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Details on a Major New Discovery included in a New AfterwordWhy do we look the way we do? Neil Shubin, the paleontologist and professor of anatomy who co-discovered Tiktaalik, the “fish with hands,” tells the story of our bodies as you've never heard it before. By examining fossils and DNA, he shows us that our hands actually resemble fish fins, our heads are organized like long-extinct jawless fish, and major parts of our genomes look and function like those of worms and bacteria. Your Inner Fish makes us look ...
Details on a Major New Discovery included in a New AfterwordWhy do we look the way we do? Neil Shubin, the paleontologist and professor of anatomy who co-discovered Tiktaalik, the “fish with hands,” tells the story of our bodies as you've never heard it before. By examining fossils and DNA, he shows us that our hands actually resemble fish fins, our heads are organized like long-extinct jawless fish, and major parts of our genomes look and function like those of worms and bacteria. Your Inner Fish makes us look at ourselves and our world in an illuminating new light. This is science writing at its finest—enlightening, accessible and told with irresistible enthusiasm.
FINDING YOUR INNER FISH
Typical summers of my adult life are spent in snow and sleet, cracking rocks on cliffs well north of the Arctic Circle. Most of the time I freeze, get blisters, and find absolutely nothing. But if I have any luck, I find ancient fish bones. That may not sound like buried treasure to most people, but to me it is more valuable than gold.
Ancient fish bones can be a path to knowledge about who we are and how we got that way. We learn about our own bodies in seemingly bizarre places, ranging from the fossils of worms and fish recovered from rocks from around the world to the DNA in virtually every animal alive on earth today. But that does not explain my confidence about why skeletal remains from the past—and the remains of fish, no less—offer clues about the fundamental structure of our bodies.
How can we visualize events that happened millions and, in many cases, billions of years ago? Unfortunately, there were no eyewitnesses; none of us was around. In fact, nothing that talks or has a mouth or even a head was around for most of this time. Even worse, the animals that existed back then have been dead and buried for so long their bodies are only rarely preserved. If you consider that over 99 percent of all species that ever lived are now extinct, that only a very small fraction are preserved as fossils, and that an even smaller fraction still are ever found, then any attempt to see our past seems doomed from the start.
DIGGING FOSSILS—SEEING OURSELVES
I first saw one of our inner fish on a snowy July afternoon while studying 375-million-year-old rocks on Ellesmere Island, at a latitude about 80 degrees north. My colleagues and I had traveled up to this desolate part of the world to try to discover one of the key stages in the shift from fish to land-living animals. Sticking out of the rocks was the snout of a fish. And not just any fish: a fish with a flat head. Once we saw the flat head we knew we were onto something. If more of this skeleton were found inside the cliff, it would reveal the early stages in the history of our skull, our neck, even our limbs.
What did a flat head tell me about the shift from sea to land? More relevant to my personal safety and comfort, why was I in the Arctic and not in Hawaii? The answers to these questions lie in the story of how we find fossils and how we use them to decipher our own past.
Fossils are one of the major lines of evidence that we use to understand ourselves. (Genes and embryos are others, which I will discuss later.) Most people do not know that finding fossils is something we can often do with surprising precision and predictability. We work at home to maximize our chances of success in the field. Then we let luck take over.
The paradoxical relationship between planning and chance is best described by Dwight D. Eisenhower’s famous remark about warfare: “In preparing for battle, I have found that planning is essential, but plans are useless.” This captures field paleontology in a nutshell. We make all kinds of plans to get us to promising fossil sites. Once we’re there, the entire field plan may be thrown out the window. Facts on the ground can change our best-laid plans.
Yet we can design expeditions to answer specific scientific questions. Using a few simple ideas, which I’ll talk about below, we can predict where important fossils might be found. Of course, we are not successful 100 percent of the time, but we strike it rich often enough to make things interesting. I have made a career out of doing just that: finding early mammals to answer questions of mammal origins, the earliest frogs to answer questions of frog origins, and some of the earliest limbed animals to understand the origins of land-living animals.
