinds of sensory and neural equipment they bring to bear on it. Hence to speak of “learning” here is to label an outcome rather than to refer to a shared mechanism or process, contra the generality of “laws of learning” assumed by most behaviorist learning theory (Schneirla, 1960).

Schneirla made comparable comparisons of the kinds of factors governing social organization in insects and mammals (e.g., Schneirla and Rosenblatt, 1961). In insects, by and large, social interaction is determined by physiological response to stimuli, as in trophallaxis (passing of alimentary fluid between colony members), rather than individual relationships. Such systems can be described as “biosocial.” In contrast mammalian social relations involve expectations based on experience, bonding of the sort entailing individual recognition, adjustment according to learned status, a system describable as “psychosocial.” Example for the mammalian case was provided by a study of behavioral development in kittens, which Schneirla undertook with Jay Rosenblatt (Schneirla and Rosenblatt, 1961, 1963; Rosenblatt, 1971). They found a succession of phases, intertwining growth changes and experience, constituting an epigenetic progression in which direction was localized neither in an internally situated program, nor in dictation by environmental contingency. This kind of view of development derived from and gave support to Schneirla’s theoretical position in comparative psychology.

Theory and Criticism Fundamental to Schneirla’s theorizing was the concept of levels of organization as applying in both evolutionary and developmental contexts. He maintained that there are qualitative differences between animals of different kinds in their morphological design,

neural functioning, and behavioral capacities. So, for example, an understanding of how an animal locates itself in its world (indeed the nature of that world as it exists for the animal) depends upon what sensory capacities it possesses, the manner in which it processes the sensory input, and the means by which it translates the results of the processing into movement or action. Compared with how a ciliate protozoan finds its way about, a planarian flatworm is in another league; but the flatworm, in turn, is put in the shade by comparison with a bee. The radial symmetry and diffuse neural network of a coelenterate polyp confine the creature to a spare behavioral world, which is a mere speck in the universe opened up by the bilateral symmetry and segmented centralized nervous system of an annelid worm (Maier and Schneirla, 1935). The radical contrasts between phyletic (evolutionary) levels of organization oppose the indiscriminate use of terms such as learning and instinct, and both anthropomorphic and zoomorphic suppositions riding on notions of continuity comparable to the venerable “great chain of Being” (e.g., Lovejoy, 1936).

Similarly Schneirla viewed behavioral development as involving transitions between progressively more sophisticated and qualitatively distinct levels of attainment—such as reflex, motivational drive, trial-and-error learning, intelligence—rather than a seamless continuum of additive assembly. But he also took an epigenetic position that vigorously opposed talk in terms of genetic programs or instinct versus learning. For him developmental processes interweave genetic and environmental contributions so intimately that they cannot be separated in the changes due to growth, maturation, and experience. At any point in behavioral ontogeny the interaction is not between what is innately given and what is externally imposed, but between what has already been jointly synthesized and the new circumstances, which (at least to some extent) are constituted by the achieved capacities of the growing individual.

Another important strand of Schneirla’s thinking, woven through the texture of levels of organization in both their phyletic and developmental manifestations, was his notion of “biphasic approach-withdrawal processes.” According to this idea animals generally tend to move toward mild stimulation and retreat from strong stimulation. In its simplest form, as exemplified by protozoa, the movements are forced responses, comparable to reflexes. In more advanced forms, both evolutionary and developmental, the movements have come under the control of the animal, so that approach has graduated to seeking, and withdrawal to avoidance. Schneirla deployed this conception liberally. For instance he saw it as exemplified by the vanguard column of his nomadic ants, propelled forward by the intensity of stimulation from the colony, reeled back in when stimulation is lessened by distance.

Sometimes his construals stretched credibility, as when he argued against the claim of Konrad Lorenz and Nikolaas Tinbergen that certain species of ground-nesting birds have a built in “bird of prey” detector which responds to birdlike silhouettes having short necks and long tails. Schneirla (1954) proposed that the short-necked silhouettes presented more abrupt (= intense) stimulus onset than the long-necked shapes, and that could account for the fleeing response. (It turned out that both interpretations were wrong. One of Lorenz’s associates showed that familiarity was the key: short-necked birds were rare in the circumstances of the study.) On occasion circular reasoning could creep in, as when intensity of stimulation was judged on the basis of direction of response.

Be that as it may, Schneirla maintained a consistently tough-minded stance, adhering to Lloyd Morgan’s canon according to which interpretations of animal behavior should assume the minimal psychological capacity consistent with observation. He was opposed to vitalism in all its forms, and to failure to appreciate the full variety of behavioral phenomena displayed by the animal kingdom. In this he was a psychologist worthy to be called comparative.

Aftermath T. C. Schneirla died while still engaged on a number of projects, both in research and on theoretical themes. His contribution to knowledge of the biology of ants is well recognized by experts in the field. His more theoretical writings are not as well known as they should be, partly, perhaps, because they can be hard going for the less dedicated reader. He worked mightily to get down on paper exactly what he had in mind to say, but the results could leave something to be desired in terms of clarity and elegance.

