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).