The battle for survival between bacteria and bacteriophages can be framed according to the Red Queen hypothesis. To avoid extinction bacteria must evolve new mechanisms of resistance, such as CRISPR immunity. Viruses, in turn, must evolve countermeasures to inactivate these resistance mechanisms, such as anti-CRISPR proteins. These natural inhibitors may well become biotech tools useful to keep genome-editing in check and are a minefield waiting to be explored. Jennifer Doudna and Joseph Bondy-Denomy used bioinformatics to find some of them, and have just published their findings in Science. Paraphrasing Dobzhansky’s famous dictum, nothing in biotechnology makes sense except in the light of evolution.