This chapter started off with humor as Aarti said. Even though the salamander larvae, fish embryos, fertilized chicken eggs, and human embryos all look the same as cells, we all turn out differently. The fact that every animal organ originated from the three layers just shows that we are all related somehow. The concept of us being a tube is very interesting, how we have a tube-within-a-tube structure. As Shubin continues explaining the three layers it really made sense to me why all animal organs are made the same. When Ernst Haeckel said that “Accordingly, the embryo of a human went through a fish, reptile, and a mammal stage” (103) I was really amazed. I was happy to learn that Spemann’s experiment on the newt eggs resulted in twin salamanders, it was quite intriguing. But Mangold’s experiment was AMAZING, she discovered the Organizer! And the embryo came out with two heads, how cool was that! At first when I read about fly mutations being important, I really didn’t think so, but then turning the page to find that they “tell us why our vertebrae change shape from the head end to the anal end of the body” (108), well that was pretty important. The diagrams were and always have been very helpful :) The Hox gene is very dangerous and can mess with the body plan, but they also proportion our bodies. Just when we thought the Organizer was old news, what were the chances of one of the Hox genes being in the Organizer? This chapter just added one more thing that I didn’t think was important complexities to life :)
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