Monday, March 31, 2008

For Once, Chris Mooney Talks Sense

 
Read Chris Mooney's latest posting on The Intersection where he addresses the framing controversy [A Dialogue on Framing, the F-Word, and the Future of ScienceBlogs, Part I: Framer Culpa].
When I teamed up with Matthew Nisbet a year ago to talk about the subject of framing science--which I still believe to be a very important one--it was not my goal to alienate or outrage a group that I consider one of my most important audiences, namely, ScienceBlogs bloggers and readers. And yet when you look at the latest blowup over what I have posted, Sheril has posted, and Nisbet has posted about Expelled, it's undeniable that there is now an audience that reacts very negatively even to any basic mention of the concept of framing.

And there's just no other way to spin it--this is a painfully ironic communication failure on the part of those of us who wanted to introduce what I view as a very important communication tool to the science world. If we can't explain something so useful to an important segment of our own audience, how can we possibly hope to use it to counter the other side?
Good for you Chris. The irony has been apparent to many of us and it's really good to see you confess to having created the problem. My respect for you just went up several notches.

Let me just correct one little thing. There are plenty of science bloggers out there who don't like your views on framing science. Not all of us belong to the ScienceBlogsTM consortium.
Now, to be sure, the concept of framing has been quite influential already for many people who care about science, but who are not seemingly well represented on ScienceBlogs. When I go around lecturing with Matt Nisbet, we constantly encounter enthusiastic, receptive scientist-laden audiences at universities. There is simply nothing like the response that we've seen here over the last week. Indeed, I believe the reactions at lectures may have skewed my perceptions, and made me neglect or dismiss, to a significant extent, the way our ideas were faring in the science blogosphere.

But no success on the lecture circuit can change the fact that somehow--and I'll have ideas about how it happened in later posts--the concept of framing has been blackened on Scienceblogs, which I consider a truly tragic occurrence. And while I'm hardly the only guilty party here, I certainly played a role in that, whether actively or by omission.
It's very common for people on the lecture circuit to get an exaggerated—and false—impression of their message. This is because the only people who come to your talks are the true believers. When dissenters do show up it's often hard for them to debate the speaker just by posing questions from the audience.

I'm not surprised that the Nisbet/Mooney road show fooled you into thinking that your ideas were widely accepted in the scientific community. The other way of fooling yourself is to organize a conference where the only people invited are those who agree with you. This is what Nisbet did at AAAS.

Allow me to re-iterate the point I made earlier. It's not just on ScienceBlogsTM that the concept of framing has been blackened. I've met many scientists who think that your views on framing1 are an unacceptable way to teach science. A good many of those scientists have never read a single posting on any ScienceBlogsTM blog and, furthermore, they have never even heard of Seed and the group it supports.

I admire the fact that you confess to poor framing of your ideas. Now. how about discussing whether they are even correct? Up to now all you've done is reject any criticism on the ground that we don't really understand framing. Maybe we do, but we're still opposed. Have you ever thought of that?

Your message still seems to be that you just made the mistake of not presenting your ideas correctly. In other words, you didn't frame properly. I hope that subsequent postings won't continue in that vein. It's time to realize that it was not only the medium that was flawed but also the message.


1. Framing is deliberately altering what you want to say in order to make it more acceptable to your audience.

Is Faith Inevitable?

 
Last Thursday evening I watched a panel discuss the question "Is Faith Inevitable?" Unlike previous shows on TV Ontario, this one had a balance of believers and non-believers.

Two of the non-believers, Robert Buckman and Ronald de Sousa, are well-known in Canada (see below). You can watch the entire show at The Agenda.

I agree with the comments made by an undergraduate here at the University of Toronto when he says that the discussion got sidetracked [The Unexamined Life ...]. The real question is not whether faith is valuable, it's whether there is a God that you should have faith in.

Furthermore, I was very disappointed in Buckman and de Sousa because both of them bought into the line that we have evolved a need for religion. This is ridiculous. There is no gene for believing in supernatural beings and there's no reason to think that atheists need to overcome their genetic makeup in order to reject the notion of God. I wish we could put an end to this silly meme before it spreads any further.




Gene Genie #28

 
The 28th edition of Gene Genie has been posted at Greg Laden's Blog [Gene Genie #24]. (It really is number 28, in spite of what Greg says. See Gene Genie.)
Welcome to Gene Genie #24: with a heavy emphasis on Personal Genetics.
The beautiful logo was created by Ricardo at My Biotech Life.

The purpose of this carnival is to highlight the genetics of one particular species, Homo sapiens.


Canada Wins World Championship!

 
I'm sure you've already heard the news. The Canadian women's team of Dawn Askin (lead), Jill Officer (second), Cathy Overton-Clapham (third) and Jennifer Jones (skip) beat China yesterday to win the World1 Women's Curling Championship.

Most of you were probably watching the game so I don't need to remind you how exciting it was.


1. Just to clarify for my American friends ... this was not a tournament where only teenagers in colleges like UNC could play and it was not a tournament confined to a single country. This is a world title. The USA didn't even make the playoffs.

[Photo Credit: Ford World Women's Curling Championship]

Stuff White People Like

 
Check out the blog Stuff White People Like, especially, Paris, San Francisco, and Having Gay Friends.


[Hat Tip: Jane at Beer with Chocolate.]

Monday's Molecule #66

 
This is a very important enzyme. Most living organisms on this planet could not survive if this enzyme didn't do its job. Very few species have this enzyme but we depend on those few species for our very existence.

Your task for today is to identify the enzyme (1) and the species from which this particular enzyme was isolated (2). You also have to write out the complete reaction that is catalyzed by this enzyme (3).

In addition you have to identify the Nobel Laureate who is associated with the reaction that is catalyzed by the enzyme. (Hint: the Nobel Laureate studied the chemical reaction, not the biological one.)

The first person to correctly identify the enzyme and species, write the chemical equation, and name the Nobel Laureate. wins a free lunch at the Faculty Club. Previous winners are ineligible for one month from the time they first collected the prize. There is only one ineligible candidate for this week's reward.

THEME:

Nobel Laureates
Send your guess to Sandwalk (sandwalk (at) bioinfo.med.utoronto.ca) and I'll pick the first email message that correctly answers the questions and names the Nobel Laureate(s). Note that I'm not going to repeat Nobel Laureates so you might want to check the list of previous Sandwalk postings.

Correct responses will be posted tomorrow along with the time that the message was received on my server. I may select multiple winners if several people get it right.

Comments will be blocked for 24 hours. Comments are now open.

UPDATE: We have a winner! The enzyme is nitrogenase from Azotobacter vinelandii. It fixes atmospheric nitrogen into ammonia by catalyzing the following reaction ...

The Nobel Laureate is Fritz Haber (1918) who worked out a chemical method of synthesizing ammonia from nitrogen.

Bryant Ing of the University of Toronto was the first person to get it right.


