The greatest show on Earth : the evidence for evolution

One major linguistic confusion that creationists exploit in debates is a confusion with the word "theory," as in the "Theory of Evolution." The scientific community uses the word theory to mean "a well-verified conceptual framework for explaining scientific data." Creationists exploit another definition of the word, where it is used as "a synonym for an unverified hypothesis," to make it seem that the theory of evolution is merely a guess. Early in the book, Dawkins deals with the ambiguity by making up a new word, "theorum" to mean a well-verified scientific framework, as scientists use the word, and he only uses the word "hypothesis" for the non-scientific meaning of theory. I find this construction clumsy, and he only uses it in the opening chapters.

After the unfortunate theorum, Dawkins compares artificial and natural selection. He argues that some instances of natural selection amount to mutual semi-artificial selection between two different species, with each breeding the desired characteristics in the other. Next, he tackles questions of assigning an age to the earth itself and fossils. He starts with using tree rings (dendrochronology) to show how one can have multiple mutually calibrated time rulers. Next, the discussion turns to several examples where evolution was observed in real time, such as Lenski's experiments with bacteria in a glucous and citrate environment, and Endler's experiments with guppies in both lab and wild settings.

Next, Dawkins discusses the fossil record and the logical absurdity of more evidence meaning more gaps. He sees the pernicious effect of the concept of the great chain of being. Animals have more "primitive" traits if they have retained the same version as the common ancestor. Then, he discusses the fossils that show the original vertebrate transition from sea to land, especially Tiktaalik roseae, followed by a discussion of the return to the sea by whales and manatees. He does not mention Carl Zimmer's "At the Water's Edge," a book which I also recommend. Dawkins discusses human fossils, with an emphasis on skulls whose genus and species are disputed. Creationists criticize the ambivalence, but that only means that they are intermediates.

Next, Dawkins deals with embryology. How do genes make bodies? Through embryos. DNA is not a blueprint: there is no one-to-one correspondence between a section of DNA and a part of the body. Instead, an algorithm for self-assembly. After discarding several analogies, Dawkins settles on "auto-origami" to describe the process. He goes on to discuss how "switch genes" (ex. HOX genes) orchestrate the behavior of each cell in the embryo to get the cells to follow their bottom-up behavior in creating the body.

What is interesting here is that Dawkins is still very gene-centric. He does not go into a detailed explanation of the short binding sites in the DNA that surround the section of DNA that actually codes for the gene. Sean Carroll in "Endless Forms Most Beautiful" and Kirschner and Gerhart in "The Plausibility of Life" explain that these binding sites, which either promote or suppress the expression of the nearby gene, have a major impact on phenotypic variation. Dawkins has always bowed down before the selfish gene, and he does not seem to have embraced the new findings from evo devo that reduce the importance of the gene itself in phenotypic expression. Dawkins does agree with Carroll and Kirschner and Gerhart that the driving force within embryo development is grass-roots in nature, but he is still too gene-centric. Dawkins also does not emphasize enough that the HOX compartments within the developing embryo allow for the rapid evolution of changes within that specific compartment, as explained by Kirschner and Gerhart. Though this is an introduction to evolution, defending it against creationism, the points by Carroll and Kirschner and Gerhart are really worth discussing. Those points make the idea of life via natural processes more plausible.

Dawkins discusses genetic islands and speciation. Dawkins then goes over the insurmountable problems that creationists face trying to explain the patterns of biogeography through a hypothesis that all species started on Mount Ararat after Noah's flood. He rounds out this section discussing plate tectonics. What is interesting about plate tectonics is that young-earth creationists are willing to allow that it is true; they just believe that South America separated from Africa during the forty days of Noah's flood. Dawkins argues that there is more evidence for evolution than for plate tectonics.

Next, Dawkins discusses homologies. He claims that evolution has no need to use fossils to defend it. He reviews the mammalian skeleton as manifest in bats, horses, etc. Dawkins then discusses genetic homologies. He points out that because you can compare the same gene in many different animals, you can construct a tree of life for each separate gene. The different trees should agree with one another, allowing for minor statistical variation. Also, the genetic distance from human to dog should be statistically about the same as the distance from monkey or lemur to dog. Any violations would be evidence against evolution. But the data strongly support evolution.

Dawkins discusses many instances of anatomy that demonstrate that animals were not intelligently designed. There are many examples of post-hoc tinkering, where a major change caused many problems and where those problems were fixed by slapdash tinkering by natural selection. Dawkins compares the tinkering of evolution to the handling of the Hubble Space Telescope. Once the telescope was in space, we could only build work-arounds to its problems, like the corrective optics. We couldn't just replace the main mirror with an entirely new and improved one.

Dawkins compares an ecosystem that an Intelligent Designer would have planned to an ecosystem that has evolved. For example, a designed orchard would keep trees short. An evolved forest will have an arms race of height. If a designer crafted animals, he crafted cheetahs to be maximal gazelle-killers, and he designed gazelles to be maximal cheetah-fleers. Which side is he on? Did he who made the lamb make thee?

Dawkins discusses evolutionary theodicy (justice of God) and the existence of pain:moral philosophy puts a value on minimizing suffering. The devil's chaplin could write on the cruelty of nature. Dawkins investigates why there is no evolutionary value in having a cognitive system that did not cause great pain.

Finally, Dawkins takes each sentence from the final paragraph of Origin of Species. He claims the mention of a creator was a sop that Darwin threw to critics and later regretted. Dawkins defines life in terms of information storage and types of memory. He views culture as a form of life's memory. He then speculates about whether life on Earth only started once (likely), and what the likelihood is for life elsewhere. He discusses the confusion creationists have with entropy, and states, "Natural selection is an improbability pump." He then explains the reasons why some favor RNA as the original replicating molecule.

In the appendix, he reviews the statistics on the percentages of the public in various countries that believe in young earth creationism, intelligent design, and evolution by natural selection alone. The anti-evolution public in Britain is growing, especially in the Muslim community.

Basically, well done and entertaining.

The audio CD version has both Dawkins and his wife, Lalla, alternatively reading sections of the book. However, if the listener has any vision at all, one might want to check out a paper copy of the book from the library, as there are about 100 illustrations that are referred to in the text. The audio gives a tone when one should look at the illustration. The audio has good pacing, unlike some audio books.