Creationist’s Nightmare: An Evolutionary Anatomy Lesson

In deference to the Inuit on whose land the fossil was found, Dr. Shubin and his colleagues named the new species Tiktaalik roseae—“Tiktaalik” means “large freshwater fish” in Inuktitut. The scientists, however, came to a slightly different conclusion: The fossil was a “beautiful intermediate” between land- and water-dwellers, a fish with the first signs of the limbs, head and neck that would eventually evolve into some of the appendages we recognize as parts of us.

“This fish doesn’t just tell us about fish; it also contains a piece of us,” writes Dr. Shubin. He adds, “Seeing Tiktaalik is seeing our history as fish.”

As the book’s title suggests, this is the central conceit of Your Inner Fish, an idea repeated so relentlessly that, by the final page, it’s hard to look at your hand without seeing the faint traces of a fin lining its edges. Nor does the book stop here, at our history as scaly creatures of the deep; our inner fly, sponge and sea anemone are also excavated in all their wild, unexpected detail.

Who knew, for instance, that “the essence of our head goes back to worms, organisms that do not even have a head”? Or that every “limbed animal” possesses a gene called Sonic Hedgehog that helps differentiate our digits and shape our limbs “from shoulder to fingertip”? Who even knew there was a gene called Sonic Hedgehog, after the video game?

Your Inner Fish is full of these surprises, wacky factoids that help propel the book through some of its drier sections—which do exist. So, even as we wade through the descriptive mire of gene interactions and fly experiments, we also get to delight in odd little facts like humans “are a package of about two trillion cells assembled in a very precise way” or “our sense of smell allows us to discriminate among five thousand to ten thousand odors.”

The result is a book that probes deep into the heart of what we are, pushing well past our inner fish to reveal something even more mysterious and profound: our Darwin-loving inner geek.

books@observer.com

Lizzy Ratner, now a freelance writer, was formerly a reporter at The Observer.

Creationist’s Nightmare: An Evolutionary Anatomy Lesson