Thursday, October 8, 2009

Review: The Greatest Show on Earth

The Greatest Show on Earthconstitutes must-read material for both evolutionists and creationists. If you care at all about how life came to be so complex and diverse, you should read this book. If you're an evolutionist, it will do you good to see the evidence of evolution and learn some good come-backs to creationist arguments. If you're a creationist, you ought to read this book so that you can take a look at the other side of things and fully understand the opposite view. If you want to argue against evolution, why not look at one of the best presentations of the evidence for it? Although it's not the perfect book on evolution, it's still a great (if lengthy) introduction.

What follows is a chapter-by-chapter analysis of the book:

Chapter 1 Only a Theory?

This is just a general introduction to the book which discusses the meaning of the word 'theory', how human beings can know things about the world, etc.

Chapter 2 Dogs, Cows, and Cabbages

Dawkins discusses the amazing wonders humans have wrought through selective breeding or 'artificial selection'.

Chapter 3 The Primrose Path to MacroEvolution

Artificial selection is discussed further, Sexual Selection is introduced, and finally Natural Selection is introduced. Dawkins discusses a fascinating experiment in Russia in which wild foxes were bred selectively for tameness until the breeders ended up with foxes that were very much like domesticated dogs. Dawkins closes by asking us to imagine: If so much progress and diversity can be achieved through selective breeding in a human lifetime, what if we had natural selection acting for eons upon species? This makes it very plausible that evolution can account for the diversity of life. Plausible, but not proven. Dawkins insists that we first confirm that the earth is very, very old, and so he devotes the next chapter to this.

Chapter 4 Silence and Slow Time

Dawkins explains elementary geology and radiometric dating. He also tackles a creationist explanation of the order in which we find fossils: Creationists, who believe that all of our fossils come from Noah's flood, have a problem with the fossil record. Instead of the fossils showing that all life has existed, essentially unchanged, from the very beginning, we see instead that life apparently changed over time: The earliest fossils are single celled organisms, later invertebrates, then vertebrates, then fish, amphibians, reptiles, mammals, etc. Creationists have sought to explain this by saying that marine invertebrates, like sea urchins, would not move very fast and so would have been buried first in the flood. Amphibians would have been buried next, since they are closest to the sea, and so on and so on. I was rather disappointed by Dawkins response: He only pointed out that this hypothesis just predicts a statistical tendency for some animals to be buried before others: Amphibians would, under this hypothesis, be less likely to be buried first. Dawkins points out that Darwinism predicts that there absolutely cannot be (for instance) a human skeleton buried very early in the fossil record. Darwinism gives a more precise prediction about the fossil record, and since we observe it to hold true, Darwinism is to be preferred.

It's not that this is a bad point. But creationists could attempt to say that we have so few fossils that we only see what's statistically likely. They are still not making a prediction as precise as Darwin's, but it's a little too close for comfort. What I would point out is that, first of all, the creationist theory, if it were true, predicts the following fossil record:






And there is something important to keep in mind: If fossils were buried in this order based on their ability to escape from flood waters, then we ought to find some strata with nothing but fish (few or no other animals). On top of that should lie strata with mostly or completely amphibian fossils, followed by strata with mostly or completely reptilian fossils, and so on. But we don't find this. What we find is that fish make their first appearance in the lower strata, but they don't disappear in later strata. We find fish throughout the fossil record. Ditto for the other groups of animals. The fossil record we have is one we would expect from Darwinism, not Creationism.

Later Dawkins attempts to dispel a creationist myth about radiometric dating: That the rate of radioactive decay may not be constant. Dawkins ask to imagine the complicated and improbable fiddling God would have had to do with the laws of physics in order to make each and every dating method inaccurate, and even worse: To make all the dating methods inaccurate but in total agreement with each other! It's an excellent point, but remember creationists do make other arguments against radiometric dating: Like that parent or daughter isotopes could be added, removed, etc. to the rock over time. However, one could adjust Dawkins' reply to this argument as well: It is still implausible to assume that numerous dating methods all reveal the same false age by means of random additions of daughter isotopes or random loss of parent isotopes.

Chapter 5 Before Our Very Eyes

Dawkins recounts several fascinating examples of evolution that have taken place within human lifetimes. Through these examples, Dawkins demonstrates that new genetic information can be produced by mutation, and enlightens us to the awesome power of evolution, which we are lucky enough to catch glimpses of.

Chapters 6 & 7

These chapters are essentially the same. One is devoted to transitional fossils of other animals, one is devoted to transitional fossils of humans.

Chapter 8 You Did It Yourself in Nine Months

A Fascinating Digression into embryology. I learned quite a bit from this chapter, but won't attempt to summarize it or what it has to do with the book's main point. You'll have to read the book yourself to find out!

Chapter 9 Ark of the Continents

Discusses the evidence that Biogeography provides for Evolution, and the problems it poses for creationists. Frank Zindler makes points very similar to Dawkins:

"Consider the mammalian fauna of Australia... The marsupial population of Australia contains animal families, genera, and species found nowhere else on earth - not even in fossil form. We are to suppose that each species of marsupial managed to get from Mt. Ararat to Australia, but couldn't find its way to any other part of the world - including those regions located between Turkey and Australia. Despite the fact that most marsupial species seem to be out-gunned when they are forced to compete with placental mammals (hence the extinction of so many marsupial species after the introduction of European mammals), we are to suppose that wombats and wallabies, bandicoots and koalas, kept ahead of lions-'n-tigers-'n-bears all the way to Indonesia, and then - although the superior placental predators couldn't manage it - continued on to Australia. As if this were not mind-boggling enough, after all this implausible world travel, and after all the dust had settled, it turns out that the types of marsupials that made it to Australia just happened to form an ensemble able to fill all the ecological niches available!"

Chapter 10 The Tree of Cousinship

Dawkins reviews the anatomical evidence for common descent: The commonalities in bone structure shared by all vertebrates. Also discussed are the patterns of life that reflect common descent, such as the fact that one can find almost identical degrees of relationships in different genes.

Chapter 11 History Written All Over Us

This is mostly vestigial organs and bad design seen in living things.

Chapter 12 Arms Races and 'Evolutionary Theodicy'

Dawkins develops an argument for evolution based on the fact that evolution predicts that arms races must have occurred in the past: Predators getting better and better at finding and killing prey, prey getting steadily better at getting away from the predators. The evidence for past arms races is overwhelming, and it is what we expect from evolution but we do not expect from design.

Chapter 13 There is Grandeur in this View of Life

The closing chapter which goes over the origin of life and various other loose ends.

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