Your Inner Fish- Week 3

In Chapter 2, Shubin spends most of his time describing the origin of our limbs and hands. He introduces viewpoints from well-known surgeon, Sir Charles Bell (who believed that the anatomy of the hand was merely perfect because of its complexity and it being ideally arranged for the way we live) and anatomist, Sir Richard Owen (who believed that there were exceptional similarities among creatures that were as different as frogs and humans).  Owen found that there was some sort of fundamental design among all vertebrate land animals and marine mammals.  He specifically mentions lungfish and talks about how they have a single bone at the base of the appendage, just like humans. Shubin talks more about the Tiktaalik fish and how it had a flat body, eyes that were located on top of its head, and powerful limbs allowing them to maneuver more easily through the water. They lived in an environment that consisted of very large predators. This strong musculature allowed for them to have the ability to move to locations where predators could not reach/harm them. I think it’s pretty intriguing  how the Tiktaalik had this certain type of musculature (similar to that of humans) because of the environment that they lived in. So far, I have noticed that the book mentions many homologous relationships between humans and fish and I remember that we went over this concept in class! Chapter 2 is about the structural homology of the fins and hands while chapter 3 touches on the particular gene in the hand (the ZPA gene) "that controls how they form and how they look like" (page 51). So once I finish reading chapter 3, I believe that I will be able to connect the dots by having background on both, the structural homologies introduced and the molecular homologies between humans and fish that will be talked about in the Handy Genes chapter. I like that the book is allowing me to make these connections and I hope to make some more as I continue reading.