[Image Credit: Dixon and Kahn (2004) based on the structure PDB 1n2c by Schindelin et al. (1997)]

Dixon, R. and Kahn, D. (2004) Genetic regulation of biological nitrogen fixation. Nature Reviews Microbiology 2, 621-631. doi:10.1038/nrmicro954

Schindelin, H., Kisker, C., Schlessman, J.L., Howard, J.B. and Rees, D.C. (1997) Structure of ADP x AIF4(-)-stabilized nitrogenase complex and its implications for signal transduction. Nature 387: 370-376 [PubMed]

Thursday, March 27, 2008

Make Your Own Phylogenetic Tree

 
Sandra Porter at Discovering Biology in a Digital World has prepared a short video presentation on how to make your very own phylogenetic tree from DNA sequences [A beginner's guide to making a phylogenetic tree].


Monday, March 24, 2008

Nisbet Reveals His True Colors

 
Framing is about spin, censorship, and, above all, it's about agreeing with Matt Nisbet and Chris Mooney. If you don't agree with them then it's because you just don't understand framing.

It's about time we started to ignore Nisbet and Mooney. Fortunately, they are making it easy by posting drivel like Why the PZ Myers Affair is Really, Really Bad for Science and PZ Myers, Mind Your Manners (see comments).

I'm opposed to censorship of any kind but I really wish Matt Nisbet and Chris Mooney would voluntarily decide to keep their stupid mouths shut for a few years. I'm with PZ Myers on this one [I'm supposed to sit down and shut up?].

If anyone is really interested in seeing exactly what the blogosphere thinks of Matt Nisbet and Chris Mooney you need only check the links that Greg Laden has posted at The Framing Critique (Dawkins-Myers-Expelled! -Gate). I really hope this spells the beginning of the end for the Nisbet/Mooney tag team.



Wells Takes a Rain Check on Apology

 
The misreporting of the evolution issue is one key reason for this site. Unfortunately, much of the news coverage has been sloppy, inaccurate, and in some cases, overtly biased. Evolution News & Views presents analysis of that coverage, as well as original reporting that accurately delivers information about the current state of the debate over Darwinian evolution.

Evolution News & Views
I challenged Jonathan Wells to agree to a simple statement that, I believe, might reflect his true beliefs about evolution [A Challenge to Jonathan Wells].

In one of the biggest surprises of the 21st century (not!) Wells has backed off [What’s in a Word?].
Darn. I guess I’ll have to take a rain check on that apology – because I don’t agree with this – and not just because Maurice et al. (2008) are cited incorrectly. Here’s why.

"Evolution" has many meanings. It can mean simply "change over time." The present is different from the past. The cosmos evolves. Technology evolves. No sane person denies evolution in this sense.
Biological evolution never means just change over time, but that's not the real problem with Wells' post. You're going to have to scoot on over to Evolution News & Views and read the whole thing.

I can't make head nor tail of it. I wonder if Wells actually thinks it makes sense?

John Pieret takes on the task of dissecting the Wells definition of evolution on Thoughts in a Haystack [Falling in the Wells]. He's a braver man that I.


Sunday, March 23, 2008

Watch and Weep

 
ABC News follows a group of home-schooled Christian children on a museum tour. The tour leaders are interviewed. They attempt to defend the lies they are telling the children.




[HatTip: Friendly Atheist: How to Ruin a Trip to the Museuam.]

Saturday, March 22, 2008

Evil and Sin

 
Yesterday's issue of the Toronto Star had an article on The fundamentalist atheists.

I'm getting real tired of hearing this phrase but I haven't completely given up trying to understand what people mean when they use it. In this case, the article is by Stuart Laidlaw, who is billed as the "faith and ethics" reporter. Laidlaw is commenting on a recent talk by Chris Hedges. Hedges seems to be one of those "sophisticated" Christians who have all the answers.1 Naturally, he denigrates the "new atheists" like Richard Dawkins because they just don't understand serious Christianity.

Serious Christians seem to be very concerned about evil and sin.
Hedges, in Toronto recently to promote his book, attacks both fundamentalists and the new breed of atheists as not only intolerant, but wrong about both the Jesus story and the nature of sin.

Sin, he says, is a personal thing that will always be with us. Humans will never outgrow it through evolution, as the atheist authors contend, nor can anyone (Jesus included) relieve us of it, as fundamentalist Christians believe, Hedges says.

The best we can do, he says, is try to mitigate evil by living a good life, and having democratic institutions in place to ensure that we can get rid of bad leaders from time to time.
Sin, as I understand it, is when you violate a moral rule of some kind. It usually means you are disobeying the wishes of supernatural beings. It's not a word used by atheists.

Evil is something I can understand. People do bad things. Religious people do bad things and atheists do bad things. No atheist that I know would ever claim that humans will evolve to the point where they don't do bad things. What a ridiculous idea. What in the world is Hedges thinking?
For fundamentalists, evil and sin are an external force – often represented by Satan – to be vanquished by giving yourself over to Jesus. For the new atheists, evil and sin are the fault of religion, and can be defeated by getting rid of all religion and giving yourself over to scientific, reasoned thought.

For Hedges, it's the same argument: People are basically good, but external forces make us do bad things. Get rid of those forces, and people will be good.

No more effort is needed to achieve utopia, he says.
Just because religions can be evil does not mean that all evil is due to religion. No atheist believes this, as far as I know.

I believe that people are basically good but they still do bad things and they don't need external forces to do them. People are quite capable of being evil all by themselves. What in the world motivates people like Hedges to make up false stories about athiests? It makes him look very silly.

The question of evil and sin seems to be so intertwined with the existence of God that religious people (Christians?) seem to have difficulty untangling them. They seem to think that atheists are as obsessed about evil and sin as they are when, in fact, most of us don't give it much thought. Perhaps that's because we don't have to deal with the paradox of a good God who allows evil and sin?
Hedges draws a distinction between the new breed of atheists and such past non-believers as Albert Camus or scientists of the Enlightenment, whose skepticism he says helped drive human knowledge and understanding.

But Hedges has few such hopes for the new atheists. Where atheists of the past used their disbelief as a stepping off point to find something else to believe in, the new atheists claim to have already found it in what he calls a "cult of science."

Anything that can't be proved scientifically is simply discounted, Hedges says, warning that such a narrow approach to study thwarts the pursuit of knowledge by denying a voice to those who disagree.
The "new atheists" claim there are no supernatural beings because there's no evidence of such beings. This has nothing to do with evil and sin. When are these sophisticated Christians going to address the real question instead of going off on weird tangents? If they have a good argument for the existence of god then let's hear it. Otherwise, their "sophistication" looks more like "obfuscation" to me. (Or like The Emperor's New Clothes and the Courtier's Reply.)

It's time to stop whining and face up to the real question. Is there a god? Questions about evil and sin are irrelevant until that question is settled.


1. In spite of his confusion about religion, he seems to be a pretty good guy. He was right about Iraq, for example.

The Spin Begins

 
The misreporting of the evolution issue is one key reason for this site. Unfortunately, much of the news coverage has been sloppy, inaccurate, and in some cases, overtly biased. Evolution News & Views presents analysis of that coverage, as well as original reporting that accurately delivers information about the current state of the debate over Darwinian evolution.

