Domains of life identified through genetic codes

The theory is presented according to which the domains of life are identified by their genetic codes. That is to say, each progenote- > cell transition, the evolutionary point in the formation of a domain of life, is associated with a unique and specific genetic code. Criticisms of this theory are analysed, although they fail to undermine it. The theory's predictions are compared with those of the main hypotheses regarding the domains of life. According to the theory, there would be a strong incompatibility between the number of domains of life reported in the literature and the genetic code considered universal, that is, unique. The two-domain hypothesis might eliminate this incompatibility by suggesting the existence of two genetic codes. Finally, another hypothesis is discussed, suggesting the existence of three domains of life (two of which are within archaea) and three different genetic codes, which would be consistent with the theory.