Daily Archives: February 12, 2012

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.

Out of the discomfort zone?


Follow that branch??

Years ago, I worked on a college campus near a wooded area full of walking trails. After a while, I started spending some of my lunch hours exploring the trails…which weren’t marked in any way. I suspect they were created with no planning by other people who liked to walk in the woods; in some places, there were “trails” that were so faint you could only see the slight depression in the ground if the sun was at just the right angle to highlight it.

Anyway, on one of my first explorations, I almost didn’t get out again. I walked, and walked, and finally decided I had definitely passed the same trees a couple of times before. So the next time a couple of paths crossed, I took what felt like the wrong choice, and escaped from the woods at last. Later, when I got familiar with the major routes, I realized that I had been walking around and around a loop. (But it was a nice loop, with a swath of ferns stretching downhill from the edge of the path.)

This past week I’ve felt like I was going in circles, without the pretty scenery to make it worthwhile. I’ve been doing pretty well lately finding time to write, even with the necessary several phone calls each day to keep my mother on track. But there wasn’t much time left over. And when you start out with Too Much Stuff and no talent for organization, chaos is never far away. By the end of last week, I could see things were out of control, and didn’t know what to do.

So I did nothing. I spent the first several days of this week neither writing nor organizing, making ineffectual starts on one problem after another and then going off and reading. It wasn’t a comfortable place to live, literally or metaphorically. And yet it was so easy to go on being stuck there, as easy as if it was a comfort zone.

Like being in a maze full of potholes

I’m not as far out as I’d like to be, but by Thursday I realized that I had to force myself to stay in focus on one thing at a time and just go on until I got out of the woods. It didn’t much matter what project I worked on, as long as I kept moving.

Getting out of your comfort zone from time to time is a useful exercise. Getting out of that discomfort zone, by any path that offers itself, is vital.