Quetzal

Okay - I need some help. I've got a smart creationist (yeah, I know that sounds like an oxymoron, but it really isn't in this case) on the line <a href="http://www.evcforum.net/ubb/Forum17/HTML/000003.html" target="_blank">here</a>.

He begins with the usual creationist arguments on information (conflating Shannon entropy with something akin to Kolomgorov-Chaitan AIT). I have used my usual argument that "information" has no intrinsic reality in genetics - that it is merely a useful analogy - and hence can neither prevent anything or create anything. He is pretty well-read in the actual sciences, and is using quotes from Nature and Dawkins on how biologists use information concepts in their work. Unfortunately, information IS a very useful concept - but one that creationists stretch to the breaking point.

I need some compelling argument(s) to counter the assertion of the existence of a physical correlation between the chemistry of DNA replication and the analytical property "information".

Thanks.

tronvillain

Do you really want to try and counter that assertion? Have a look at this <a href="http://www.findarticles.com/cf_0/m2843/2_25/71563254/p1/article.jhtml" target="_blank">Skeptical Inquirer</a> article.

tronvillain

Or perhaps you mean the assertion DNA encodes information about an organism. Again, I don't see why you would want to counter it - "information" is just as useful a description in the case of genome as it is in the case of a dictionary. Of course, it presents absolutely no obstacle to evolution.

Peter Soderqvist

Richard Dawkins, The Information Challenge

information
The technical definition of "information" was introduced by the American engineer Claude Shannon in 1948. An employee of the Bell Telephone Company, Shannon was concerned to measure information as an economic commodity. It is costly to send messages along a telephone line. Much of what passes in a message is not information: it is redundant. You could save money by recoding the message to remove the redundancy. Redundancy was a second technical term introduced by Shannon, as the inverse of information. Both definitions were mathematical, but we can convey Shannon's intuitive meaning in words.

Redundancy is any part of a message that is not informative, either because the recipient already knows it (is not surprised by it) or because it duplicates other parts of the message. In the sentence "Rover is a poodle dog", the word "dog" is redundant because "poodle" already tells us that Rover is a dog. An economical telegram would omit it, thereby increasing the informative proportion of the message. "Arr JFK Fri pm pls mt BA Cncrd flt" carries the same information as the much longer, but more redundant, "I'll be arriving at John F Kennedy airport on Friday evening; please meet the British Airways Concorde flight". Obviously the brief, telegraphic message is cheaper to send (although the recipient may have to work harder to decipher it - redundancy has its virtues if we forget economics). Shannon wanted to find a mathematical way to capture the idea that any message could be broken into the information (which is worth paying for), the redundancy (which can, with economic advantage, be deleted from the message because, in effect, it can be reconstructed by the recipient) and the noise (which is just random rubbish).

"It rained in Oxford every day this week" carries relatively little information, because the receiver is not surprised by it. On the other hand, "It rained in the Sahara desert every day this week" would be a message with high information content, well worth paying extra to send. Shannon wanted to capture this sense of information content as "surprise value". It is related to the other sense - "that which is not duplicated in other parts of the message" - because repetitions lose their power to surprise. Note that Shannon's definition of the quantity of information is independent of whether it is true. The measure he came up with was ingenious and intuitively satisfying. Let's estimate, he suggested, the receiver's ignorance or uncertainty before receiving the message, and then compare it with the receiver's remaining ignorance after receiving the message. The quantity of ignorance-reduction is the information content. Shannon's unit of information is the bit, short for "binary digit". One bit is defined as the amount of information needed to halve the receiver's prior uncertainty, however great that prior uncertainty was (mathematical readers will notice that the bit is, therefore, a logarithmic measure).

In practice, you first have to find a way of measuring the prior uncertainty - that which is reduced by the information when it comes. For particular kinds of simple message, this is easily done in terms of probabilities. An expectant father watches the Caesarian birth of his child through a window into the operating theatre. He can't see any details, so a nurse has agreed to hold up a pink card if it is a girl, blue for a boy. How much information is conveyed when, say, the nurse flourishes the pink card to the delighted father? The answer is one bit - the prior uncertainty is halved. The father knows that a baby of some kind has been born, so his uncertainty amounts to just two possibilities - boy and girl - and they are (for purposes of this discussion) equal. The pink card halves the father's prior uncertainty from two possibilities to one (girl). If there'd been no pink card but a doctor had walked out of the operating theatre, shook the father's hand and said "Congratulations old chap, I'm delighted to be the first to tell you that you have a daughter", the information conveyed by the 17 word message would still be only one bit.

Information and evolution
That's enough background on information theory. It is a theory which has long held a fascination for me, and I have used it in several of my research papers over the years. Let's now think how we might use it to ask whether the information content of genomes increases in evolution. First, recall the three way distinction between total information capacity, the capacity that is actually used, and the true information content when stored in the most economical way possible. The total information capacity of the human genome is measured in gigabits. That of the common gut bacterium Escherichia coli is measured in megabits. We, like all other animals, are descended from an ancestor which, were it available for our study today, we'd classify as a bacterium. So perhaps, during the billions of years of evolution since that ancestor lived, the information capacity of our genome has gone up about three orders of magnitude (powers of ten) - about a thousandfold.

This is satisfyingly plausible and comforting to human dignity. Should human dignity feel wounded, then, by the fact that the crested newt, Triturus cristatus, has a genome capacity estimated at 40 gigabits, an order of magnitude larger than the human genome? No, because, in any case, most of the capacity of the genome of any animal is not used to store useful information. There are many nonfunctional pseudogenes (see below) and lots of repetitive nonsense, useful for forensic detectives but not translated into protein in the living cells. The crested newt has a bigger "hard disc" than we have, but since the great bulk of both our hard discs is unused, we needn't feel insulted. Related species of newt have much smaller genomes. Why the Creator should have played fast and loose with the genome sizes of newts in such a capricious way is a problem that creationists might like to ponder. From an evolutionary point of view the explanation is simple (see The Selfish Gene pp 44-45 and p 275 in the Second Edition).

