The same may be said of climate, floras and faunas. The inventive skill that leads to mechanical improvements in social industries, and the rise of pastoral and agricultural occupations, are essentially the outcome of long experience under the unprogressive influences inherent in mankind. In fact, the fundamental principles of the two civilizations are so divergent that the Neolithic can hardly be regarded as a local development of that of the Palæolithic period. It was the striking difference between the practical elements of the two civilizations that gave rise to the theory that after the close of the Palæolithic period there was a break, or hiatus, in the continuity of human existence in Western Europe. Hence arose an animated controversy which divided archæologists into two opposing camps—one contending that the Quaternary population followed the retreating ice and its associated fauna northwards, leaving behind them a desert land; the other maintaining that they became amalgamated with new races from Eastern lands, and that their blood still permeates the veins of the modern inhabitants of Europe. In earlier days the former doctrine was advocated by some of the foremost authorities, such as Ed. Lartet, G. de Mortillet and others, but it is now largely discarded. On the other hand, Paul Broca and a few other distinguished archæologists maintained from the very outset that the flint tools of the later Palæolithic stations and those of Neolithic times were not so dissimilar as to
