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Sunday, June 22, 2008

Book review: "Your Inner Fish"

I just finished "Your Inner Fish: a journey into the 3.5-billion year history of the human body," by Neil Shubin. Shubin is provost of the fabulous Field Museum, as well as professor of anatomy at the University of Chicago, and a clear, lively writer. His thesis is this: it is possible to trace a common blueprint for life from human beings all the way back to primitive multi-cellular organisms. As Shubin writes,

A subset of these multicellular animals have a body plan like ours, with a front and a back, a top and a bottom, and a left and a right....

A subset of multicellular animals that have ... a body plan like ours....also have skulls and backbones...

A subset of multicellular animals that have ... skulls and backbones ... also have hands and feet ...

A subset of multicellular animals that have ... hands and feet also have a three-boned middle ear ...

A subset of multicellular animals that have ... a three-boned middle ear also have a bipedal gait and enormous brains.

Shubin makes some truly fascinating observations. For instance, embryos of many species follow a common order of development: "arches" -- simple swellings that look like blobs, at first -- eventually develop into cranial nerves, or jawbones, etc. What they develop into changes according to species; but the logic of that development has a long history.

On a recent trip to Denver's Museum of Science and Nature, I delighted in expounding to my family on on the skeleton of a whale: see the common design of the arm in the whale's fin (one big bone, two joined bones, then little blobs, then "fingers")!

Shubin's other big point is this: the thesis of "descent with modification" -- evolution, ladies and gentlemen, although I don't believe he ever even uses the word -- is testable. If this is true, one should be able to predict that one might find fossils of intermediate stages of evolution in rocks that correspond to the approximate age at which that change might have happened. And guess what? Shubin goes to such areas -- and the fossils are there (including many new discoveries). Or as he writes, "we see a pattern of descent with modification deeply etched inside our own bodies. That pattern is reflected in the geological record. The oldest many-celled fossil is over 600 million years old. The earliest fossil with a three-boned middle ear is less than 200 million years old. The oldest fossil with a bipedal gait is around 4 million years old. Are all these facts just coincidence, or do they reflect a law of biology we can see at work around us every day?"

I also got a kick out of this statement, in a section about common human ailments: "Virtually every illness we suffer has some historical component. ... [D]ifferent branches of the tree of life inside us -- from ancient humans, to amphibians and fish, and finally to microbes -- come back to pester us today. Each of these examples show that we were not designed rationally, but are products of a convoluted history."

Or as I have written before, I'm losing the hair on the top of my head, and growing it on my toes. What's intelligent about that design?

But don't take my comments to mean that this is some kind of mean-spirited attack against Creationists. Rather, it's a rapt, lively summary of what science has learned lately. The author's conclusion is one of deep appreciation: "I can imagine few things more beautiful or intellectually profound than finding the basis for our humanity, and remedies for many of the ills we suffer, nestled inside some of the most humble creatures that ever lived on our planet."

Highly recommended.

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