Chapter 3: Handy Genes

From the title itself, I knew this chapter was getting into similarities in our limbs on the basis of DNA and genes. This chapter was pretty smooth and straight-forward, and Shubin managed to clearly explain ZPA and Sonic hedgehog. This chapter was a complete learning experience for me, and it fascinated me how a limb could be changed just by slightly altering an embryo's ZPA. For instance, I was in awe when reading that just adding vitamin A would create a duplicate structure. Seeing that from a genetic level, the development of flies, chickens, sharks, and skates are all very similar such as in its growth of limbs using ZPA and Sonic hedgehog already gave me the notion that creatures developed from a similar ancestor's genes that caused the formation of different structures. I find it great that Shubin is connecting us to our "inner fish" through different means of evidence: first bones, and now genes.