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.

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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.