In many ways, field paleontologists have a significantly easier time finding new sites today than we ever did before. We know more about the geology of local areas, thanks to the geological exploration undertaken by local governments and oil and gas companies. The Internet gives us rapid access to maps, survey information, and aerial photos. I can even scan your backyard for promising fossil sites right from my laptop. To top it off, imaging and radiographic devices can see through some kinds of rock and allow us to visualize the bones inside.
Despite these advances, the hunt for the important fossils is much what it was a hundred years ago. Paleontologists still need to look at rock—literally to crawl over it—and the fossils within must often be removed by hand. So many decisions need to be made when prospecting for and removing fossil bone that these processes are difficult to automate. Besides, looking at a monitor screen to find fossils would never be nearly as much fun as actually digging for them.
What makes this tricky is that fossil sites are rare. To maximize our odds of success, we look for the convergence of three things. We look for places that have rocks of the right age, rocks of the right type to preserve fossils, and rocks that are exposed at the surface. There is another factor: serendipity. That I will show by example.
Our example will show us one of the great transitions in the history of life: the invasion of land by fish. For billions of years, all life lived only in water. Then, as of about 365 million years ago, creatures also inhabited land. Life in these two environments is radically different. Breathing in water requires very different organs than breathing in air. The same is true for excretion, feeding, and moving about. A whole new kind of body had to arise. At first glance, the divide between the two environments appears almost unbridgeable. But everything changes when we look at the evidence; what looks impossible actually happened.
In seeking rocks of the right age, we have a remarkable fact on our side. The fossils in the rocks of the world are not arranged at random. Where they sit, and what lies inside them, is most definitely ordered, and we can use this order to design our expeditions. Billions of years of change have left layer upon layer of different kinds of rock in the earth. The working assumption, which is easy to test, is that rocks on the top are younger than rocks on the bottom; this is usually true in areas that have a straightforward, layer-cake arrangement (think the Grand Canyon). But movements of the earth’s crust can cause faults that shift the position of the layers, putting older rocks on top of younger ones. Fortunately, once the positions of these faults are recognized, we can often piece the original sequence of layers back together.
The fossils inside these rock layers also follow a progression, with lower layers containing species entirely different from those in the layers above. If we could quarry a single column of rock that contained the entire history of life, we would find an extraordinary range of fossils. The lowest layers would contain little visible evidence of life. Layers above them would contain impressions of a diverse set of jellyfish-like things. Layers still higher would have creatures with skeletons, appendages, and various organs, such as eyes. Above those would be layers with the first animals to have backbones. And so on. The layers with the first people would be found higher still. Of course, a single column containing the entirety of earth history does not exist. Rather, the rocks in each location on earth represent only a small sliver of time. To get the whole picture, we need to put the pieces together by comparing the rocks themselves and the fossils inside them, much as if working a giant jigsaw puzzle.
That a column of rocks has a progression of fossil species probably comes as no surprise. Less obvious is that we can make detailed predictions about what the species in each layer might actually look like, by comparing them with species of animals that are alive today; this information helps us to predict the kinds of fossils we will find in ancient rock layers. In fact, the fossil sequences in the world’s rocks can be predicted by comparing ourselves with the animals at our local zoo or aquarium.
How can a walk through the zoo help us predict where we should look in the rocks to find important fossils? A zoo offers a great variety of creatures that are all distinct in many ways. But let’s not focus on what makes them distinct; to pull off our prediction, we need to focus on what different creatures share. We can then use the features common to all species to identify groups of creatures with similar traits. All the living things can be organized and arranged like a set of Russian nesting dolls, with smaller groups of animals comprised in bigger groups of animals. When we do this, we discover something very fundamental about nature.
Every species in the zoo and the aquarium has a head and two eyes. Call these species “Everythings.” A subset of the creatures with a head and two eyes has limbs. Call the limbed species “Everythings with limbs.” A subset of these headed and limbed creatures has a huge brain, walks on two feet, and speaks. That subset is us, humans. We could, of course, use this way of categorizing things to make many more subsets, but even this threefold division has predictive power.
