Zoologically, man is merely one of the creatures that arrived in the course of time, along with other mammals. Just when he arrived and how he looked at the time of his coming cannot be determined from a study of fossils. Perhaps it is of no importance. There is nothing to indicate his existence before the Cenozoic, no completely satisfactory proof of existence before the Pleistocene period. As with other inhabitants of the earth, it is probable that he became prominent only after a great deal of competition with other creatures which kept his ancestors submerged for thousands of years. The Ice Age, with its check upon the progress of competing animals, undoubtedly gave him an advantage. His superior mentality enabled him to overcome adversity by methods not available to other mammals; his inventive and mechanical genius must have been greatly strengthened by his experience during this interval. At about this point, where prehistory begins to merge into history, the geologist and paleontologist must let other interpreters carry on. Archeologists and anthropologists take up the work, and through their efforts many details have been added to our knowledge of the human race. The study of biology, which is the science of life, has provided an instructive viewpoint that enables us to see ourselves against the vast background built up by investigations into the nature of the earth and its ancient inhabitants. This science deals with living creatures as _organisms_—plants and animals so organized as to be capable of existence only in an environment which provides exact life requirements. The Age of Man has been variously characterized as an age of soul, of higher intelligence, of culture, and finally, of civilization, freedom and democracy. The “crowning glory” of the organic world is pictured in history as a creature who has busied himself for thousands of years with the building up and tearing down of civilizations. Prehistory reveals this habit as something unique in the human character, for there is no other organism that has specialized so persistently in the creation of its own environment, no other that has had the combined power and talent to produce so much change. More than anything else, the prehistoric record is a lesson in adaptation, which in its broadest sense means fitness for life under particular conditions, and always subject to organic law. Man’s efforts to bring about an adjustment between himself and his civilization have centered largely on the method of forcing himself into the mold that happens to be present, one pattern today, another tomorrow. No creature of the past has had to adapt itself to anything so radically new or so thoroughly revolutionary. The vital problem now is whether this man-made environment will prove helpful or disastrous.