Your Inner Fish: A Journey Into the 3.5-Billion-Year History of the Human Body

Your Inner Fish: A Journey Into the 3.5-Billion-Year History of the Human Body

by Neil Shubin


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Product Details

ISBN-13: 9780307277459
Publisher: Knopf Doubleday Publishing Group
Publication date: 01/06/2009
Edition description: Reprint
Pages: 256
Sales rank: 55,505
Product dimensions: 5.10(w) x 7.90(h) x 1.00(d)

About the Author

Neil Shubin is the author of the best-selling Your Inner Fish, which was chosen by the National Academy of Sciences as the best book of the year in 2009. Trained at Columbia, Harvard, and the University of California at Berkeley, Shubin is associate dean of biological sciences at the University of Chicago. In 2011 he was elected to the National Academy of Sciences.

Read an Excerpt


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.


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.

Table of Contents

Preface ix

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

Epilogue 199

Afterword to the Vintage Books Edition 203

Notes, References, and Further Reading 211

Acknowledgments 223

Index 227

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Your Inner Fish 4.2 out of 5 based on 0 ratings. 108 reviews.
Guest More than 1 year ago
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.
Tunguz More than 1 year ago
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.
owl484 More than 1 year ago
A very good book. Well written. The author makes a good case of connecting with our past(500 million years ago as a fish) As a human being it is good to know that "Natural Selection" is a feasible cause and affect than a belief in a myth. I'm ready for a more realistic interpretation of how I came to be,even if it means in updating of my personal beliefs.
wisdomloverPA More than 1 year ago
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.
Miguel Anguiano More than 1 year ago
This book is not about faith please put that behind you and you enjoy it.
CalBear2010 More than 1 year ago
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!
AnnieBM More than 1 year ago
This is a wonderfully written and engaging book which takes one on a paleontologist's journey to undersrtand the human body. The story line of discovery is quite enganging and the writing is basic and accessible to general readers yet makes accurate connections to recent discoveries and work. I highly recommend this book as essential reading for those who have a human body or know any human bodies. For Human Anatomy and Physiology students: it is a great way to quiz yourself!
Guest More than 1 year ago
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.
dchaikin on LibraryThing 8 months ago
Neil Shubin is a mixture of a paleontologist and some kind of a DNA researcher, which gives him a unique take as a professor of human anatomy. He brings these all together in an enjoyable and very accessible form here.As this subtitle tells us, this is a look at why we humans are constructed the way we are from an evolutionary perspective. So we learn that the nerves which control our facial expressions follow crazy whirling paths through our heads, and also connect to our ears ¿ and Shubin tells us why. Or he gives us an evolutionary explanation of why we lose our balance when we get drunk. (Our inner ears developed form little organs fish use to detect water movement. And the fluid they developed happens to mix poorly with alcohol.) In general he points out that we are kind of like a souped-up Volkswagen Beetle ¿ we are a more primitive life form that has been awkwardly modified for each new evolutionary challenge ¿ and that is the source of practically all our health problems.Shubin spends the book tracing many of these modifications back as far down the evolutionary tree as he can get, and quite a few go all the way to the single-cell animals. It's a good story.One of the more enjoyable aspects of the book are his asides about his personal experience searching for fossils in the field. In one story he describes being a grad student and looking so carefully at an outcrop and failing to find a single fossil ¿ while the rest of the group were filling bags with fossils. His problem was that he had to learn to tune his eyes to recognize the right kinds of patterns and textures. This was something I can relate to. I remember a day as grad student looking so carefully at a Kansas roadside outcrop, and seeing just a simple flat limestone bed of certain vague characteristics. After a while our professor walked up and starting pointing out various features right in front of us ¿ fossil root trails, discolored surfaces, textural changes. I had looked right at them without seeing them. These are fossil soil features on a marine rock unit. Suddenly I was able to get new a sense of the ocean rising and falling; an entire dynamic environment began to come alive.
mensenkinderen on LibraryThing 8 months ago
I've read quite a lot of books regarding evolution, but "Your inner fish" offers an original approach to evolution and the evolution of (our) anatomy in particular. Shubin illustrates his tale with stories about his interesting fieldwork in paleontology and anatomy.
kaelirenee on LibraryThing 8 months ago
There are many aspects to the body that make us human. Limbs, eyes, stature, genetics. None of it just happened. And this is evident by looking at all those that have come before us. By clearly showing how evolution is decent with modification, Neil Shubin shows how we can better understand the whys and wherefores of our own bodies by looking at the structure of simpler organisms, namely fish. An excelent example (to me) was the examination of the cranial nerves. I remember them from my anatomy class as seemingly tangled and I couldn't understand why they were so random. But by looking at embryology, fish, and many other aspects of comparative vertebrate anatomy, I now understand how beautifully arranged they really are.Shubin examines many examples like this, showing how the fossil record show evolutionary history, and how many of these conclusions have been drawn in his field. Included are examples of how body plans form, limbs form, teeth end up in the mouth, and how the ear is formed. The book is engaging, entertaining, and informative. The author strikes an excellent balance between not talking over the audiences head and not dumbing down the information. Recommended for anyone interested in evolution, paleontology, body plans, and examining many of the missing links that have been discovered.
TheCrow2 on LibraryThing 8 months ago
