Excerpt from the book:

The contributions of biogeography and natural history to the study of evolution in the historic past have been outstanding and continue to be important. In recent years nearly every discipline of biology and many of the earth sciences have been involved. Sensational progress in genetics and molecular biology have tended to obscure the fact that these disciplines, as well as paleontology and developmental biology, all have different roles to play in the total picture. Approaches based on the physical sciences, in which experimental methods and mathematical modeling seek general laws, fail to account for the historical nature and changing complexities of living organisms. The theory of intermittent frontiers takes these ecological, historical, and geographic variables into account in explaining the courses and rates of evolution at the level of individual populations. It is my view that an understanding of how natural selection operates requires study of a wide variety of variable factors changing through time. This is characteristic of nature today, as it was in the past.