|Here's the book cover for The Greatest Show on Earth: The Evidence for Evolution, by Richard Dawkins.|
Or, ha, not exactly. I “studied the evidence” a lot, back in my anti-evolution days. I knew all about how comparative anatomy showed a common designer rather than a common ancestor, how the peppered-moth thing was a hoax, vestigial organs are totally NOT evidence for evolution, amino acids in the primordial soup could never have combined to create life, and all the transitional fossils are missing.
I’d only ever “studied the evidence” from a creationist perspective, defensive and ready to argue with all of it.
So that’s why I read this book: The Greatest Show on Earth: The Evidence for Evolution, by Richard Dawkins. Because now I actually want to know the evidence. I actually want to learn evolution. Not learn how to argue against it.
(So, if you’re a little turned off because it’s a book by Dawkins- this book is all about biology and other areas of science, something Dawkins is an expert in. Yeah, I don’t like when he talks about religion- but he doesn’t talk about religion in this book. He does talk about “scientific” arguments made by creationists, which was helpful for me, because he addressed creationist arguments that I think most scientists never address because they see them as just too ridiculous to even answer.)
You guys, I loved this book. It was so interesting! Dawkins covers all sorts of different topics- from dog breeding to predators’ effect on the color of male guppies to embryology to the role of DNA to hominid fossils to plate tectonics to radioactive dating to predators and prey to turtles to bacteria to marsupials to insects that look like plants. It’s really cool! And he connects all these things to evolution, as the one theory that really brings everything together. (And yes, he also spends time telling us why “theory” doesn’t mean there’s doubt about whether it’s true.)
Like I said, this was my first time ever really learning about evolution. And, maybe this sounds kind of strange, but it feels a lot like learning about how the bible was written. Because, in the past, I viewed with the highest suspicion anything that suggested the bible was something other than a series of true statements given to us directly by God. I never allowed myself to learn about how some passages were written by combining two different and slightly contradictory oral accounts, or how there’s not really archaeological evidence for the exodus or conquest of Canaan… sure, I might have read about those claims, but I knew from the outset that I wasn’t allowed to believe them. I “learned” about them in a defensive way, searching for some small detail that I could declare was illogical and which would allow me to dismiss the entire thing. That’s how I “learned” evolution too.
One thing that really surprised me was the part about “clocks”, ie, methods to determine how old something is. First of all, tree rings. The book says that the thickness of rings is affected by the climate during the year the ring was made, so you can take a tree sample and match up the pattern of thinner and thicker rings with a sample whose age is known. Actually, you can take today’s trees and line the rings up with older ones, and older ones, and older ones, with wood from European houses built hundreds of years ago, with petrified forests, etc- this method actually gives us a calendar stretching back 11,500 years. Dawkins says, “It is nevertheless a tantalizing thought that, if only we could find enough petrified forests, we could date to the nearest year over a timespan of hundreds of millions of years.” (p 90)
First of all, holy crap that’s amazing. Second of all, yeah young-earth creationists are really NOT OKAY with that. They think the world is only 6000 years old, so this is a bit of a problem. (And I would like to present the young-earth creationist counter argument to this: Well, sometimes trees can grow two rings in one year, so you don’t really know if it’s accurate.) And as a former young-earth creationist, I was like, wait, is this true???!!! A little skeptical.
Well. It’s for real. Look at this searchable database of tree ring data. And here’s a result I found, just a mundane result from that very normal online search engine, which has data from trees that lived 12000 to 14000 years ago, like it’s no big deal.
(And here’s another site that says you can’t just count the rings, because it’s not always exactly one per year. So. Look, scientists already thought of that. Creationists, go make up a new argument.)
The part about radioactive dating was really mind-blowing too. Page 102 says, “Among all the elements that occur on earth are 150 stable isotopes and 158 unstable ones, making 308 in all. Of the 158 unstable ones, 121 are either extinct or exist only because they are constantly renewed, like carbon-14 (as we shall see). Now, if we consider the 37 that have not gone extinct, we notice something significant. Every single one of them has a half-life greater than 700 million years. And if we look at the 121 that have gone extinct, every single one of them has a half-life less than 200 million years. … Isotopes whose half-life is less than a tenth or so of the age of the Earth are, for practical purposes, extinct, and don’t exist except under special circumstances.” (I can’t find an online source that matches these numbers exactly, but this page about primordial nuclides more or less says it.)
