Discussion of theoretical ecology, like discussion of ecology generally, is plagued by the problem of determining what it is in order to ascertain how it got that way or even what it should be. Consideration of theoretical ecology is difficult in that it requires conceptions of what is theory, what is ecology, and how they combine. Some recent writers on theoretical ecology resolved the problems I suggest with disarming simplicity. E. G. Leigh, Jr. (1968), for example, opened an article with a “historical sketch of ecologic theory,” moving directly to the “pioneers of mathematical ecology, Lotka and Volterra,” the founders in the 1920s of the “Golden Age of theoretical ecology” as it was described by Scudo and Ziegler (1978). Robert May (1974a), the editor of the first book, entitled simply Theoretical Ecology (May 1976) offered a similar history, but overlooked Lotka in writing, “Theoretical ecology got off to a good start in the 1920s with Vito Volterra's seminal and still central contributions.” This view of the alliance of mathematical theory and ecology had been described earlier in the volume Theoretical and Mathematical Biology (Waterman and Morowitz 1965): “There are few areas of biology where theoretical mathematical studies have had as much impact as they have had in ecology” (Morowitz 1965). The author of a volume entitled An Introduction to Mathematical Ecology wrote, “Ecology is essentially a mathematical subject” (Pielou 1969:v). Mathematical theory was described as the big advance in ecology over Elton's conceptual contributions to ecology (Christiansen and Fenchel 1977).

The rapid, even “revolutionary,” emergence of self-conscious ecology from the amorphous body of classical natural history and the overshadowing presence of experimental laboratory-based physiology, which was the dominant aspect of late 19th century biology, is a remarkable, and poorly studied, phase in the history of biology (Frey 1963a; Coleman 1977; Egerton 1976; Lowe 1976; Mclntosh 1976, 1983a; Cox 1979; Cittadino 1980, 1981; Tobey 1981). Oscar Drude, an eminent German plant geographer and a major influence on the development of plant ecology in America, aptly described the sudden recognition of ecology at the Congress of Arts and Sciences meeting at the Universal Exposition in St. Louis in 1904:

In spite of the fact that ecology was coined in 1866 and had been, unnoticed, in the literature since then, it was, as Drude stated, essentially unknown in 1890.

Whatever may be said of the origins of ecology in the Greek science of Hippocrates, Aristotle, and Theophrastus, or in 18th-century natural history as exemplified by Linnaeus and Buffon, or even in Darwinian evolutionary biology, its rise as a named and “self-conscious” discipline with its own practitioners was essentially in the last decade of the 19th century (Allee et al. 1949). Ecologists began to define ecology by doing it and recognizing that they were doing it.

An attempt to write a general account of the origins, development and current problems of ecology, even within the constraints noted below, might well be thought foolhardy. Ecology built upon traditions of natural history beginning in classical antiquity but developed as a science in the context of late 19th-century biology, natural history surveys, and conservation. It became widely known to the general public, often in distorted forms, only in the 1960s. It has been called polymorphic because it appeared and continues in numerous and different forms appropriate to the enormous variability and complexity of the things studied by ecologists. Until recently, ecology has not excited the interest of historians of science, and detailed historical studies of ecology or biographical works about ecologists are few. This volume was not, however written to fill the need for careful historical analyses of ecology and its relation to biology and to environmental concerns, although it leans heavily on those now available. It is an attempt to provide an account of the background of ecology and suggest its relevance to current problems of ecology as a science. It has an underlying assumption that some of the difficulties and conflicts now manifest in ecology can be better resolved if ecologists, particularly younger ecologists, become familiar with what went before them and their mentors and outside their immediate interests.

Like the word ecology, ecosystem was applied to a concept with a long history. It also had a number of competing synonyms when it was coined, suggesting that the time was ripe for its appearance, and there was a lag period between its coinage and its widespread incorporation into ecological science. The British plant ecologist Tansley (1935) introduced ecosystem in the context of a discussion of the superorganism concept of the plant community and succession which was developed around 1905 by F. E. Clements and was still being strongly advocated in the 1930s by the South African botanist John Phillips. Tansley commented that Phillips's articles “remind one irresistably of the exposition of a creed – of a closed system of religious or philosophical dogma,” a flavor not entirely missing from some later expositions of “systems ecology,” facetiously called “theological ecology” (Van Dyne 1980).

Godwin (1977) noted that Tansley, like many biologists of his era, was “remarkably unspecialized” and a man “of wide culture and familiarity with many sciences,” just what the ecosystem concept called for. Tansley was also well read in philosophy and psychology, having studied with Freud, which, perhaps, influenced his ecological thought. He defined ecosystem as

Ecology in its early years was sometimes decried as not a science at all but merely a point of view. After nearly a century of trying to erect a conceptual, methodological, and theoretical framework for the most complex phenomena encountered in nature, ecology was familiar only to a relatively small number of academic biologists and applied biologists, range managers, foresters, and fishery and game managers. These shared an overlapping, but not coincident, network of concepts, methodologies, professional associations, publications, funding sources, and concerns about the relations of organisms as populations and communities to their environment. In the wake of widespread recognition, in the 1960s, of the “environmental crisis,” ecology was abruptly thrust into the public arena and widely hailed as an appropriate guide to the relation of humans, as well as other forms of life, to their environment. Strikingly, ecology became a watchword, even in high political circles, just when Paul B. Sears, one of its most articulate practitioners and expositors, described ecology as “a subversive subject” (Sears 1964). Sears's point was that the view of nature derived from ecological studies called into question some of the cultural and economic premises widely accepted by Western societies. Chief among these premises was that human civilizations, particularly of advanced technological cultures, were above or outside the limitations, or “laws,” of nature (Dunlap 1980b).