Evolution News & Views
The Discovery Institute website has skirted around the obvious hypocrisy and attacked Dawkins and Myers. Bruce Chapman has posted an article on Evoluton News & Views about the expulsion of PZ Myers from a viewing of EXPELLED [Richard Dawkins, World’s Most Famous Darwinist, Stoops to Gate-crashing Expelled].
Amazingly, the best selling Oxford scientist/author Richard Dawkins also crashed a showing of Expelled in Minnesota last night and he not only was let in, but introduced at the end of the showing.

Dawkins apparently acknowledged that he had not been invited and did not have a ticket. A sophomoric side to his ideological campaign is thus revealed.

Dawkins, understandably is nervous about this film, among other reasons because Ben Stein has him on camera acknowledging that life on Earth may, indeed, have been intelligently designed, but that it had to have been accomplished by space aliens! This is hilarious, of course, because Dawkins is death on intelligent design. But it turns out that that view applies only if it includes the possibility that the designer might be God.

Myers, of course, relished being expelled from Expelled, but objective observers know that Myers is the most vociferous advocate of expelling Darwin critics from academia. Not from movie pre-screenings where he wasn’t invited, mind you, but from their jobs. Too bad the film doesn’t show (and I wish it had), his promotion of advice to attack teachers and professors who dare question Darwin’s theory. The whole point of Myers is that he is a take-no-prisoners, crusading atheist scientist who has made it his purpose in life to harass people who disagree with him. Dawkins turns out to be his buddy and mutual admirer.
Those of you who have been following the issue on the various blogs, and in newspaper articles, know full well that Dawkins did not "crash" the movie. People did not have to be invited and there were no tickets. Chapman and his friends must know this too. Therefore, he is lying.

I'm not surprised that most of the IDiots are behaving this way. What will surprise me is that all of them might behave like Bruce Chapman. I expect at least one prominent IDiot to admit that expelling PZ Myers was a mistake and to admit that he should have been allowed to see a movie that featured him.

Let's see if there's at least one IDiot with the guts to speak the truth. Bill Dembski is not going to be that person (suprise!) because he has just posted the Chapman piece on his blog [Discovery News Release on Richard Dawkins Crashing EXPELLED Screening]. I'm hoping that Denyse O'Leary will be the one with the gumption. Or maybe Michael Behe. I expect Jonathan Wells to weigh in with even more lies about the incident.


PZ Myers and Richard Dawkins Discuss "EXPELLED"

 
New York Times article by Cornelia Dean: No Admission for Evolutionary Biologist at Creationist Film.




[HatTip: RichardDawkins.net]

Friday, March 21, 2008

EXPELLED! - Waiting for the Creationists to repsond ...

 
By now you've all heard the news. PZ Myers was standing in line to see a screening of the propaganda movie EXPELLED when security guards asked him to leave. They didn't bother with his family or his friend, Richard Dawkins. Read PZ's account at EXPELLED!.

Now let's see how the creationists respond to this incident. Remember, the movie is about discrimination by scientists against people who are religious. It will be very interesting to see how they can justify keeping PZ Myers out of the movie when all kinds of other people were let in.

Here's one response, posted on the EXPELLED website [Richard Dawkins crashes the party at a screening of “Expelled”]. The writer is Stuart Blessman, a Christian who was given tickets to see the movie by his pastor. Blessman was present at the theater on Wednesday evening. He is responding to the charge that PZ Myers was prevented from seeing the movie because he (PZ) is an evolutionist. Here's what Stuart Blessman says ...
I just happened to be standing directly in line behind Dawkins’ academic colleague. Management of the movie theatre saw a man apparently hustling and bothering several invited attendees, apparently trying to disrupt the viewing or sneak in. Management then approached the man, asked him if he had a ticket, and when he confirmed that he didn’t, they then escorted him off the premises. Nowhere was one of the film’s producers to be found, and the man certainly didn’t identify himself. If a producer had been nearby, it’s possible that he would have been admitted, but the theatre’s management didn’t want to take any chances.
This sounds very much like a blatant, bare-faced, lie. Anyone who knows PZ Myers would know that he would bot be "hustling" and "bothering" the people waiting in line. Quite the contrary, PZ and his colleague Richard Dawkins would have been trying to keep a low profile.

In his followup posting, PZ responds by saying that Blessman's account is a complete fabrication [A late night quick one].

Now, I'm going to be looking in on creationist blogs to see how they handle this story. So far there has been deathly silence. Is that because the creationists are embarrassed? Is it because they never criticize their own kind? Or, is it because they don't see the hypocrisy? Please let me know of any creationist responses.



Communicating Science in a Religious America

 
"Communicating Science in a Religous America" was the title of a session at the AAAS meeting in February. Here's a summary of the meeting from someone who seems to have been paying attention [Puttin Science in a Frame]. Here's a teaser ...
Framing has not been without controversy, as some have viewed it as little more than a form of empty platitude or an attempt to dumb down science. What became clear from Nisbet's talk, however, is that there can also be people left out of the ostensibly-shared values; it should be no surprise they are objecting.


Going Public with the Scientific Process

 
Ruth Cronje is a faculty member of the Scientific and Technical Writing Program at the University of Wisconsin-Eau Claire in Eau Claire, WI (USA). She has written a letter that was published in Science last week [Going Public with the Scientific Process]. Many of you will never get to read it but you should. It is wonderful.

I'm going to take a chance here and publish her entire letter just so it gets as wide a coverage as possible.
The idea of using framing strategies to communicate science to the public has recently been taken up in scientific forums (1, 2), the mainstream media (3), and the blogosphere (4, 5). Most participants in the framing science debate limit their notion of scientific information to scientific facts. However, confining science messages to just the facts interferes with public understanding of science as a systematic, logical process of human inquiry and effaces the distinction between data and scientists' reasoning about data. To communicate successfully, we should focus on scientific process by emphasizing two important elements of scientific rationality: skepticism and dynamicism (6, 7).

Scientists deliberately integrate skepticism into their procedures by trying to refute their own hypotheses, retaining them only when confronted with compelling evidence sought through carefully controlled procedures. Scientists tend to shy away from revealing the intrinsic skepticism of science to the public, fearful that it will open the door to doubt about the validity of their conclusions. But communicating only the facts of science (framed or unframed) destabilizes public confidence in science. A fact doesn't allow science communicators to reveal, justify, and ultimately promote the skeptical reasoning process that helps make scientists more confident that their reasoning is correct.

Science is also dynamic; it is a cumulative enterprise that requires scientists to situate their instrumental activities and interpretations against the evidence that has come before and to alter them in light of new evidence. Insisting that new data be interpreted within the context of past and future data will ferret out and correct error over time, but it means that a fact cannot, by definition, be anything more than the (ephemeral and fallible) consensus of scientists at a given point in time. A "just the facts" strategy can and often does backfire, ultimately fueling public alienation from science. When scientists inform the public of "facts" (like the "fact" widely disseminated in the 1970s that all dietary fats are bad for us), and then that "fact" is refined or altered (now we're told olive oil is good for us), the public is justifiably confused. Studies suggest that the public tends to regard normal scientific refinement and self-correction as equivocation or incompetence (8-10). Instead of sweeping uncertainty under the rug, science communicators should help the public understand the logical and systematic procedures by which scientists confront it.