Nevertheless, Schneirla’s ideas have been kept alive by a small number of devoted disciples, Ethel Tobach and Gary Greenberg being chief among them. They inaugurated a series of conferences honoring his life and work, the proceedings of which have been published in book form (Greenberg and Tobach, 1984–1990). Among the more widely read of Schneirla’s writings is the article he contributed to the 1958 edition of the Encyclopaedia Britannica. It brought to a generation of readers the view that “on different levels, comparable biological factors promoting specialization can differ in their developmental consequences, according to phyletic differences.”

BIBLIOGRAPHY

A more comprehensive compilation can be found in Aronson et al., 1970.

WORKS BY SCHNEIRLA

With N. R. F. Maier. Principles of Animal Psychology. New York: McGraw-Hill, 1935.

“Further Studies on the Army-Ant Behavior Pattern: Mass-Organization in the Swarm Raiders.” Journal of Comparative Psychology 29 (1940): 401–460.

“The Nature of Ant Learning, II: The Intermediate Stage of Segmental Maze Adjustment.” Journal of Comparative Psychology 35 (1943): 149–176.

With G. Piel. “The Army Ant.” Scientific American 178 (1948): 16–23.

“Levels in the Psychological Capacities of Animals.” In Philosophy for the Future: The Quest for Modern Materialism, edited by R. W. Sellars, V. J. McGill, and M. Farber. New York: Macmillan, 1949. The first full and explicit statement of Schneirla’s views on levels of organization.

“Interrelationships of the ‘Innate’ and the ‘Acquired’ in Instinctive Behavior.” In L’instinct dans le comportement des animaux et de l’homme, edited by P.-P. Grasse. Paris: Masson, 1956. A paper delivered at a conference of ethologists and comparative psychologists, sponsored by the Singer-Polignac Foundation in Paris in the wake of D. S. Lehrman’s critique of ethological instinct theory.

“The Concept of Development in Comparative Psychology.” In The Concept of Development, edited by D. B. Harris. Minneapolis: University of Minnesota Press, 1957.

“Psychology, Comparative.” Encyclopaedia Britannica, vol. 18, edited by Walter Yust. Chicago: William Benton, 1958.

“An Evolutionary and Developmental Theory of Biphasic Processes Underlying Approach and Withdrawal.” In Nebraska Symposium on Motivation 7, edited by M. R. Jones. Lincoln: University of Nebraska Press, 1959. The major statement of Schneirla’s approach-withdrawal theory.

“L’Apprentissage et la Question du Conflit chez la Fourmi: Comparaison avec le Rat.” Journal du Psychologie Normal et Pathologique 57 (1960): 11–44.

With J. S. Rosenblatt. “Behavioral Organization and Genesis of the Social Bond in Insects and Mammals.” American Journal of Orthopsychiatry 31 (1961): 223–253.

———. “‘Critical Periods’ in the Development of Behavior.” Science 139 (1963): 1110–1115.

“Aspects of Stimulation and Organization in Approach/Withdrawal Processes Underlying Vertebrate Behavioral Development.” Advances in the Study of Behavior 1 (1965): 1–74. Schneirla’s last extended discussion of his approach-withdrawal theory applied to behavioral development.

Army Ants: A Study in Social Organization, edited by Howard Topoff. San Francisco: W.H. Freeman, 1971.

OTHER SOURCES

Aronson, L. R., E. Tobach, D. S. Lehrman, et al., eds. Development and Evolution of Behavior: Essays in Memory of T. C. Schneirla. San Francisco: Freeman, 1970.

Aronson, L. R., E. Tobach, J. S. Rosenblatt, et al., eds. Selected Writings of T. C. Schneirla. San Francisco: Freeman, 1972.

Burkhardt, R. W. Patterns of Behavior: Konrad Lorenz, Niko Tinbergen, and the Founding of Ethology. Chicago: University of Chicago Press, 2004.

Dewsbury, D. A. Comparative Psychology in the Twentieth Century. Stroudsburg, PA: Hutchinson, 1984.

Greenberg, G., and E. Tobach, eds. T. C. Schneirla Conference Series, vols. 1–4. Hillsdale, NJ: Erlbaum, 1984–1990.

Hölldobler, Bert, and Edward O. Wilson. The Ants. Cambridge, MA: Harvard University Press, 1990.

Lehrman, D. S. “A Critique of Konrad Lorenz’s Theory of Instinctive Behavior.” Quarterly Review of Biology 28 (1953): 337–363.

Lovejoy, A. O. The Great Chain of Being: A Study of the History of an Idea. New York: McGraw-Hill, 1936.

Rosenblatt, J. S. “Suckling and Home Orientation in the Kitten: A Comparative Developmental Study.” In The Biopsychology of Development, edited by E. Tobach, L. R. Aronson, and Evelyn Shaw. New York: Academic Press, 1971.

Colin Beer