Anencephaly and right-wing moralizers

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There’s an important phenomenon in development called neurulation. This is a process that starts with a flat sheet of ectodermal cells, folds them into a tube, and creates our dorsal nervous system. Here’s a simple cross-section of the process in a salamander, but in general outline we humans do pretty much the same thing. Cells move up and inward, and then zipper together along the length of the animal to produce a closed tube.

It’s a seemingly simple event with a great deal of underlying complexity. It requires coordinated changes in the shape of ectodermal cells to drive the changes in tissue shape, and invisible in simple diagrams to the right are all the inductive interactions going on that trigger the differentiation of the tube into a nervous system.

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Bird brains

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I’m teaching a course in neurobiology this term, and it’s strange how it warps my brain; suddenly I find myself reaching more and more for papers on the nervous system in my reading. It’s not about just keeping up with the subjects I have to present in lectures (although there is that, too), but also with unconsciously gravitating toward the subject in my casual reading, too.

“Unconsciously”…which brings up the question of exactly what consciousness is. One of the papers I put on the pile on my desk was on exactly that subject: Evolution of the neural basis of consciousness: a bird-mammal comparison. I finally got to sit down and read it carefully this afternoon, and although it is an interesting paper and well worth the time, it doesn’t come anywhere near answering the question implied in the title. It is a useful general review of neuroanatomical theories of consciousness—even if it left me feeling they are all full of crap—but in particular it’s an interesting comparative look at avian brain organization.

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More shameless namedropping

Let’s see…what did I do today? I met with a whole bunch of people at Seed. They were cool, but they won’t notice that I mentioned them because they never read my blog.

I also had dinner with Niles Eldredge, James Watson, Adam Bly, and Laura McNeil (big guns at Seed).

It was an engrossing evening, but now you’re all going to really hate me: I can drop names, but I’m not going to reveal private conversations…other than to mention that I was honored by a toast from that distinguished crowd, which means I can either die smug, or I’ve got a heck of a lot to do to live up to it now. I fear the latter, unfortunately.

Worms and death

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If you’ve seen BladeRunner, you know the short soliloquy at the end by one of the android replicants, Roy, as he’s about to expire from a genetically programmed early death.

“I’ve seen things you people wouldn’t believe. Attack ships on fire off the shoulder of Orion. I watched c-beams…glitter in the dark near Tanhauser Gate. All those…moments will be lost…in time, like tears…in rain. Time…to die.”

There’s an interesting idea here, that death can be an intrinsic property of our existence, a kind of internal mortality clock that is always ticking away, and eventually our time will run out and clunk, we’ll drop dead. There is a germ of truth to it; there are genetic factors that may predispose one to greater longevity, and in the nematode worm C. elegans there are known mutants that can greatly extend the lifetime of the animal under laboratory conditions.

However, in humans only about 25% of the variation in life span can be ascribed to genetic factors to any degree, and even in lab animals where variables can be greatly reduced, only 10-40% of the life span variation has a genetic component. There is a huge amount of chance involved; after all, there aren’t likely to be any genes that give you resistance to being run over by a bus. Life is like a long dice game, and while starting with a good endowment might let you keep playing for a longer time, eventually everyone craps out, and a run of bad luck can wipe out even the richest starting position rapidly.

In between these extremes of genetic predetermination and pure luck, though, a recent paper in Nature Genetics finds another possibility: factors in the organism that are not heritable, yet from an early age can be reasonably good predictors of mortality.

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Release the hounds! The fate of ID creationists in an educated world

The Intelligent Design creationists keep trying the same old tactics of making their case with phony PR, but I don’t think it’s working so well anymore. For example, take a look at this op-ed from Richard Buggs of “‘Truth’ in Science”; he makes a futile attempt to throw out some of the usual creationist talking points, like these:

But, whatever the limitations of Darwinism, isn’t the intelligent design alternative an “intellectual dead end”? No. If true, ID is a profound insight into the natural world and a motivator to scientific inquiry. The pioneers of modern science, who were convinced that nature is designed, consequently held that it could be understood by human intellects. This confidence helped to drive the scientific revolution. More recently, proponents of ID predicted that some “junk” DNA must have a function well before this view became mainstream among Darwinists.

It’s rather pathetic. Buggs doesn’t even seem to understand how science works, and he makes vague claims that don’t make sense, and specific claims that are simply wrong.

  • We aren’t Darwinists any more. This isn’t 1859, OK?

  • The existence of Spiderman would also profoundly affect how we think about biology, evolution, physics, etc., if true. That final clause makes the whole idea non-scientific, if we recognized that Spiderman is a fictional character…what needs to be done is to support the initial premise. IDists want us to assume that major premise and act as if what follows from that invention is science.

  • The point about “confidence” in a designer driving the scientific revolution doesn’t make any sense. Does he think people who don’t believe in a designer just throw up their hands and give up because that means the world is unknowable?

  • The idea that large swathes of the genome have no adaptive utility is non-Darwinian. Functional roles were assumed by biologists first, certain stretches of non-coding DNA were known to be essential, and in general, IDists should avoid talking about junk DNA altogether, because all they do is reveal that they don’t understand the concept.

Now read the comments on Buggs article. It’s heartening: the readers slam the poor guy unmercifully. That’s what I like to see, every false claim made by an ID flak getting swarmed and ripped apart by an informed citizenry.

You are being watched

Greg Laden makes a simple analysis of what triggers comments on Pharyngula: it turns out the least interesting subject is me (my self-esteem is being battered lately), with science close on my heels, but that you love to chatter about creationists and godlessness.

Now I wonder how strong the response will be if I say this post is about none of those things: it’s about you.