Precambrian Evolutionary Genetics
The broad features of the evolution of Precambrian organisms and of the genetic systems responsible for this evolution are outlined. The hypothetical and actual life-forms considered are pre-organisms (nucleic acid molecules multiplying free in solution), proto-organisms (membrane-bound self-replicating entities), prokaryotes (bacteria and blue-green algae), and protists (early eukaryotes with little differentiation). In each group, the nature of the hereditary material, its acquisition of function, its increase in size and variety, and its means of change and recombination are discussed.