Guest post by Evgeny Selensky:
An interesting summary of an abiogenetic hypothesis of prebiotic metabolic networks can be found here. The bottom line is, it is interesting but it raises many serious questions.
The hypothesis is based on the observed similarity of the core structure of metabolic networks across all organisms. It is then hypothesised that the core must have had an early evolutionary origin.
As is expected of a naturalistic hypothesis, it relies on extremely favourable starting conditions (the lucky concentrations of all necessary reagents in an Archean ocean, the right temperature, etc.) and other physico-chemical constraints, which, according to its proponents, helped form a prebiotic metabolic complex.
The summary makes a correct distinction between thermodynamically controlled reactions and self-replication. There is no need in replication mechanisms as long as a given product is constantly re-made because it is chemically stable. The question then is, how then did the information translation apparatus observed in all contemporary organisms arise?
Physico-chemical constraints cannot by themselves cause information translation because for translation to happen, a material symbol must be physico-chemically inert and independent of the effect it evokes in the system. Furthermore, the rules of translation from symbols (e.g. nucleotides of messenger RNAs) to their meanings (polypeptides) must be arbitrary with respect to the physico-chemical necessity that holds the system together, in order to get ‘unlocked’ from this necessity for the system to be able to encode messages. In genetic translation, this arbitrariness is ensured by the absence of any physico-chemical bias in nucleotide polymerisation: every one of the four nucleotides can polymerise every other in water.
Chemistry cannot produce the different roles that the material components of the translation apparatus play, namely: the symbol, the protocol and the effect! To organize translation it is necessary to impose an epistemic cut:
- The measured/The measurer
- The controlled/The controller
- Motion of matter/Boundary conditions
Such an epistemic cut, which is the essence of organization, is infeasible purely physico-chemically, i.e. as a consequence of solely the motion of matter. The reliance exclusively on physico-chemical constraints to produce organization is the primary category error in all naturalistic origin of life models, including this one.
Organization (rules of behaviour as opposed to physico-chemical constraints) is only possible via intelligence external to the system being organized. Since intelligence is the only empirically warranted cause of organization, it must have been the cause of biological organization as well. There is no other option.
H. Pattee (2001): The physics of symbols: Bridging the epistemic cut, Biosystems, v. 60,