If age went with size, the extinct saurians would have attained the greatest age of all animals, and in fact they seem to have grown all their lives. However it may have been in past geologic ages, it may yet appear that man, on the average, lives longer than any brutes. This he should do if the civilization he has evolved really gives him a more favorable environment than nature and instinct have provided for him. Species, like individuals, very probably have a term of life and become extinct with age, as paleontology shows us not a few have done. But here, too, there is no sufficient basis of fact at present to warrant the generalizations so often met with concerning phyletic immortality or senescence. To some aspects of this theme I shall recur later in this volume. Of the length of life of the predecessors of modern man we know almost nothing. In evolving as he did from anthropoid forms, he probably also considerably increased his span of life. It would seem, too, as if again in the transition from the unsocial, short, and still somewhat simian Neanderthal to that of the tall and more gregarious Crô-Magnon type he must have still further increased his longevity. But through all the paleolithic ages (lasting some 125,000 years as H. F. Osborn calculates[31]) there are no data either in the skeletal remains or in the implements he used that shed any clear light upon the subject; and the same is true of the neolithic cults that flowered in the lake- or pile-dwellings. Bones show different stages of development, and teeth, always remarkably well preserved, often show the effects of use; a very few represent children but not one illustrates extreme old age according to the osseous or dental criteria of modern times. Hence we may conjecture that the attainment of great age under the conditions of life then prevailing was very rare. It would seem also that if life had been long and its experiences well ripened, preserved, and transmitted (so that each new generation would not merely repeat the life of that which had preceded it but profit by its lessons), progress would not have been so very slow, as it was. On the other hand, it might be urged perhaps with equal force that if, as with lower races now, most of the people who made prehistory not only matured but grew old early, and since age always tends to be conservative and unprogressive, it would make for retardation, even though it came in years that seem premature to us. Very probably even in these rude stages of life men who felt their physical powers beginning to abate--at least the more sagacious of them--had already hit upon some of the many devices by which the aging have very commonly contrived to maintain their position and even increase their importance in the community by developing wisdom in counsel, becoming repertories of tribal tradition and custom, and representatives of feared supernatural forces or persons, etc. But of