indicates those regions where energy is highest. It is based upon
measurements of the strength of scores of individuals, upon the
scholastic records of hundreds of college students, upon the
piecework of thousands of factory operatives, and upon millions
of deaths and births in a score of different countries. It takes
account of three chief climatic conditions--temperature,
humidity, and variability. It also takes account of mental as
well as physical ability. Underneath it is a map of the
distribution of civilization on the basis of the opinion of fifty
authorities in fifteen different countries. The similarity of the
two maps is so striking that there can be little question that
today the distribution of civilization agrees closely with the
distribution of climatic energy. When Egypt, Babylonia, Greece,
and Rome were at the height of their power this agreement was
presumably the same, for the storm belt which now gives
variability and hence energy to the thickly shaded regions in our
two maps then apparently lay farther south. It is generally
considered that no race has been more closely dependent upon
physical environment than were the Indians. Why, then, did the
energizing effect of climate apparently have less effect upon
them than upon the other great races? Why were not the most
advanced Indian tribes found in the same places where white
civilization is today most advanced? Climatic changes might in
part account for the difference, but, although such changes
apparently took place on a large scale in earlier times, there is
no evidence of anything except minor fluctuations since the days
of the first white settlements. Racial inheritance likewise may
account for some of the differences among the various tribes, but
it was probably not the chief factor. That factor was apparently
the condition of agriculture among people who had neither iron