THE WHOLE INTERVIEW CAN BE FOUND HERE!
<a href="http://www.skeptics.com.au/journal/dawkins1.htm" target="_blank">http://www.skeptics.com.au/journal/dawkins1.htm</a>

Peter Soderqvist

Tom Schneider's Theory of Molecular Machines page: leads to pages on his and other sites about the application of Claude Shannon's information theory to the biological sciences.
<a href="http://www-lmmb.ncifcrf.gov/~toms/" target="_blank">http://www-lmmb.ncifcrf.gov/~toms/</a>

Soderqvist1: Quote from Tom Schneider's home side!

Soderqvist1 I have read the Blind Watchmaker, and I must say that; I like Dawkins 's digital information technological approach! Claude Shannon is the founder of informational entropy, and it is strange that, the creationists have alleged that evolution is impossible because it violates informational entropy, and they appear quite ignorant about the fact that, Shannon's information technology is used by evolutionary biologists. I will thus say that; the anti-evolutionary ideas stem from poor or no biological education!

It is fascinating to see how far the creationists like flat-earther, young-earther, old-earther are willing to differently adjust their bible readings to fit in with what they already believes. How can a simple evolutionist like me, have any real chance to be heard, in the jungle of belief? Reality is that which, when you stop believing in it, doesn't go away, conversely, we don't need to believe anything, because the reality is still there to be observed, all we need is parsimony inferences from our observations!

[ April 25, 2002: Message edited by: Peter Soderqvist ]</p>

Peter Soderqvist

TO MORPHO

I don't think abstractions versus physical materials are in dispute there, he has referred to Dawkins work, the topic is information and biology, thus ask instead your opponent Chase Nelson if he is aware about the fact, that Claude Shannon was a Darwinian? And if there is any contradiction between his information technology, (as used by Dawkins), and biological evolution?

Quetzal

Thanks all. Tron: Great SI article. Thanks. I fully concur that using information concepts is a very useful tool in genetics. It's the insistence by many creationists that somehow an ill-defined concept of "information" is an inherent property of an organism, rather that a descriptive or analytical property. This allows them to complain that somehow adding "information" to a biological system is impossible (a misuse of Shannon Communications Theory).

Peter: Excellent suggestions, and I appreciate the full Dawkin's quote. My biggest complaint with "information" is in the way creationists misuse the analogy. I am fully aware of how useful an analogy it is for biology, and especially genetics.

I think I need to get him to define his terminology. Before I attack him on misusing Shannon, I need to see if that's exactly what he is using.

Thanks again. I'll keep you posted.

Oolon Colluphid

Hi Morpho

I think he is fair to use ‘information’. I’m not sure he understands it, but he’s right that the term is used in these circumstances. I don’t know the history of your discussions with ChaseNelson, but bear in mind that the reason creationists bring up the idea of information is to argue that it cannot increase through evolution. They usually conflate this with ‘mutations are always harmful’, and it looks like that’s where he’s leading here:

Destroy genetic coding? Sometimes. How about simply ‘change’? That is what it always is, just change. It can only be described as ‘destroying’ when the change is in the coding for something and nothing else is coded for instead. That may be the majority of them, but not all. For ex, with point mutations, TTT codes for phenylalanine, but so does changing it to TTC. Change the middle T, and you’ll get TCT which codes instead for serine. Only when the final protein is assembled and coiled etc will you know whether the protein still works, works as well, or works better.

A different protein might change the body it’s in, but whether the change is positive, negative or neutral depends on the environment -- including other genes -- it finds itself in. Tell him about the nylon-digesting bacteria (which was also reproduced in the lab, incidentally).

Basically, I think you got sidetracked by information coding and missed this more obvious line of attack

But going back to mutations and increasing ‘information’, as Dawkins points out in the article Peter linked, it’s natural selection, not mutation, that increases the information content:

And don’t miss out kicking him on this:

Sure, we see constant extinction -- of individuals. We also see that the ones left alive are, de facto, the ones most adapted to the environment at that moment. Repeat. And repeat. That’s evolution. And it is observed. Tell him to take it up with Joshua Lederberg or Peter Grant in he disagrees!

He’s taking evolution to mean macroevolution, change at or above the species level. Sure, extinctions are part of this. Ask him about the definition of species, then ask him whether the apple maggot fly Rhagolettis pomonella is actually one species or two. Don’t forget the talkorigins observed speciation FAQ too.

Keep up the good work! Just wish I could get there to have a go at him meself

Cheers, Oolon

Oh, and PS: Just to pick a nit with both of you, you said that adenine always pairs with thymine, and cytosine always with guanine, and he didn't disagree. But I'm pretty sure that one sort of mutation is where, despite the fact that they should always go like that, sometimes the wrong base links up anyway. Actually, isn't that what a point mutation is?

Peter Soderqvist

TO OOLON COLLUPHID

Soderqvist1: Yes, mutations increase informational entropy in the gene pool, and natural selection decrease informational entropy in it!

TO MORPHO
I think your opponent Chase Nelson understanding is only at surface or as you have noticed that his terminology needs to be investigated, and thus, I don't think he can give you any structural explanation in the issue!

Quetzal

Thanks again everyone. I have to go work for a few hours (I hate it when reality intrudes, don't you?), but I'll try and have something substantive tomorrow AM.

Before I go - Oolon: counterquibble: "despite the fact that they should always go like that, sometimes the wrong base links up anyway". Unless, of course, it's RNA, in which case adenine binds with uracil...