In the Rhine valley along the middle of the course of the river we find a region of mingling or overlapping cultures which have not yet been satisfactorily disentangled. We have spoken of them as pioneers. It was a time and place of pioneer, frontier life. And frontier men and life have their peculiar physical, cultural, mental, and temperamental characteristics, almost apart from time and place. The people have something, at least, in common with the great American westward migrations and frontiersmen of a far later date. We have the successive waves of hunters, herdsmen, and farmers often overlapping or mingling. We have a grand mixing of peoples and cultures, if not of races. Many a fine art or technique is left behind. Life is rude, hard, vigorous, vital, joyous. It was so yesterday, it was probably so millennia ago. For the stratum of frontiersman and barbarian--not to say savage--lies just below the surface in us all, and a scratch exposes it. This was a period of vitality, hope, and promise. CHAPTER X NEOLITHIC RELIGION Man's ancestors, as we have seen, owed their progress to their training, policing, and harassing by stronger and better-armed competitors. The earliest vertebrates developed a notochordal rod of cartilage, and then a backbone, by the habit of swimming forced upon them by the mollusks and crustacea which held the rich feeding-grounds of the ocean bottom along the shores. In early Paleozoic time the sharks crowded the ganoids in successive waves toward and into fresh water, until finally some crawled out on the shore as amphibia. Land life and air-breathing gave the possibility of warm blood and high development of brain, and a strong tendency toward viviparous and finally intrauterine development of the embryo. Reptiles harassed mammals into the attainment of a certain amount of wariness and intelligence. The comparatively weak Primates were kept in the trees and forced to develop hand and brain by the fierce and well-armed Carnivora. Only a "saving remnant" has progressed, and these mostly under stern and strenuous pressure. The "aspiring" ape exists only in our imagination.