Among the authors who have directed attention to the origins of metabolism as well as genes, proteins and self-replication, Freeman Dyson is perhaps the best known. He suggested that membrane-bound structures arising from something akin to the Oparin mechanism might have been of different kinds. Some might have contained replicating equipment, others metabolic equipment. Symbiosis between the two kinds could have produced a primitive cell. But the origin of the "metabolisers" is not clear.
Prigorgine popularised the phrase "self-organising complexity" and noted that autonomous, self-maintaining complex systems adopt stable states that are far from thermodynamic equilibrium. A living cell is just such a system. Kauffman showed that a chemical mixture in which a few components catalyse reactions among the others becomes self-stabilising, self-organising and in the mathematical sense complex. A self-stabilising, autocatalytic chemical system contains the rudiments of metabolism, internal structure and homeostasis - though without genes or replication. This could in principle explain the origin of Freeman Dyson's "metabolisers". The difficulties with this abstract approach are (a) that it lacks experimental support (apart from computer simulation) and (b) that metabolism is not self-organised; its organisation is directed by gene expression and signals from the environment.
It is difficult to see how Kauffman's scheme could be related to the RNA world hypothesis or most other conjectures about the origin of life. However, could a Cairns-Smith "clay matrix" have acquired a suitably large array of organic additives for an autocatalytic system to develop? If so, then affirmative answers might be given to the previous questions, and the Cairns-Smith model might suggest a practical way of realising Kauffman's mathematical scheme for the origin of life.
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