PREFACE DURING the collegiate year 1916-1917, the conduct of the Yale Chapter of the honorary scientific society of the Sigma Xi was entrusted to my guidance, and in order to render the meetings of the chapter as profitable as possible, a symposium was proposed on the geological and biological evidences for the evolution of our planet and the earth-borne life. I therefore asked such of my colleagues as were authorities on the several subjects involved to prepare addresses to be delivered before the chapter and later to be published in the form of the present book. The course of lectures was as follows: THE EVOLUTION OF THE EARTH AND ITS INHABITANTS Lecture I. The Origin of the Earth, November 23, 1916, Professor Joseph Barrell. Lecture II. The Earth's Changing Surface and Climate, December 13, 1916, Professor Charles Schuchert. Lecture III. The Origin of Life, January 24, 1917, Professor Lorande Loss Woodruff. Lecture IV. The Pulse of Life, February 15, 1917, Professor Richard Swann Lull. Lecture V. Climate and Civilization, April 20, 1917, Doctor Ellsworth Huntington. The scope of the combined essays is of necessity very broad, ranging as it does from a conception of the universe to the trend of modern civilization. Thus the first chapter deals not alone with the genesis of the earth but of the parent solar system, and, the earth having been established, its history is traced until the time of its becoming a fit environment for the abode of life. The second lecture deals with the changing lines of demarcation between land and sea, the rise and growth of continents, the formation and severance of land-bridges, and the climatic changes which are recorded for geologic time. The physical environment once established, Professor Woodruff tells what we know and do not know of the origin of life. This is largely an academic discussion of the several theories which have been advanced to account for the evolution of lifeless into living matter, for from the nature of the problem evidences of direct observation are not available. The lecture on the pulse of life attempts to link up cause and effect; to find those forces which are responsible for the more or less rhythmic accelerations of evolution shown by the fossil record. The main cause is found to be climatic change, which in turn has as a chief controlling factor earth shrinkage and the consequent warping of the crust discussed in the second lecture. The pulse of life applies not alone to the evolution of animals and plants, but also to mankind. How climatic changes have influenced the growth of civilization and the formation of racial characteristics of mentality is set forth in the last lecture, that by Doctor Huntington. In so far as possible, these essays are the fruits of the original research of their several authors, which in certain instances are set forth here for the first time. The treatment of the entire subject and the marshaling of the facts thus assembled are entirely new. I am deeply grateful to my colleagues, not only for their having accepted the tasks thus laid upon them, which in several instances implied new and extensive research, but also for the success with which the lectures were presented, as attested by the society. RICHARD SWANN LULL, President, Yale Chapter, Sigma XI. 1916-1917. Yale University, December 1, 1917. |