19 September 2005

DNA and RNA (and Birdnow).

PZ Myers has, over at Pharyngula, taken issue with a remarkably ignorant essay written by Timothy Birdnow. Birdnow has responded with a new blog, PZ has responded to part of the response, and so the fun begins. At the risk of being seen as just piling on to an easy target, there are a couple of important points that I don't think have been raised yet. The first has to do with exactly what constitutes the "building blocks of life"; the second has to do with basic competence.

Below is a quote from the exchange between Birdnow and Myers where the question of the "building blocks of life" is raised:
What, you may ask, is the connection between Einstein`s proof of atoms [his explanation of Brownian motion] and Darwinism? Darwinism argues that all life evolved from a less complex state. Following the chain of life backwards, one eventually comes to the most basic unit of life-deoxyribonucleic Acid (the DNA molecule). The DNA molecule is composed of the even simpler RNA molecule, and is the fundamental building block of life. It is the largest, most complex molecule in nature. According to Einstein`s theory, the original DNA (and RNA) Molecules should not have formed and survived since there are being constantly buffetted by energized atoms. The establishment of life required energy, and that energy meant that the nascent DNA was exposed to more energetic particles which should, logically, have prevented the formation of such a large and complex molecule. That this molecule not only formed but spread suggests different mechanism at work then those proposed by the Darwinists.

DNA is not made of RNA. They are two molecules with similar structures, but different sugar backbones and a small difference in the bases.

Oh, so now we have two completely different molecules as the building blocks of life! Life did not begin once, but twice from seperate building blocks! You know, Doctor, that DNA is fundamentally an advance on RNA. You are playing games here, and it does not disprove a thing I have said.

Both DNA and RNA are very important to life, and they are currently important for different reasons. They are also both representatives of only one of the types of molecule that are of fundamental importance to life. Both DNA and RNA are macromolecules (big molecules) made by stringing together (polymerizing) a large number of smaller molecules. DNA and RNA are both members of the class of macromolecules known as nucleic acids. Nucleic acids have three main parts: A sugar molecule, a base, and a phosphate group. DNA and RNA differ in the sugar that they use (RNA uses ribose; DNA uses a ribose that is missing an oxygen). Both use four different bases, and share three of them (adenine, guanine, and cytosine). The fourth base in RNA molecules is uracil, while the fourth base in DNA is thymine.

In addition to nucleic acids, there are also proteins, sugars, and lipids (fats). All of those are also critical to life as it now exists. Proteins are important in allowing cells to carry out chemical reactions, sugars are important for energy storage and transfer, and lipids are important in creating the barriers that separate the inside of the cell from the outside. All of these are fundamental building blocks of life as we know it.

I've stressed that these are important to current life for a reason. Just because something is critically important now does not mean that it has always been critically important. For example, the keystone at the center of an arch is totally critical to the structural stability of the arch. Remove the keystone, and the whole thing collapses. The keystone, however, is the last structural component added to an arch. Prior to the placement of the keystone, the structural stability is provided by scaffolding. After the placement of the keystone, the scaffolding is redundant, ugly, and unnecessary, and it is quickly removed.

I'm not trying to suggest that there used to be some sort of "scaffolding" that took the place of one or more of these types of macromolecule - we don't know that. I'm simply trying to point out that the current importance of nucleic acids does not necessarily imply that nucleic acids were always as important as they are now. That is one of the things that origin of life research is currently examining.

It is possible that neither DNA nor RNA was critically important to the development of life. It is possible that both were. It is possible that either (or both) were very important, but not in the same way that they are today. Right now, those aren't questions that we can answer.

What I can say, however, is that Birdnow is entirely wrong when he claims that "DNA is fundamentally an advance on RNA." DNA is better than RNA when it comes to the long-term storage of genetic information. RNA tends to degrade relatively quickly, and stability is important if genetic information is going to be reliably stored and transmitted to the next generation. RNA, however, is better than DNA at a number of other tasks. In addition to being used to take the information from DNA to the ribosomes for use in constructing proteins (messenger RNA), RNA strands also make up part of the ribosomes (ribosomal RNA). RNA is also used to collect the amino acids that are added to the protein (transfer RNA). For these tasks, a single-stranded RNA molecule works much better than double-stranded DNA.

