Surprising as it may seem, this study indicates that similar conditions are best for all sorts of races.
America is the last great goal of these migrations.
According to the now almost universally accepted theory, all the races of mankind had a common origin.
The evidence points to central Asia as man's original home, for the general movement of human migrations has been outward from that region and not inward.
It seems strange that almost no other traces of the strong vikings are found in America.
The Indians could not undertake any widespread cultivation of the plains not only because they lacked iron tools but also because they had no draft animals.
After washing there was no place to pour the water except out of the window onto the heads of the people in the streets, which is the proper place to throw everything that is not wanted.
The geysers and hot springs of the Yellowstone are another proof of recent volcanic activity.
Today, no less than in the past, the tetrahedral form of the earth and the relation of the tetrahedron to the poles and to the equator preserve the conditions that favor rapid evolution.
Again and again, to be sure, on the way to America, and under many other circumstances, man has passed through the most adverse climates and has survived, but he has flourished and waxed strong only in certain zones.