The researchers based their hypothesis on rats’ proven ability to infiltrate most major landmasses and islands on the planet, as well as their persistence throughout the world despite widespread attempts to control their populations. Other animals, such as cats and feral pigs, also do well in diverse ecosystems around the world, but they are not as widespread as rats. In the event of a mass extinction caused either by human activity or a catastrophic event, rats are theoretically the most likely mammals to be spared, given their wide extent and ability to cope in varied conditions, Zalasiewicz said.

The time frame of this purported rat takeover would be about 3 million to 10 million years from now, based on previous rates of repopulation after mass extinctions, Zalasiewicz said, so modern humans need not worry about an impending stampede of rodents. Even so, the researchers do suggest their findings could be a wake-up call for humans to take note of thier own significant influence on the environment, and to consider how the world could change as a result of their actions.