Furthermore, different methods of radiometric dating produce the same result for the age of the earth (about 4.6 billion years). (And here’s a Wikipedia article which backs this up.) Dawkins says on page 106:
Now, a history-denier [young-earth creationist] could claim, say, that there is something wrong with the potassium argon clock. What if the present very slow rate of decay of potassium-40 has only been in operation since Noah’s flood? If, before that, the half-life of potassium-40 was radically different, only a few centuries, say, rather than 1.26 billion years? … The history-deniers would have to fiddle 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. Now that’s what I call special pleading! And I haven’t even mentioned various other dating methods which also produce the same result, for example ‘fission track dating’. Bear in mind the huge differences in timescales of the different clocks, and think of the amount of contrived and complicated fiddling with the laws of physics that would be needed in order to make all the clocks agree with each other, across the orders of magnitude, that the Earth is 6,000 years old and not 4.6 billion! Given that the sole motive for such fiddling is the desire to uphold the origin myth of a particular set of Bronze Age desert tribesmen, it is surprising, to say the least, that anyone is fooled by it.First of all, wow yeah, that is what young-earth creationists argue- radioactive dating isn’t accurate because what if the decay rates have changed? We can’t assume they’ve always been constant. But… wow, how on earth could they ALL have changed in such a way that they ALL end up with the same wrong value of 4.6 billion years?
(Dawkins is very wrong about the “it is surprising” bit though. No. Your religion says you have to believe the earth is 6000 years old, you find a way to believe it. I did. Dawkins doesn’t understand religion if he thinks this is “surprising.”)
I’m also very glad that the issue of radioactive dating for fossils was brought up in this book. It says that radioactive dating of rocks will tell you how long it’s been since the rock cooled out of its molten state- and therefore it only works for igneous rocks. But we all learned in middle school science class that fossils are found in sedimentary rocks. I don’t remember ever hearing a creationist argument along the lines of “see you can’t even use radioactive dating on fossils because they’re in sedimentary rock- this whole thing is baseless!” but it strikes me as the kind of thing they would TOTALLY say. (See Kent Hovind’s take on plate tectonics: “If you remove the water from the oceans, there is dirt underneath.”) Yeah creationists are all about taking some easily-misunderstood point and claiming, “see? Obviously this makes no sense!” So I’m really glad Dawkins talked about this (page 98-101). Here’s how it works: You don’t actually use the radio carbon dating on the rock that contains the fossil. Instead, similar sedimentary rock layers are found all over the world, and they are given labels (Devonian, Jurassic, etc). You know that a Devonian layer is older than a Jurassic one (no matter where on earth you find them), but you don’t actually know how old it is. Until you find igneous rocks above or below one of the layers, and you can use radioactive dating on the igneous rocks- and apply the result to all rocks of that label all over the world. There you go.
The part about transitional fossils between apes and humans was also mind-blowing to me. Dawkins spends a whole chapter presenting example after example, discussing the characteristics of each specimen found and how anthropologists argue about which genus they belong in- Homo or Australopithecus? Homo is the genus which includes humans (Homo sapiens) as well as some other extinct human-like species, while Autralopithecus were more ape-like and eventually evolved to produce the Homo genus. The question is, where do you draw the line? You find a hominid fossil, you look at the brain size and how it walked, and based on that, you classify it as Homo or Autralopithecus. But other scientists come to a different conclusion and classify it differently.
I remember a line I used to use back when I argued against evolution: “We don’t have very many transitional fossils from apes to humans, and the ones we do have are controversial.” I am suddenly shocked to realize that “controversial” is EXACTLY WHAT THEY SHOULD BE if evolution did in fact occur. If people evolved from ape-like creatures, then there is no definite line between Australopithecus and Homo. We SHOULD find remains which incite huge debates about which genus they belong in.
