That is a question that Marcus du Sautoy explores in a recent article in The Times Online (April 29, 2009).
The popular myth about lemmings derives from a 1958 Disney documentary called White Wilderness, which included footage that purported to show this mass suicide taking place. So convincing was the evidence that the term "behaving like a lemming" found its way into modern parlance, becoming shorthand for those who follow the masses unquestioningly, with potentially disastrous consequences. The animal's conduct even spawned a video game in which the player would attempt to save the lemmings from their own mindless march to the cliff face.
But it was revealed in the 1980s that the film crew of White Wilderness had faked the whole scene in landlocked Alberta, Canada.
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