Chapter 6: The Best-Laid (Body) Plans

This chapter talked about the layout of our body and how all the cells are packaged and assembled inside us. Humans are all created with the same design, symmetrical with a front/back, top/bottom, and left/right. When Shubin compares different embryos of varies species, he realizes that although the species ended up looking different they all started from a generally similar place. They all pale in comparison with their fundamental similarities. Shubin also talks about the three layers of tissue (germ layers) in a developing embryo which all organs in an animal can be traced. Every animal organ originated from one of these three layers. The three layers forms the same structures in every species, every heart formed from the same layer. No matter how contrasting the species look as adults, as an embryo, they all experience the same stages of development. Another factor that reveal how humans are similar to animals is that in the middle of each gene, a short DNA sequence was identical in each species. I learned that this sequence is called a homeobox and the genes that contain the homeobox are called Hox genes. It fascinated me how Shubin is able to compare and connect us to every possible creature out there, possibly even jellyfishes.