The study of prebiotic evolution divides itself into three main stages, which one may label geophysical, chemical, and biological. The geophysical stage concerns itself with the early history of the earth and especially with the nature of the earth's primitive crust, ocean, and atmosphere. The chemical stage concerns itself with the synthesis, by natural processes operating within plausible models of the primitive atmosphere and ocean, of the chemical building blocks of life. When we speak of building blocks, we tend to think of the amino acids and nucleotide monomers out of which the proteins and nucleic acids in modern cells are built. The building blocks at the beginning of life may have been very different, but the majority of experiments exploring prebiotic synthesis have been aimed at the synthesis of amino acids and nucleotides. The biological stage concerns itself with the appearance of biological organization, with the building of a coordinated population of large molecules with catalytic functions out of a random assortment of building blocks. If the building blocks were amino acids or nucleotides, the large molecules would have been proteins or nucleic acids. But biological organization probably began with a far more heterogeneous population of molecules than we see in modern cells.

Generally speaking, it can be said that the geophysical and chemical stages of prebiotic evolution are reasonably well understood. At least these two stages are in the hands of competent experts, and I have nothing significant to add to what the experts have reported.