An aggregation of people in one locality may originate in either one of two ways: by birth or by assembling. The individuals may have been born into the group from a common stock, or they may have come together from different localities and from different stocks. Genetic and demotic are the terms which Giddings uses to designate these kinds of aggregation.

Doubtless sometime in the far past lived the common ancestral stock from which the various races now on the earth have descended; but when that was, and in what region, are not now known. Nor have we positive knowledge as to when, or where, or from what other race any one of the several existing races was derived, although there are very probable inferences in regard to some. Then there are the differences of nationality added to those of race, and again there are local differences within each nationality, and finally each family has characteristics which distinguish it from others. In all our study of the human species, therefore, the population of the earth appears to us not as one stock, but as an endless variety of different stocks, with much intermingling of individuals and mixture of blood. There is no such thing as a pure race or nationality. All aggregations of people are demotic, or at least they were when they began.

On the other hand, the demotic group tends to become genetic as time passes. A family that begins by the union of two unrelated persons becomes in half a century a group of kindred. A valley that was settled a century ago by a score of persons who were all strangers to one another before they came there, has come to have a population of kindred: each inhabitant was born there and is related to every other inhabitant. The people of any one of the states of western Europe, and of the older commonwealths in the United States, have become to a considerable degree genetic; that is, some one stock or race predominates in each and gives it character.

This genetic unity is one basis of 'consciousness of kind" - another term from Giddings for which we shall have use later on. Kinship among primitive people is much more important than it is among civilized people. We to-day can with difficulty form a conception of the great part which kinship once played. We see it exemplified best among animals: "Birds of a feather flock together"; they also either ignore or fight those of any other kind. Barbarians often distinguish more kinds and degrees of blood relationship than we do, as shown by the terms they use; in one instance there are terms for seven different kinds of cousins. Among the early Greeks and Romans a foreigner could be naturalized only by being adopted into the family of a citizen; in other words, the ceremony of naturalization was what we should regard as a ceremony of adoption. The terms "Brother" and "Son" as titles of address are relics of the time when friendly relationship of any kind was supposed to be based on blood relationship. If it was desired to establish friendly relationship where blood relationship did not exist, a fictitious blood relationship was created.

Kinship still retains something of its old prominence among the aristocratic classes in old communities. But ordinarily distinctions of family, nationality, and race remain prominent only where stocks that are very different come together in such a way as to start rivalry between them; then it may become a matter of principle with the dominant stock to keep its blood pure; race prejudice against Jews, negroes, Orientals, or foreigners of any kind may be encouraged as a means to this end. The factor of heredity is important in a way which will be noticed in future chapters, but the tendency of the age is strongly against formal observance of it. The person who expects consideration because of his ancestry is likely to appear ridiculous. In 1911 the First Universal Races Congress met in London, at which distinguished speakers from every part of the globe for four days discussed race problems. The large university of to-day, instead of emphasizing the organization by "Nations" as did the medieval university, has its "Cosmopolitan Club" in which students of various nationalities and races meet on the basis of their common human brotherhood.