The eventual elongation of zymes wo

The eventual elongation of zymes would promote their entropy-driven folding
at the surface. In addition, an increase in their amount would encourage interactions
between them. Both factors may have led to the formation of hydrogen
bonds within zymes and/or between different zymes. Clustering of zymes may
have been favoured by high pressure [201] and periodic drying events, e.g. in tidal
regions [18,202], resulting in a kind of natural polymerase chain reaction (PCR)-
like process [203]. The UV-stability of double RNA strands, owing to hydrogen
bonding, is much higher than that of single-stranded RNAs [159,164,204-206].
Therefore those π-systems may have been selected – from the initially larger set of
compounds – which could make multiple hydrogen bonds with each other. Ultimately,
this selection would have led to a relative enrichment of complementary
nucleobases, including those that we know now. It is plausible that the π-systems
could have been initially linked in various ways. It would appear that one of these
constructs, the one with ribose-phosphate units connecting the stacked nucleobases,
attained the ability for self-replication and was, because of this, retained
by evolution.