• Neil Shubin’s “Your Inner Fish” reviewed: fish and common ancestry

    Kevin McCarthy, a regular commentator here, has contributed this short review of a book which certainly looks like an interesting read with regards to arming one with evidence for common ancestry and evolution. Thanks to Kevin for this!

    Neil Shubin and the discovery of Tiktaalik are triumphs of modern science. Shubin’s book “Your Inner Fish” describes the discovery and its importance in our own bodies. Yes, in our bodies.

    Unlike car designers who can start with a clean sheet of paper whenever they like, biological organisms like ourselves are limited by what came before us. Shubin, who is a paleontologist, but has also tuaght advanced anatomy classes, spends most of the book detailing how we know that humans and fish have a common ancestor deep in geologic time.

    This supposition isn’t a case of just one tiny little point of data, but literally hundreds of data points. Research into our genetic code, how our embryos (indeed all vertebrate embryos) develop, and some of the very odd anatomical features of our bodies all point to not a unique design, but to how we are very much fish.

    Hence the title of the book “Your Inner Fish”. Shubin is an excellent writer who explains detailed concepts clearly and simply. He also tells very entertaining stories about his time in the field. It’s not a long book, but so full of good information and so well written that you’ll wish it were longer.

    The book is very well laid out too.

    Chapter 1 discusses Tiktaalik and the concept of common descent. It all started with a hypothesis (as all good science should). If all vertebrate land animals are descended from a common ancestor, then all vertebrate land animals should have common features and we should be able to find an example of that common ancestor.*

    Shubin and his colleagues set out to find this organism. And they did. Tiktaalik. By knowing the evolutionary history of both fish and amphibians, Shubin was able to narrow the search to rock of a particular age and depositional style (i.e. swamps). After several years of looking, they found what was obviously a fish, but it has the wrist structure of an amphibian. It’s a transitional fossil. Is Tiktallik our common ancestor? Probably not, older fossils with similar structures have now been discovered.

    But that doesn’t change the nature of the find. Here we have an animal that obviously has lots of fish features, but it has the wrist of an amphibian.

    Shubin, spends each remaining chapter of the book discussing another feature of land vertebrates that has an origin in fish. Everything from teeth, our heads, our body plan, vision, ears, and sense of smell come from the genes and structures in fish and sharks. Even the male propensity for hernias come from sharks.

    Shubin doesn’t just make assumptions either. Each detail is laid out with genetic and embryological evidence that supports each structure. The basics of human anatomy are laid out in fish that existed 375 million years ago.

    I have a more thorough review here.

    * Note that I said “an example”. We’ll probably never know exactly which organism is THE common ancestor of all land vertebrates. I would be shocked if any scientist ever claimed this. The point of a transitional organism isn’t that it IS the transition between groups, but that it has features common to both groups. “Transitional” in paleontology doesn’t have a discussion of time or of ancestor and predecessor. Only the physical features are what makes an organism transitional. Archeoptyrex has some 4 features that are fully what we call bird and some 17 features that are fully what we call dinosaur and one or two that are intermediate between bird and dinosaur. It’s transitional, even though everyone agrees that Archeoptyrex is not the lineage that leads to birds.

    Thanks again to Kevin McCarthy for this review. A short bio for Kevin:

    Kevin McCarthy – I have a bachelor’s degree in Earth science and took a lot of extra biology courses in order to become a paleontologist, then I got married.  So I became a teacher.  I taught science at a small school where I was the only high school science teacher.  I taught biology, chemistry, physics, oceanography, and physical science.  Now, I work for a major educational publisher in the assessment division.  I’ve had an interest in evolution ever since I watched Carl Sagan’s Cosmos when I was 8.  Now, I study a lot about evolution, abiogensis, and biology for the fun of it.

    I’m also a hardcore geek who likes games, science fiction, and European dance music.

    Category: EvolutionScience


    Article by: Jonathan MS Pearce