The critter construction kit

Review – Endless Forms Most Beautiful
by Sean B. Carroll

A keeper? Definitely. And you should read it too.

Okay, you have a cell – just one – containing a bunch of genes. Where can we go from here? More to the point, since we can look around us pretty much anyplace on earth and see a lot of possible end points ranging from humans to nasturtiums, HOW can we get there from here?

For a long, long time, the details were mysterious. Some of them still aren’t clear. But now, by combining DNA analysis and embryology, an overall picture is forming out of the mist. (The “evo devo” of the subtitle is short for “evolutionary developmental biology”. Cute, and much easier to say.)

It turns out that living creatures share an amazing number of basic genes that control how their bodies are formed. Some of these genes are so universal that they must go back to before the Cambrian period, half a billion years ago. Then how can there be so much variety? It turns out that “gene” is biologist-speak for “a segment of DNA that makes a particular protein”, and there are stretches of DNA that don’t qualify as “genes”. What do they do? They control details of when and how specific genes and their proteins become active in the developing embryonic creature. (This, of course, is a horribly compressed version of what “Endless Forms” has to say. There’s more, so much more.)

Carroll shows how the interaction of genes and this “DNA dark matter” works. He also explains how such a variety of animals can be formed by tinkering with reusable parts – the dozens of ways that insects and crustaceans have started from a simple limb with a pincer on the end to build legs and mouths and feelers and gills and wings, for example.

What’s wrong with the book? First, Carroll is a specialist in fruit flies, and it shows sometimes. One or two chapters told me much more than I ever wanted to know about insect development, but even here there were unexpected nuggets of interesting stuff. Second, “Endless Forms” is not an easy read. I don’t think it could be easy and still do the subject justice. Be prepared to spend several weeks on it, and to re-read some parts and think about them before that part of the picture becomes clear.

Overall, though, if you have the slightest curiosity about the “hows” of life, if you aren’t already up to date on the latest in biology, you need to read “Endless Forms.” It’s that good.

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2 responses to “The critter construction kit

  1. Found your blog through Ellie’s Mix-it-Up challenge – I definitely want to read this! The book I just finished reading for Science and Natural History is The Brain that Changes Itself.
    Hope to see you there 🙂

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