Environmental biology is a study in the conditions of life; these conditions impact the life within it. The conditions of life are not limited to the present time; environmental biology has applications to any time in the history (or future) of any place on earth (or beyond). The environment sets limits on the life within it. The loss of habitat is the loss of the conditions of life; that is, loss of habitat is really loss of the conditions of existence necessary for the life within. The loss of habitat is the primary cause of extinction. This book clearly identifies why habitat destruction is the primary cause of extinction, not only for today, but for all time. It establishes that the degree of habitat destruction is directly proportional to the degree of past extinction event severity. Habitat destruction creates changing, isolated environments, which seem to be a component of both destructive and creative evolutionary change.