YIF: Chapter 2

            This chapter was mainly focused on the origin and evolution of the hand and arm, and where they came about and how they were proven through multiple discoveries. Also, while going through what limbed animals have in common the topic of Owen came up. While the author was mentioning Owen, he talked about the patterns that he saw and how they were accurate and how they are related with all limbed animals. Those patterns would be: all creatures with limbs, have a common design; the differences between creatures lie in differences in the shapes and sizes of the bones and the numbers of blobs, fingers, and toes; and lastly, probably the most important pattern in the chapter, the skeleton of a human arm has one bone in the upper part of the arm, two bones in the forearm, several bones at the wrist, then the series of rods that are the fingers, and this arrangement is similar to all other limbed animals and the differences between different animals is explained in the second pattern. This overview shows scientist that we have similar characteristics to other animals, like frogs, horses, and seal, which show that the evolution of the human body and the evolution of these animals, and animals like them, are similar in many ways, only by looking at the arm. The most interesting part of this chapter was when the author when back to the fish that he discovered, the Tiktaalik, and analyzed it and told us how its fin has the same pattern that Owen described and it had similar bone structures to ours. And what was even more surprising was when he said that this fish had the ability to do pushups! It is simply amazing how a fish that existed so long ago has some human capabilities and that is possible that we could have gotten some of these abilities from this animal! The overall topic from this chapter can answer two Big Ideas of biology, one being the process of evolution drives the diversity and unity of life, and the other being biological systems interact, and these systems and their interactions possess complex properties. The first idea encompasses the obvious, that evolution of animals like Tiktaalik unify the limbed animals and us together. The second idea can be thought of how the interactions that occur in the hand from performing simple maneuvers make the hand have unique and complex properties. All in all, the chapter creates one essential question, “How does evolution of the same animal create separate species?”