ABSTRACT
The pre-Darwin belief was that species don’t change. They were created as perfect entities and always remain the same. However, Darwin showed that species do change. New species also come into being, whereas older species may go extinct. In this chapter, we shall discuss how species arise, change and disappear, and what forces influence those occurrences. These concepts are important to all living things, of course. However, we are particularly interested in how they help us understand the transformations that changed a tree-dwelling ape into a ground-dwelling, upright walking, large-brained human. In order to properly understand these changes, we need to understand the basic principles of evolution. For
example, changes do not occur in a species unless those changes benefit the existing species members. There is no such thing as long-term planning. Another principle is that changes can only operate on the existing plant or animal. Bat wings are made from stretched skin and not feathers for this reason.
