Under the severe strain of the glacial conditions the weak and incapable doubtless succumbed to the cold and deficiency of food; the strong and capable survived, gained superior powers, devised new weapons and implements, and became adapted to a new and decidedly adverse situation. From long depending, in considerable measure, on his physical powers, man came to trust more fully than before in his mental faculties, the result being a much greater variation in the size and activity of his brain than in other portions of his physical structure. While it had become more difficult to find and capture food animals, he was at the same time in greater danger from carnivorous beasts, which were forced by partial starvation to overcome their dread of man. He was thus obliged to become as alert and ready in defence as he was in attack, to associate himself more fully with his fellows in his hunting excursions and his other labors, and to adapt the forms and forces of nature still more to his needs, his career as a tool-making animal being greatly stimulated by the necessities of his situation. It is conceivable that the art of agriculture may have been one of the outcomes of the situation in which man now found himself. The decrease in the food supply must have put all his powers of invention to the test, and the probable diminution in number and productiveness of food plants may have served as an instigation to the cultivation of useful plants, and the preservation of their products, where possible, for winter supply. It is not unlikely that in this way and under this stimulation agriculture began, and that it made its way subsequently from this locality to more southern regions. In this, however, we cannot go beyond conjecture. It seems useless to pursue this topic further, since the absence of facts forces us to confine ourselves largely to suggestions and probabilities. We have arrived at two definite hypotheses: first, that the original stage of man's progress upward from the apes was completed when he gained dominion over the animal kingdom and attained the condition of the forest pygmies; second, that an advanced stage was reached when he achieved the conquest of nature, so far as overcoming the exceedingly adverse conditions of the Glacial Age was concerned. At the close of this period of frigid cold man emerged as a higher being than the forest nomad or the agricultural people of the tropics, possessed of much superior arts and implements and with largely enhanced mental powers. The long and bitter struggle for existence through which he had passed had lifted him to a much higher level in the upward progress of life.