The 18th century produced at least the beginning of a change in natural history from a view of nature as a divinely ordered, essentially static system following a providential mandate to a dynamic “historically changing” entity endowed with “self-activating” and “self-realizing” powers (Lyon and Sloan 1981). This conception of natural history persisted in the early 19th century in “Humboldtian science” (Cannon 1978). Its canon of “accurate measured study of widespread but interconnected phenomena . . . to find a definite law and a dynamical cause” was continued by the rising science of ecology in the late 19th century. A major theme of functional, experimental biology as it developed in the 19th century was its emphasis on progressive change as the most significant characteristic of natural phenomena (Coleman 1977). Whether ecology is seen as emerging from 18th- or 19th-century natural history, from 19th-century mechanistic physiology, or some amalgam of these, the conception sometimes encountered of early self-conscious ecology as descending from and embodying a static, typological, descriptive progenitor needs to be reconsidered. Certainly in the view of most of its early proponents and practitioners, the key word for ecology was dynamic. This was explicit in the writings of the leading figures of ecology as it became a self-conscious science. If they or lesser ecologists failed immediately to emphasize all of the ideas that later came to typify the “new” dynamic or functional ecology, it should not be assumed that first-generation ecologists were content with description as the aim of ecology.

All definitions of ecology agree that it has to do with the interrelationships of organisms and environment. The organism of greatest concern is Homo sapiens. Glacken (1967) commented that every thinker from the 5th century B.C. to the end of the 18th century A.D. had something to say about the earthly environment and humans' relation to it. There has been no letup in the 19th and 20th centuries. Indeed, concern with the environment, or broadly speaking nature, became central to human concerns (Ekirch 1963; Nash 1967; Passmore 1974; Sheail 1976). Ekirch (1963:1) wrote, “Man and nature is the basic fundamental fact of history.” Although the concept of nature has a long history and many diverse interpretations (Hepburn 1967; Kormondy 1974, 1978; Hausman 1975), the antithesis implied in Ekirch's phrase is characteristic of most traditional Western environmental thought. Nature is commonly thought of as that part of the physical world other than humanity and its constructions, and natural commonly implies phenomena taking place without human involvement. Some, like Kormondy, question the distinction but retain it as useful. Passmore wished he could avoid the word nature, describing it as “ambiguous” but also “indispensable.” In familiar usage, nature is “man's” environment and clearly has shaped “his” biological and cultural history. Stilgoe (1982) contrasted the landscape as the environment created by humans with wilderness as a threatening, evil area beyond human control, a contrast to the romantic view of wilderness.

The early traditions of self-conscious ecology were marked by the tendency of ecologists to study either an individual species or aggregates of species. Proponents of the new biology of the 19th century concentrated on morphological and physiological properties of species, typically in the laboratory. As protoecologists returned to study of organisms in the field, they combined some of the interests and skills of physiologists and morphologists with the concerns of biogeographers and natural historians about distributions of and interrelations among species. One of the earliest terminological distinctions made in the emergence of “self-conscious” ecology was (in 1896) the addition of prefixes to create “autecology” and “synecology” (Chapman 1931). Aut-literally designates “self” or “individual,” but in ecological practice it described studies of a small group of individuals of a species, which was regarded as a unit. Ambiguity was avoided, temporarily, by Adams (1913), who distinguished three classes of ecology: “individual,” “aggregate,” specifying the taxonomic unit, and “associational,” citing Mobius's biocoenose as an example of the last. Adams's contemporary, Shelford (1929:608), had little use for autecology. To Shelford, at that date at least:

Among the more startling assertions in the contemporary ecological literature are “Community ecology is in its infancy” (Pianka 1980) and “Recently ecologists have expanded their scope from studies of single species populations to include analysis of broader assemblages of several co-occurring species loosely defined as communities” (Peterson 1975). In fact, the study of communities or assemblages of co-occurring species is one of the oldest of concerns that may be reasonably identified as ecological. The clearest way to distinguish self-conscious ecology from the other elements of natural history, genetics, physiology, or evolution with which it overlaps is its concern with organisms as members of multispecies aggregates, under a variety of pseudonyms: census, formations, coenoses, associations, societies, guilds,or more generally, communities.The long tradition of natural history, the ordinary experience of farmers, seamen, woodsmen, hunters, anglers, and herbalists, indeed, of the earliest of food gatherers, and the plethora of words in many languages describing particular kinds of aggregates of organisms, and often their associated habitats, testifies that the earth is covered with a complex pattern of “more or less” recognizable plant and animal communities.

Biogeographical origins

Although references to communities studded the classic literature of natural history, it is usual to attribute to Humboldt the earliest formal recognition of “association” based on the growth forms of the plants which gave the association the distinctive appearance or physiognomy by which it was recognized (Humboldt and Bonpland 1807).