The inhabitants of the caves and rock-shelters did not clean house every spring and fall, or, indeed, at any other time; the refuse and debris of the household were allowed to accumulate upon the floors of the caves and rock-shelters, and to this we owe nearly all the knowledge possessed by civilized man of the domestic arts, weapons, food, etc., and the general conditions under which the cave-men lived, as well as of the animals which were their contemporaries. The floors of these ancient dwellings, when excavated by scientists, show several feet of debris or accumulations, which are called "brecchia," being a conglomeration of dirt, bones of animals, bones of human beings, weapons, implements and other artifacts, which are frequently cemented with limestone formations caused by the drippings of the rocks and caves, in the nature of stalactites and stalagmites.

Not only have we learned from this "brecchia" what progress the cave-men had made in domestic art, but our knowledge of the animals which lived in the locality and were their contemporaries is almost wholly derived from rude pictures made by these cave people, who seem to have suddenly developed an artistic sense and made such pictures by etching or scratching them with sharp flints upon pieces of bone, ivory and slate. These drawings are by no means so crude and wanting in artistic skill as we would be inclined to expect. The animals depicted are readily recognizable; such drawings show groups of reindeer, now found only in the arctic regions; the wild horse; the single horned rhinoceros; the giant elk; and on a smooth piece of his own tusk, we see the curved-tusked, hairy elephant of gigantic size—the mammoth, or elephas primigenius, whose bones have been found in many parts of Europe and Asia, and of which at least one specimen was found whole with the flesh intact, in the frozen tundra of Siberia. But for these drawings—the natural history of his time—left by cave-men, we would not know that immense animals, now long extinct in Europe, had contested with men of the cave period, the ownership of the forests, swamps, plains and mountains.

In the "brecchia" of these caves, are often found long bones of animals which have been split longitudinally to obtain the marrow, which was regarded as a great delicacy by primitive man; and as some long bones of the human body have been found split in the same manner, some scientists have concluded that cave men were cannibals, or at least occasionally made a feast upon the bodies of prisoners captured in war, or upon such sacrifices when offered to the gods.

At the time when rock-shelters became favorite habitations of the people at the fire-cave, marriage relations were still loose, and any idea of male parentage was yet to come, but in a few generations, instead of accepting the birth of children without thought, it was generally believed that the supernatural beings with whom their imaginations peopled the hills, valleys, groves and ravines, were responsible for their advent. However, the more frequent and intimate association of the sexes around the fires and in preparing food by roasting, had a great effect, and it was noticeable that men and women began to pair off in the caves and rock-shelters; that such cohabitation continued for longer periods of time, and there were a number who appeared to have formed permanent unions. There was something about the fire—the social hearthstone—which tended to prolong such associations. The cheerful light of the fires; the measure of comfort they furnished, and the talkativeness promoted by companionship as the hunters related around the evening fires the adventures and experiences of that and former days, all combined to make man more of a social being, and the same influences promoted more permanency of union between couples who found themselves at all congenial.

Perhaps the example of Longhead and Broken Tooth, who had remained true to each other, had something to do with this gradual change in the relations of the sexes, but it was not until many generations after when the fact of male parentage became known to mankind, that anything at all like marriage was known or any man regarded any child or children as his own. There being no settled custom in this matter, many couples continued to unite and separate as they might feel inclined. The most that can be said is, that the use of fire in some manner appeared to promote a longer union than was common before its discovery, and that, in the progress of ages, fire seems to have been one of the agencies which greatly assisted in bringing about the present sacredness of home and marriage.

The hunters of the group still continued their coöperative search for food, and the fact that it was often impossible to determine who had killed a particular animal, while it was frequently certain that the weapons and efforts of several had a part in it, brought about a system for making an equitable distribution of all the animals taken in each expedition. First the share required by Longhead and Broken Tooth would be set apart, then the remainder was apportioned to each member of the group or to each habitation in proportion to the number of persons to be supported.

The women, too, whose task it was to find the roots and vegetables, eggs, berries and nuts which entered into their diet, began to imitate the actions of the men in this respect. They soon arranged to leave the older and more feeble women at the settlement to maintain the fires and look after the younger children, and to these was allotted a share of the food secured by the others.

These customs were established gradually and without definite enactments, or even agreements, but by common consent; they were, however, greatly promoted by Longhead, who seemed to make coöperation a sort of a hobby. They seemed to have just happened, but they were, in fact, the natural outgrowth of fire and the changed conditions due to its influence. In the course of years these customs crystallized into a communal organization in which all things, except perhaps, the weapons of a hunter and a very few personal belongings upon which the owner had expended thought and labor, were regarded as the property of the group or tribe. This communal organization of society continued for thousands of years and its vestiges still exist amid the highest enlightenment, as the foundation for business corporations, partnerships, and, indeed, all commercial and other coöperation,—communism—the greatest good to the greatest number, being the basis of all civilized laws.