The fossils inside the rocks of the world generally follow this order, and we can put it to use in designing new expeditions. To use the example above, the first member of the group “Everythings,” a creature with a head and two eyes, is found in the fossil record well before the first “Everything with limbs.” More precisely, the first fish (a card-carrying member of the “Everythings”) appears before the first amphibian (an “Everything with limbs”). Obviously, we refine this by looking at more kinds of animals and many more characteristics that groups of them share, as well as by assessing the actual age of the rocks themselves.
In our labs, we do exactly this type of analysis with thousands upon thousands of characteristics and species. We look at every bit of anatomy we can, and often at large chunks of DNA. There are so much data that we often need powerful computers to show us the groups within groups. This approach is the foundation of biology, because it enables us to make hypotheses about how creatures are related to one another.
Besides helping us refine the groupings of life, hundreds of years of fossil collection have produced a vast library, or catalogue, of the ages of the earth and the life on it. We can now identify general time periods when major changes occurred. Interested in the origin of mammals? Go to rocks from the period called the Early Mesozoic; geochemistry tells us that these rocks are likely about 210 million years old. Interested in the origin of primates? Go higher in the rock column, to the Cretaceous period, where rocks are about 80 million years old.
The order of fossils in the world’s rocks is powerful evidence of our connections to the rest of life. If, digging in 600-million-year-old rocks, we found the earliest jellyfish lying next to the skeleton of a woodchuck, then we would have to rewrite our texts. That woodchuck would have appeared earlier in the fossil record than the first mammal, reptile, or even fish—before even the first worm. Moreover, our ancient woodchuck would tell us that much of what we think we know about the history of the earth and life on it is wrong. Despite more than 150 years of people looking for fossils—on every continent of earth and in virtually every rock layer that is accessible—this observation has never been made.
Let’s now return to our problem of how to find relatives of the first fish to walk on land. In our grouping scheme, these creatures are somewhere between the “Everythings” and the “Everythings with limbs.” Map this to what we know of the rocks, and there is strong geological evidence that the period from 380 million to 365 million years ago is the critical time. The younger rocks in that range, those about 360 million years old, include diverse kinds of fossilized animals that we would all recognize as amphibians or reptiles. My colleague Jenny Clack at Cambridge University and others have uncovered amphibians from rocks in Greenland that are about 365 million years old. With their necks, their ears, and their four legs, they do not look like fish. But in rocks that are about 385 million years old, we find whole fish that look like, well, fish. They have fins, conical heads, and scales; and they have no necks. Given this, it is probably no great surprise that we should focus on rocks about 375 million years old to find evidence of the transition between fish and land-living animals.
We have settled on a time period to research, and so have identified the layers of the geological column we wish to investigate. Now the challenge is to find rocks that were formed under conditions capable of preserving fossils. Rocks form in different kinds of environments and these initial settings leave distinct signatures on the rock layers. Volcanic rocks are mostly out. No fish that we know of can live in lava. And even if such a fish existed, its fossilized bones would not survive the superheated conditions in which basalts, rhyolites, granites, and other igneous rocks are formed. We can also ignore metamorphic rocks, such as schist and marble, for they have undergone either superheating or extreme pressure since their initial formation. Whatever fossils might have been preserved in them have long since disappeared. Ideal to preserve fossils are sedimentary rocks: limestones, sandstones, siltstones, and shales. Compared with volcanic and metamorphic rocks, these are formed by more gentle processes, including the action of rivers, lakes, and seas. Not only are animals likely to live in such environments, but the sedimentary processes make these rocks more likely places to preserve fossils. For example, in an ocean or lake, particles constantly settle out of the water and are deposited on the bottom. Over time, as these particles accumulate, they are compressed by new, overriding layers. The gradual compression, coupled with chemical processes happening inside the rocks over long periods of time, means that any skeletons contained in the rocks stand a decent chance of fossilizing. Similar processes happen in and along streams. The general rule is that the gentler the flow of the stream or river, the better preserved the fossils.
