28 October 2009


Evolution book review: Dawkins's "Greatest Show on Earth," Coyne's "Why Evolution is True," and Shubin's "Your Inner Fish"

Three of this year's books on evolutionNext month, it will be exactly 150 years since Charles Darwin published On the Origin of Species in 1859. This year also marked what would have been his 200th birthday. Unsurprisingly, there are a lot of new books and movies and TV shows and websites about Darwin and his most important book this year.

Of the books, I've bought and read the three of the highest-profile ones: Neil Shubin's Your Inner Fish (actually published in 2008), Jerry Coyne's Why Evolution is True, and Richard Dawkins's The Greatest Show on Earth: The Evidence for Evolution. They're all written by working (or, in Dawkins's case, officially retired) evolutionary biologists, but are aimed at a general audience, and tell compelling stories of what we know about the history of life on Earth and our part in it. I also re-read my copy of the first edition of the Origin itself, as well as legendary biologist Ernst Mayr's 2002 What Evolution Is, a few months ago.

Why now?

Aside from the Darwin anniversaries, I wanted to read the three new books because a lot has changed in the study of evolution since I finished my own biology degree in 1990. Or, I should say, not much has changed, but we sure know a lot more than we did even 20 years ago. As with any strong scientific idea, evidence continues accumulating to reinforce and refine it. When I graduated, for instance:

  • DNA sequencing was rudimentary and horrifically expensive, and the idea of compiling data on an organism's entire genome was pretty much a fantasy. Now it's almost easy, and scientists are able to compare gene sequences to help determine (or confirm) how different groups of plants and animals are related to each other.
  • Our understanding of our relationship with chimpanzees and our extinct mutual relatives (including Australopithecus, Paranthropus, Sahelanthropus, Orrorin, Ardipithecus, Kenyanthropus, and other species of Homo in Africa) was far less developed. With more fossils and more analysis, we know that our ancestors walked upright long before their brains got big, and that raises a host of new and interesting questions.
  • The first satellite in the Global Positioning System had just been launched, so it was not yet easily possible to monitor continental drift and other evolution-influencing geological activities happening in real time (though of course it was well accepted from other evidence). Now, whether it's measuring how far the crust shifted during earthquakes or watching as San Francisco marches slowly northward, plate tectonics is as real as watching trees grow.
  • Dr. Richard Lenski and his team had just begun what would become a decades-long study of bacteria, which eventually (and beautifully) showed the microorganisms evolving new biochemical pathways in a lab over tens of thousands of generations. That's substantial evolution occurring by natural selection, incontrovertibly, before our eyes.
  • In Canada, the crash of Atlantic cod stocks and controversies over salmon farming in the Pacific hadn't yet happened, so the delicate balances of marine ecosystems weren't much in the public eye. Now we understand that human pressures can disrupt even apparently inexhaustible ocean resources, while impelling fish and their parasites to evolve new reproductive and growth strategies in response.
  • Antibiotic resistance (where bacteria in the wild evolve ways to prevent drugs from being as effective as they used to) was on few people's intellectual radar, since it didn't start to become a serious problem in hospitals and other healthcare environments until the 1990s. As with cod, we humans have unwittingly created selection pressures on other organisms that work to our own detriment.

...and so on. Perhaps most shocking in hindsight, back in 1990 religious fundamentalism of all stripes seemed to be on the wane in many places around the world. By association, creationism and similar world views that ignore or deny that biological evolution even happens seemed less and less important.

Or maybe it just looked that way to me as I stepped out of the halls of UBC's biology buildings. After all, whether studying behavioural ecology, human medicine, cell physiology, or agriculture, no one there could get anything substantial done without knowledge of evolution and natural selection as the foundations of everything else.

Why these books?

The books by Shubin, Coyne, and Dawkins are not only welcome and useful in 2009, they are necessary. Because unlike in other scientific fields—where even people who don't really understand the nature of electrons or fluid dynamics or organic chemistry still accept that electrical appliances work when you turn them on, still fly in planes and ride ferryboats, and still take synthesized medicines to treat diseases or relieve pain—there are many, many people who don't think evolution is true.

No physicians must write books reiterating that, yes, bacteria and viruses are what spread infectious diseases. No physicists have to re-establish to the public that, honestly, electromagnetism is real. No psychiatrists are compelled to prove that, indeed, chemicals interacting with our brain tissues can alter our senses and emotions. No meteorologists need argue that, really, weather patterns are driven by energy from the Sun. Those things seem obvious and established now. We can move on.

