June 25, 2008
Information Theory / Enabling Conditions for Open-Ended Evolution
I just finished reading Enabling Conditions for 'Open-Ended Evolution'. In a word - fantastic.
These three put together the best summary of a defence for a designed origin of life as I've seen. Of course, they didn't say that - they couched everything in evolutionary terms. Nonetheless, I would recommend it for anyone's reading.
My one major critique is that they seem to be focused on the idea of "open-ended evolution". While I agree that the conditions that they list would be necessary conditions for life to meet in order for open-ended evolution to occur, I disagree that truly open-ended evolution could occur, at least as they have defined it. Specifically, one of the definitions they seem to agree with for this term says:
Also, by using the term ‘open-ended’ I wish to imply that an indefinite variety of phenotypes are attainable through the evolutionary process, rather than continuous change being achieved by, for example, cycling through a finite set of possible forms.
I'm not sure if I would argue that my own view is that the set is necessarily finite, but that it is necessarily bounded by some properties rather than open-ended.
Anyway, the case they argued was this:
- In order for a complex metabolic network to be sustainable (i.e. exist as a proto-organism), it must be cyclic
- In order for that network to be reproduceable, it has to have a way of encoding relevant information about the network in a way that is:
- Sequenceable (i.e. the information must be able to sequence complex interactions)
- The same chemical system cannot be used to store information and perform metabolic activity, because:
- The chemical composition of the information must be relatively inert, in order to be able to encode arbitrary configurations of metabolic networks
- The chemical composition of the metabolic network must not be inert, in order to perform the tasks of metabolism
- The information must be readable/copyable, which implies a 3D configuration optimized for reading
- The metabolic network must function, which implies a 3D configuration optimized for engaging in dynamic behavior with the environment
- Evolutionarily, changes in the "information" part of the system to encode new functions cannot interfere with the existing metabolic network, or it would fall apart during evolution (changing the sequences would cause the information itself to change its own role as an active player - so it wouldn't code for information, but rather be an active component).
- The metabolic network, in order to read the information to reconstruct itself, must be under formal constraints instead of physical constraints (i.e. it has to obey an established formal rule of interpretation in order to use the information) -- "At the roots of this coupling between endergonic and exergonic processes there must be
the capacity of a chemical system to build and rebuild (maintain) by itself a diverse set of boundary conditions, or ‘constraints’. We do not refer here to the standard (typically structural and external) constraints that help to solve a dynamical problem in physics, by reducing the degrees of freedom of a system; but to self-generated constraints (new ‘highlevel rules’ that affect ‘low-level molecular interactions’) coming both from self-assembly and self-organization phenomena"
So, while using the language of self-assembly, self-organization, RNA world, etc., the authors were able to show why life is a holistic unit, unexplainable in a reductionistic manne, and certainly not by the mechanisms mentioned.
In fact, it is amusing - each stage that was mentioned was shown to be incapable of open-ended evolution, yet the paper, with some magic words, was able to transition us to the next "stage", despite the fact that the author had just said that the previous stage was not open to open-ended evolution!
Anyway, it was a great paper. Creation researches should pay special attention tothe separation of the metabolism from the information and why that is important. Also, I thought that it was an excellent description of a non-reductable (i.e. irreducibly complex) system, with explicit functional/theoretical reasons (not just complexity) as to why all parts of the system are needed at once.