Ch3. Handy Genes

This chapter was a bit confusing compared to the last two chapters, making me doing a double take on many of the sentences that really didn't make sense the first time I saw them. Although being confusing, the chapter is laid out in a very logical fashion. Shubin starts out with talking about Dahn's experiment with skate eggs, in which then Shubin transitions to past, talking about the discovery of ZPA from chickens and Sonic Hedgehog genes from fruit flies, then goes back to the results of Dahn's skate experiments. Shubin's method of connecting one experiment to another and how they benefit each other helped me realize that almost all animals share some connection to one another. It astounds me how chickens, flies, skates, sharks, and humans all share the Sonic Hedgehog gene. Does this mean that all animals with fins or hands received the Sonic Hedgehog gene from the Tiktaalik? Or do fish in the ocean have the gene too?

When I saw Shubin's diagram of adding extra ZPA to the wing bud of a chicken, I tried to picture a chicken with two wings on one side, which would look pretty disturbing. There were very few diagrams and pictures in this chapter than the others, which negatively impacts how the reader is able to process the information because they can not create a picture in their mind. Also in this chapter there is little mention of the Tiktaalik, but is understandable because it is impossible to experiment with Tiktaalik embryos. Hopefully in the next chapter Shubin reveals further connections between humans and the Tiktaalik.