May 25th, 2010

Alien tech

I Sing the Body Aquatic

I cannot remember who recommended the book or why I bought it, but I've just finished Your Inner Fish: A Journey into the 3.5-Billion-Year History of the Human Body, by Neil Shubin. Neil Shubin co-discovered Tiktaalik, the "fish with hands" (yeah, we already knew they existed, io9), in 2004. This creature represents an intermediate between aquatic animals and land animals, and he uses it as a focal point for his thesis, which is that we can trace the development of the human body all the way back to prehistoric fish.

The first couple chapters feature a lot of paleontology anecdotes in order to show the reader how we learn information from fossils. Shubin is a paleontologist, so it makes sense, but I found myself less interested in reading about a bunch of a dudes digging up bones than I thought I would, given that I wanted to be a paleontologist when I was a kid. While they were mildly interesting, I think they diverted too much from the main point, which, when Shubin is really on, is truly fascinating. Using many examples, he makes you see every little part of your human body as something that's been in the works for millions of years. He tracks the emergence of characteristics as fundamental as limbs. I was already familiar with the fact that the structure of our arm and hand bones are conserved throughout animals, but he shows you how they got that way. Hell, he goes even further back and tries to figure out when and why life decided it needed a body in the first place. Each chapter has a specific focus, and rather than try to summarize the entire book, I will give you one awesome thing I learned in each chapter. It's up to you to read the book and learn the rest.

"Finding Your Inner Fish"—One of the defining characteristics of land animals is that they have a neck. Fish don't have necks; they can't move their heads independently of their bodies. Tiktaalik had a neck.

"Getting a Grip"—Tiktaalik was capable of doing push-ups.

"Handy Genes"—The Sonic hedgehog mouse protein, which is used in the development of limbs, can also induce the development of fins in skates. That is how conserved this gene is, even after hundreds of millions of years. (Okay, I pretty much knew everything in this chapter already, but it's always cool to be reminded of it.)

"Teeth Everywhere"—The emergence of teeth was responsible for the development of scales, hair, feathers, sweat glands, and mammary glands. They are all made using the same basic process that was used to originally make teeth.

"Getting Ahead"—The structure of our head is determined by four arches in the embryo. A shark embryo has those same four arches; they just develop into slightly different things. But they have virtually all the same cranial nerves we do, and they even exit the brain in the same order. The blueprint for our head has been around for a long time.

"The Best-Laid (Body) Plans"—Even a sea anemone, which looks completely bizarre, has a body axis determined by a version of Noggin. And if you take this Noggin protein and inject it into a frog embryo, the frog embryo reacts the same as if you'd used frog Noggin. Again, there's far more genetic conservation than you might think. You do have something in common with a sea anemone.

"Adventures in Bodybuilding"—It took almost 3 billion years after the first life appeared on Earth for the first bodies to form. But within a few hundred million years, the first land animals developed. What was likely responsible for this sudden acceleration in evolution? Oxygen. And...predation.

"Making Scents"—Humans devote about 3 percent of our genome to odor genes, but at least three hundred of the genes are useless beyond repair. Why did we lose so many of those genes? Because we focused instead on color vision.

"Vision"—Color vision probably arose around 55 million years ago, when the monochromatic forests of figs and palms began to have foods of different colors that needed to be distinguished. We develop features when we need them, and no earlier.

"Ears"—The bones in our inner ear used to be the jawbones of fish and reptiles.

"The Meaning of It All"—The reason we get hiccups is because we're related to fish and tadpoles.

Although the book isn't universally riveting, it made me look at my body and animals in a whole new way. It's mind-boggling to think of all the evolution that has gone into creating us, every little feature being developed over millions of years, adapting to an ever-changing world. Even though we're special creatures, we share so much with the rest of the animal kingdom. LL Cool J, it is your hand, not your hat, that is like a shark's fin!