Neil Shubin, a leading paleontologist and professor of anatomy who discovered Tiktaalik--the "missing link" that made headlines around the world in April 2006--tells the story of evolution by tracing the organs of the human body back millions of years, long before the first creatures walked the earth. By examining fossils and DNA, Shubin shows us that our hands actually resemble fish fins, our head is organized like that of a long-extinct jawless fish, and major parts of our genome look and function like those of worms and bacteria.--From publisher description.
As this subtitle tells us, this is a look at why we humans are constructed the way we are from an evolutionary perspective. So we learn that the nerves which control our facial expressions follow crazy whirling paths through our heads, and also connect to our ears — and Shubin tells us why. Or he gives us an evolutionary explanation of why we lose our balance when we get drunk. (Our inner ears developed form little organs fish use to detect water movement. And the fluid they developed happens to mix poorly with alcohol.) In general he points out that we are kind of like a souped-up Volkswagen Beetle — we are a more primitive life form that has been awkwardly modified for each new evolutionary challenge — and that is the source of practically all our health problems.
Shubin spends the book tracing many of these modifications back as far down the evolutionary tree as he can get, and quite a few go all the way to the single-cell animals. It's a good story.
One of the more enjoyable aspects of the book are his asides about his personal experience searching for fossils in the field. In one story he describes being a grad student and looking so carefully at an outcrop and failing to find a single fossil — while the rest of the group were filling bags with fossils. His problem was that he had to learn to tune his eyes to recognize the right kinds of patterns and textures. This was something I can relate to. I remember a day as grad student looking so carefully at a Kansas roadside outcrop, and seeing just a simple flat limestone bed of certain vague characteristics. After a while our professor walked up and starting pointing out various features right in front of us — fossil root trails, discolored surfaces, textural changes. I had looked right at them without seeing them. These are fossil soil features on a marine rock unit. Suddenly I was able to get new a sense of the ocean rising and falling; an entire dynamic environment began to come alive.
Shubin examines many examples like this, showing how the fossil record show evolutionary history, and how many of these conclusions have been drawn in his field. Included are examples of how body plans form, limbs form, teeth end up in the mouth, and how the ear is formed.
The book is engaging, entertaining, and informative. The author strikes an excellent balance between not talking over the audiences head and not dumbing down the information. Recommended for anyone interested in evolution, paleontology, body plans, and examining many of the missing links that have been discovered.
My only complaint is the title of this book. It put me off reading it for a long time. It's too cute and suggests a superficial approach to the topic. Happily, such is not the case. While much of the technical detail is smoothed over, the essence of the new understand provided by molecular and developmental biology is explained in clear and interesting prose that makes the general ideas extraordinarily compelling. It is interesting to me that we have come so far in biology that you can have a paleontologist and and a molecular biologist working side by side in the same lab and not think it is the least bit strange.
While Shubin shared the excitement of paleontologists unwrapping clues to missing links I really got a sense of the timespan of the fossil record. The story of each body slowly changing into the next step is truly amazing. Who knew that the three bones of our inner ear are re-fashioned pieces of reptile jaws?
From reading this book, I've gained a new understanding of not only how our various body parts and organs evolved and why, but how the evolution works in general. Time and again, some genes got duplicated by mistake, and then eventually one of the copies mutated into something useful, and the mutation survived because it gave an advantage to the descendants who had inherited it. In this way, for example, two kinds of color vision receptors that most mammals have increased to three in Old World monkeys, and the number of odor genes have multiplied from a handful in jawless fish to over a thousand in mammals. However, evolution is apparently a two-way street. Once something becomes less useful, mutations that prevent that gene from functioning properly don't harm the animal too much and get passed on to the next generation. Thus, once colorful fruit appeared in the jungles and monkeys developed a richer color vision "in response" and began relying more on sight and less on smell to identify the best fruit to eat, their sense of smell deteriorated. Shubin writes that "fully three hundred" of their (and our) odor genes "are rendered completely functionless by mutations that have altered their structure beyond repair."
