Saturday, February 6, 2010
The Greatest Show on On Earth
It's quite difficult to encapsulate a book such as this in a single post. It is so literally chock full of interesting "stuff", that it took me twice as long to get through the book than I expected. So much so, that as I sit down to write this post, I realize I barely remember the earlier parts of the book.
Unlike other books about evolution that I've read, the stated claim of this book is not to explain how evolution works, but rather to build the case for the truth of the theory of evolution. In reality, I find that most of the book still discusses how evolution works and considerably less than making the Case for Evolution (CFE).
He begins by stating what is necessary. That there are no proofs in the scientific world, just theories. If you're looking for proofs, study Math, not science. As we should all be know by know, theory, in scientific terminology, is not the same as used in the vernacular. I'll add one concept. I'll break down "evolution" into two . A) What scientists call the "fact" of evolution, namely that evolution has occurred and B) the theory of Evolution, namely how evolution has occured.
Dawkins begins, as darwin did, by demonstrating that everyone admits to artifical selection and breeding as having the ability to cause significant change in species. He states that in a mere few centuries, wild cabbage has evolved, through artifical selection, into different varieties (species?) such as cauliflower, brussel sprouts, broccoli and other of my favorite dishes. Dawkins does the same for Dogs. He shows that dogs have literally been molded and shaped by selective breeding. Case in point Chihuahuas's and Great Danes are descendants of the same species of dogs, also evolved in a mere few centuries. The book implies, but fails to spell out, whether these changes in cabbage and dogs are true "genetic" changes and constitue different species according to the scientific definition of species, namely that different species do not interbreed.
The importance of this first step, artifical selection, can't be overstated. (This is not a post on Evolution. If you don't understand "selection", and think of it in terms of "nose, grow nose", then this post is not for you.) As a next step, Dawkins shows that artificial selection can occur not just with Human agency acting as breeders, but with unthinking insects playing that same role. The next step is natural selection, any unthinking selector acting upon genetic variation. This natural selector includes weather, predators, geography, etc.
The above begins to demonstrate the CFE, but more importantly it breaks down psychological barriers that induce us to think of species and animal as unchanging.
He hammers home the point that one species does not give birth to another species in a single generation. No offspring is ever unrecognizable from it's own parents. It is the accumulation of change over thousands of generations that adds up to different species. And with a single set of parents, two separate diverging paths lead to specication over long periods of time.
For example (taken from elsewhere). Humans and chimps are said to diverge from a common ancestor around 5 Million years ago. Assuming a new generation every 25 years, that anounts to 200,000 generations. I've heard if said that if your ancenstors started walking past a line, single file 24 hours a day, it would take two weeks to meet that ancestor of 5 millions years ago.
But there's much much more.
Like the section on clocks. This section bought back hazy memories of my high schools studies disussing carbon dating and other radiometric techniques. The one thing it did not explain is how scientists derived that some half lives date back to millions of years. Obviously, it's some sort of extrapoltation. The section on clocks is coupled with the fact that different classes of life are always fossilized in the same geological strata and in a sequence that is blindingly evolutionary. In other words fossils of mammals never appear in strata that contradicts an evolutionary sequence. This is a powerful argument for the fact of evolution. How else would one reasonable explain that all species did not enter into the fossil record at the same time as would be expected if all creatures had been created together.
As an aside, Dawkins explains that there are numerous radioactive clocks which indicate an Earth that is dated as 4.6 billion years old. Claims of a 6,000 or 10,000 earth are preposterous in light of the synchonization of these clocks. Flood explanations and other special pleadings of Nishtane Hatevah to justify a young earth are non-sensical. As Dawkins writes "The history deniers would have to fiddle with the half-lives of all the isotopes in their separate proportions, so that they all end up agreeing that the Earth began 6,000 years ago". Powerful.
Dawkins proceeds to demonstrate that Evolution occurs "Before our very eyes", in Guppies, Bacteria, etc. While technically accurate, most people do not equate this with Evolution, as there is no speciation. Nevertheless, his point is made and it's strong. Evolution does occur in a matter of months.
Dawkins spends a long time discussing several issues that I'd categorize as a defensive position, or more accurately an explanatory discussion, rather than an offensive position which demonstrates that Evolution is true.This includes the missing links issue and Embryology (fascinating stuff!)!.
A powerful chapter then follows, "The Ark of the Continents". This includes a discussion of plate techtonics, speciation and most significantly, the observation that certain animals are found only on certain continents. How on earth does one explain that by way of Noah's Ark? However, as I write this, an argument forms in my mind. This may disprove the Bible, but it does not preclude special individual creation. A quirky God may have decided to place Kangaroos only in Australia. Why not?
That is followed by chapters that highlight that the closer species are on the proposed evolutionary tree, the greater the physical and Genetic similarities between them. This is a very powerful argument and special thanks to Dr. Clare D'alberto's "one for the team!" (nice tatoo).
An intriguing chapter is "History written all over us", in which he demonstrates some really quirky anatomy (eye, vas deferens, larangeal nerve in Giraffes). Think of it as unintelligent design, if you catch my drift.
Anyhow, this post is rambling on way too long.
To sum it up. I'd say, that this book provides extremely strong evidence that
A) All of life is related and
B) We did not all arrive at the scene at the same time.
While discrediting the traditional religious notion of creation and early history, there may be room for God in the Greatest Show on Earth.
(To be disabused of the God notion, try The God Delusion by the same author. I would really love to see a chapter by chapter rebuttal of that book).