The book also includes a bit from an interview Dawkins did with Wendy Wright, president of Concerned Women for America (an anti-feminist group). In the interview, Wright kept saying over and over that transitional fossils do not exist, and Dawkins kept telling her Australopithecus exists, Homo habilis exists, Homo erectus exists. This interview excerpt illustrates how creationists are taught to say, over and over, there is no evidence, there are no fossils- but in reality, there are fossils, there are SO MANY fossils. And OH MY GOODNESS yes. Yes. When I was a creationist, I very much believed “there are no transitional fossils.” I mean, sure there was archaeopteryx, but just that one, and it totally didn’t count, because reasons.
And … wow. I’m … I need to research this more. If the fossil record is full of “transitions” everywhere, then … damn. Then brace yourselves for a whole bunch more blog posts on how creationism is all about lying and taking the Lord’s name in vain.
However, there was also a lot of evidence presented in this book which totally would not have challenged my creationism at all, back in the day. Specifically, I was one of those “we believe in microevolution but not macroevolution” creationists. Creationists define those terms in this way:
Microevolution: small changes. One animal evolves into another animal that’s pretty similar, so it’s totally believable. For example, dogs evolved (or rather, were domesticated) from wolves. Darwin’s finches are an example of microevolution because, come on, they’re all finches. Nothing new arose; a finch just evolved into a different finch.
Macroevolution: one animal evolves into another animal which is substantially different from it, so you go “what? no way.” For example, the claim that all animals share a common ancestor. Come on, really?
And actually, as I was reading the book, I started to wonder, “wait… is the distinction between ‘microevolution’ and ‘macroevolution’ something that ONLY creationists talk about? Do real scientists even use those words?
I found that, yes, these are real words, but they don’t mean what creationists say they mean. Here are the definitions from Wikipedia:
“Microevolution is the change in allele frequencies that occurs over time within a population.”
“Macroevolution is evolution on a scale of separated gene pools. Macroevolutionary studies focus on change that occurs at or above the level of species, in contrast with microevolution, which refers to smaller evolutionary changes (typically described as changes in allele frequencies) within a species or population. Macroevolution and microevolution describe fundamentally identical processes on different time scales.”
Hmm. So in regular-science-land, microevolution is about changes within a species, and macroevolution is about changes at or above the species level. Sort of. Seems like it’s hard to really draw the line, because they’re really the same thing- you accumulate a lot of microevolution and it becomes macroevolution. Yeah, that’s completely different from the creationist definition where “microevolution” is small changes which, though they might produce new species, don’t actually make any difference if you’re trying to evolve from, say, a fish to a human, and “macroevolution” is the one that involves changes big enough that we don’t buy it.
Everything Dawkins says about natural selection, artificial selection, sexual selection in this book is very “yeah so?” for the “microevolution but not macroevolution” creationist. I mean, natural selection just makes sense. Animals that can reproduce better end up having a bigger effect on the gene pool, causing the whole species to change in that direction. I have never encountered any type of creationism that claimed that it’s impossible for a species to adapt to its environment or for new species to arise.
(I have also never encountered the “God put fake fossils in the rocks to test us” flavor of creationism- I guess this is just a strawman, but… I also kind of wouldn’t be surprised if there’s some Christian group somewhere teaching it.)
Anyway, if you’re a creationist reading this book, you read all about dog breeding and say “oh that’s really interesting. It’s NOT evidence for evolution.” You read about how predators and prey force each other to evolve- predators evolve to be faster and more deadly, prey evolve better ways to run and hide- and how this results in all the animals putting so much energy into the “evolutionary arms race.” Why would an intelligent designer have made them this way? Whose side is the designer on, when lions are “designed” so well for hunting and killing, and antelope are “designed” so well for running away? Umm, hello, it wasn’t like that in the Garden of Eden. All the animals lived peacefully together, and the animals which were ancestors of today’s lions weren’t fierce at all. After the fall, microevolution took over to make predators more and more powerful and prey more and more able to escape.
Yeah. There were a lot of examples in this book, where Dawkins seems to be writing with a “how could creationists explain THIS?” view, and … it’s microevolution. No challenge at all for the creationist.
But there were so many things that were convincing. I’ve already mentioned a bunch, about the age of the earth, hominid fossils, etc. Here’s another one: marsupials are only found in Australia. A huge variety of very different species, but all sharing certain characteristics which are found nowhere else on earth. If you’re a young-earth creationist, you have two options for explaining this fact:
1. There were several different marsupials on Noah’s ark, and they all just happened to come to Australia.
2. There was only one marsupial pair on Noah’s ark, and they came to Australia, and then microevolution produced all the different marsupials we now have.