The true majesty and promise of science lies in its systematic, logical, skeptical, and dynamic reasoning procedures. "Successful" science communication should not be regarded as any message that enlists public support for science. Rather, we should define "success" in scientific communication as achieving a public that celebrates scientific reasoning procedures.
In case Mathews and Nisbet don't get it, the new version of Science journal isn't going to let them get away with distorting science for political ends. Nisbet comments on this letter and hopes to discuss the topic with Cronje when he visits her next week [At Science, Still More Reaction to Framing]. I'd love to be there.


Bruce Alberts on Science Education

 
Bruce Alberts, the former President of the National Academies (USA), has now taken over as Editor-in-Chief of Science.1 Judging by his editorial in this week's issue [Considering Science Education] there could be some interesting times ahead in the Science offices.

Here's part of what Bruce has to say about science education ...
I consider science education to be critically important to both science and the world, and I shall frequently address this topic on this page. Let’s start with a big-picture view. The scientific enterprise has greatly advanced our understanding of the natural world and has thereby enabled the creation of countless medicines and useful devices. It has also led to behaviors that have improved lives. The public appreciates these practical benefits of science, and science and scientists are generally respected, even by those who are not familiar with how science works or what exactly it has discovered.

But society may less appreciate the advantage of having everyone aquire, as part of their formal education, the ways of thinking and behaving that are central to the practice of successful science: scientific habits of mind. These habits include a skeptical attitude toward dogmatic claims and a strong desire for logic and evidence. As famed astronomer Carl Sagan put it, science is our best “bunk” detector. Individuals and societies clearly need a means to logically test the onslaught of constant clever attempts to manipulate our purchasing and political decisions. They also need to challenge what is irrational, including the intolerance that fuels so many regional and global conflicts.

So how does this relate to science education? Might it be possible to encourage, across the world, scientific habits of mind, so as to create more rational societies everywhere? In principle, a vigorous expansion of science education could provide the world with such an opportunity, but only if scientists, educators, and policy-makers redefine the goals of science education, beginning with college-level teaching. Rather than only conveying what science has discovered about the natural world, as is done now in most countries, a top priority should be to empower all students with the knowledge and practice of how to think like a scientist.
Those of you who have been reading Sandwalk know that this is exactly how I think science education should be fixed. We need to teach students how to think like a scientist. The facts of science are important but they aren't nearly as important as the way in which scientific facts are determined. Science is a way of knowing—that's what students need to learn.

I think we have a long way to go. At SciBarCamp last weekend we discussed the ten things everyone needs to know about science. One of the things on my original list was that science is a way of knowing [Ten Things Everyone Should Know About Science]. Before the meeting someone had written a comment on the poster to the effect that science may not be the only way of knowing and another participate wrote in that "it kinda was."

When it came time for the discussion the moderator handed out three topics to each of the panel members. One of them got the topic "Science doesn't have all the answers" and I was given the topic "Science has all the answers." When it came time for me to present I said that science doesn't have all the answers and nobody I know claims otherwise.

I changed the topic to "science is a way of knowing" and suggested that it may be the only way of knowing. Considerable debate followed. It was clear that many participants were new to this topic since the old arguments about love and morality came up.

At the end of the session, the moderator wrapped up and concluded that there was consensus on three things everyone needs to know about science. One of them was "science doesn't have all the answers." This is completely wrong, in my opinion. Of course, science doesn't have all the answers. The real question is whether it has all the questions.


1. In the interests of full disclosure, I should reveal that he was also my graduate supervisor. (See Bruce Alberts in Toronto.)

Tangled Bank #101

 
The latest issue of Tangled Bank is #101. It's hosted at Tangled Up in Blue Guy [Tangled Bank #101].
When I first found that I would be hosting this edition of Tangled Bank, I tried to come up with a theme centered on Highway 101. It runs along the West Coast in the US and A and a stretch of it through San Francisco is also known as Van Ness Boulevard. I lived a block away from Van Ness for a year and one of my favorite pubs was an English Local, known as Highway 101. The idea for a clever theme vanished when I started receiving and reading the submissions that people sent. I decided I didn’t want to detract from the entries featured by making the show gimmicky. The Tangled Bank isn’t about me, it’s about science and the excitement of discovery as people unravel the mysteries of the natural world.


If you want to submit an article to Tangled Bank send an email message to host@tangledbank.net. Be sure to include the words "Tangled Bank" in the subject line. Remember that this carnival only accepts one submission per week from each blogger. For some of you that's going to be a serious problem. You have to pick your best article on biology.


Fun in Guelph

 
Katie Kish has a brief description of my visit to Guelph on her blog Liberal Debutante [Larry Moran At Guelph. I stole the photograph from her, I hope she doesn't mind.

The question about the evolution of the bombardier beetle was really a question about irreducible complexity in general and I tried to answer that question rather than the specific question that was asked. I was pretty sure that Dawkins had refuted the bombardier beetle "paradox" with real examples of transitional forms but I wasn't sure about this and didn't know the reference. (I said at the talk that I thought it was in The Blind Watchmaker).

Ryan Gregory, who I met for the first time on Wednesday night, has come to the rescue with a posting on Genomicron [Bombardier Beetles]. He has even found a video of Richard Dawkins "exploding" the myth of exploding bombardier beetles. Go and watch it on Ryan's blog.

There's an important lesson here. It is 2008. The evolutionary "problem" represented by the bombardier beetle was addressed—and refuted—by evolutionary biologists over 20 years ago and yet it's still being raised today by creationists as if it were a serious problem. What does that tell you about creationists?

Dealing with IDiots is very frustrating.


Wednesday, March 19, 2008

Nobel Laureate: Paul Flory

 

The Nobel Prize in Chemistry 1974.

"for his fundamental achievements, both theoretical and experimental, in the physical chemistry of the macromolecules"


In 1974, Paul J. Flory (1910 - 1985) was awarded the Nobel Prize in Chemistry for his work on the physical chemistry of macromolecules in solution. His work led to an understanding of the dynamics and conformation of proteins and that's why his contributions are covered in biochemistry courses.

The presentation speech was delivered by Professor Stig Claesson of the Royal Academy of Sciences.THEME:

Nobel Laureates
Your Majesty, Your Royal Highnesses, Ladies and Gentlemen,

This year's Nobel prize in chemistry has been awarded to Professor Paul Flory for his fundamental contributions to the physical chemistry of macromolecules.

Macromolecules include biologically important materials such as cellulose, albumins and nucleic acids, and all of our plastics and synthetic fibers.

Macromolecules are often referred to as chain molecules and can be compared to a pearl necklace. They consist of long chains of atoms which, when magnified one hundred million times, appear as a pearl necklace. The pearls represent the atoms in the chain. One should realize that this chain is much longer than the necklaces being worn here this evening. To obtain a representative model of a macromolecule all of the necklaces here in this hall should be connected together in a single long chain.

