One of the tenets of evolutionary naturalism is that before life
evolved, an RNA-only world existed (the “RNA world” hypothesis)
in which the RNA molecule functioned to both transmit
information and perform enzymatic reactions.1 In eukaryotic
(i.e. nucleus-containing) organisms, genes are composed of
alternating regions of coding and non-coding DNA (exons and
introns, respectively). In order for a given protein to be made,
these intron sequences must be excised or “spliced” from the RNA
message that was derived from the DNA sequence. Three classes of
introns have been described: group I, group II, and nuclear pre-
mRNA.2 Both group I and II introns are self-splicing (meaning
that the RNA itself acts as an enzyme and carries out the
splicing reaction without the need for proteins). These introns
are found in organelles in eukaryotes (i.e., mitochondria) and
bacteria. The ability of group I and II introns to catalyze
self-splicing reactions bolstered the RNA world hypothesis,
since proteins would not be needed i