562 THE AMERICAN JOURNAL OF SOCIOLOGY
of the species with the environment. The same conquest is achieved, as we shall see through the creation of progressive social organizations and more and more perfect social types.
All social structures, either vegetable, animal, or human, have been due to adaptation, habit, heredity, and natural and artificial selection. Among human societies the species itself intervenes systematically and consciously in the play of these natural factors. It directs and modifies them to its advantage, but always, how- ever, by conforming to the laws of nature. It acts somewhat after the manner of the man-midwife who facilitates and assures parturition.
Lamarck attributed a predominance to the influence of environment, habit, and heredity, while Darwin attributed the predominance to selection. These influences perfectly reconcile themselves. They complete each other. Adaptation and selec- tion are the factors which chiefly explain the variations. Habit and heredity intervene in order to fix and consolidate the varia- tions without which the gains would always be eventual and never capitalized.
The Darwinian theory of natural selection and struggle for existence is an extension to the whole organic kingdom of the theory of Malthus concerning population. But selection and adaptation not only imply the destruction of the most feeble individuals and species that is to say, they imply not only an action destructive and negative in character, but they comprehend also the organic, conservative, ameliorative, and positive func- tions. In human societies the question is imposed upon the societies themselves of discerning the types which would be in reality most advantageous to conserve, even though the present social state may seem to place the types chosen in a sort of inferiority.
We have already shown in the organic life in general that the struggle gives the supremacy to the superior collective forms which tend to place the very feeble individuals, considered sepa- rately, in more favorable conditions than the very powerful indi- viduals in an isolated or imperfectly aggregated state (forests, prairies, gregarious animals, etc.).
