I think it's a complexity problem. Someone downthread pointed out that there are some viruses that are small - so small they consist of only two genes. It's po

I think it's a complexity problem. Someone downthread pointed out that there are some viruses that are small - so small they consist of only two genes. It's possible that the super simple minimalist viruses are spontaneously produced and abundant in the universe. If all that's necessary is a strand of nucelic acids and a repetitive peptide unit, then it's within the realm of possibility that these would form simply because it's thermodynamically favorable for them to fall together in some systems. Then, if they encounter a living being, they're able to piggyback on it to multiply, mutate, and recombine. This could be further supported by the fact that viruses can coinfect cells and effectively transfer genetic and protein material between each other. By this model the simplest viruses are just products of chemistry that, when exposed to life, gradually become more and more complex. I guess the underlying point is that they could very well be forming on earth, continuously. If they are, then that would explain the baffling, unending diversity. They're just always forming new genetic material that gets iterated on until it works well.