ABSTRACT
The first important thing to note is that the creative process of natural selection is driven by the environment; ultimately by the climatic changes which inevitably occur. The environment, with its ever-changing climatic, mineral, and organic components, brings about the evolutionary process through its effect on heritable variation and is a primary factor in the creation of the multitudinous species of animal and plant life. An examination of the history of humankind's environments can therefore give us direct insight into the actual process of human evolution. The ecosystem is the basic analytical unit of ecology, and it is thus a very complex arrangement of components such that change in any one component will effect most if not all other components. The expression of such changes in ecosystems is theoretically predictable, but in practice the system is usually so complex that a reliable prediction of the outcome is impossible.
