The origin and evolution of life as continuing expansion of viral hosts

Emergence of life on Earth, presumably beginning from “cosmic chemistry” and culminating in the last universal common ancestor, likely involved a complicated evolution of the primeval residues via basic intermediate forms capable of self-replication. These primordial replicators could have further evolved into archaic virus-like structures, which in turn became the precursors of the cellular life forms. The hypothesis presented in this article suggests that viruses were not only predecessors of the first cellular life forms, but that their hosts themselves emerged and evolved as factories and reservoirs for virus production and dissemination. In other words, it expands the role of viruses as not only originators of cellular life forms and the selfish driving force behind their evolution, but as the primary reason for their existence and biological heterogeneity.