One entry in the carnival roundup for today:
Otherwise, I’m running about in Minneapolis, paying another visit to the airport and going to a meeting at UMTC, so talk among yourselves. I’ll be back later.
You may recall that Martin Brazeau was going to spend July doing fieldwork—well, he’s back, and is going to be telling us about his exciting month in a Canadian cow pasture, if ever you wanted to hear a first-hand account of paleontological research.
The carnivals du jour:
Again, this is also an open thread. I got a comment on the last one that more open threads are needed. Is that true? I don’t need to go to Atrios-level open-threadery, of course, but if you’d like these a little more often, let me know.
The other day, I was asked a simple question that I knew the answer to, right off the top of my head, and since I’m nothing but lazy and lovin’ the easy stuff, I thought I’d expand on it a bit here. The question was, “How do flounder get to be that way, with their eyes all on one side of the head?” And the answer is…pedantic and longwinded, but not too difficult.
The Pleuronectiformes, or flatfish, are a successful teleost order with about 500 known species, some of which are important commercially and are very tasty. The key to their success is their asymmetry: adults are camouflaged ambush predators who lurk on the sea bottom, taking advantage of their flat shape to rest cryptically and snap up small organisms that wander nearby. They lie on their sides, and have peculiarly lop-sided heads in which one eye has drifted to the other side, so both eyes are peering out from either the left or right side (which side is consistent and characteristic for a particular species, although there is at least one species with random assignment of handedness to individuals, and mutant strains are known in others that reverse the handedness.)
Carel Brest van Kempen has posted one of his paintings of Cambrian animals—be sure to click on it to get the larger size. I wish I had a pet anomalocarid in my aquarium.
Assuming that none of my readers are perfectly spherical, you all possess notable asymmetries—your top half is different from your bottom half, and your front or ventral half is different from you back or dorsal half. You left and right halves are probably superficially somewhat similar, but internally your organs are arranged in lopsided ways. Even so, the asymmetries are relatively specific: you aren’t quite like that Volvox to the right, a ball of cells with specializations scattered randomly within. People predictably have heads on top, eyes in front, arms and legs in useful locations. This is a key feature of development, one so familiar that we take it for granted.
I’d go so far as to suggest that one of the most important events in our evolutionary history was the basic one of taking a symmetrical ball of cells and imposing on it a coordinate system, creating positional information that allowed cells to have specific identities in particular places in the embryo. When the first multicellular colony of identical cells set aside a particular patch of cells to carry out a particular function, say putting one small subset in charge of reproduction, that asymmetry became an anchor point for establishing polarity. If cells could then determine how far away they were from that primitive gonad, evolution could start shaping function by position—maybe cells far away from the gonad could be dedicated to feeding, cells in between to transport, etc., and a specialized multicellular organism could emerge. Those patterns are determined by interactions between genes, and we can try to unravel the evolutionary history of asymmetry with comparative studies of regulatory molecules in early development.
I’m not a cosmologist and I don’t even pretend to be one on the internet, but as an evolutionist I hear far more about the Big Bang from creationists than I should…and it’s everything from the Big Bang never happened to the Big Bang disproves evolution, and often both opinions are held by the same person, who will often also tell me both that the Cambrian is proof of sudden creation and that the earth is less than 10,000 years old (consistency is not a quality valued by most creationists). It’s therefore rather handy to have a summary of misconceptions about the Big Bang all in one place.
I am going mildly nuts right now—somehow, I managed to arrange things so multiple deadlines hit me on one day: tomorrow. I’ve got a new lecture to polish up for our introductory biology course, a small grant proposal due, and of course, tomorrow evening is our second Café Scientifique. Let’s not forget that I also have a neurobiology lecture to give this afternoon, and I owe them a stack of grading which is not finished yet. I’m really looking forward to Wednesday.
Anyway, so my new lecture for our introductory biology course is on…creationism, yuck. What I’m planning to do is to describe some of the most common creationist arguments and then give a biologist’s rebuttal. Creationism is really a waste of our class time, but using it to explain some general concepts that any informed biologist should understand (and that the creationists, including Mike Behe, are astonishingly clueless about) will make it a little more productive, I hope. We’ll find out tomorrow.
One of the common creationist claims I plan to shoot down is the whole idea of “irreducible complexity” as an obstacle to evolution. I was going to bring up two ideas that invalidate it: the principle of scaffolding (which I discussed here), and exaptation, in which features evolved for some other purpose than the one that they play in an organism we observe today. I was looking for a good example, and then John Wilkins fortuitously sent me a paper that filled the bill (we evilutionists, you know, are sneakily sending each other data behind the scenes to help in our assault on ignorance. We’re devious that way.)
Peter Doran published a paper several years ago showing that parts of Antarctica were actually cooling, rather than warming—that there were local variations in temperature trends. This is not surprising. It’s also not surprising that he was quote-mined like mad by the global warming denialists. He has now written a calm, solid rejection of the misuse of his data in the NY Times.
Our results have been misused as “evidence” against global warming by Michael Crichton in his novel “State of Fear” and by Ann Coulter in her latest book, “Godless: The Church of Liberalism.” Search my name on the Web, and you will find pages of links to everything from climate discussion groups to Senate policy committee documents—all citing my 2002 study as reason to doubt that the earth is warming. One recent Web column even put words in my mouth. I have never said that “the unexpected colder climate in Antarctica may possibly be signaling a lessening of the current global warming cycle.” I have never thought such a thing either.
Our study did find that 58 percent of Antarctica cooled from 1966 to 2000. But during that period, the rest of the continent was warming. And climate models created since our paper was published have suggested a link between the lack of significant warming in Antarctica and the ozone hole over that continent. These models, conspicuously missing from the warming-skeptic literature, suggest that as the ozone hole heals—thanks to worldwide bans on ozone-destroying chemicals—all of Antarctica is likely to warm with the rest of the planet. An inconvenient truth?
This is great stuff, but anyone want to take any bets on whether the anti-scientific global warming crackpots will now extract that penultimate sentence and use it to urge easing the ban on fluorocarbon release?
John Wilkins has been off visiting the ghosts of Owen, Darwin, Buffon, and Saint Hilaire, while I’m sitting in Morris. Ah, if only I had an excuse (and the means!) to escape…
