Chapter Three: Handy Genes

Well.... I am beginning to come to an educated guess that Shubin always starts a new chapter with an interesting and somewhat off the wall opening story (mermaid's purses??). This does however work very effectively in getting my attention. I also found it interesting that in this chapter Shubin stepped away from the fossils and instead focused on the DNA and cells of living animals. A lot of foreign information came to me in this chapter, for example I didn't know that genetic switches turned on and off at the right moments of development determine the assembly of our bodies. A limb being formed is a complex thought on its own but to then learn that it is a certain lone strip of tissue that controls this development is amazing. To think that that your arm coming out normal, deformed, or under-developed all depends on how long the strip of tissue goes without being removed. I will be honest in sharing that I didn't completely understand the ZPA's purpose but I believe it has something to do with a certain patch of tissue being able to realize when and where to construct certain limbs. The Sonic Hedgehog was also interesting to learn that it was universal among all organisms. Excited to learn more... :)