1 Finding Your Inner Fish 3
2 Getting a Grip 28
3 Handy Genes 44
4 Teeth Everywhere 60
5 Getting Ahead 81
6 The Best-Laid (Body) Plans 97
7 Adventures in Bodybuilding 116
8 Making Scents 139
9 Vision 148
10 Ears 158
11 The Meaning of It All 173
Afterword to the Vintage Books Edition 203
Notes, References, and Further Reading 211
Posted January 28, 2008
Dr. Schubin has truly succeeded in tracing a fun and informative account of human evolution by looking at fossil and extant homologues. Drawing (especially) from paleontology, but also from fields such as molecular genetics, Schubin takes the reader on an introductory ride through vertebrate form, function, and genetics. I would highly recommend this title as a must-have to any person interested in the biological, medical, or paleontological sciences, whether professional or avocational.
6 out of 6 people found this review helpful.Was this review helpful? Yes NoThank you for your feedback. Report this reviewThank you, this review has been flagged.
Posted May 21, 2011
Among many reasons that make evolution of life such a fascinating subject to study, the fact that we can learn more about how we humans have become what we are today must rank close to the top. This is the basic premise behind Neil Shubin's "Your Inner Fish." Shubin's day job is field paleontologist, but the idea for this book came about when he taught some laboratory exercises in human anatomy. It turns out that his training in recognizing and categorizing bones of long-extinct creatures is an excellent preparation for understanding of how the human body works.
The book is a fascinating and insightful journey into the 3.5 billion years of evolution. It combines scientific facts and information with personal stories and anecdotes. The scientific information is fresh and relevant, and it is not just a regurgitation of the material that can be found in a myriad other books on evolution. These facts really help you with gaining insight into how exactly all life on Earth is related.
The last major chapter is probably the most interesting. It is an examination of the way that many of our chronic diseases and illnesses can be traced to the very restricted design options that evolution had. There really is a price that we pay for getting to where we are in the evolutionary development.
2 out of 2 people found this review helpful.Was this review helpful? Yes NoThank you for your feedback. Report this reviewThank you, this review has been flagged.
Posted February 25, 2011
Posted May 5, 2010
I Also Recommend:
The prominent University of Chicago Paleontologist and Professor of Anatomy Neil Shubin graciously narrates the long Geological journey that has led to the structure and function of our current biological system. Shubin's account of his discovery of the 375 million year fish from Ellesmere Island is a warm tale of modern science in one of its finest lights. The timeline he provides of the 375 million years passed since Tiktaalik is thoroughly engaging and bound to have any curious reader interested in our life history and common ancestry hooked until the end. Shubin's work is certain to enlighten all. Scientist or non-scientist, you will learn something new, and at the very least you are destined to gain a greater appreciate of life!
1 out of 1 people found this review helpful.Was this review helpful? Yes NoThank you for your feedback. Report this reviewThank you, this review has been flagged.
Posted March 8, 2009
This book by Neil Shubin was an easy read, although I was not convinced with the author's opinions of how the human body came to be. Neil Shubin talked about how the human body was related to ancient fish found in fossils. He explores all over the world and shares his findings in this book. This book was an easy read with great pictures and graphs to explain each thought. The author had definite opinions about how the human form came to be. The author left no room for any religious theory.
-OSU Comp. Student 2009
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Posted February 21, 2008
A fascinating read that really makes you think. So interesting to see an esteemed scientist like Shubin taking on this subject so successfully, getting into the nitty gritty of what evolution is and what it is not. The only problem was that at times it could be quite dry and sometimes slow to read. On that note, I just finished another book that also really made me think. NATURAL SELECTION by Dave Freedman. It's a Jurassic Park type book - a science-based action-thriller about the evolution of a new species of flying predator. What made it special - besides how incredibly fast those pages turned - was how fun, relatable and easy-to-understand it made evolution, a great 'fictional compliment' to anything by Shubin.
1 out of 1 people found this review helpful.Was this review helpful? Yes NoThank you for your feedback. Report this reviewThank you, this review has been flagged.
