Meet Your Inner Fish

I recently read Your Inner Fish: A Journey Into the 3.5-Billion Year History of the Human Body (Pantheon Books, 2008) by Neil Shubin, a paleotologist and professor of anatomy at the University of Chicago. By coincidence, Jared at LDS Science Review had posted the same book in his “Currently Reading” list. Here is our conversation about this interesting book.

Dave: I’ve read at least a dozen books on evolution and natural history, but this is the first one I’ve read that uses a comparative anatomy approach. Anatomy may sound like dull reading, but I found the book to be both informative and entertaining. Its subtitle, “a journey into the 3.5 billion-year history of the human body,” is a tipoff to how much the topic of anatomy directs the discussion. The “inner fish” of the title is a reference to the many aspects of human anatomy that resemble similar aspects of fish anatomy, sometimes in surprisingly fundamental ways.

Jared: Yes, when I read in a book review that Your Inner Fish was written at a high school reading level, I thought it might be a collection of simple explanations of well-worn material. While the explanations may be simple (which made for easy reading), there was enough material unfamiliar to me to keep me interested. It may seem strange to think that Shubin (a paleontologist) teaches anatomy to medical students, but as he explains, his knowledge of comparative anatomy enables him to illuminate otherwise strange aspects of human anatomy. And although he is a paleontologist, Shubin studies living organisms as well, so this is not a book only about fossils. I think that this book could very well inspire some students to study paleontology or developmental biology.

Dave: One example of a discussion I liked is in Chapter 6, “The Best-Laid (Body) Plans.” Shubin summarizes the standard animal body plan as follows:

Like us, fish, lizards, and cows have bodies that are symmetrical with a front/back, top/bottom, and left/right. Their front ends (corresponding to the top of an upright human) all have heads, with sense organs and brains inside. They have a spinal cord that runs the length of the body along the back (p. 97).

Shubin then spends most of the chapter discussing comparative embryology to show the deep connections between all creatures with this standard body plan. It is the presence in widely different species of similar or even identical genes (encoded in the DNA of each species) that gives rise to the amazing anatomical resemblances we observe. Even sea anemones, whose physical form is not outwardly similar to that of mammals, turn out to have “primitive versions of some of our major body plan genes,” in particular those genes that orient embryonic development along front-to-rear and belly-to-back axes (p. 113).

Jared: A fact that caught my eye was that cetaceans (whales and dolphins) have genes for smelling, but the genes are all broken remnants of the past. I think that the highlight of the book is Shubin’s telling of how he got involved in paleontology, culminating in his discovery of the fossil Tiktaalik. He writes in an accessible style such that you might think that you are reading something written by a neighbor down the street. I’ve never found a fossil in my life, but anybody who has searched for shark’s teeth on a beach can appreciate his description of searching landscapes for signs of fossils. (Then again, maybe I have found fossil shark’s teeth after all.) Reading his tales of fossil hunting, I almost felt like I was right there alongside him–and sometimes I wished I was.

Dave: Yes, his tales of field work adventure give a sort of travel story feel to some chapters, which helps to spice up the narrative. I’m guessing some readers might also relate to his experience as a student in the anatomy lab. It wasn’t until he and other students began dissecting the hands of the lab cadavres that Shubin suddenly felt a human connection with the person the cadavre once was (the second chapter is all about the human hand). Later, while alone in the lab very late one night studying for the final, Shubin became unnerved by the surroundings and fled the building.

Jared: Shubin was surprisingly low-key about evolution. Tiktaalik roseae, the fossil species discovered by Shubin, has gotten a lot of press because it is a great example of a transitional fossil. Moreover, Shubin and his team went looking for it near the arctic based on certain geological criteria. In other words, they knew what they were looking for, and they knew where to look for it, then they just went out and found it. This kind of success helps to answer the challenge of various anti-evolutionist canards. But while I enjoy smackdowns of anti-evolutionist rhetoric as much as the next guy, I don’t recall a single negative reference in the book to creationism or intelligent design, which I found refreshing. Shubin has a science story to tell and he sticks to it–and I think he does it well.

