A brief history of viruses Before we can begin talking about CRISPR, we need to cover some basics about how it was discovered. A very, very long time ago, before the dinosaurs or even the formation of the great forests of the Carboniferous era, an evolutionary arms race seethed beneath the troubled waters of an adolescent Earth. There are several leading theories for when they first appeared, but it is generally accepted that the first viruses began existing by about 3 billion years ago. One theory in particular postulated by Gustavo Caetano-Anolles and his colleagues at the University of Illinois proposed (see paper here) that bacteria and viruses share a…