Emerson White wrote:
Archaological evidence suggests that it took rats about 500 years to move from the periferie of human society to its place right now, gnawing on the heart. Presumably another rat would eventually move in (there are 56 species of them). rats do probably eat a certain number of cockroaches and getting rid of them might increase that problem, but rats also gnaw through containers and open up tunnels for roaches. Mouse and vole populations could probably also be expected to rise, as well as bird and snake populations. Rats really eat every living thing.
There is a review process, done by people who know a whole lot about what is going on.