Why Do We Believe in Evolution
A Brief Review of Your Inner Fish
With his passionate and readable language, Neil Shubin tells us in Your Inner Fish about his adventure to find the fossil of Tiktaalik, an ancient creature believed to be the missing link of trans-specific evolution from fish to amphibian. Systematically relating some other evidences, Shubin explains human as an evolutionary product (not necessarily the result, though) of an ancient fish, and argues for the fundamental role of evolution in understanding biological phenomena. According to their implications, evidences provided in the book can be divided into: similarities of body parts between existing species, and molecular biology evidence; embryonic development; and detailed examination of Tiktaalik fossil. Similarities of body parts between existing vertebrate species indicate a common ancestry of those species, while molecular biology evidence confirm the assumption and extend it to almost all existing species. Significant analogies are found between anatomical characters (for example, structure of bones) of different species. Among head, bones in ears, teeth and many other examples illustrated in the book, the upper limb is the most persuasive. No matter what function the upper limb serves for the vertebrate animal (flying for birds and bats, swimming for fish and marine mammals, walking for quadruped, and holding for human), the bone structures are remarkably similar: for nearly all terrestrial amphibian, reptile, mammal and bird, the upper limb is composed of a major bone, two lower bones, and a wrist with five fingers. Even in species that do not have a functional upper limb, the remnant bones are at the same position with respect to the spine. Molecular biology tells a lot more. Cells in almost all species use adenosine triphosphate as the major coenzyme for metabolism, makes same choices on 20 (or 22) kinds of standard amino acids among thousands of amino acids, and code their...
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