  Even the simplest organisms are too complex to have spontaneously arisen
fully-formed, yet precursors to first life must have emerged ab initio from
their environment. A watershed event was the appearance of the first entity
capable of evolution: the Initial Darwinian Ancestor. Here we suggest that
nucleopeptide reciprocal replicators could have carried out this important role
and contend that this is the simplest way to explain extant replication systems
in a mathematically consistent way. We propose short nucleic-acid templates on
which amino-acylated adapters assembled. Spatial localization drives peptide
ligation from activated precursors to generate phosphodiester-bond-catalytic
peptides. Comprising autocatalytic protein and nucleic acid sequences, this
dynamical system links and unifies several previous hypotheses and provides a
plausible model for the emergence of DNA and the operational code.
