Page:American Journal of Sociology Volume 4.djvu/671

Rh 2. Individual selection, which is natural selection working upon individuals who are brought into competition with one another for life and death. For instance, let us suppose that a man of genius who has not yet given to the world his invention — his machine which, if produced by him, would have great influence upon the condition of the working classes — that this man meets a burglar in his library and is shot dead. Here is a case of natural selection which determines the course of social evolution in a nation or in the world by the elimination of an individual. Such a case shows that the natural selection of individuals is a condition of importance — when the individuals are important — in social development. But it is not a force even in biology, as we have just seen. It is a negative condition ; a statement — in sociology as in biology — of evolution as it is, rather than as it would have been if the conditions had been other. This again is of especial importance in those stages of sociality in which the direct competition of individuals by physical strength or mental acuteness is in full operation.

3. The intrusion of the "physiological cycle." — In an earlier place (Sec. 43) we saw that the "cycle of causation" which psychological and sociological facts, such as beliefs, desires, etc., represent, often intrudes upon the operation of the "physiological cycle" by the personal selection of individuals in marriage. The physical heredity of the individuals is due to the mixed strains of the parents, and is in part, therefore, determined by their mutual choice of each other. The converse is also true : the physiological intrudes upon the sociological, and thus becomes an "extra-social condition" in its determination. This is seen in all cases in which physical heredity works results in individuals or groups which incapacitate them, especially endow them, or modify in any way their social fitness. A tall, manly race of men would have social advantages in winning wives from a higher group, and such marriages would tell at once inside their