This book is in large measure an experiment. In the first place, it is an experiment in method, a method devised and tried out several years ago upon the data relating to the peoples of the Oceanic area, in an attempt to bring some sort of order out of the anthropological chaos which seemed there to prevail. The results were to me so encouraging that I was led to apply the method to the data for all the rest of the world, with what success the following pages will show. The book is also something of an experiment in that I have attempted to approach the whole racial problem de novo; have concerned myself primarily, therefore, only with the actual data, the raw facts of physical measurements, and have intentionally paid little or no heed to the conclusions of previous students.