theory, all the races of mankind had a common origin. But where
did man make the change from a four-handed, tree-dwelling little
ape to a much larger, upright creature with two hands and two
feet? It is a mistake to suppose that because he is hairless he
must have originated in a warm climate. In fact quite the
opposite seems to be the case, for apparently he lost his hair
because he took to wearing the skins of slain beasts in order
that he might have not only his own hair but that of other
animals as a protection from the cold.

In our search for the starting-place of man's slow migration to
America our first step should be to ascertain what responses to
physical environment are common to all men. If we find that all
men live and thrive best under certain climatic conditions, it is
fair to assume that those conditions prevailed in man's original
home, and this conclusion will enable us to cast out of the
reckoning the regions where they do not prevail. A study of the
relations of millions of deaths to weather conditions indicates
that the white race is physically at its best when the average
temperature for night and day ranges from about 50 to 73 degrees
F. and when the air is neither extremely moist nor extremely dry.
In addition to these conditions there must be not only seasonal
changes but frequent changes from day to day. Such changes are
possible only where there is a distinct winter and where storms
are of frequent occurrence. The best climate is, therefore, one
where the temperature ranges from not much below the
freezing-point at night in winter to about 80 degrees F. by day
in summer, and where the storms which bring daily changes are
frequent at all seasons.