It can be safely said that both rats and mice have played a massive role in shaping the course of events in the history of the world. Both rodent types have played key roles in the history of the planet. One for the common good and the other for more negative reasons.
The impact rats have had on history can be said to be negative as a whole. Rats were the vehicle that brought the fleas that carried the Bubonic Plague or Black Death to the shores of the European continent and beyond. This simple act resulted in the death of between 75 and 200 million humans, and was responsible for thinning the European population by about 60%.
The population did not rebound for almost 300 years after this catastrophic event occurred. This is the most devastating impact that rats have had on the world.
Mice on the other hand have given humans the opportunity to expand their knowledge in medical science communities in ways that have created vaccines and cures for several diseases, and allowed researchers to establish facts on the effects of medications and procedures that were to be attempted on human beings.
While the use of lab mice to further medical knowledge is a controversial procedure, the fact remains that without having done the experiments that have been performed; the medical community would be much farther behind in medical knowledge than they are now.
There are caveats to that however. If the experimentation is not 100% necessary or can be conducted by any other means then, as a humane species, humans are obligated to forego the procedure using live animals of any species.
This certainly includes the use of any animal, whether it is a lab rat, mouse or a monkey or chimpanzee for testing of beauty products and other frivolous items that one can live without.