We know that there must be sudden integrated increases in information from the nature of the systems that we have discovered operate within a cell.
All life as we know it operates in membrane bound units. This means that the first membrane bound cell had to occur at a specific moment when the membrane sealed on a blob of protoplasm. For this object to be really alive it needed
(a) All the information to code for the apparatus to replicate its own information
(b) All the information to gain sufficient energy to power replication of the information and the doubling of the structural molecules is needed.
(c) All the information to produce the machinery to double all the structural materials of that first living cell.
It is impossible to have this happening without a sudden increase in integrated information.
The origin of a new protein system from scratch.
If we imagine a tree of ancestry for all proteins then there is a limit to the degree with which new protein can be thought of as deriving from other proteins. A large number of proteins must be present to make the simplest living organism but there are large numbers of families of proteins which are additional to those which would have been derived from those necessary for the origin of life.
My understanding is that it is this clustering of interdependent information which is at the heart of Behe’s argument in Darwin’s Black Box and which is the insight which is at the heart of the biological ID debate.
7 comments:
Your post is really addressing the very grey area of the emergence of life from non-life. I think most abiogenesis researchers would say that the first "replicators" were not living - they were simply molecules with the ability to replicate. Whether these molecules were RNA, PNA (peptidyl nucleic acids), TNA (threofuranosyl nucleic acids) or something else is unknown. It is likely that they didn't arise already enveloped in a membrane. We still observe catalytic nucleic acids today, so it is a fair guess to say they may have been around before the emergence of protein.
I think you're tied up on the idea that all the systems you describe had to arise at the same time. I think few abiogenesis researchers would agree with you.
Andy,
Using lots of technical names is just hocus pocus and blinding people with terminology. Its what used to really get me heated in teaching. Just because we have lots of long acronyms for something we give the impression we know all about it when in fact if we were honest we would say... we don't have a clue!
Listing TNA PNA and RNA does not escape from the main issue which I was mentioning here. It is a fact that all life on earth that we know is membrane bound. Sealing a membrane is a binary event and this has implications for what sort of event we are talking about.
Replication of a molecule is not what I was talking about.
What I am hung up about is that the gap between alive and not alive is not a gap which any thinking person can bridge with chance, necessity or both together unless for other reasons you are determined to believe that it must have happened.
I was just trying to make the point that there is a lot of chemistry that can happen before a cell becomes "alive" and that that the gap may not be as concrete as you think, precisely because what you define as "alive" is subjective. I personally don't think trying to come up with a definition of "living" is very productive.
I wasn't trying to suggest the problem has been solved.
Jeff,
Very good questions!
1. Information - this is a fascinating word! The SOD list of definitions has only one which can be their suggestion of the definition:
sense 6 - "The giving of a form or essential character to something."
That doesn't really help!
I would say something more like "stored data" but then if you look up "data" it is really defined as "information"!
It is something analogous to writing and reading I think. Which is why all that terminology was immediately applied to the DNA-RNA-Protein system.
It is a system which uses and recognises a code for a useful purpose.
2. Evidence for sudden integrated increases in information.
(a) The origin of a coding system for the construction of biological machines. By its very nature a coding system requires a whole **system**
(b) The origin of an integrated energy storage and usage system.
(c) The origin of structural molecules and their production.
(d) The motor function of the bacterial flagellum is the best and most well studied example.
You either have the system/function or you do not and the system/function depends on having multiple coordinated elements together at once for its function.
The analogy of language is I think very useful here. To get a story you need multiple coordinated examples of sentences put together in a certain way for it to work.
Getting a story by random assembly of sentences is I think not a good way to make money as a writer!
"I personally don't think trying to come up with a definition of "living" is very productive."
Andy,
That really sounds like a council of despair! I am looking at the origin of life but I personally do not think it is productive to define what life is!
If you ask ten biologists what they think life is, you will get at least eleven answers. That's why it's unproductive.
On the other hand, asking how protein synthesis arose, or how high energy phosphate bonds ended up as a ubiquitous energy currency, or how DNA and RNA arose.....those are all interesting questions.
I just thought i'd suggest a definition of information I heard from a cybernetics bod. Information, he said, was a 'surprise event', that is, something that the normal laws of nature or the environment would not produce. Therefore, a rock that looks like a face is not information if it merely follows the natural erosion of the rock layers. However, if the face is present in the rocks despite the rock layers (such as Mt Rushmore) then you know that is information.
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