But biologists continue to encounter resistance to the idea that differences in how living organisms survive and reproduce are enough to build all of life's complexity—over hundreds of millions of years, without any pre-existing plan or coordinating intelligence. But that's what happened, and we know it as well as we know anything.

If the Bible or the Qu'ran is your only book, I doubt much will change your mind on that. But many of the rest of those who don't accept evolution by natural selection, or who are simply unsure of it, may have been taught poorly about it back in school—or if not, they might have forgotten the elegant simplicity of the concept. Not to mention the huge truckloads of evidence to support evolutionary theory, which is as overwhelming (if not more so) and more immediate than the also-substantial evidence for our theories about gravity, weather forecasting, germs and disease, quantum mechanics, cognitive psychology, or macroeconomics.

Enjoying the human story

So, if these three biologists have taken on the task of explaining why we know evolution happened, and why natural selection is the best mechanism to explain it, how well do they do the job? Very well, but also differently. The titles tell you.

Shubin's Your Inner Fish is the shortest, the most personal, and the most fun. Dawkins's The Greatest Show on Earth is, well, the showiest, the biggest, and the most wide-ranging. And Coyne's Why Evolution is True is the most straightforward and cohesive argument for evolutionary biology as a whole—if you're going to read just one, it's your best choice.

However, of the three, I think I enjoyed Your Inner Fish the most. Author Neil Shubin was one of the lead researchers in the discovery and analysis of Tiktaalik, a fossil "fishapod" found on Ellesmere Island here in Canada in 2004. It is yet another demonstration of the predictive power of evolutionary theory: knowing that there were lobe-finned fossil fish about 380 million years ago, and obviously four-legged land dwelling amphibian-like vertebrates 15 million years later, Shubin and his colleagues proposed that an intermediate form or forms might exist in rocks of intermediate age.

Ellesmere Island is a long way from most places, but it has surface rocks about 375 million years old, so Shubin and his crew spent a bunch of money to travel there. And sure enough, there they found the fossil of Tiktaalik, with its wrists, neck, and lungs like a land animal, and gills and scales like a fish. (Yes, it had both lungs and gills.) Shubin uses that discovery to take a voyage through the history of vertebrate anatomy, showing how gill slits from fish evolved over tens of millions of years into the tiny bones in our inner ear that let us hear and keep us balanced.

Since we're interested in ourselves, he maintains a focus on how our bodies relate to those of our ancestors, including tracing the evolution of our teeth and sense of smell, even the whole plan of our bodies. He discusses why the way sharks were built hundreds of millions of years ago led to human males getting certain types of hernias today. And he explains why, as a fish paleontologist, he was surprisingly qualified to teach an introductory human anatomy dissection course to a bunch of medical students—because knowing about our "inner fish" tells us a lot about why our bodies are this way.

Telling a bigger tale

Richard Dawkins and Jerry Coyne tell much bigger stories. Where Shubin's book is about how we people are related to other creatures past and present, the other two seek to explain how all living things on Earth relate to each other, to describe the mechanism of how they came to the relationships they have now, and, more pointedly, to refute the claims of people who don't think those first two points are true.

Dawkins best expresses the frustration of scientists with evolution-deniers and their inevitable religious motivations, as you would expect from the world's foremost atheist. He begins The Greatest Show on Earth with a comparison. Imagine, he writes, you were a professor of history specializing in the Roman Empire, but you had to spend a good chunk of your time battling the claims of people who said ancient Rome and the Romans didn't even exist. This despite those pesky giant ruins modern Romans have had to build their roads around, and languages such as Italian, Spanish, Portuguese, French, German, and English that are obviously derived from Latin, not to mention the libraries and museums and countrysides full of further evidence.

He also explains, better than anyone I've ever read, why various ways of determining the ages of very old things work. If you've ever wondered how we know when a fossil is 65 million years old, or 500 million years old, or how carbon dating works, or how amazingly well different dating methods (tree ring information, radioactive decay products, sedimentary rock layers) agree with one another, read his chapter 4 and you'll get it.

Alas, while there's a lot of wonderful information in The Greatest Show on Earth, and many fascinating photos and diagrams, Dawkins could have used some stronger editing. The overall volume comes across as scattershot, assembled more like a good essay collection than a well-planned argument. Dawkins often takes needlessly long asides into interesting but peripheral topics, and his tone wanders.

Sometimes his writing cuts precisely, like a scalpel; other times, his breezy footnotes suggest a doddering old Oxford prof (well, that is where he's been teaching for decades!) telling tales of the old days in black school robes. I often found myself thinking, Okay, okay, now let's get on with it.