Dave: And he did it in a short 200 pages, including roughly 45 illustrations and photographs, a real aid to understanding some of the unfamiliar topics discussed. I, too, liked the fact that he stuck to his scientific knitting and didn’t, for example, garnish his descriptions of the development of the human eye and inner ear with derogatory asides directed at believers, an approach rooted in false portrayals of all scientists as unbelievers and all believers as being anti-science. Not only is that sort of stereotyping factually inaccurate, it is especially out of place when applied to Mormons, given how open LDS theology is to science and how friendly LDS colleges and universities are to scientific education and research.

I like to give the author the last word in these online reviews, so here is Neil Shubin likening the exciting biological discoveries of the present generation to the astronomical discoveries of the space age sixties.

Just as the space program changed the way we look at the moon, paleontology and genetics are changing the way we view ourselves. As we learn more, what once seemed distant and unattainable comes within our comprehension and grasp. We live in an age of discovery, when science is revealing the inner workings of creatures as different as jellyfish, worms, and mice. We are now seeing the glimmer of a solution to one of the greatest mysteries of science–the genetic differences that make humans distinct from other creatures. Couple these powerful new insights with the fact that some of the most important discoveries in paleontology–new fossils and new tools to analyze them–have come to light in the past twenty years, and we are seeing the truths of our history with ever-increasing precision. … I can imagine few things more beautiful or intellectually profound than finding the basis for our humanity, and remedies for many of the ills we suffer, nestled inside some of the most humble creatures that have ever lived on our planet (p. 201).

9 comments for “Meet Your Inner Fish

  1. I read this when it first came out and absolutely loved it: warm fuzzies at the miracle of creation and the whole nine yards. Thanks for this post and I hope lots of people read this book.

  2. Thanks for the review, gents. I don’t get around to much popular science reading lately; so it is nice to get a feel for what is going on in the presses. This sounds like an excellent volume. The story of the the tiktaalik discovery does quicken the hearts and minds of scientists, for sure.

  3. # 2: Talk about mixed metaphors! 1) Warm fuzzies. 2) Whole nine yards. This refers to the 27 foot bullet belt use by side gunner on planes in WWII. To shoot all your bullet at an enemy plane was to ” give them the whole nine yards!”

  4. Thank you for that interesting tidbit, Bob. You just moved “whole nine yards” way up my list of favorite metaphors.

  5. Dave or Jared, since reading the book, can you think of an interaction with your body that evoked thoughts of the inner fish?

  6. Bob #5,

    Not to burst your bubble or anything, but there are actually several explanations of the whole nine yards, none of which is definitive:

    Sorry, word origins are a hobby of mine. Does sound like an interesting book. In fact I was just wondering yesterday about the development of the inner ear, with all its intricacies. It would be interesting to read what he has to say about it.

  7. Sounds like a fascinating book.

    I have always been puzzled by the people who want to point to the Big Bang as evidence of creation ex nihilo, but don’t want to accept that the same evidence tells us it happened about 14 billion years ago. It seems obvious that an eternal God does not have to be in a hurry to create a world populated with living creatures, especially when we contemplate the idea that there may be millions of such worlds in our galaxy alone. There still seems to be a strong assumption by many Christians, even those who accept some version of evolution, that God’s supreme creation of mankind is limited to only one planet in all the heavens. Some in that group, recognizing the randomness of evolution, seem to think that God put the entire universe into motion just to ensure that there would be one world that, through random evolution, would produce creatures “in his image” with intelligence.

    The commonalities at the foundations of the chordata that appear all the way into mammals and primates and mankind tell of a basic conservatism in life, that contrasts with the innovation that produces the great variety of species. But this observed pattern does not tell which of the innovations were produced by lucky mutations versus intentional tweaking of genes, of the kind human scientists now routinely practice. We certainly know that intelligent, purposive action is one potential source of these variations, since we observe it all the time. There are also some instances, primarily at the cellular level, where random mutation has been observed to create persistent differences.

    It would be human arrogance, a violation of the so-called principle of Copernican humility, to assert that no other species of intelligence comparable to a 21st century biologist could ever have existed in our universe before we showed up. When materialists respond that allowing for the possibility of an intelligent agent in our biological past opens the question of an infinite succession of such, we Mormons can say, Yes, precisely. If you have a problem even allowing the concept of infinite time, what are you doing in science, where one of the serious hypotheses advanced to avoid the suspicious life-friendly settings on the arbitrary physical constants of matter is to posit a literally infinite number of parallel universes?

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