Chapter 6: The Best-Laid (Body) Plans

Shubin opens the chapter by describing our bodies as "a package of two trillion cells assembled in a very precise way" (97). This is what differentiates us from more primitive creatures. Shubin claims that all the basic structures of the embryos are the same, saying that the "fundamental similarities" of these embryos allow us to disregard their differences. He also mentions the famous scientist Karl Ernst von Baer, who discovered that all organs of the chicken can be identified with one layer of tissue. Von Baer then discovered that every animal organ followed this arrangement of three layers. The outer layer, the ectoderm, forms the skin and the nervous system while the endoderm forms the many parts of the internal structure. The mesoderm, the middle layer, forms tissue in between our "guts and skin." I find it very interesting how this basic paradigm reveals how similar we are to many other organisms. To encompass the idea that our complex genetic-makeup is similar to those of basic organisms is nearly impossible. However, reading this book made me appreciate the connection between our bodies and nearly every organism on Earth, even an organism as simple as the fruit fly.