One can readily appreciate that the development of a theory for these molecules presented considerable difficulties. The forms of the chain itself, whether extended or coiled, represents a property difficult to rationalize.

A statistical description is of necessity required, and Professor Flory has made major contributions to the development of such a theory. The problem is more difficult, however. How can one compare different molecules in different solvents?

When chain molecules are dissolved in different solvents they become coiled to different degrees, depending on the interaction between repulsive and attractive forces in the solution. In a good solvent the chain molecules are extended. In a poor solvent, in contrast, the chain molecules assume a highly coiled form.

Professor Flory showed that if one takes a solution of extended chain molecules in a good solvent, and slowly cools the solution, then the molecules become progressively more coiled until they are no longer soluble.

Thus, there must be an intermediate temperature where the attractive and repulsive forces are balanced. At this temperature the molecules assume a kind of standard condition that can be used, generally, to characterize their properties.

This temperature Professor Flory named the theta temperature. A corresponding temperature exists for real gases at which they follow the ideal gas law. This temperature is called the Boyle temperature after Robert Boyle who discovered the gas laws. By analogy, the theta temperature for macromolecules is often referred to as the Flory temperature.

Profssor Flory showed also that it was possible to define a constant for chain molecules, now called Flory's universal constant, which can be compared in significance to the gas constant.

When one, in retrospect, reads about an important scientific discovery, one often feels that the work was remarkably simple. This actually indicates, however, that it was brilliant insight in a new and until then unexplored research area. This is highly characteristic of Professor Flory's scientific discoveries, not only those concerned with the Flory temperature and Flory's universal constant but also many of his other important research studies. Further examples are found in his investigation of the relationship between the reaction mechanism and the length of the chains formed when chain molecules are prepared synthetically, as well as his important contribution to the theory of crystallization and rubber elasticity. These achievements have been of major importance for technological developments in the plastics industry.

In recent years Professor Flory has investigated, both theoretically and experimentally, the relation between rotational characteristics of the chain links and the form of the chain molecules. This is of fundamental significance for the understanding of both biological macromolecules and synthetic chain molecules.

During the time Professor Flory has been active as a scientist, macromolecular chemistry has been transformed from primitive semi-empirical observations into a highly developed science. This evolution has come about through major contributions by research groups from both universities and many of the world's largest industrial laboratories. Professor Flory has remained a leading researcher in the area during this entire period, giving further evidence of his unique position as a scientist.

Professor Flory,

I have tried to describe briefly the fundamental importance of your many contributions to macromolecular chemistry and in particular those concepts introduced by you and now referred to as the Flory-temperature and the Flory universal constant.

On behalf of the Royal Academy of Sciences I wish to convey to you our warmest congratulations and I now ask you to receive your prize from the hands of His Majesty the King.


Gene Genie #27

 
The 27th edition of Gene Genie has been posted at DNA Direct Talk [The Gene Genie: Yes, But What About Me?].
Welcome to another edition of Gene Genie, the blog carnival about genes, genomics and gene-related diseases. With Craig Venter and 23andMe and decodeME all over the news, I thought this edition might be appropriately focused on genes and “me.” What does the gene genie have to say about us?
The beautiful logo was created by Ricardo at My Biotech Life.

The purpose of this carnival is to highlight the genetics of one particular species, Homo sapiens.


Dawn of Man

 
In his tribute to Arthur C. Clarke, John Dennehy mentions the opening scene from 2001: A Space Odyssey [Goodbye Arthur C. Clarke]. That was a scene that made a big impression on me as well, although I was a good deal older than John when I first saw it. Here it is.




Arthur C. Clarke (1917 - 2008)

 

Science can destroy religion by ignoring it as well as by disproving its tenets. No one ever demonstrated, so far as I am aware, the non-existence of Zeus or Thor - but they have few followers now.

                                                      Arthur C. Clarke

It may be that our role on this planet is not to worship God-but to create him.

                                                      Arthur C. Clarke

I don't believe in God but I'm very interested in her.

                                                      Arthur C. Clarke

The greatest tragedy in mankind's entire history may be the hijacking of morality by religion.

                                                      Arthur C. Clarke

Information is not knowledge1, knowledge is not wisdom, and wisdom is not foresight. Each grows out of the other, and we need them all.

                                                      Arthur C. Clarke


1. This simple statement of fact is much more important in today's world than most people realize. Information should not be confused with knowledge.

[Photo Credit: ABCNews - Arthur C Clarke turns 90]

Billboard Censorship

 
According to the Grand Rapids Press, the Freedom From Religion Foundation is having trouble renting billboard space to advertise its message "Beware of Dogma" [Atheists claim censorship by billboard company].
The group that asked Hudsonville to remove God from the city's mission statement says it is having a hard time placing a billboard espousing its position.

"This is new, that a billboard company is censoring us," said Annie Laurie Gaylor, co-president of the Freedom From Religion Foundation. The Madison, Wis.-based group, dedicated to the separation of church and state, bills itself as North America's largest group of atheists and agnostics with 12,000 supporters.

The billboard with the words "Beware of Dogma" and the group's Web address has been used around the country, she said.

Gaylor said CBS Outdoor Advertising in Grand Rapids declined to rent a billboard to Freeedom From Religion, telling her it had been through controversy in the past and community reaction would force the billboard down within a day. She is working with other area firms, she said, but their locations are not her first choice.
We discussed this issue before when I declared that this was a "freedom of speech" issue [What Freedom of Speech Really Means]. Many readers disagreed , stating that a private company had the right to discriminate on the basis of religious beliefs (or lack of them).

This time there's a very interesting discussion going on at RichardDawkins.net [ Atheists claim censorship by billboard company]. Read the comments on that site.

This is clearly a gray area but, personally, I'd like to live in a society where a private billboard company wasn't afraid to rent space to all kinds of groups—including those groups whose opinions aren't shared by the management of the company. I'd like to live in a society where everyone understood that this was ethical behavior on the part of the billboard company and they didn't hold the company responsible for the message on the billboard. Even better would be to live in a society where the average person celebrated diversity of opinion and looked forward to seeing and hearing about contrary views. They would also look forward to debating and discussing those views.1


1. In case anyone is wondering whether this can be construed as support for teaching the controversy, the answer is yes. I think Christian private schools should be teaching about evolution and the scientific views on the age of the Earth. I think public school students should be discussing the conflict between evolution and creationism (and science vs. religion).

[Photo Credit: More Billboards in Chambersburg PA]

Tuesday, March 18, 2008

Are You as Smart as a Third Year University Student? Q7

 
Question 1
Question 2
Question 3
Question 4
Question 5
Question 6
Choose the INCORRECT statement about protein folding.

a) protein folding is a cooperative phenomenon
b) the energy of the final folded protein is at the bottom of a free energy well
c) most proteins fold extremely rapidly
d) folding is an enthalpy-driven reaction (ΔH)
e) protein folding can be assisted by molecular chaperones


Are You as Smart as a Third Year University Student? Q6

 
Question 1
Question 2
Question 3
Question 4
Question 5
Here are the names and structures of the aldohexoses. The common ones in biology are shown in blue.


