The discussion of the extraordinary develop ment of intellectual history in the last half cen tury furnishes the logical transition from a dis cussion of those recent trends in historiography which have grown primarily out of the Indus trial revolution to those which have been a product of the remarkable progress in natural science in the last hundred years. As the in dustrial revolution was the great event in the economic and social history of the 19th century, so• the discovery of the Darwinian theory of evolution was the central fact in the develop ment of natural science in this period. While, as Professor Osborn and others have shown, the idea of evolution is an old one which orig inated in a certain crude and formal sense, at least, with the same Ionic Greeks that began the writing of prose and of history, its true significance as a fact in science and philosophy began with the publication of Darwin's of the Species) in 1859. With the subsequent controversies over the details of the doctrine of natural selection one is not here concerned. Its reaction upon the outlook of the alert and pro gressive historical student was profound. Spen cer worked over the whole field of social sci ence from the evolutionary standpoint and gave it a genetic trend and meaning from which it could never escape. Enterprising biologists and sociologists like Schallmayer and Ammon in Germany, Lapouge in France, Galton in Eng land and Keller to America have attempted to work out a science of social evolution con ceived in terms of biological evolution carried over into the social field. Others, among them several distinguished historians, have essayed histories of religion and ethics based upon the new revolutionary conceptions and criteria. In this field the work of Spencer, Lecky, Leslie Stephen, Kidd, Hobhouse, Fiske and Suther land has been most notable. Finally, an at tempt to put the of law and •politics upon an evolutionary basis was initiated in the suggestive writings of the school of sociologists and political scientists and of Maine, Bagehot and Ritchie. On the whole, however, the outstanding reaction of the new evolutionary conceptions upon historiography did not consist so much in the various special phases of their application to historical prob lems which have been mentioned above as in fixing upon the historian's mind the perception of the genetic nature of the social process and in giving him a firm basis upon which to develop a sound theory of progress.
With the general acceptance of the evolution ary hypothesis as to the origin and development of the human race it was inevitable that much greater attention would be given to the in fluence of the physical environment upon his torical development. The general notion of the effect of physical environment upon- human types and their behavior was an exceedingly old one which had originated with Hippocrates and had been passed on through the ages by Aristotle, Strabo, Vitruvius, Aquinas, Ibn Khaldtm, Bodin and Montesquieu. While their general observations had some rough similarity to the conclusions of modern students,. their ex planations of environmental causation were most crude, being based primarily upon the doctrine of the alleged planetary influences upon the physiological processes of the human body. The foundations of a scientific study of the relation between geography and history were laid by the monumental studies of Karl Ritter in the first half of the 19th century, which were interpreted to the public in a more popular form by Guyot. Ritter found a worthy successor in Friedrich Ratzel whose profound and voluminous works are conventionally held to have founded the science of anthropogeog raphy. His researches were rivalled in France by those of Elisee Reclus and were interpreted to the English and American world by his pupil, Miss Ellen Semple. In addition to the
systematic works of Ratzel and Reclus, many suggestive contributions have been made to special phases of the influence of geography upon history. Metchnikoff has pointed out the significance of the great river systems of the world in the development of the chief historic civilizations. Demolins has dwelt in detail upon the importance for history of the configuration of the land which has determined the routes which the peoples have travelled in their various dispersals from original seats of culture. Especially noteworthy has been the suggestive, if not entirely convincing, work of Professor Huntington, whose investigations in Asia Minor have enabled him to ascertain the existence of considerable climatic oscillations in the past which throw new light on the hitherto unexplained problems of the shifting of the centres of civilization from Egypt to north western Europe and of the invasions of Europe by successive waves of Asiatic peoples. The net result of this work of students of anthropo geography has been to compel every self respecting historian to acquire some knowledge of the geographical setting of a nation before attempting to narrate its history. Historians have not been slow to appreciate the value of these studies upon the relation of ,geography to the development of civilization. Professor George has produced a stimulating attempt to indicate the general dependence of history, particularly in its military aspects, upon geographical conditions. Professor Myres has sketched in a brilliant fashion the geographic background of the rise of the earliest seats of civilization. The signifiance of geographical elements in the history of antiquity has been abundantly recognized by Professors Hogarth, Olmstead and Breasted. Ernst Curtius, a disciple of Ritter, for the first time made clear the geographical basis of the history of Greece. Freeman described in great detail the topog raphy of Sicily. Nissen has shown with admir able thoroughness the effect of Italy's topog raphy and situation upon its historical develop ment. The importance of local geographical conditions for the development of national his tory was made apparent in the case of France by Michelet; with regard to England by Green; for Germany by Riehl ; and with respect to the settlement and history of North America by Payne, Shaler, Semple, Hulbert, Brigham and Turner. Finally, Buckle and Hellwald have, with less success, attempted general surveys based upon the conception of the interdepend ence of nature and the human mind, while Hel molt has presided over the production of the first extensive co-operative history which has made a consistent attempt to emphasize the anthropological and geographical factors in his torical development according to the general doctrines of Ratzel. The above bald enumer ation of the chief phases of progress in modern anthropo-geography and its contributions to his torical interpretation, perhaps, calls for some critical reservations. In no field has there been greater exaggeration of a single set of "causes," or a more persistent flouting of the rules of critical methodology. Particularly have the adherents of this type of interpretation failed to distinguish between a "conditioning' and a "determining' influence. Finally, it is a gen erally accepted doctrine among all critical students of cultural evolution that environmen tal influences decrease in importance in propor tion as the progress of science and civilization enables man to subdue nature to his own pur poses. For these valuable criticisms of too enthusiastic an acceptance of the geographical interpretation students are more indebted to the analytical anthropologists, such as Boas, Wissler, Lowie and Goldenweiser, than to the criticism of historians.