Grown up Fish

Embryonic recapitulation. That’s what it used to be called. I didn’t learn about this in biology class, but rather in the Creationist literature that challenged the very concept. I suppose those deep evolutionary roots are what led me to read Neil Shubin’s Your Inner Fish: A Journey into the 3.5-Billion-Year History of the Human Body. Not that anyone who’s considered the facts can question evolution, but this book nevertheless took me back along my own evolutionary descent from Fundamentalism to a reluctant rationalism. I recall the frequently repeated Fundie catch phrase, “no transitional forms.” Probably what they were looking for was a mermaid-like creature that was half reptile and half bird, divided down the middle. Even at a tender age, while accepting their rhetoric, I wondered why archaeopteryx didn’t qualify. A flying feathered lizard? Sounded pretty transitional to me. Shubin opens his fascinating account with the discovery of Tiktaalik, a transitional form in every sense of the word. Here is a fossil that shows the tell-tale limbs and organs of moving from fish to amphibian. Yes, Virginia, there is evolution.

Shubin doesn’t stop there, however. He traces the various features of human bodies back to our piscine ancestors. From gills to gonads, we are bipedal, air-breathing, mammalian fish. No surprises there, really. One gets the sense that Shubin’s book wouldn’t be such a wonder if there weren’t organized Creationists out there constantly challenging the obvious. All living things on this planet are clearly related. Some of the cousins may be very, very distant, but we are all part of the same family. This threatens Creationists and others who need to feel different, special. People are related to God, they suppose, in ways that mere animals are not. Biology gainsays that concept, so no matter how much evidence we might marshal, the Fundamentalist is duty-bound to reject it. We’re trying to break up a personal relationship here, after all.

While Shubin does a wonderful job of explaining whence our biological features, I was nevertheless heartened to read him referring to the essence of being human. Some scientists reject “essence” as a vague concept that can’t be examined in a laboratory. That may be true, but we all know what an essence is. As a concept it too has explanatory value. It would be very difficult to read Your Inner Fish and come out doubting evolution. At the same time, Shubin realizes that people write books, and fish do not. That’s not to say that we’re superior to our fishy family, but that we are different. We have our own essences. That doesn’t mean we were created this way—maybe we’ve just evolved with them. Either way, Shubin is charming romp though 3.5 billion years of our history.