In anatomy I have especially profited by the co-operation of my former student and present university colleague Professor J. Howard McGregor, of Columbia, who has shown great anatomical as well as artistic skill in the restoration of the heads of the four races of _Trinil_, _Piltdown_, _Neanderthal_, and _Crô-Magnon_. The new reconstruction of the Piltdown head is with the aid of casts sent to me by my friend Doctor A. Smith Woodward, of the British Museum of Natural History. The problem of reconstruction of the Piltdown skull has, through the differences of interpretation by Smith Woodward, Elliot Smith, and Arthur Keith, become one of the _causes célèbres_ of anthropology. On the placing of the fragments of the skull and jaws, which have few points of contact, depends the all-important question of the size of the brain and the character of the profile of the face and jaws. In Professor McGregor's reconstruction different methods have been used from those employed by the British anatomists, and advantage has been taken of an observation of Mr. A. E. Anderson that the single canine tooth belongs in the upper and not in the lower jaw. In these models, and in all the restorations of men by Charles R. Knight under my direction, the controlling principle has been to make the restoration as _human_ as the anatomical evidence will admit. This principle is based upon the theory for which I believe very strong grounds may be adduced, that all these races represent stages of advancing and progressive development; it has seemed to me, therefore, that in our restorations we should indicate as much alertness, intelligence, and upward tendency as possible. Such progressive expression may, in fact, be observed in the faces of the higher anthropoid apes, such as the chimpanzees and orangs, when in process of education. No doubt, our ancestors of the early Stone Age were brutal in many respects, but the representations which have been made chiefly by French and German artists of men with strong gorilla or chimpanzee characteristics are, I believe, unwarranted by the anatomical remains and are contrary to the conception which we must form of beings in the scale of rapidly ascending intelligence. HENRY FAIRFIELD OSBORN. AMERICAN MUSEUM OF NATURAL HISTORY June 21, 1915. CONTENTS INTRODUCTION PAGE GREEK CONCEPTIONS OF MAN'S ORIGIN 1 RISE OF ANTHROPOLOGY 3 RISE OF ARCHÆOLGY 10 GEOLIGIC HISTORY OF MAN 18 GEOGRAPHIC CHANGES 34 CLIMATIC CHANGES 37 MIGRATIONS OF MAMMALS 42 CHAPTER I ANCESTRY OF THE ANTHROPOID APES 49