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I Sing the Body Aquatic - The Book of the Celestial Cow

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May 25th, 2010


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06:49 pm - 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!
Current Mood: hungryhungry
Current Music: Nine Inch Nails - Beside You in Time

(18 memoirs | Describe me as "inscrutable")

Comments:


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From:musesfool
Date:May 26th, 2010 02:42 am (UTC)
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That sounds like an awesome book! I will have to add it to my to.read list.
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From:spectralbovine
Date:May 26th, 2010 06:56 am (UTC)
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I have just crossed it off mine! Mine is very very long.
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From:robyn_migratori
Date:May 26th, 2010 06:46 am (UTC)
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Oh, excellent. This book came up a lot when I took developmental biology and I meant to read it and forgot. Then it came up again when I took evolution, and again I meant to read it and forgot. But this time I will go to the library website straight away and request it, so thank you for reminding me of this book's existence!
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From:spectralbovine
Date:May 26th, 2010 06:53 am (UTC)
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Ha ha ha ha. My pleasure! It would certainly come up in both developmental biology and evolution.

AWESOME ICON.

Edited at 2010-05-26 06:53 am (UTC)
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From:robyn_migratori
Date:May 27th, 2010 08:19 am (UTC)
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Oh, I felt the need to correct myself, having picked up the book from the library today and noticing the 2008 publishing date: I must not have heard about the book in those courses (taken in 2006 and 2007), but rather just about Shubin and Tiktaalik. My bad. Still: thanks for the rec. I know I'd been meaning to read the book for some reason.
(Deleted comment)
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From:spectralbovine
Date:May 26th, 2010 03:44 pm (UTC)
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Tell me what it explains, Nicole. TELL ME WHAT IT EXPLAINS.
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From:the_narration
Date:May 26th, 2010 12:23 pm (UTC)
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I read this a year or two ago. (Did I recommend it to you?) Really interesting book, full of all sorts of fascinating information. You can recognize the basics of body design throughout the animal kingdom and track their slow change due to evolution. Watching limbs go from fin to claw to paw to hand, all while retaining the basic structure... it's amazing.

We develop features when we need them, and no earlier.
Not precisely. It's more like "new features become prevalent and widespread when they become advantageous enough to increase the chances of those with the new features surviving and reproducing over those without, and no earlier." Evolution isn't an intelligent or sentient agency, but the result of random mutations which prove favorable having a better chance to propogate themselves.
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From:spectralbovine
Date:May 26th, 2010 03:44 pm (UTC)
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I read this a year or two ago. (Did I recommend it to you?)
I don't think so.

"new features become prevalent and widespread when they become advantageous enough to increase the chances of those with the new features surviving and reproducing over those without, and no earlier."
That's not glib enough for me, man!
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From:the_narration
Date:May 26th, 2010 10:09 pm (UTC)
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That's not glib enough for me, man!
Science cares not for your glibness! Information must be accurate... FOR SCIENCE! *trumpets play*

(Seriously, tho. One of the big reasons most people don't understand how evolution works is that they keep wanting to treat it like it's something alive that deliberately adds new features in response to the environment, instead of the result of blind processes.)
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From:equustel
Date:May 26th, 2010 05:09 pm (UTC)
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The reason we get hiccups is because we're related to fish and tadpoles.

Oh boy, now I have something to blame! I get them without fail whenever I laugh too hard. (Which is often.) It is obnoxious, although I am a master at getting rid of them.
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From:spectralbovine
Date:May 26th, 2010 05:24 pm (UTC)
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Tadpoles basically breathe by hiccuping. And you can stop them by, you guessed it, having them breathe carbon dioxide. Science!
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From:tackdriver56
Date:May 26th, 2010 06:13 pm (UTC)

Perhaps defragmentation is in order? Or not?

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You hear about all the "junk" DNA we carry around, that seems to be irrelevant to our phenotype, and wonder if we could clean things up, maybe redesign the eye, so that the retina is exposed directly, rather than through blood vessels.

Then you learn that a mouse retrovirus causes prostate cancer and Chronic Fatigue Syndrome in humans, but mice don't get it. How do we know it's a mouse retrovirus: 'cause big chunks of it are in the "junk" DNA of every living mouse. So maybe all this "junk" DNA is our biological equivalent of McGyver's library or junk drawer: a reference for how to recognize bad stuff, and build things to cope, when SHTF? A biological Swiss Army Knife and Necronomicon/Encyclopedia Biologica, all rolled into one.
[User Picture]
From:spectralbovine
Date:May 26th, 2010 06:21 pm (UTC)

Re: Perhaps defragmentation is in order? Or not?

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Well, a lot of the junk DNA is also a mutation buffer. The number of times our DNA replicates during our lifetimes, we're going to get mutations once every few million or billion or however many it is, but when they happen in junk DNA, it doesn't matter.
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From:tackdriver56
Date:May 26th, 2010 08:27 pm (UTC)

Re: Perhaps defragmentation is in order? Or not?

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I can't imagine how the "junk" DNA would provide a buffer. Why would mutations preferentially alter the "junk"?
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From:spectralbovine
Date:May 26th, 2010 09:02 pm (UTC)

Re: Perhaps defragmentation is in order? Or not?

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It's not that they preferentially alter the junk. It's that if 100% of your DNA is useful, 100% of mutations will hit something useful. I just found a pretty good blog post summarizing the arguments for and against the hypothesis. Heh, mostly it says that it's not really a strong hypothesis, so...there's that. There are many hypotheses about the potential benefits of junk DNA.

Edited at 2010-05-26 09:11 pm (UTC)
[User Picture]
From:tackdriver56
Date:May 27th, 2010 12:33 am (UTC)

Re: Perhaps defragmentation is in order? Or not?

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Interesting. It seems that the jury is still out...
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From:tamarai
Date:May 28th, 2010 03:53 pm (UTC)
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Very interesting! I don't read enough science stuff.

"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.

I wonder if that means that sharks get migraines...

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