The Edge of Evolution - Contents

Contents

Behe begins the book with an observation that the theory of evolution consists of a coherent relationship of three related ideas: common descent, natural selection, and random mutation. He continues by stating he believes they are distinct ideas, with implications for the theory as a whole; common descent and natural selection he accepts without question but questions the scope and power of random mutation to produce beneficial mutations that lead to novel, useful structures and processes. He terms "Darwinian evolution" the type of evolution relying on all three of these factors, applies the label "Darwinists" to scientists who hold the view that Darwinian evolution is the only existing form of evolution, and who take exception to intelligent design as well as other theistic and non-theistic complexity theories.

Behe's central assertion regarding Darwinian evolution is that it exists, but that it is better at disturbing existing metabolic pathways (referred to as 'molecular machinery') than making new ones, and therefore plays only a limited role in the development and diversification of life on Earth. He examines the genetic changes undergone by the malaria plasmodium genome and the human genome in response to each other's biological defenses, and identifies that "the situation resembles trench warfare, not an arms race". He contrasts this hemoglobin-destroying, protein pump-compromising "war by attrition" with the "creative process" required to develop complex structures such as the bacterial flagellum as well as stupendously complex systems such as the immune system.

Behe calculates the "edge of evolution" - the point at which Darwinian evolution is no longer an efficacious agent of creative biological change - by taking into account the number of mutations required to "travel" from one genetic state to another, as well as population size for the organism in question. He concludes that purposeful design plays a major role in the development of biological complexity, through the mechanism of producing "non-random mutations", which are then subjected to the sculpting hand of natural selection.

Design that favors the development of intelligent life, argues Behe, is not only demanded by "the most recent findings concerning biological complexity", but also by discoveries in the fields of chemistry (he uses the example of the peculiar, life-supporting structure of water), and of cosmology (referring to the anthropic principle).

Behe argues strongly for common descent of all lifeforms on earth, including that humans and chimpanzees have a common ancestor. He states that there is such overwhelming evidence for common ancestry that it should not only be obvious, but "trivial". Behe claims that the mutations required for speciation are not possible without design, and that this is the "edge of evolution". The argument hinges on the low probability of an organism having two or more simultaneous mutations to yield some advantage for the organism.

Behe acknowledges his support for intelligent design represents a minority view within the scientific community, alluding to his awareness of this fact several times in the book. He implies that for this reason, he avoids detailed discussion about the nature of life's designer, and takes deliberate steps to distinguish himself from the Young Earth creationism movement.