A great book about the human body and what we have common with out ancestors like fish, jellyfish or even sponges. Paleontological, anatomical and genetical proofs that we are a close relative of the great family of Earth's animals. And yes, the explanation why we hiccup...
Stbalbach on LibraryThing 8 months ago
Your Inner Fish is a popular science book and scientist memoir - the author digs up millions year old fossils for a living in exotic parts of the world. The main idea is that humans evolved from more primitive creatures, like fish, and we still have the vestiges of those creatures in our biology and anatomy. The first and last chapter are very good, but the meat of the book was somewhat uninteresting, for me. The author is clearly excited about it, and other readers really enjoyed it, but for some reason I just didn't find much of interest.
Sovranty on LibraryThing 8 months ago
This book allows the reader to own the evolutionary path of the human species. Often, it seems books focusing on evolution use other species to example and follow. This book may lend convincing to those weary of human evolution. Entertaining and well illustrated.
Alina100 on LibraryThing 8 months ago
The book talks about our fishy origins and shows how life on Earth is interrelated. This book is intended for the kind of people who are interested in the evolution process, as well as science in general.
ChrisRippel on LibraryThing 8 months ago
Reveals how the physiology of our distant ancestors remains in our human bodies. Lots of illustrations to clarify points. Generally readable though it dragged in places. Afterword updates the January 2008 hardback. A good complement to Endless Forms Most Beautiful.
meggyweg on LibraryThing 8 months ago
A good biology/evolution book for the layman. I'm not all that interested in science, but this held my attention, and it demonstrates many concepts of evolution in easy to understand terms. I was amazed to learn just how much I had in common with fish, primitive worms, etc.
nancenwv on LibraryThing 8 months ago
An engaging tour of human evolution. He answered a lot of things I have wondered about as a curious science layperson- like how and why did this move toward specialized multi-celled bodies begin and how could an eyeball ever evolve? While Shubin shared the excitement of paleontologists unwrapping clues to missing links I really got a sense of the timespan of the fossil record. The story of each body slowly changing into the next step is truly amazing. Who knew that the three bones of our inner ear are re-fashioned pieces of reptile jaws?
mykl-s on LibraryThing 8 months ago
Fun science. Clearly written, with simple and helpful drawings. Why we hiccup, why the three-boned middle ear is important, and the evolution of bozos. I want to run out and search for fossils.
woodge on LibraryThing 8 months ago
Neil Shubin is a paleontologist who delves briefly into the history of the human body by way of fossils and DNA evidence. Sure, I learned stuff... like how interconnected all the species really are; and that mammals have three bones in the inner ear while other species have fewer; and that there's a gene called Sonic hedgehog; and how to extract DNA using common household appliances and items you could easily buy in a store (a blender is involved and I'm easily reminded of the Bass-O-Matic). But, really this short book (just over 200 pages) was a bit of a slog to get through (although the explanations are clear enough). I've read other non-fiction that was much more compelling. But if you've an interest in fossils and DNA and where we came from, you might find this enlightening. But since this book deals with actual science, I definitely wouldn't recommend this book to Creationists. Though I suppose a Creationist wouldn't be picking up a title like this one in the first place. They're probably looking for something more along the lines of Your Inner Godliness: A Journey Into the Four Thousand Year History of the Human Body. But I digress.
nbzottel on LibraryThing 8 months ago
The first time I picked up "Your Inner fish" I was taken aback at all the terminology Shubin throws at his readers - and that even though I myself was studying anatomy at that moment. Two years later it proved to be an interesting read on how all animal life is related in often not very obvious ways. Nice to know where hiccups come from and who we have to thank for them: thanks for that, mr. tadpole!
norabelle414 on LibraryThing 8 months ago
Oh hey, a book on science for the masses that uses tons of unnecessary metaphors that don't really apply! How original! The last chapter is good though. It talks about the evolutionary basis of health problems. It's mostly straightforward, and only uses one stupid metaphor comparing the human body to a souped-up VW Beetle.
deslni01 on LibraryThing 8 months ago
Your Inner Fish is a wonderful and enthusiastically written book on evolution and the connection between all species of creatures on Earth. What do humans have in common with fish? A lot, actually. Neil Shubin takes the reader on an adventure of paleontology and biology to examine different body parts and where they originated and how they developed. In Neil's own words, Looking back through billions of years of change, everything innovative or apparently unique in the history of life is really just old stuff that has been recycled, recombined, repurposed, or otherwise modified for new uses. This is the story of every part of us, from our sense organs to our heads, indeed our entire body plan.From the arms, forearms and wrists to the eyes, brain, nerves and ears, to embryonic development and various genetic similarities, Neil combines his excitement for his work with a remarkable prose to provide a basic and general overview of evidence for evolution and common ancestry, in a very simplified way. The many pictures and diagrams interspersed do an excellent job simplifying many ideas, and provide wonderful clarity for many of the ideas.
Beej415 on LibraryThing 8 months ago
A fascinating and very approachable explanation of the evolution of humans from the first excursions out of the pond. Shubin steers clear, mostly, from any reference to the "debate" between creationists and scientists, but the book so superbly and plainly presents the connections between modern humans and our ancestors of every type, that it should be used as a teaching tool as part of every high school science curriculum in the country.
Devil_llama on LibraryThing 8 months ago
A fun exploration of human evolution, tracing our relationship with the fish. This is a good way to find a new approach to human evolution, which all too often is obsessed with the other primates only, and neglects our fishy lineage.