It was also fascinating for me to learn how precursors of some of our organs and various structures existed in very early animals, biding their time till the situation changed and they could evolve into something useful.
I also found out many interesting facts about how our organisms from this book. For instance, I was surprised to learn that an odor receptor can interact with only one kind of molecule, and that's why we need so many of them, and consequently so many odor genes. But a particular smell may be composed of many molecules in various quantities, and so the author likens the signals our brain receives from various activated odor receptors to a chord. Another thing that surprised me was that a gene that switches on, say, hand- or eye-building genes in one animal would do the same in a totally different animal if inserted into its embryo, simulating its genes to build an eye or a hand wherever it's inserted. Thus, a mice gene can trigger a fly's eye-building genes to make an extra eye – a fly's type of eye, of course – wherever it's inserted.
A paleontologist, Neil Shubin also writes about their work: how they decide where to go to search for fossils, how they look for them in the field, and the work that gets done with the fossils after they get home. He says that it may take several expeditions to the same place to discover something significant, and since they usually search in most undisturbed places – deserts or high Arctic where it snows even in July – they have to put up with prolonged stays in tents in uncomfortable conditions. However, he manages to write with humor about the lifestyle necessitated by his profession. In general, I've found this a very well written book. No matter what he writes about, it never gets boring.
But going through each aspect of our anatomy, bit by bit, with relatively little analytic content (or at least not much that was new to me) could drag at times. And there wasn't nearly as much to take away from the book as there was from, for example, Sean Carroll's Making of the Fittest.
Essentially, the book traces the ancient antecedents of our human anatomy back to their evolutionary beginnings. Some of our traits are relatively newly acquired – our sense of smell, for instance. But the basic genes that establish our body shape – that distinguish “head” from “tail”, and “left” from “right”, for instance – are ancient indeed, originating from genes that have been around since the first jellyfish populated primordial oceans.
The book tackles our basic body systems one at a time, using evidence from paleontology, embryology and genetics to painstakingly track the evolution of each body part from its origins to its modern day form/function. For instance, the author tracks how bones that used to form part of reptilian skulls in time came to be repurposed as mammalian earbones; how nerves that used to enable fish to use their throats to both breathe and eat gradually came to control the muscles that pump our heart (inefficiencies in this “jury rigged system” are to blame for hiccups, by the way); and how the genes that used to produce gills in fish have been repurposed by evolutionary pressures to create the features of our human faces.
Though the first few chapters were on the dry side, I eventually began warming to the topic and by the end was reading enthusiastically. This experience, however, inclines me to be cautious about recommending Inner Fish to others. In spite of the author’s herculean efforts to make the content entertaining and accessible, folks looking for a light scientific read or who have forgotten most of what they learned in 9th grade biology may find parts of this a tough slog. If, however, you find yourself (like me) wondering how the millions of specialized creatures inhabiting the earth today can possibly have evolved from clumps of primodial ooze, then I think you’ll find this book both fascinating and informative.
Looking back through billions of years of change, everything innovative or apparently unique in the history of life is really just old stuff that has been recycled, recombined, repurposed, or otherwise modified for new uses. This is the story of every part of us, from our sense organs to our heads, indeed our entire body plan.
From the arms, forearms and wrists to the eyes, brain, nerves and ears, to embryonic development and various genetic similarities, Neil combines his excitement for his work with a remarkable prose to provide a basic and general overview of evidence for evolution and common ancestry, in a very simplified way. The many pictures and diagrams interspersed do an excellent job simplifying many ideas, and provide wonderful clarity for many of the ideas.
We are given a tour of human evolution from the fish stage. Yes read that again. Whilst most people accept evolutionary theory, this still comes as a bit of a shock to most.
We are given insight into the search for a famous "missing link", now named Tiktaalik, the bones in our arms and hands, our "fish genes", our teeth, ears, nose and eyes. Good clear illustrations help to convey several otherwise difficult to describe issues.
I enjoyed this book. It made me stop and think which is always a good sign. This author goes on to my "read" list.