Identify the monosaccharide shown below in three different views.



               a) D-allose
               b) D-altrose
               c) D-galactose
               d) D-glucose
               e) D-mannose


THEME: Protein Structure

 
Jan. 28, 2007
Free Love, the '60's, and Protein Synthesis

Feb. 8, 2007
How Proteins Fold

Feb, 11, 2007
Heat Shock and Molecular Chaperones

Feb. 13, 2007
Disulfide Bridges Stabilize Folded Proteins

THEME:

More posts on
Protein Structure
Feb. 14, 2007
The Anfinsen Experiment in Protein Folding

Feb. 15, 2007
Gene HSPA5 Encodes BiP-a Molecular Chaperone

Feb. 20, 2007
Glycoproteins

Feb. 27, 2007
Collagen

March 12, 2007
How Cells Make Tryptophan, Phenyalanine, and Tyrosine

June 5, 2007
Protein Turnover

July 10, 2007
Fixing Carbon: the Structure of Rubisco

Aug. 1, 2007
Hemoglobin

Aug. 1, 2007
Myoglobin

Aug. 1, 2007
Heme Groups


Oct.13, 2007
HSP90 Structure

March 2, 2008
The α Helix

March 10, 2008
β Strands and β Sheets

March 13, 2008
Loops and Turns

March 13, 2008
Levels of Protein Structure

March 13, 2008
Examples of Protein Structure

March 14, 2008
Evolution and Variation in Folded Proteins


April 3, 2008
The Peptide Bond

April 3, 2008
Ramachandran Plots

April 4, 2008
Levinthal's Paradox

April 6, 2008
One Protein - Two Folds


Monday, March 17, 2008

A Challenge to Jonathan Wells

 
On February 29th Jonathan Wells published a short review of a scientific paper by Maurice et al. (2008). You can read the original Wells posting at: The Irrelevance of Darwinian Evolution to Antibiotic Resistance.

Wells was trying to make a point. Concerning the work from Dardel's lab (Maurice et al, 2008), Wells claimed ...
Yet Darwinian evolution had nothing to do with it.

First, some bacteria happen to have a very complex enzyme (acetyltransferase), the origin of which Darwinism hasn’t really explained. Come to think of it, most cases of antibiotic resistance (including resistance to penicillin) involve complex enzymes, and the only “explanations” for them put forward by Darwinists are untestable just-so stories about imaginary mutations over unimaginable time scales.

Second, the acetyltransferase story is about minor changes in an existing species of bacteria. But Darwin’s theory isn’t really about how existing species change over time. People had been observing those long before 1859, and most of the new insights we’ve gained since then have come from genetics, not Darwinism. Yet Mendel’s theory of genetics contradicted Darwin’s, and Darwinists rejected Mendelian genetics for half a century. And although an understanding of genetics is important when dealing with antibiotic resistance, Darwin’s theory of the origin of species by natural selection is not.

Third, Dardel and his colleagues made their discovery using protein crystallography. They were not guided by Darwinian evolutionary theory; in fact, they had no need of that hypothesis.
We all know how creationists use the word "Darwinism." Most of the time, it's a synonym for evolution. All of the time, it's an attempt to obfuscate and confuse their audience. What Wells is saying is that evolution had nothing to do with the paper. All that happened was a bit of genetics. According to Wells, "Darwin's theory of the origin of species by natural selection" was not involved.

The senior author of the paper posted a comment on Pharyngula saying, "Actually, we did indeed use darwinian evolution within this work (something unusual in structural biology)." [see Why the Right People Hate IDiots, and links within that posting].

Michael Egnor gallops to the defense of his hero. Today he posted a rebuttal to my criticism of him and Wells [Dr. Larry Moran, Darwinism, and Vicious Personal Invective]. Here's what Egnor says,
Dr. Wells pointed out that research on antibiotic resistance wasn’t guided by Darwinian evolutionary theory. That evolution occurred — that is, that the population of bacteria changed over time — is obviously true, and obviously was relevant to the antibiotic resistance research. Dr. Wells made the observation that the research owed little to Darwin’s theory that all biological complexity arose by natural selection without teleology.
This is an incredible admission from a creationist. Egnor admits that the bacteria evolved. He then goes on to define some bizarre version of "Darwin's theory."1 But the cat is out of the bag. What we see here folks, is the recognition that there is a distinction between Darwinism and evolution by natural selection. We're still not clear about the difference but it seems that bacteria can evolve resistance to antibiotics.

Egnor admits that the paper used evolution but it just wasn't Darwinism.

Now let's see if Jonathan Wells agrees. I'll apologize to Wells if he will post a comment here, or on Evolution News & Views, agreeing to the following ..
I, Jonathan Wells, agree that Maurice et al. (2006) employed evolution by natural selection in their methodology. My position is that evolution by natural selection is not what I mean when I use the word Darwinian.
Note that I'm not asking him to agree that "Darwinism" was involved in the paper. All he has to do is admit that evolution by natural selection is not what he means when he uses the word "Darwinian."

Michael Egnor has indicated that this is what Wells actually means. Now let's see if Wells himself will admit it.


1. The standard version of Darwin's Theory of Evolution by Natural Selection is that populations evolve due to the differential survival of individuals with a fitter genotype.

Maurice, F., Broutin, I., Podglajen, I., Benas, P., Collatz, E. and Dardel, F. (2008) Enzyme structural plasticity and the emergence of broad-spectrum antibiotic resistance. EMBO Rep. 2008 Feb 22 [Epub ahead of print] [PubMed]

What Is Consciousness?

 
There are two broad traditional and competing metaphysical views concerning the nature of the mind and conscious mental states: dualism and materialism. While there are many versions of each, the former generally holds that the conscious mind or a conscious mental state is non-physical in some sense. On the other hand, materialists hold that the mind is the brain, or, more accurately, that conscious mental activity is identical with neural activity.

Consciousness
There were lots of interesting things going on at SciBarCamp over the weekend but I want to pick out one topic that came up several times.

At one point there was a group of us talking about a number of different things when the topic of consciousness arose. One member of the group happened to mention that humans were special because they are "conscious."

Now, I happen believe that there's no such thing as "consciousness" in the sense of something tangible that we can point to and say. "That's consciousness." I think it's merely a descriptive term for brain activity. It's an epiphenomenon. Consciousness may be an important and useful word for describing the phenomenon but that's all it is. I don't know whether an octopus is conscious, or a dolphin, or a dog, or a chimpanzee. The reason I don't know this is because nobody can tell me what consciousness is.

Nobody in the group seemed to share my view. They all seemed to think that consciousness was something tangible and real—something that set humans off from the rest of life. Lee Smolin, a physicist at the Perimeter Institute, was particularly vocal about this. He expressed a great deal of surprise at the fact that anyone could question the existence of consciousness. In fact, Smolin insisted that the onus was on me to prove that consciousness doesn't exist.

