44 of 46 people found the following review helpful
Hands, hyoids and . . . hiccups??,
This review is from: Your Inner Fish: The amazing discovery of our 375-million-year-old ancestor: A Journey into the 3.5 Billion-Year History of the Human Body (Hardcover)
What a pity there is no Nobel for palaeontology. Some sort of award should be given to Neil Shubin for finding "Tiktaalik" in the Canadian Arctic. It wasn't a chance find - he relates the detailed planning steps leading to its discovery. An extra ribbon should grace the medal for explaining that fossil's significance in this book. There have been recent accounts on the evolutionary path of animals emerging from the sea to take up the role of landlubber. Carl Zimmer's "At The Water's Edge" and Jenny Clack's "Gaining Ground" are examples. Both preceded the "Tiktaalik" find, but more to the point here is that while both are excellent writers, Shubin demonstrates communicative skills bordering on the superb. This is truly a book for everybody. Especially if you want to know why you develop hiccups.
A great fuss was made over the "Tiktaalik" discovery. What is its significance? For starters, it was flat-headed ["So what? I know lots of people who are flat . . ."]. While we may consider flat heads in derogatory terms, for life emerging from the sea, it was a vital step. That the head could move independent of the rest of the body was even more significant. Fish cannot do this, and except for bottom dwellers, don't have flat heads. Further, "Tiktaalik's" eye structure gave it forward vision. In a creature 375 million years old, these characteristics are significant. They offer clues to how you and I are put together and why. Shubin offers a meaningful example of this when he showed "Tiktaalik" to his daughter's preschool class and they declared it to be both fish and reptile - which is the key to the value of his work here.
Land dwelling, Shubin reminds us, requires major changes in body plan. Instead of fins propelling the body through the water, limbs capable of supporting that body must develop. Those limbs must have flexible contact points, leading to the formation of fingers from fin bones. Lifting the body reformed the bones' arrangement leading to our wrist and hand structures. Air breathing shifts the location of oxygen-capturing equipment and distribution. Predation techniques change, which might render some bones superfluous. The author's description of how the former jaw bones of fish relocated over time to become the delicate transmitters of sound in our inner ears. Making sound turns out to be derived from other fish. The ancestors of sharks left a string of arches as part of our bodybuilding mechanisms. One of those arches nestles in your throat as the hyoid bone, essential in making speech. Another of those arches evolved into the diaphragm separating our lungs from other internal organs. Hiccuping, Shubin says, "has its roots in fish and tadpoles" because the pattern set in our brain that controls breathing has been "jury-rigged" in the steps to becoming human. In fish, the distance from the brain to the gills is short, but in mammals, the convoluted path those nerves take allows for signal disruptions - hence, hiccups.
Shubin spends much time explaining the development of embryo studies. Watching the progress of a fertilised egg in becoming a finished organism gave researchers insight in how to look for signs of how today's life is assembled. In Freshman Biology, we are still told of "ontology recapitulates phylogeny" - the idea that a human embryo goes through fish, reptile and mammal stages during development. Karl von Baer had already discovered this was incorrect, but it took modern genetic analysis to overturn Ernst Haekel's enduring axiom. Embryos, von Baer observed, form in triple layers, and depending on the signals from the genome, enable one of the layers to begin dominating to produce the appropriate body plan. Shubin uses these studies to further explain the rise in understanding leading to the appropriate HOX genes triggering the chosen layer. As he notes, his work area is braced by two seemingly irrelevant facilities - a fossil preparation facility at one side, and a genetics laboratory at the other. This book brings the two disciplines together with seamless effectiveness. Graced with some photographs, but many fine line drawings to enhance the text, the book is a prize addition to everybody's library. [stephen a. haines - Ottawa, Canada]