Write 4 pages with APA style on At The Water’s Edge : Fish With Fingers , Whales, with legs, and how life came ashore but then went back to sea. He offered to explanations as to why evolution came about. The first one, of course would be exaption or what we refer to as the evolutionary change which involved the mutation of certain body parts in order to adapt. The second one is the correlated progression which pertains to the mutation of one part and the rest of the morphological structure will also mutate in order to adjust to the changes of that part. He provided theories and new discoveries pertaining to the evolution of tetrapods as water animals with gills into tetrapods travelling on land and breathes air and for some yet unknown reason, returned of some back into the water. He used a prose form for the book wherein the stories of the scientists are intertwined used as a basis for the chapters of the book as the story of evolution is studied by scientists and research would be later on be picked up by the next generation of scientists who would further aid the development of the story of evolution. Zimmer aimed to answer the puzzles in the gap of the story of evolution and find the cause of why our fishy ancestors climbed out of the water to migrate to the dry land, and why, for some reason, the whales went back into the water.