Posted February 8, 2013
Posted January 11, 2013
This was interesting and well structured, i learned several things about how parts our bodies evolved from simpller ancestor forms
It flowed so well it was a pleasure to read
I Highly recommend it
Posted July 8, 2012
Posted June 12, 2012
The ideal of design is perfection - an object so well put together that the alteration of the slightest detail ruins the overall effect. La Gioconda. More commonly, design can be classified as "organic". A simple concept embellished by contingency. Make do with what you have available. Sometimes contingency can lead to its own beauty - more often it's a mess.
In this little book, Neil Shubin provides an overview of a number of perspectives by which one can trace the evolutionary history of the human body from the earliest single-cell (despite the title) organism. The author takes us on a somewhat breathless romp through evolutionary anatomy and physiology in what amounts, often, to a textbook update. He opens Your Inner Fish with an excellent description of the frustrations, triumphs, luck and hard work of paleontological field exploration. In the chapters that follow he combines humor and expertise in detailing the evolutionary paths to human appendages, the parallels between anatomy and genetics, between physiology and biochemistry. Along the way he finds time to discuss the evolutionary implications of such diverse topics as hiccups and hernias.
Like S. J. Gould, Shubin comes up short in making the fundamental connection between architecture and phylogeny. Why not, in the assembly of limbs, 5, many, 2, 1 or even 4, 1, 3, 2 instead of 1, 2, many, 5? Is the order inevitable or accidental? Is ET a cute joke or a reasonable alternative?
The book could well have been titled "A brief introduction to human comparative anatomy", but that would not have been very sexy. However, "brief" should have been appended to the title, for that would have helped to soften the books major flaw - too much is attempted in too little space, especially when one takes into account a bit too much repetition. The author does redeem himself to some degree with an excellent set of annotated notes that includes a solid selection of additional readings.
Shubin deserves kudos for taking on such a daunting task and coming up with a fine book that is well worth the read and an excellent starting point for further exploration.
Richard R. Pardi Environmental Science William Paterson University
Posted March 28, 2012
This small-sized book teaches many of the key aspects of evolution by focusing features of you and me, like our hands and eyes and necks, and shows how they developed over the millennia from more ancient critters, not just earlier mammals or vertebrates but all the way back to bacteria. A really fun book to read, and nonetheless solidly accurate and never over-simplifying complex issues.Was this review helpful? Yes NoThank you for your feedback. Report this reviewThank you, this review has been flagged.
Posted March 25, 2012
Posted November 4, 2011
My comments should be received in light of the fact that I'm a self-admitted science nerd. However, this book was liked by my wife also (English degree). Any person curious about the history of life on Earth will find this book fascinating. This fish (Tiktaalik) establishes an anatomical connection between it and goes all the way up the chain to mammals.Was this review helpful? Yes NoThank you for your feedback. Report this reviewThank you, this review has been flagged.
Posted April 18, 2011
Posted April 8, 2011
Posted March 7, 2011
This book is great for anyone that wants to learn more about where we came from, and why we are the way we are. It take's you back to when we were all swimming around, and beyond. It contains all the logic and evidence that it needs to support its claims, and puts it all out there in an easy to read, easy to understand way. What a great book. I have it in paperback, and nookbook format.Was this review helpful? Yes NoThank you for your feedback. Report this reviewThank you, this review has been flagged.
Posted November 22, 2010
Posted November 1, 2010
This was a book club choice so I had no idea what I was buying.
As a Christian I find that it is sad that a person would dedicate so much time and research into proving "Where we come from"!
It all comes down to faith....Fish don't talk or have feelings, so where does that come from????
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Posted March 13, 2010
reading it put me in the mind set of the old natural history journals, translating well between the clinical scientific mind set and the more common workings mans logic that you don't always see. all in all a good book.Was this review helpful? Yes NoThank you for your feedback. Report this reviewThank you, this review has been flagged.
Posted January 26, 2010
This is a fascinating book on a topic that is typically presented dryly: paleontology. A very readable and layperson assessable book, Dr. Neil Shubin has great story telling skills. He successfully incorporates a behind the scenes personal view of his research with facts from the fossil world and the paleontological thought process.
A great introduction to the researchers and fossil record supporting evolution!