A review of Your Inner Fish: A Journey into the 3.5-Billion-Year History of the Human Body by Neil Shubin
We can walk because we have teeth. More than 500 million years ago, in some primordial sea, a soft-bodied, worm-like creature developed hard, pointed growths inside its mouth. These growths were a mutation, a freak accident in the replication of its genetic code, but they proved quite useful when it came to eating other soft-bodied, worm-like creatures. The code for these hard growths was passed on, and over eons, it was muddled even more. Eventually mutants arose with hard growths that covered their entire heads, and these new features also came in handy—this time to fend off all the soft-bodied, worm-like creatures swimming about with big teeth. After this, the genetic code for the hard structures continued to morph, giving rise over the ages to backbones, ribs, fins, and then, some 375 million years ago, legs.
Your Inner Fish comes in the aftermath of Neil Shubin’s historic co-discovery of Tiktaalik, a “found link” between prehistoric fish and the world’s first amphibians. Shubin, a paleontologist and professor of anatomy at the University of Chicago, found the fossil in 2004, after years of scouring Devonian aged sedimentary rocks in the high arctic of Ellesmere Island, right where a chronological sandwiching of other fossils said it should be. In this quick, enlightening, and entertaining read, Shubin recounts the motivation for hunting for Tiktaalik and the details of its discovery, and then he uses this “fish with wrists” as a jumping off point for a discussion—conversational in tone but compelling in content—on the origins and implications of many of our distinguishing features. Full Review »