Despite the growing appreciation of the fundamental relation between biology and sociology, it is still far from universal.  That the latter science is in a sense a division of the former is more often recognized by the biologist than by the average well-informed student of human social phenomena.  The layman in sociology too often concerns himself solely with the complexities of the human problems, and he remains unaware of the manifold products in the way of communal organisms far lower in the scale of life firmly established as primitive biological associations ages before the first human beings so advanced in mental stature that tribal unions were found good.  Among insects especially the biologist finds many types of organized living things, ranging widely from the solitary individual—­a counterpart of something even more primitive than the most unsocial savage now existing—­up to communities that rival human civilization, as regards the concerted effect of the diversified lives of the component units.  The student of the whole of living nature is favored still more in that he learns how the make-up of such a simple organism as a jellyfish displays principles underlying the structure of the whole and the interplay of the parts that are identical with principles of organization everywhere else.  And all of these things can be dealt with in a purely impersonal way which is impossible when attention is restricted to the human case alone.  Thus it becomes the biologist’s privilege and his duty as well to place his findings before those who wish to understand the constitution of human society in order that evils may be lessened and benefits may be extended.  He does this so far as he may be able in full confidence that the elements and basic principles are discoverable in lower nature, just as they are in the case of the material make-up and mental constitution of the single human individual.

A more explicit preliminary statement must now be given of the grounds for the belief that social evolution is but a part of organic evolution in general.  Some of these reasons are not far to seek, but their cogency can scarcely be appreciated until we have examined the concrete facts of the whole biological series.  Any human society selected for examination—­be it a tribe, a village community, or a nation—­is in last analysis an aggregate of human units and nothing besides.  Its life consists of the combined activities of such components—­and nothing else.  Could we subtract the members one by one, there would be no intangible residuum after all the people and their lives had been taken away.  When these simple facts are recognized, it is clear at once that the concerted activities performed by biological units cannot be anything but organic in their ultimate basis and nature; the evolution of such activities thus takes its place as a part of organic evolution.