Viruses did not evolve first, they found. Instead, viruses and bacteria both descended from an ancient cellular life form. But while – like humans – bacteria evolved to become more complex, viruses became simpler.

Do viruses come from bacteria?

The origins of viruses in the evolutionary history of life are unclear: some may have evolved from plasmids—pieces of DNA that can move between cells—while others may have evolved from bacteria.

Are viruses discovered before bacteria?

Viruses, then, may have existed before bacteria, archaea, or eukaryotes (Figure 4; Prangishvili et al. 2006). Most biologists now agree that the very first replicating molecules consisted of RNA, not DNA.