Your Inner Fish Summary

While reading the book, Your Inner Fish, I initially struggled to understand the significance of this book to the lecture material. I could plainly see that much of the material presented in the book was similarly discussed in lecture. In lecture we learned the three factors necessary to find fossils and Neil Shubin elaborated this by recognizing the significance of a geological survey in an old test book that helped him realize where he need to look to find these fossils. The transition from aquatic like to life on land was revealed through his discovery of Tiktaalik, which filled a missing gap in the phylogenic tree. Another point discussed in lecture and the book was how specific genes differentiate into our forelimbs, common to land animals

was the formation of the one bone, two bone and many bones. Zwilling and Saunders did early experiments on embryos by removing sections of various tissues during various stages of embryonic development resulting in the loss of limb development. Building on this Gasseling was able to remove tissue and replace it and apply a vitamin A derivative creating duplicate set of digits.

This led to an understanding that this was controlled by a set of genes discovered by Tabin in his research into fruit flies. This lead to experiments into fin development experiments in sharks and skates by Randy Dhan. Dhan’s experiments were conducted around the time of Shubin’s discovery, which he describes, Dhan’s experiment as discovering his inner fish. Later Hox genes are discussed and it is revealed that these gill arches in human embryos are responsible for the formation of the jaw, ear nose and throat. These Hox genes are not unique to us, they are found in smaller segments in other animals. Shubin’s obsession with the nesting doll ties into this as well. Smaller portions of these HOX genes are found in other living organisms. A segment of human HOX genes is found in beavers, a segment of beavers HOX genes is found in fruit flies and the nesting pattern continues. This nesting pattern continues with organ development, body plan development and sequences of genetic code. This same order of subset of our genes found within the gene of other multicellular organisms is seen with our sense of smell as

well. At one point Shubin discusses placozoans or the “Blob” as he puts it. Seeminly unrelated in appearance, is a multicellular organism with cells that differentiate to form other cells much like all multicellular organisms. Life comes from life and following these modifications from the simplest multicellular organism to the most complicated multicellular organism reveals a road map of our evolutionary history.

This leads students to the understanding that while scientific endeavors may seem unrelated they help us unlock the mysteries in the phylogenic tree of life. When I first started reading the book, I was like Shubin roaming the dessert in search of fossils, I failed to see what was right in front of me the whole time. Then it struck me as I continued reading, this book was not just about the similar facts discussed but rather the painstaking journey and tedious hours spent arriving at these conclusions. I can look at a phylogeny and see morphological changes, but what is not initially evident is the countless hours cataloging fossilized remains and studying them to determine their place on a phylogenic tree. While Shubin made a significant advancement in our understanding of our evolutionary history, the significance of his findings relies on the tedious work of his predecessors, the same could be said for any advancement in the pursuit of knowledge. Our knowledge in the field of science is advanced in much the same way as Shubin’s nesting doll. This insight brings a greater appreciation for phylogenic tree used in the last PowerPoint slide of our last

class lecture. At the beginning of the semester a similar figure was used and I saw it as a figure showing just the evolution of life and now I see it for more than just a question on a test or a PowerPoint slide. I now see it as an evolutionary representation of our combined knowledge obtained through the hard work of our predecessors. These facts learned in class were not obtained from conjecture but rather the unrelenting pursuit of knowledge in understanding who we are and where we come from. No matter what direction we take in our pursuit of knowledge in science, we are working towards a common goal of discovering our inner fish, worm, placozoans and the list can go on. Through this discovery process we can obtain the knowledge to cure disease, correct gene abnormalities and gain insights into our origins.