For the source of any characteristic so widespread and uniform as this adaptation to environment we must go back to the very beginning of the human race.

Although mountains may guide migrations, the plains are the regions where people dwell in greatest numbers.

With every throb of the climatic pulse which we have felt in Central Asia,, the centre of civilisation has moved this way and that. Each throb has sent pain and decay to the lands whose day was done, life and vigour to those whose day was yet to be.

The whole history of life is a record of cycles.

The coast of British Columbia was one of the three chief centers of aboriginal America.

Although farming of any sort was almost as impossible in the plains as in the dry regions of winter rains farther west, the abundance of buffaloes made life much easier in many respects.

For the source of any characteristic so widespread and uniform as this adaptation to environment we must go back to the very beginning of the human race.