Many of the earliest pithouses, perhaps the very first ones, were built in caves. The people had used the caves for centuries and it was only natural that they should build houses there. Within a short time, however, there was a movement toward the open country and soon pithouse villages were being built on the mesa tops and in open valleys. The caves, although they provided shelter from the winter’s storms, were cold and uncomfortable for the sun shone in only a few hours each day. With substantial houses the people no longer feared the rigors of winter and life in the open was far more pleasant than in the cold, shadowy caves. By the seventh century most of the people seem to have moved out of the caves and they were seldom used until the time when the cliff dwellings were built. One of the far-reaching effects of the permanent house was its influence on true family life. Before this time the people probably had lived in haphazard groups with little opportunity for development of the true family. The house changed all this. In most instances a small pithouse probably served as the dwelling place of a single family and this gave new meaning to the family as a compact unit. Family ties, relationships and inheritance probably took on new meanings. As generations passed the houses improved and toward the end of the period an important development came. For some time the people had built slab-lined storage rooms around their pithouses. At first they were small but gradually they were enlarged until they could serve as living rooms. The floor was slightly below ground level and the walls of the pit were lined with stone slabs. The above-ground walls were built of poles and adobe and the flat roof was of similar materials. The rooms became rectangular and the side walls vertical making it possible to join them together in long rows. At the end of the period many of the villages consisted of long rows of living rooms in front of which were a few of the old-type pithouses. These pithouses grew deeper and gradually seem to have developed into ceremonial rooms. This was the beginning of the kiva, a subterranean room which is still used for this purpose by present-day Pueblo Indians. Ruins of the type described above are called slab-house villages because of the stone slabs which lined the walls of the living rooms. The third cultural trait which set the Modified Basket Makers apart from their ancestors, the Basket Makers, was the bow and arrow. Again the people borrowed. The bow and arrow is such a complicated combination that it is easier to believe it was invented once, then spread over the world, than that it was invented several times by different people. The invention occurred in the Old World and the weapon was brought to America by many bands of immigrants.