33 pages • 1 hour read
Neil ShubinYour Inner Fish: A Journey into the 3.5-Billion-Year History of the Human Body
Nonfiction | Book | Adult | Published in 2008A modern alternative to SparkNotes and CliffsNotes, SuperSummary offers high-quality Study Guides with detailed chapter summaries and analysis of major themes, characters, and more.
Summary
Chapter Summaries & Analyses
Key Figures
Themes
Symbols & Motifs
Important Quotes
Essay Topics
Tools
BetaKey Figures
Neil Shubin
Shubin is a paleontologist and evolutionary biologist, and the author of Your Inner Fish: A Journey into the 3.5-Billion-Year History of the Human Body. Shubin serves as a protagonist of Your Inner Fish, and includes personal anecdotes about his research and life throughout his discussions of evolutionary biology. Shubin introduces each chapter’s subject by describing a personal encounter with the body part whose evolutionary history he will discuss. For instance, Chapter 9, the chapter on eyesight, opens with an anecdote about a rare fossilized salamander eye in a Chinese mineral shop.
Shubin plays a more central role in the opening two chapters, in which he describes one of his most important scientific discoveries: the fossil of the ancient creature Tiktaalik. Shubin’s hunt for the Tiktaalik fossil begins in 1995, when he is searching for fossils in rock fields in Pennsylvania. Together with his colleague Ted Daeschler, Shubin hopes to discover fossils that can shed light on the evolutionary transition that allowed fish to begin walking on land, some 350 million years ago. Shubin discovers a fossilized portion of an ancient fish, which appears to show a shoulder bone inside a fin. Hoping to find a fully preserved fossil of the ancient fish, Shubin arranges an arduous expedition to a region of the Arctic which contains rocks from the Devonian Period, similar to those where Shubin found the fossilized fin. Though the original expedition proves fruitless, Shubin eventually discovers the desired fossil on a subsequent expedition. Shubin names the newly discovered ancient fish Tiktaalik, in the language of the local Inuit people where Shubin’s expedition took place.
Tiktaalik
Though not a character in the traditional sense, Tiktaalik, a fish that existed around 375 million years ago during the Devonian Period, is an important figure throughout Your Inner Fish. Tiktaalik symbolizes the ways parts of our body—from our limb structure to our eyesight—stem from ancient creatures.
Tiktaalik are scientifically significant due to the fact that their bodies exhibit traits of both reptiles and fish. While Tiktaalik has fins like a fish, it also features a flat head typically associated with reptiles. Additionally, the Tiktaalik’s fin houses a bone structure remarkably similar to those found in limbs, suggesting that Tiktaalik is one of the first fish to begin walking on land—a crucial step in the development of limbs in later animals.
Randy Dahn
Dahn is an evolutionary biologist working in Neil Shubin’s research lab described in Chapter 3 of Your Inner Fish. The goal of Dahn’s experiments is to recreate in shark and skate embryos experiments that originally discovered Sonic hedgehog, the gene that controls animal limb development, in chicken embryos. Dahn’s research confirms that Sonic hedgehog exists in sharks and skates, where it controls the development of fins. In one of Dahn’s experiments, he injects a mouse Sonic hedgehog gene into a skate embryo, causing the skate to develop a bone structure in its fin similar to the structure of digits in mammals.
Sir Richard Owen
Owen is a 19th century anatomist whose research on animal limbs Shubin discusses at length in Chapter 2 of Your Inner Fish. Owen is well known for his comparative studies of the skeletons of both living and fossilized animals. Owen recognized that the same basic bone structure exists in all animals with limbs, from humans to reptiles to birds. This structure consists of a single base bone, then two interlocking bones, then a group of many small bones, and finally a series of digits. At the time of his writing, Owen interpreted this similarity in bone structure as evidence that God had created all animals according to an intentional design. Shubin uses Owen’s limb pattern to identify the existence of a primitive limb in Tiktaalik.
