Lemmings, little hamster-like creatures, do in fact perish by falling over cliffs. An evolutionary population control development causes them to over-breed, and by systematically running over cliffs, the size of the population is limited.

Lemmings, little hamster-like creatures, do in fact perish by falling over cliffs. An evolutionary population control development causes them to over-breed, and by systematically running over cliffs, the size of the population is limited.