With added leisure, there is usually increasing development in the arts and in religion. As more time can be devoted to religious practices, ceremonies tend to become more elaborate and more formalized. Often a priestly caste will arise which, as in the case of the concentration of secular power, may result in autocracy. The Pueblos seem to have avoided this danger too. The many kivas suggest that religion and its ceremonial expression must have played a strong part in their daily lives, as it does today. Undoubtedly there were priests who were figures of importance in the community, but there is no evidence that they wielded an autocratic power which gave them great material advantages over other members of the group. Community living will have other far-reaching influences. When only a small family group is living together, it must be almost entirely self-sufficient and must produce practically everything which it uses. As the group increases in size, specialization also tends to increase. For example, a woman who makes exceptional baskets, but is not a particularly skillful potter, may come to specialize in the making of baskets which she can exchange for pottery made by someone who produces a finer ware. Familiarity with the work of others will also stimulate development, for new ideas will have a wider distribution and competition will serve as a stimulating factor. There was no basic change in type of structure, for the great houses were, in a sense, much enlarged and modified unit houses. The great change lay in the joining together of great numbers of people. It must not be thought, however, that all of the people lived in huge communal dwellings such as those of Mesa Verde or Chaco Canyon. Actually many groups continued to live in unit houses at a considerable distance from the main centers, and many of the so-called great houses contained only a small number of rooms. The really big houses were in the minority and would appear to have been capable of sheltering only a small fraction of the total population.