Truth to be found

On the other hand, Jerry Coyne strikes the right balance and uses the right structure. On his blog and in public appearances, Coyne is (like Dawkins) a staunch opponent of religion's influence on public policy and education, and of those who treat religion as immune to strong criticism. But that position hardly appears in Why Evolution is True at all, because Coyne wisely thinks it has no reason to. The evidence for evolution by natural selection stands on its own.

I wish Dawkins had done what Coyne does—noting what the six basic claims of current evolutionary theory are, and describing why real-world evidence overwhelmingly shows them all to be true. Here they are:

  1. Evolution: species of organisms change, and have changed, over time.
  2. Gradualism: those changes generally happen slowly, taking at least tens of thousands of years.
  3. Speciation: populations of organisms not only change, but split into new species from time to time.
  4. Common ancestry: all living things have a single common ancestor—we are all related.
  5. Natural selection: evolution is driven by random variations in organisms that are then filtered non-randomly by how well they reproduce.
  6. Non-selective mechanisms: natural selection isn't the only way organisms evolve, but it is the most important.

The rest of Coyne's book, in essence, fleshes those claims and the evidence out. That's almost it, and that's all it needs to be. He recounts too why, while Charles Darwin got all six of them essentially right back in 1859, only the first three or four were generally accepted (even by scientists) right away. It took the better part of a century for it to be obvious that he was correct about natural selection too, and even more time to establish our shared common ancestry with all plants, animals, and microorganisms.

Better than other books about evolution I've read, Why Evolution is True reveals the relentless series of tests that Darwinism has been subjected to, and survived, as new discoveries were made in astronomy, geology, physics, physiology, chemistry, and other fields of science. Coyne keeps pointing out that it didn't have to be that way. Darwin was wrong about quite a few things, but he could have been wrong about many more, and many more important ones.

If inheritance didn't turn out to be genetic, or further fossil finds showed an uncoordinated mix of forms over time (modern mammals and trilobites together, for instance), or no mechanism like plate tectonics explained fossil distributions, or various methods of dating disagreed profoundly, or there were no imperfections in organisms to betray their history—well, evolutionary biology could have hit any number of crisis points. But it didn't.

Darwin knew nothing about some of these lines of evidence, but they support his ideas anyway. We have many more new questions now too, but they rest on the fact of evolution, largely the way Darwin figured out that it works.

The questions and the truth

Facts, like life, survive the onslaughts of time. Opponents of evolution by natural selection have always pointed to gaps in our understanding, to the new questions that keep arising, as "flaws." But they are no such thing: gaps in our knowledge tell us where to look next. Conversely, saying that a god or gods, some supernatural agent, must have made life—because we don't yet know exactly how it happened naturally in every detail—is a way of giving up. It says not only that there are things we don't know, but things we can never learn.

Some of us who see the facts of evolution and natural selection, much the way Darwin first described them, prefer not to believe things, but instead to accept them because of supporting scientific evidence. But I do believe something: that the universe is coherent and comprehensible, and that trying to learn more about it is worth doing for its own sake.

In the 150 years since the Origin, people who believed that—who did not want to give up—have been the ones who helped us learn who we, and the other organisms who share our planet, really are. Thousands of researchers across the globe help us learn that, including Dawkins exploring how genes, and ideas, propagate themselves; Coyne peering at Hawaiian fruit flies through microscopes to see how they differ over generations; and Shubin trekking to the Canadian Arctic on the educated guess that a fishapod fossil might lie there.

The writing of all three authors pulses with that kind of enthusiasm—the urge to learn the truth about life on Earth, over more than 3 billion years of its history. We can admit that we will always be somewhat ignorant, and will probably never know everything. Yet we can delight in knowing there will always be more to learn. Such delight, and the fruits of the search so far, are what make these books all good to read during this important anniversary year.

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Thank you. This is an extremely well written article.

It captures my take on those three books and on evolution.
If you haven't read Dawkins' 'The Ancestor's Tale' I highly recommend it. Dawkins is at his best a s a story teller, and tells the story all the way back to the first single celled organisms we know of, and describes in eloquent detail the way 'common ancestry' actually works.

I really consider it his best work.
Excellent review. I have read both the WEIT and TGSoE and found them both to be very educating, interesting and enjoyable to read, especially for the layperson amongst us. I will be ordering "Your Inner Fish" as a result of reading your review.
I to, can recommend "The Ancestors Tale".