Complex biochemical systems slap Behe upside the head

Ian Musgrave does a wonderful job explaining the recent Science paper on the evolution of hormone binding sites. This is the work that Behe has called “piddling”, and claims that it has no relevance to the evolvability of complex biochemical systems. Ian takes this idea apart with a quick tour of the wandering goalposts of irreducible complexity:

Behe and the Discovery Insitute have reacted quickly and negatively to this paper. But in doing so they display a curious amnesia. Behe says:

I certainly would not classify their system as IC. The IC systems I discussed in Darwin’s Black Box contain multiple, active protein factors. Their “system”, on the other hand, consists of just a single protein and its ligand.”

Yet this “system” is precisely the thing that Behe uses in his exemplar for the Behe and Snoke paper, the binding of DPG to haemoglobin. And Behe has said in testimony to the Dover trial that the Behe and Snoke paper on evolution of binding sites is about irreducible complexity. So if the evolution of the DPG binding site (where you only need two mutations to make a functioning DPG binding site) is an example of IC, then the evolution of the aldosterone binding site is also.

Poor Behe. The man continues his ever-accelerating slide into the land of pathetic jokes.

RU486

After I summarized how Plan B contraception works, I’m still getting letters confusing it with RU486. RU486 induces abortions. Plan B does not. RU486 is the opposite of Plan B.

Remember that what Plan B is is an artificially high dose of progesterone (it actually uses a progesterone analog, but it’s effectively the same.) Progesterone is a hormone that maintains the uterine lining in a nice, rich, spongy, receptive state, and it also suppresses another hormone, LH, that is what triggers ovulation. Plan B keeps the uterus primed for implantation, but tells the ovary to hold its fire and not release an egg.

RU486 can’t get much different. It’s a compound, mifepristone, that antagonizes progesterone—it binds to progesterone receptors and blocks their function, so that it looks to the cells as if progesterone levels have all all dropped to zero. The cells of the uterus, whether implantation has occurred or not, are tricked into menstruating right away, shedding the uterine lining and anything growing in it.

Now I personally think RU486 is a fine idea and a perfectly reasonable and relatively safe way to induce an abortion, and I think it ought to be legal and available. However, it is nothing like Plan B. Plan B is a completely separate issue from any argument over the ethics or utility of abortion.

Where have I been?

It’s been a long day for me—I made yet another of those long drives into Minneapolis and back. It was worth it, though. We had the first meeting of a new group, Minnesota Citizens for Science Education; I think it’s going to be a useful resource for the state. It consists of several of us college professor types, plenty of K-12 educators, and a few business people, and we’re all going to be working together over the next few months to put together information to further the cause of good science teaching in Minnesota.

Details will have to wait, though. We’ll be aiming for a formal announcement in the Fall, with a public meeting on the topic at about the same time. Give us some time to get organized.

Isn’t it nice how crazy organizations like the Discovery Institute and Answers in Genesis are inspiring scientists and educators to get together and work to help our kids learn science better?

Why the wingnuts hate Plan B

There has been an oddly evasive struggle going on in Washington DC for the last several years. We have a safe, easy method of emergency contraception that has been turned into a political football, with Republicans playing their usual role of criminally stupid thugs, trying to crush a simple idea: Plan B contraception. It illustrates exactly how the Religious Right is trying to intrude on your private life, and in particular, how they want to control women.

I’ll explain how Plan B works, but to do so I’m going to have to explain some basics of the hormonal control of the menstrual cycle.

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Malacology morning

My wife thought this story about left-handed snails having a competitive advantage, in that they seem to be better able to escape predation by right-handed crabs, was pretty cool. She also recalled that I’d scribbled up something about snail handedness before, so to jump on the bandwagon, I’ve brought those stories over from the old site.

The handedness of snail shells is a consequence of early spiral cleavages in the blastula. It’s a classic old story in developmental biology—everyone ought to know it!

There was also a story last year about shell chirality in Euhadra. There, it wasn’t a matter of predation, but a potential isolating mechanism, and one where mating compatibility and character displacement could play a role.

Everyone can read up on snails while I’m off at class this morning.

Chirality in Euhadra

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Since Coturnix turned me on to this paper on snail chirality in PLoS (pdf), I had to sit down and learn something new this afternoon.

Chirality is a fascinating aspect of bilaterian morphology. We have characteristic asymmetries—differences between the left and right sides of our bodies—that are prescribed by genetic factors. Snails are particularly interesting examples because snail shells have an obvious handedness, with either a left-(sinistral) or right-handed (dextral) twist, and that handedness derives from the arrangement of cell divisions very early in development.

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Spiral cleavage

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Developmental biologists are acutely interested in asymmetries in development: they are visible cues to some underlying regional differences. For instance, we’d like to know the molecules and interactions involved in taking a seemingly featureless sphere, the egg, and specifying one side to go on to form a head, and the the opposite side to form a tail. We’d like to understand why our back (or dorsal) side looks different from our belly (or ventral) side. One particularly intriguing distinction, though, is the left-right axis. For the most part, left and right are nearly identical, mirror-images of one another, but there are also key asymmetries. Your heart, for instance, is larger on the left side than the right, your liver lies mostly on the right side of your abdomen while the stomach arcs to the left, and these arrangements are essential for normal function. Left-right asymmetries are more subtle than anterior-posterior or dorsal-ventral differences, and that makes them especially fascinating.

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Tiktaalik makes another gap

Paleontologists have uncovered yet another specimen in the lineage leading to modern tetrapods, creating more gaps that will need to be filled. It’s a Sisyphean job, working as an evolutionist.

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This creature is called Tiktaalik roseae, and it was discovered in a project that was specifically launched to find a predicted intermediate form between a distinctly fish-like organism, Panderichthys, and the distinctly tetrapod-like organisms, Acanthostega and Ichthyostega. From the review article by Ahlberg and Clack, we get this summary of Tiktaalik‘s importance:

First, it demonstrates the predictive capacity of palaeontology. The Nunavut field project had the express aim of finding an intermediate between Panderichthys and tetrapods, by searching in sediments from the most probable environment (rivers) and time (early Late Devonian). Second, Tiktaalik adds enormously to our understanding of the fish-tetrapod transition because of its position on the tree and the combination of characters it displays.

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The swiftboating of Eric Pianka

Pianka speaks out. Nick Matzke has a good post on Pianka at the Thumb, addressing the smear campaign against him*. He links to an interview with the good Dr—what he’s saying is simple sense, common in the biological community, and he’s not endorsing mass murder…he’s talking about conservation and planning ahead. Mims is a “crazy kook” who distorted the story and turned it into screaming match.

Get used to it. This is part of the right-wing strategy to attack the academy: when scientists honestly state bad news (and there is much bad news, and it’s growing), they are going to be rabidly accused of all kinds of outrageous crimes. It’s the new McCarthyism. The majority of us do not support short-sighted policy, we don’t endorse jingoism, we are going to urge people to think before acting, we are going to predict the consequences of bad policy, and we are generally going to be critical of demagogues and fools…and that is being treated as a crime.

*Quite unlike the situation with Paul Mirecki; I can’t help but interpret this to mean you’re going to be left twisting in the wind if the right-wing mobs try to lynch you, and you admit you’re godless.