I tried out some of my standard approaches on the group. For example, I asked them whether the character Data on Star Trek (TNG) was conscious. (The question applies equally well to any sophisticated robot.) Several people said yes. To me, this means that they define consciousness as simply complex electronic activity. If a robot/android can possess consciousness then how, exactly, do you define consciousness as anything else?

Other weren't sure whether Data was conscious or not. Unfortunately, they weren't able to explain why Data was not conscious and the other members of the Star Trek crew were conscious. At that point the group broke up because sessions were starting. My suspicion is that some people at the meeting were true dualists and they had never thought seriously about any other possibility.

The question is complex. Even a cursory review of the Wikipedia entry will be enough to confuse almost everyone [Consciousness]. What surprised me the most about the group I was talking to is that they seemed to take for granted that there was such a thing as a meaningful definition of consciousness that could be used to separate humans from all other animals. Some of them seemed to be genuinely puzzled by the fact that they couldn't define consciousness. It was as though they had never thought about the problem before.

The question came up again in the afternoon when I attended a discussion led by Robert Sawyer. Sawyer is a science fiction author, and a very good one at that. One of his books Calculating God is an excellent story about discovering God. I highly recommend it. His latest book is Rollback and I will be buying a copy as soon as I get to a bookstore.

I've met Robert Sawyer before. He's been to Skeptics meetings and to the Centre for Inquiry. He's a smart guy, and he knows it. I like people like that.

Sawyer is currently working on a series of books where the World Wide Web acquires consciousness. He organized a session to talk about his books under the title "World Wide Web Gaining Consciousness." As he explained it, this was supposed to be a brainstorming session to help him with his book. It was also pretty good publicity.

Sawyer began by explaining that consciousness evolved in humans about 40,000 years ago. We know this, according to Sawyer, because that's when we see the first signs of human adornment. Apparently, the ability to be self-aware is the hallmark of consciousness. In his book, the World Wide Web becomes self-aware and conscious.

There was a lot of discussion about what it meant for the WWW to be conscious. There were some questions about how the characters in the book knew that the WWW had become conscious. This was quite interesting. Most of the people in the room seemed to be having some difficulty understanding what it meant for Web to be conscious.

At one point I asked whether consciousness was ever defined and whether the characters in the book discussed the idea that there might not be any such thing as consciousness. Sawyer responded that, of course, everyone thinks about such things and so will his characters. I mentioned that some people don't seem to know about the difficulty in defining consciousness and don't seem to have thought about the fact that it may not actually exist.

I called for everyone to raise their hands if they had thought about the idea that consciousness may not exist. Everyone raised their hands. This is when Sawyer said that it's not a good idea to think you are the smartest person in the room, Larry.

It was embarrassing. The result of the survey indicated that everyone in the room had pondered the consciousness problem and all but one (me) had reached the same conclusion after careful thought. Consciousness, which none of them could define, exists and furthermore, it evolved uniquely in humans in the recent past.1 Whatever it is, the same kind of consciousness was also able to arise spontaneously in a network of fiber optic cables.

I admit I was wrong. The evidence is clear. All smart people have thought about these things. Most of them have made a "conscious" decision to be dualists and reject the notion of consciousness as a mere epiphenonenon. The lunch group seems to have been an exception.

Later on the the same session, another science fiction writer named Peter Watts mentioned that consciousness arose by natural selection. I pointed out that there was another possibility; namely that it could evolve by accident. This would be similar to how it evolved in the World Wide Web. (Sawyer did not indicate that natural selection was involved there.) Peter assured me in no uncertain terms that he knew as much about evolution as I did.

Science fiction writers sure know a lot of things.

In case you want the see another version of this story go to Robert Sawyer's blog and read what he has to say about this discussion [SciBarCamp].


1. I wonder how this actually worked. Since consciousness evolved it must have a genetic component. Otherwise it's not evolution. Presumably a mutation causing consciousness arose some 40,000 years ago. It rapidly spread though the population in a short period of time. It must have been interesting times. In some families you would have had a mixture of children; some were conscious and some were not. How did they tell which was which?

Happy St. Patricks Day!!!

 

Today's the day when the Irish—and people who want to be Irish—celebrate by doing typically Irish things; like drinking green beer, dancing Irish jigs, and going to mass. (?)1

My ancestors on my mother's side are (mostly) Irish. My grandfather was a Doherty (O'Doherty). That's the name at the top of the map in country Donegal. That side of the family came to Canada in 1802 and the Irish blood has been diluted—most notably by American refugees from the Revolutionary War (United Empire Loyalists) (gasp!).

The O'Doherty's are descended from Niall Noigíallach who kidnapped St. Patrick.

My grandmother was a Foster from Fermanagh. That's by the two lakes (Lower Lough Erne and Upper Lough Erne) in the upper central part of the country near the seat of the Maguires. Her family came to Canada in 1865 but both of her parents were Irish so at least 1/4 of my genes are undiluted Irish. I'll drink to that.

We don't talk about the nasty little fact that the Foster's were probably English invaders from the 1600's. As they say, somebody had to civilize the Irish and it might as well have been the English!

One of the reasons why the topic was avoided by my grandparents was because the O'Doherty clan was almost wiped out by the English during the O'Doherty rebellion in 1608 led by Sir Cahir O’Doherty. Some of the survivors had to flee to Skye to avoid being hung. I descend from those refugees.




1. This entire post is a copy of my first St. Patrick's Day post in 2007.

Monday's Molecule #65

 
Some of the most important contributions to the biological sciences aren't associated with a particular molecule. This is one of those cases.

The figure on the right is taken from the Nobel Lecture of the Laureate who will be featured on Wednesday. It illustrates the problem that was being addressed. The real contribution of this Nobel Laureate is more easily illustrated by using a mathematical equation. The equation is shown below.

Your task is to identify the general field that's being discussed and to describe the significance of the equation. You must explain all the variables in the equation and why it was important enough to contribute to the award of a Novel Prize. Naturally, you also have to name the Nobel Laureate.

The first person to correctly describe the equation and name the Nobel Laureate wins a free lunch at the Faculty Club. Previous winners are ineligible for one month from the time they first collected the prize. There is only one ineligible candidate for this week's reward.

THEME:

Nobel Laureates
Send your guess to Sandwalk (sandwalk (at) bioinfo.med.utoronto.ca) and I'll pick the first email message that correctly identifies the equation and the Nobel Laureate(s). Note that I'm not going to repeat Nobel Laureates so you might want to check the list of previous Sandwalk postings.

Correct responses will be posted tomorrow along with the time that the message was received on my server. I may select multiple winners if several people get it right.

Comments will be blocked for 24 hours. Comments are now open.

UPDATE: We have a winner! Haruhiko Ishii of the Dept. of Physics at UCSD got the right answer. I've issued an invitation to meet for lunch.

