Taking his point of departure from the Darwinian notion of the "web of life," Park conceived of a biotic order, common to animals and plants, to which he applied the term "community." "The essential characteristics of a community," he writes, "are those of: 1) a population, territorially organized, 2) more or less completely rooted in the soil it occupies, 3) its individual units living in a relationship of mutual interdependence that is symbiotic." "These symbiotic societies are not merely unorganized assemblages of plants and animals which happen to live together in the same habitat. On the contrary, they are interrelated in the most complex manner." Within the limits of a symbiotic community, different individual units of the population are involved in a complex form of competitive cooperation leading to a spatial order in which each individual unit is assigned a niche in the environment commensurate with its ability to impose itself. Competition gives rise to the two main ecological principles, dominance and succession. "In every life-community this dominance is ordinarily the result of struggle among the different species for light." Succession, on the other hand, denotes the various stages, the "orderly sequence of changes, through which a biotic community passes in the course of its development."
Park maintained that the processes characterizing the growth and development of plant and animal communities applied to human communities as well. The spatial location of various groups in the city reflects ecological processes as much as the spatial order of an animal community. But, and this has often been overlooked, Park also argued that while human communities exhibited an ecological or symbiotic order quite similar to that of nonhuman communities, they also participated in a social or moral order that had no counterpart on the nonhuman level. Park studied the ecological order to understand better man's moral order.
The competitive struggle for economic advantage among men had many analogies, Park reasoned, with the impersonal struggle for existence among animals. "The principle of dominance operates in the human as well as in the plant and animal communities. The so-called natural or functional areas of a metropolitan community . . . owe their existence directly to the factor of dominance, and indirectly to competition.'' Similarly, the territorial succession of immigrant groups in the "natural areas" of the city can best be conceived in analogy with successions in the development of animal and plant communities. "It has been observed," Park writes, ̉that immigrant people ordinarily settle first in or near the centers of cities, in the so-called areas of transition. From there they are likely to move by stages . . . from an area of first to areas of second and third settlement, generally in the direction of the periphery of the city and eventually into the suburban area. . . . To these movements, seeing in them the effects of natural tendencies in the life of the urban community, students have applied the term 'succession.' ̉
Park argued that human groupings, insofar as they participate in biotic communities and form a distinctive ecological order, can be studied through methods borrowed from biologists who investigate nonhuman communities. Yet, if only such methods were used, one could not hope to capture that which is distinctly human, the creation of a moral order. Human societies have a double aspect: they are made up of interdependent individuals competing with each other for economic and territorial dominance and for ecological niches, but who are, at the same time, involved in common collective actions.
[Societies] are composed of individuals who act independently of one another, who compete and struggle with one another for mere existence, and treat one another, as far as possible, as utilities. On the other hand, it is quite as true that men and women are bound together by affections and common purposes; they do cherish traditions, ambitions, and ideals that are not all their own, and they maintain, in spite of natural impulse to the contrary, a discipline and a moral order that enables them to transcend what we ordinarily call nature, and through their collective action, recreate the world in the image of their collective aspirations and their common will. . . . Society . . . always includes something more than competitive cooperation and its resulting economic interdependence. The existence of a society presupposes a certain amount of solidarity, consensus and common purpose . . . [societies] grow up in the efforts of individuals to act collectively.
In the moral or social order, as distinct from the ecological order, men participate as self-conscious individuals in communication with one another and hence are able to engage in collective action. The social order softens the impact of the competitive struggle for existence through social control and involvement in common tasks.
From Coser, 1977:363-364.