A Recipe to Evolve Complex Life Chemically on Earth

Sequences of tRNAs are highly patterned in easily identifiable RNA repeats and RNA inverted repeats (stem-loop-stems). Because of patterning, the multi-step evolution of tRNA can be described in remarkable detail. To evolve life on Earth or another planet or moon, requires evolution of tRNA or a tRNA-like molecule to act as a genetic adapter. To replace tRNA with an alternate or improved genetic adapter is a remarkably challenging problem, indicating strong chemical selection of RNAs in pre-life. The genetic code, translation systems and first proteins coevolved with tRNAomes (all of the tRNAs of an organism). Because tRNA sequence can be separated into component parts, a simple pathway for chemical evolution of life and genetic coding can be described in sufficient detail to allow assembly of a living entity in laboratories.