>>12893441The origin of viruses is actually somewhat mysterious, because they are extremely limited in their evolvability. Viruses can only speciate through cross-species infection and wandering around a little bit in genome-space, and they are not evolvable enough to cross types, so an RNA virus can never become a dsRNA virus, or a ssDNA virus, or a retrovirus, or anything other than a slightly different RNA virus. This is in stark contrast to eukaryotes, where there is a smooth evolvability path linking an oak tree to a baboon (through a single celled common ancestor).
This is the limit of evolution of self-replicating entities with errors. It is very different from entities which are truly alive.
Since viruses cannot really evolve, if new ones can't be formed, you would think they should all be extinct. As soon as one type is gone for good, nothing can replace it. One can make two hypotheses here:
a. There are on their way to going extinct, but it's taking forever, so the viruses are remnants of early viruses which were around at the origin of life.
b. There are new viruses produced from scratch from something else.
I prefer hypothesis b, because I can't imagine that dinosaurs got influenza, or hepatitis. There must be a source.
The source then is in self-packaging genetic material which can leave and enter cell bodies, which has nothing to do with virus infections. Such entities do exist (surprisingly), the endo-retroviruses are an example.
