The Edge of Evolution
The Edge of Evolution: The Search for the Limits of Darwinism is an intelligent design book by Discovery Institute fellow Michael Behe, published by the Free Press in 2007. Behe argues that while evolution can produce changes within species, there is a limit to the ability of evolution to generate diversity, and this limit (the "edge of evolution") is somewhere between species and orders. On this basis, he says that known evolutionary mechanisms cannot be responsible for all the observed diversification from the last universal ancestor and the intervention of an intelligent designer can adequately account for much of the diversity of life. It is Behe's second intelligent design book, his first being Darwin's Black Box. While the book has been well received by creationists and non-biologists, reviews by certain scientists, especially those working in the field of biology, have been highly critical of Behe's methods, information and conclusions in the book. 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