Virus ARE Living Things

On my daily commute to work today, I had a passing random thought: Virus are living things. Ok, every biologist would say "But they cannot reproduce on their own!" / "They have no metabolism outside of host cell!" etc etc etc.

Well, I subscribe to the view that life begins from simple molecules - the so-called "RNA world". We do have RNA viruses, which suggests that viruses are extremely old - think "billions of years" old. According to this "RNA world" hypothesis, DNA came into being after RNA. Many of the viruses' hosts use DNA as their "store" of genetic material. So viruses precede their hosts.

Viruses, through infecting their hosts, gain access to the hosts' protein synthesis machinery and nucleic acid synthesis machinery (to a certain extent) to enable the viruses to replicate. Why do viruses not reproduce on their own? Well, if they can rely on host cells to do that, why would they need to retain this ability? By not needing to reproduce, to metabolize, the viruses are actually "streamlining" themselves - they got rid of functions which they can "outsource" to. 

For those who believe in evolution, let me put this picture to you: Virus started out as some living organism, needing to feed and reproduce by itself. Over the years (not decades or centuries or even millenniums, think tens or hundreds of millions of years), new organisms came about (maybe viruses are their predecessors?). Competition for food/materials to live drove the original viruses towards extinction - the original viruses are being selected against. However, a small group of viruses, through mutations, gained parasitic ability - they can invade host cells and produce within host cells (like some bacteria). However, as selection favours faster growing/replication population, over time, the original viruses ditch their own systems and streamlined their genome, relying on host cells to do all these jobs for them (perhaps because small genomes can be replicated more rapidly? because these host cells are more capable or efficient at obtaining nutrients than the viruses?).

Of course, I have no proof to support what I have said thus far. However, this is still a tantalizing thought is it not?