Quite often the cave gave way to the pressure of the surrounding rock. Then man was hurled amidst the bones of his own victims. Thousands of years later the anthropologist (ask your father what that means) comes along with his little spade and his wheelbarrow. He digs and he digs and at last he uncovers this age-old tragedy and makes it possible for me to tell you all about it. THE END OF THE STONE AGE The struggle to keep alive during the cold period was terrible. Many races of men and animals, whose bones we have found, disappeared from the face of the earth. Whole tribes and clans were wiped out by hunger and cold and want. First the children would die and then the parents. The old people were left to the mercy of the wild animals who hastened to occupy the undefended cave. Until another change in the climate or the slowly decreasing moisture of the air made life impossible for these wild invaders and forced them to find a retreat in the heart of the African jungle where they have lived ever since. This part of my history is very difficult because the changes which I must describe were so very slow and so very gradual. Nature is never in a hurry. She has all eternity in which to accomplish her task and she can afford to bring about the necessary changes with deliberate care. Prehistoric man lived through at least four definite eras when the ice descended far down into the valleys and covered the greater part of the European continent. The last one of these periods came to an end almost thirty thousand years ago. From that moment on man left behind him concrete evidence of his existence in the form of tools and arms and pictures and in a general way we can say that history begins when the last cold period had become a thing of the past. The endless struggle for life had taught the survivors many things. Stone and wooden implements had become as common as steel tools are in our own days. Gradually the rudely chipped flint axe had been replaced by one of polished flint which was infinitely more practical. It allowed man to attack many animals at whose mercy he had been since the beginning of time. The mammoth was no longer seen. The musk-ox had retreated to the polar circle. The tiger had left Europe for good. The cave-bear no longer ate little children. The powerful brain of the weakest and most helpless of all living creatures--Man--had devised such terrible instruments of destruction that he was now the master of all the other animals. The first great victory over Nature had been gained but many others were to follow. Equipped with a full set of tools both for hunting and fishing, the cave-dweller looked for new living quarters. The shores of rivers and lakes offered the best opportunity for a regular livelihood. The old caves were deserted and the human race moved toward the water. Now that man could handle heavy axes, the felling of trees no longer offered any great difficulties.