(If you’re an old-earth creationist that doesn’t believe in a world-wide flood, you have more options.)
Option 1 is pretty unbelievable. Really, they all came to Australia? (Actually, option 2 also requires you to believe that the pair on Noah’s ark came all the way to Australia without leaving any offspring anywhere along the way… so… that’s also pretty unbelievable…) If you choose option 2, you’re admitting that microevolution has the power to turn one common ancestor into everything from koalas to kangaroos to flying squirrels [in less than 6000 years? ugh this is not a path a creationist wants to be on], and this calls your whole “microevolution doesn’t really count for anything” into question.
And I suspect it’s not just Australia. I wonder if there are other examples of very diverse species which all share a few unique characteristics and are close geographically. Because, wow. That’s tough for young-earth creationism to explain.
Another very interesting section in the book was about “bad design.” (By “bad design” I mean examples where animals’ bodies are structured badly, so it doesn’t make sense to believe somebody intelligent actually designed them.) I remember hearing about the panda’s thumb back in my anti-evolution days, reading some creationist article about how the panda’s thumb is totally NOT an example of “bad design.” Didn’t hear any other arguments about “evolutionists think xyz is an example of ‘bad design.’”
But wow, you guys. There are SO MANY examples in this book. The eye (which is the poster child for the creationist concept of “irreducible complexity”, so I’m pretty surprised to hear the claim that it’s “badly designed”). The laryngeal nerve, which goes from the head to the chest and back, for no apparent reason (err, actually, because we evolved from fish). The vas deferens. The koala’s pouch opens downwards. Here is a quote from pages 370-371:
When we look at animals from the outside, we are overwhelmingly impressed by the elegant illusion of design. … When we look inside, the impression is opposite. Admittedly, an impression of elegant design is conveyed by simplified diagrams in textbooks, neatly laid out and colour-coded like an engineer’s blueprint. But the reality that hits you when you see an animal opened up on a dissecting table is very different. I think it would be an instructive exercise to ask an engineer to draw an improved version of, say, the arteries leaving the heart. I imagine the result would be something like the exhaust manifold of a car, with a neat line of pipes coming off in orderly array, instead of the haphazard mess that we actually see when we open a real chest.(And creationists would respond by saying actually, it’s designed that way for a reason, and if it had a more simple layout, that would ruin everything. Or, alternatively, everything was perfect at the time of creation, and then sin entered the world and everything got worse and that’s why we see “bad design” now.)
Also, it turns out “convergent evolution” is totally different from what I thought it was. I thought, “So if two species have similar characteristics, evolutionists say they evolved from a common ancestor. And if they have similar characteristics but they’re not supposed to have a common ancestor which shared those characteristics, then it’s convergent evolution. So basically, no matter what, it’s evidence for evolution. Yeah real scientific guys.” Haha. Nope. It turns out, when you have convergent evolution, the animals look similar, but the internal structures and processes which create those outward similarities are very different. Being similar because of a common ancestor and being similar because of convergent evolution are very different things.
For example, whales look like fish. They’re well adapted for swimming and doing all kinds of fish-like things. But a whale is completely different from a fish. They breathe air. They move their tails up and down to swim, rather than side to side like a fish. Convergent evolution means that animals developed the same outward adaptations to the same environment, but the ways in which their bodies perform those adaptations are very different.
So… this blog post has become massively long but I am NOT SORRY AT ALL, because you guys, I love science and this was my first time actually learning evolution. Back when I was a creationist, I knew all about evolution and how to argue against it, but I never learned it, you know, the way you learn and marvel at how wonderful knowledge is, let yourself get lost in discovering new things. No, back then I “learned” with my defenses on. I had to make sure I didn’t believe any of it, so I never went beyond the surface.
If you’re an ex-creationist like me, I encourage you to go learn about evolution. I totally recommend this book, but if you don’t want to read a Dawkins book, I understand that. (This one is fine though, he doesn’t talk about religion. Or feminism.) But go learn. Learn about tree rings and how the turtle’s shell evolved and vertebrates’ skeletal structure. The world is amazing.