The Greatest Show on Earth - Chapter 2

Summary of Chapter 2: Dogs, Cows, and Cabbages

• Why did it take humans so long to discover evolution?
• Ernst Mayr speculate it was due to Plato essentialism, what we see is a shadow of true reality.  For example, a triangle drawn in the sand is just a shadow of a true, essential triangle
•  In essentialism thinking, there is a "standard rabbit", and all rabbits we see are statistical variations on the standard
• Population thinking is the antithesis of essentialism ... there is no standard rabbit
• All life forms are linked to all other life forms via a chain of intermediates
• Thought experiment ... think of a rabbit, then imagine a chain of ancestors, each link in the chain looking nearly identical, but changing slowly.  Mentally traverse back to the common ancestor of rabbits and leopards.  Perhaps the animal look a little like a shrew, but certainly looked nothing like either a rabbit or leopard.  Now make the hairpin turn and begin walking forward in time, this time taking the path the leads to leopards
• Note there is never a direct cross between a rabbit and a leopard
• "Modern species do not evolve into other modern species, they just share ancestors: they are cousins"
• Humans have very successfully domesticated plants and animals via artificial selection
• The wild cabbage has been turned into broccoli, cauliflower, kohlrabi, kale, brussel sprouts, spring greens, and romanescu
• The wolf has been turned into two hundred breeds of dogs
• All domestic dogs are descended from wolves, not jackals, not coyotes, and not foxes
• What we are really doing is sculpting gene pools
• Gregor Mendel is the father of genetics
• Genes are shuffled between generations
• Darwin came very close to discovering Mendel's law of non-blending genes
• Geographic barriers inhibit gene shuffling.  For example, it will take time for the genes of a rat in Madrid to migrate all the way over to rat populations in Siberia
•  Evolution occurs when there is a systematic increase or decrease of a gene within a gene pool
• A lengthy discussion of dog breeding follows
• Overly muscular cows and pigs are bred by disabling a gene that makes myostatin
• Although morally problematic, there seems little doubt that eugenic breeding of humans could produce superior body-builders, pearl fishers, musicians, poets, etc.
• Next, there's a discussion of computer simulations that can derive new forms based on a human selecting desirable features on each generation, but without an overall master plan or design
• Darwin also discussed artificial selection extensively in Chapter 1 of On the Origin of Species
• Via non-random survival, natural selection over a longer period of time can produce that same affects as artificial selection can in a short timeframe

Kevin's Commentary on Chapter 2

As Dawkins points out in the last paragraph of the chapter, Charles Darwin's first argument in Chapter 1 of On the Origin of Species, Variation Under Domestication, discusses artificial selection that occurs as humans domesticate plants and animals to better serve our purposes.  Thus, it's no surprise that Dawkins would devote his first chapter to the same topic.

The basic argument here is that artificial selection proves that descent with modification can happen, at least under special circumstances.  Thus, we know that it's at least possible.  It doesn't violate any laws of physics, and therefore doesn't require, at least in principle, supernatural guidance.

The thought experiment that Dawkins walks us through, showing how rabbits and leopards are linked via common ancestry, is fascinating to think about.  Dawkins believes that there is sufficient evidence to say that all living creatures are descended from a single ancestor.  If that's true, then any two organisms living today, no matter how different from each other, can be linked together via their ancestry and the hairpin turn.  The greater the difference between the two organisms, the farther back in time one will have to go to find the common ancestor that defines the hairpin turn in the thought experiment.   Try doing this thought experiment yourself using two organisms of your choosing.  When I do it, I try to imagine what the common ancestor might have looked like.

Darwin himself commented on the temptation of trying to imagine an intermediate between two modern species.  It's natural for us to want to do that, and creationists seem to seize upon this as an opportunity to lead the unwary astray.  It is absolutely critical to remember that modern species don't evolve into other modern species.  There is no rabbit-leopard cross.  The common ancestor looked nothing like either.  It might have looked a bit like a shrew, but even then, probably not a modern shrew.

The Greatest Show on Earth - Chapter 1

Summary of Chapter 1: Only a Theory?