DNA is no more of an advance over RNA than humans are an advance over the cockroach. DNA is different from RNA and does different things than RNA. Similarly, if you want a poem written or a city built, you want a human. If you want something that is likely to live through a nuclear holocaust, the cockroach is a better choice. Along the same lines, the hammer is not an advance over the wrench. Different tasks simply call for different tools - and this happens to be as true within the cell as it is at a construction site.

In addition to the misconceptions over DNA and RNA, Birdnow's uninformed diatribe also provides an illustration of a very interesting phenomenon: the tendency of people who have a minimal understanding of science to believe that they are as qualified, if not more qualified, to comment on scientific issues as professional scientists are. Let's take another look at part of Birdnow's statement:
You know, Doctor, that DNA is fundamentally an advance on RNA.
Later on in the post, he goes on to complain of part of Myers response:
This is the old ``I know more than you and I say so`` canard.
When Myers complains - entirely correctly - that Birdnow displays a massive knowledge deficit in the field of biology, Birdnow is apparently highly offended:
Boy, if that isn`t the pot calling the kettle black! The main reason I wrote this was because I became increasingly irritated with the monstrous arrogance and utter closed mindedness of Darwinists such as Dr. Myers. Perhaps, Dr., if you found this essay hard to understand you should find yourself a fifth grader to explain it to you. You don`t seem to have a command of logic.

Birdnow, who is a property manager, apparently feels that his understanding of biology is secure enough that he can tell a professional biologist what is what. Similar beliefs about the nature of science seem to be very common, as was pointed out over at Photon in the Darkness a while back. The people over at American Thinker, who posted the original Birdnow piece, seem to find this completely normal. Yet, in virtually any other area of American society, such beliefs would be considered completely ridiculous.

In fact, scientists who dare to suggest that they might be more qualified to comment on scientific matters than non-scientists run the risk of being branded as "elitists". It's not elitism, folks, it's specialization. Modern society is far, far too complex for everyone to be good at everything. Most people select career paths that are specialized fields, and they are (normally) better at their own field than they are in other fields. This means that they are (normally) better able to develop informed opinions about matters within their fields than are people who lack the strong background in that area.

I suspect that Tim Birdnow knows a hell of a lot more about property management than I do. I also suspect that when the roof is leaking at a property that he is responsible for, he calls a roofer to fix the problem, not a plumber. Yet, despite this, he thinks that he has a sufficient knowledge of biology to publicly claim that, "Any way you look at the issue, Darwinism is on the ropes."

Mr. Birdnow, if I tried to tell a plumber how to fix a sewer problem, I'd look like a fool. And rightly so. If I tried to tell you how to manage property, I'd look like a fool. And rightly so. When you try to tell me that you know more about biology than I do, you look like a fool. The truth is that, as far as anyone can tell from reading your post and response, you don't know diddly squat about biology, geology, or paleontology. Your writing is, in fact, jam packed with misconceptions, misunderstandings, and outright errors.

When I tell you that, I am not being arrogant any more than a teacher is when they point out errors in a student's test. I am presenting an evaluation of your work that I am actually qualified to make. PZ Myers is even more qualified (much more qualified) to make that evaluation. Both of us have taken numerous classes in biology, both of us have undertaken research, both of us know the field. We understand biology, and we can tell when other people don't. You don't.

Suggesting that I may be more qualified than you are to determine how well you understand biology is also not "elitism". It is specialization. The fact that I am a biologist does not make me any better or worse, in a general sense, than a butcher, a baker, a property manager, a janitor, or any other trade. It just means that I know more about biology than people who aren't biologists, and that I am, for that reason, more qualified to make statements about biology than people who aren't biologists. I don't know why so many people have a problem with that.
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