Avoiding Catch-22 of early evolution by step-wise increase in copying fidelity

One of the most famous problems of early evolution is the reconstruction of the evolutionary processes creating a so-phisticated, enzymatically aided replication apparatus from a system of primitive self-replicating oligomers. It is known that the selectively maintained length, and thus the amount of information coded in replicators, are limited by their copying fidelity, and that this length was too short in the primordial phase to code for specific replicase en-zymes. However, as argued generally, copying accuracy could not be increased without the help of specific en-zymes. In this paper, we suggest a step-by-step solution to this paradoxical situation through studying both non-enzymatic or enzymatic replication. In the nonenzymatic case, longer templates may enhance replication fidelity by their structural modification, while longer macromolecules could be a bit more precise replicase enzymes in the enzymatic situation. If this increased copying accuracy is sufficiently high, and naturally if the longer replicators outcompete the shorter ones, then the information content maintained in the winner template is increased. I use simple strategic models to study the possibility of these coevolutionary processes. It is pointed out that the neces-sary per unit increase of copying fidelity decreases rapidly with increased template size, and it could be very small even at shorter templates. Comparing the results to experimental data suggests that most probably it is the speed of replication and decomposition of macromolecules rather than copying accuracy, that limits the length of replicators