• Dawkins asks us to imagine we are a teacher of Roman history but you were distracted by "ignoramuses" who denied Romans ever exists.  You were demanded to "teach the controversy" ... how frustrating
•  Things like this really happen, as is the case with Holocaust-deniers
• Science teachers today face similar opposition w.r.t. teaching evolution
•  Many religious leaders accept evolution and don't find that it conflicts with their faith. 
•  Dawkins doesn't intend this as an anti-religious book, only a book that defends the evidence for evolution (he's ripped religion to shreds in other books, no reason to do it again here)
• However, religious leaders accepting evolution doesn't seem to transfer to their congregations ... 40% of Americans deny that humans evolved, and instead were created by God in the last 10,000 years.  He refers to this group as "history deniers", or "40 percenters"
• Perhaps this is true because clergy talk a lot in symbolism, and don't make it clear what's symbolic and what's literal.  How is the congregation supposed to know the difference?
• Evolution is a fact beyond reasonable, serious, sane, intelligent doubt
•  "No reputable scientist disputes it, and no unbiased reader will close the book doubting it"
• Next, Dawkins spends time discussing the definition of a "theory", and why there is so much confusion around it, especially since people of faith love to apply the label "only a theory" to evolution
• The definition of theory has 2 meanings 1) A set of ideas that explains a group of facts; a hypothesis confirmed by observation or experiment, etc. OR 2) A hypothesis, speculation, conjecture, etc.
•  He thinks scientists mean Sense 1 and creationists "mischievously" mean Sense 2
• Evolution is a theory in the same sense as the theory that the Earth orbits the Sun (heliocentric theory)
• He then discusses whether evolution has been or can be 'proved'.  He discusses what it means to prove something.  By a certain philosophy, only mathematicians can ever prove anything, such as the Pythagorean Theorem.  By this view, scientists can never prove anything.
• However, scientists can accumulate so much evidence for a theory that continuing to deny it a fact becomes ridiculous
• When theories are beyond sensible doubt, we call them 'facts'
•  Even labeling something a 'fact' does not have the same rigorous status as a mathematical proof
• He discusses the definition of a 'fact', and points out that even things we think are facts are not always reliable, such as the case with false-convictions based on eye-witness testimony
• Evolution happens too slowly for eye-witness testimony, so scientists must use inference
• "This book will take inference seriously - not mere inference but proper scientific inference"
•  Example of inference: Understanding continental drift, we can infer that South America was once joined to Africa
• Evolution is both fact and theory ... all living things are cousins is a fact, the process that drives it, natural selection, is a theory (Sense 1 theory, not Sense 2)
• In Darwin's day, evolution was more conjectural, but now we have compelling evidence that it is true
•  "Nowadays it is no longer possible to dispute the fact of evolution itself"
• All reputable biologists agree that natural selection is one of the most important driving forces
• Because we cannot directly observe evolution, we will examine the case for evolution much the way a detective examines a crime scene

Kevin's Commentary on Chapter 1

I have personally engaged in conversations and debates with people of faith, namely Christians, that attack or dismiss evolution as "only a theory."  Therefore, I find Dawkins lengthy discussion of theories, hypotheses, facts, and proofs both useful and relevant to my experience.

I watched a YouTube video with Kenneth Miller not long ago, and I thought his explanations of theories vs. facts was as good, if not even better than Dawkin's treatment.  Miller said that people generally think that facts are things that scientists are sure of, and theories are things we're not so sure of.  But, he explains, theories are actually more powerful than facts because theories explain facts.  I love that explanation.  Dawkins says nearly the exact same thing when he quotes the dictionary definition of theory.

Evolution by natural selection is an elegant, powerful theory that explains an enormous variety of facts we've collected, such as the fossil evidence facts, the facts about cells and DNA, the fact that life is so diverse and different around the world, and the facts about the behaviors of different forms of life.  Labeling evolution as a "theory" does not drag it down into the depths of doubt, but rather, lifts it up to a higher place in the world of science.

The creation hypothesis, on the other hand, does a terrible job of explaining the facts of the world around us (more on this in future chapters).  The contrast between these two world views I find very compelling.

The Greatest Show on Earth - Preface Notes

a book by Richard Dawkins

Summary of Preface:

• ·         Evidence for evolution grows every day, yet paradoxically opposition is stronger than ever
• ·         The 'theory' of evolution is actually a fact
• ·         Dawkins briefly mentions some of his earlier books related to evolution, but thinks none of them explicitly laid out the evidence for evolution, so he wrote this book
• ·         He wrote a highly favorable review of Jerry Coyne's "Why Evolution is True"
• ·         Considered using "Only a Theory" as the title for the book, but Kenneth Miller was already using it, and settled on the Greatest Show On Earth, with Only a Theory? (emphasis on the question mark) as the title of the first chapter

Kevin's Commentary on the Preface

The canonical source for the evidence of evolution is, of course, from Charles Darwin himself, "On The Origin of Species", and yes, I've actually read it.  However, the Victorian prose makes it a difficult read for many Americans, and therefore it always helps to have modern interpretations.  Also, there has been a lot more tangible evidence discovered since the original publishing of "On The Origin of Species" (1859), and it's therefore useful to augment Darwin's original arguments.

I've only read one other Dawkins book so far, The God Delusion, but I intend to eventually read all of Dawkins works.

I've read Jerry Coyne's "Why Evolution is True" and agree with Dawkins that it is excellent.

I've read Kenneth Miller's book, "Finding Darwin's God" and have also watched various debates and lectures of him on YouTube.  His defense of evolution is superb, but as a Catholic he still ultimately, in the broadest sense, believes in a creator and accepts many aspects of the Christian faith, which is a bit of a paradox I have trouble understanding.