A glance at the respective antecedents of individual organisms and social organisms shows why the last admit of no such definite classification as the first. Through a thousand generations a species of plant or animal leads substantially the same kind of life; and its successive members inherit the acquired adaptations. When changed conditions cause divergences of forms once alike, the accumulating differences arising in descendants only superficially disguise the original identity do not prevent the grouping of the several species into a genus; nor do wider divergences that began earlier prevent the grouping of genera into orders and orders into classes. It is otherwise with societies. Hordes of primitive men, dividing and subdividing, do, indeed, show us successions of small social aggregates leading like lives, inheriting such low structures as had resulted, and repeating those structures. But higher social aggregates propagate their respective types in much less decided ways. Though colonies tend to grow like their parents, yet the parent societies are so comparatively plastic, and the influences of new habitats on the derived societies are so great, that divergences of structure are inevitable. In the absence of definite organizations, established during the similar lives of many societies descending one from another, there cannot be the precise distinctions implied by complete classification.

Two cardinal kinds of differences there are, however, of which we may avail ourselves for grouping societies in a natural manner. Primarily we may arrange them, according to their degrees of composition, as simple, compound, doubly-compound, trebly-compound; and, secondarily, though in a less specific way, we may divide them into the predominantly predatory and the predominantly industrial those in which the organization for offense and defense is most largely developed and those in which the sustaining organization is most largely developed...

Social evolution begins with small, simple aggregates; that it progresses by the clustering of these into larger aggregates; and that, after consolidating, such clusters are united with others like themselves into still larger aggregates. Our classification, then, must begin with societies of the first or simplest order.

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