The figure shows the transition from a random coiled polymer to one that has more structure. The process was studied by Paul Flory who won the Nobel Prize in 1974 for his work on the physical chemistry of macromolecules. One of his important contributions was the concept of intrinsic viscosity [η]. This is a measure of viscosity that takes into account the contribution of a solute. The intrinsic viscosity depends on the viscosity of the solvent in the absence of solute and the change that takes place when the solute occupies a certain volume of the solution.

The equation for solving intrinsic viscosity can be written several ways. In the example shown above, K and α represent constants that depend on the type of solute. M is the molecular weight of the polymer.


IDiots Get Public Funding for their Schools in Alberta

 
Scott Rowed is one of the Alberta representatives for the Centre for Inquiry. He has an op-ed piece in Saturday's Edmonton Journal where he points out the dangers of giving public money to faith-based schools. These schools are permitted by law to discriminate on the basis of religious belief. That's not new. Here in Ontario we have a Roman Catholic school system that is fully funded by taxpayer money.

The shocking thing is the extent to which some faith-based schools will go to exclude rational thought and genuine education. For example, Scott says,
To have this choice of placing their children into a faith school, parents must obtain a letter from a preacher praising their church devotion and sign a statement of faith. This quote, from the constitution and bylaws of Fort McMurray Christian School Society, is typical: "We believe the Genesis account of creation is to be understood literally; that man was created in God's own image and after His own likeness; that man's creation was not by evolution or change of species or development through interminable periods of time from lower to higher form."

Parents who believe that the first cowboy saddled up a triceratops have more choice as their children can attend either a faith school or a public school. On the other hand, Christians who accept evolution, non-believers, and followers of other faiths can enrol their children only in a public school.
I agree with Scott. This is outrageous. Any school system that explicitly denies one of the fundamental facts of science should not receive a single penny of taxpayer's money.1

There's only one rational solution to the problem. The government must fund a single secular school system. That means eliminating funding for the Catholic schools as well as the IDiot schools. If you live in Ontario, join the One School System Network and work toward achieving this goal.


1. I wonder if Ben Stein will make a movie about this kind of discrimination? It's obvious that any teacher who believes in evolution will never get a job in one of these schools and any student who starts to believe in evolution will be EXPELLED.

[Photo Credit: Rahime at Prayer for Rain]

Friday, March 14, 2008

A Visit to Guelph

 
Next Wednesday I'll be visiting Guelph University (Ontario, Canada) to give a lecture on "Evolution as a Fact and a Theory." The hosts are Guelph Skeptics [Lecture].

Maybe I'll see some of you there?


Evolution and Variation in Folded Proteins

As a general rule, the primary structure of a protein (amino acid sequence) ultimately determines it's final three-dimensional shape1. Proteins fold spontaneously to adopt a specific structure that minimizes free energy. The folded protein occupies the bottom of a free energy well [How Proteins Fold, The Anfinsen Experiment in Protein Folding, Disulfide Bridges Stabilize Folded Proteins, Heat Shock and Molecular Chaperones].

Each protein has a characteristic shape associated with its function. When we discuss the evolution of proteins, we like to divide the residues into three categories as shown below for the structure of myoglobin from sperm whale (Physeter catodon) [PDB 1A6M].

Myoglobin is a small protein with a bound heme group (shown as a space-filling molecule). It carries oxygen in the bloodstream and tissues. The oxygen molecule binds to the active site of the protein near one side of the heme group. There are specific amino acid residues at the active site that are absolutely required for binding oxygen. As you might expect, these amino acids are highly conserved—they will be found at that position in myoglobin from humans or any other species.

The second category of amino acid residues makes up the hydrophobic interior of the protein. Myoglobin is an all-α-helical protein and several of the helices group together to form a helix bundle. The interior of that bundle consists largely of hydrophobic amino acid residues. This is what stabilizes the three-dimensional structure and causes the polypeptide chain to spontaneously fold after it is synthesized.

The third category of residues is the surface residues. These are usually hydrophilic residues that interact with the surrounding water. The surface residues don't make as much of a contribution to the overall three-dimensional structure so their exact composition can be quite variable.

The class of proteins to which myoglobin belongs is called "globins." There are two other globins that you are probably familiar with: α-globin and β-globin are the two polypeptides that come together to form an α2β2 hemoglobin tetramer.

The three proteins (myoglobin, α-globin, and β-globin) descended by gene duplication from a common ancestral globin several hundred million years ago. Today their amino acid sequences are quite different due to the accumulation of random mutations and fixation by random genetic drift. In spite of the differences in primary structure, the three-dimensional structures of the three proteins are very similar. This can easily be shown by superimposing the three structures as shown in the figure (myoglobin=green, α-globin=blue, β-globin=purple).

Most people don't appreciate the amount of variation that underlies this conserved three-dimensional structure. It's worth taking a look at a bunch of aligned globin sequences from different species to see exactly which amino acids are highly conserved and which positions can tolerate almost any amino acid.

Let's go to the Pfam (protein family) database at the Sanger Institute in Cambridge (UK). The entry for the globin family is Globin PF00041. Click on "Alignments" in the left sidebar. This link takes you to the alignment page where you can create an alignment of all the known globin sequences. Choose 75 seeds (default) in the first table and select "Pfam viewer" from the pull-down menu under "Viewer." Click "View" to see the alignments.

Highly conserved amino acid residues are highlighted by vertical shading in the Pfam view. The first thing you should notice is that there are very few amino acids that are invariant. The conserved residue on the left (blue) is tryptophan (W). It's present in most of the globins from different species but not all. Look at the other positions and note that in most cases a variety of different amino acid residues can be substituted. Sometimes only hydrophobic residues (blue) can be found at a particular site and sometimes there are other restricted choices. Lots of insertions and deletions (dots) can be tolerated without major disruption to the overall three-dimensional structure.

Data like this reveals that the amino acid residues in the active site are usually conserved. Residues in the hydrophobic core are moderately conserved. And residues on the surface are hardly conserved at all.

The point is that there are literally billions of different proteins that have the same shape as globins and still function as carriers of oxygen. This is an important point. Opponents of evolution often take a single globin from a single species and calculate the probability that such a structure will form. They assume that only one out of twenty amino acids can be found at each position and the resulting probability (e.g., 20020) is enormous. Thus, they conclude, such a protein could never form by chance. They don't seem to appreciate the fact that we already know of billions of different proteins that can function as globins.

There are many other examples of this observation. The four structures below show the conformation of the cytochrome c polypeptide chain from tuna, rice, yeast, and a bacterium. The amino acid sequences have diverged considerably from their common ancestor of 3 billion years ago but the structures are very similar.

We conclude that the amino acid sequence of a polypeptide determines how it will fold in three-dimensional space but there are billions of different amino acid sequences that will adopt the same structure.

Finally, let's look at a more complicated example. The enzymes lactate dehydrogenase (below left) and malate dehydrogenase (below right) share a common ancestor even though they are different enzymes. This is a case where substitutions of amino acid residues in the active site gave rise to a new activity. Today the amino acid sequence similarity is barely above the threshold for defining homology but the structures are still very similar.




1. Other factors that contribute are bound ligands, such as heme groups, and interactions with other proteins as in multimeric proteins with sifferent subunits.