1. April Fools' science fables2. Suicidal rodents3. Half rot, half right4. Mocking mimics5. Booked for bunk6. Ignorance = bliss

 

Brown lemmings turn white in winter.
Copyright and courtesy Helen and Bill Thayer

  April Fools! Science fable vs. science fact
     
    Lemming theory jumps in the lake
Lemmings are strange little mammals, but they don't jump off cliffs in large numbers to "end it all."

At least, nobody's seen them jumping, and nobody's found a suicide note -- say, a heap of lemming bones along a seashore. Nor does oral tradition among northern people mention jumping lemmings. And evolutionary biology would be hard-pressed to explain how a suicide tradition would get passed from one generation to the next.

A white lemming crouches on the snow, looking rather mouselike.Still, although most people couldn't say where lemmings live or whether they are closer to a kangaroo or a hippo, everybody knows lemmings have this curious habit of throwing themselves into the ocean in a rodent version of the Jonestown suicides.

In the elaborated myth, the little rodents migrate dozens or hundreds of kilometers before taking the final plunge.

And that's just it: The whole thing is a complete myth.

Don't trust us. Trust Canadian biologist Dennis Chitty, who -- and this fact is a fact -- spent six decades trying to figure out why lemming populations surge and crash. In Chitty's scientific memoir, published in 1996, he wrote that the mystery was just as baffling as when he started looking in 1935. "We still don't know" what happens to lemmings (see "Do Lemmings..." in the bibliography).

Facts behind the myth
The lemming suicide pattern exemplifies a "scientific" explanation that sounds so good it must be true. Certainly, the fable did try to explain some facts.

Lemmings are weird. They commit suicide in large groups by throwing themselves from cliffs. They do, don't they?Some lemming corpses do appear on the ice in the Canadian Arctic, and populations of lemmings -- as well as snowshoe hares, voles and defoliating insects -- rise and fall in four- to 10-year cycles.

Something must explain the cycles, but Chitty says the only explanations that's been thoroughly disproven is the one "everybody knows" --the cliff-jumping suicide routine.

In his long quest, Chitty found that population cycles were not governed by obvious factors like predators, food supply, density, or anything else he or his colleagues could test.

As to what actually causes the cycles -- maybe you will solve that mystery, if you can brave the Arctic cold. At any rate, you could do worse than study lemmings, whose strange behavior allows them to survive truly awful conditions. Unlike most mammals that winter in the high Arctic, lemmings don't hibernate.

All winter long, they live between the snow and the permafrost, at temperatures of about -25 ° Celsius! In some years, they even breed in the winter... which helps explain the strange surges in population that once were attributed to long-distance migration.

Want to hear a lemming?Disappointed after years of frustration, Chitty concluded that the migrate-and-jump explanation for lemming populations shows how the "The theoretical hare hit the ground running long before the experimental tortoise left the starting gate."

Despite the lack of scientific evidence, the use of "lemming" to indicate an animal that travels in herds and commits suicide is well entrenched in English.

In 2000, for example, Sen. John Kerry quoted former diplomat George Kennan describing the two sides in the Cold War: "We have gone on piling weapon upon weapon, missile upon missile, new levels of destructiveness upon old ones, helplessly, almost involuntarily, like victims of some sort of hypnotism, like man in a dream, like lemmings headed for the sea."

In fact, suicidal behavior may have been more apparent in the two Cold War superpowers than the bitty Arctic rodent...

One final question: Was Chitty describing himself when he wrote that those who try to solve the lemming mystery "... pursue it with the obsessive zeal of Ahab in pursuit of the great white whale"?

Cola will rot your teeth overnight, right?

 

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