ABSTRACT
With respect to biological change, a number of factors have been cited as initiating the struggles from which new species emerge. A change in the climate, for example, might reduce the availability of some foods, while making others more plentiful. Stimuli, whether internal or external, modest or extreme, entail conflict. In the real world, no single cause, or set of causes, explains how every change occurs. Fluctuations in our thought processes, for instance, involve different mechanisms than modifications in our personal relationships. The territory in need of investigation is vast. As we have seen, we humans belong to cognitive communities. Norms and values also cover a lot of ground. Rising to crisis proportions were disputes over slavery, alcohol, Nazism, and feminism. Many textbooks on social change identify technology as the greatest impetus to change. The number of persons in a society can grow or decline. Communities experience overpopulation and depopulation.
