owth of the community and with the
changing institutions under which men have lived. Institutions are not
only themselves the result of a selective and adaptive process which
shapes the prevailing or dominant types of spiritual attitude and
aptitudes; they are at the same time special methods of life and of
human relations, and are therefore in their turn efficient factors of
selection. So that the changing institutions in their turn make for a
further selection of individuals endowed with the fittest temperament,
and a further adaptation of individual temperament and habits to the
changing environment through the formation of new institutions.

The forces which have shaped the development of human life and of social
structure are no doubt ultimately reducible to terms of living tissue
and material environment; but proximately for the purpose in hand, these
forces may best be stated in terms of an environment, partly human,
partly non-human, and a human subject with a more or less definite
physical and intellectual constitution. Taken in the aggregate or
average, this human subject is more or less variable; chiefly, no doubt,
under a rule of selective conservation of favorable variations.
The selection of favorable variations is perhaps in great measure a
selective conservation of ethnic types. In the life history of any
community whose population is made up of a mixture of divers ethnic
elements, one or another of several persistent and relatively stable
types of body and of temperament rises into dominance at any given
point. The situation, including the institutions in force at any given
time, will favor the survival and dominance of one type of character in
preference to another; and the type of man so selected to continue and
to further elaborate the institutions handed down from the past will in
some considerable measure shape these institutions in his own likeness.
But apart from selection as between relatively stable types of character
and habits of mind, there is no doubt simultaneously going on a process
of selective adaptation of habits of thought within the general range of
aptitudes which is characteristic of the dominant ethnic type or types.
There may be a variation in the fundamental character of any population
by selection between relatively stable types; but there is also a
variation due to adaptation in detail within the range of the type, and
to selection between specific habitual views regarding any