Chapter 5: Getting Ahead

When first reading this chapter, I had no idea where Shubin was going with the profoundness of the anatomy of the cranium. However, with the introduction of arches, the subject started to make more sense. Each of the four arches form the blueprint for nerves, cartilage, bones, plates, and structures. Thus, even though a single system of nerves such as the trigeminal nerve have confusing twists and multiple purposes, it is still connected because it all originated from the first arch. From this point, it was more of the diagram of the shark and human embryos that gave me visual persuasion of the similarities between human and shark development. In addition, Shubin explains that although sharks and humans have different structures, they are not actually that different. In support, he points out that a bone that is formed for our throats in an arch is used for the jaw in a shark. Thus, Shubin returns to the theme of how we are merely variations of an ancient blue print and not a completely new creature. In relation, Shubin alludes to the genetic similarities by pointing out genes such as the Otx and the Hox that guide the arches. This is one of the elements I find great about this book; so far, each chapter supports a common theme. I felt that the comparison between humans and shark was the section I understood the most in this chapter. However, the section I still find confusing is how humans are linked to other creatures such as worms. I understood both creatures had a notochord, but I felt like it should have been a different topic.