What Is Unusual about Lemmings?
The strange thing about lemmings is the way they, apparently, commit mass suicide. These grey or reddish-brown rodents look like mice, but are slightly larger. They live in large areas of the northern world, including Alaska, north-west Canada and Scandinavia.
But, in fact, only the Scandinavian lemmings stampede in such a suicidal manner. Now and then thousands of them travel miles over land in panic to the sea. Many die on the way, but those that arrive leap immediately over the cliffs into the sea, and swim until they become exhausted and drown.
No one is certain what makes the lemmings behave so strangely. It may be because the weather becomes too warm for them, or because their foods supply changes, or simply because they feel they are getting overcrowded. It is in fact not a mass suicide but the result of their migratory behavior.
This fact, combined with the unexplained fluctuations in the population of Norwegian lemmings, gave rise to the misconception. Misconceptions about lemmings go back many centuries.
In the 1530s, the geographer Zeigler of Strasbourg proposed the theory that the creatures fell out of the sky during stormy weather (also featured in the folklore of the Inupiat/Yupik at Norton Sound), and then died suddenly when the grass grew in spring.
This description was contradicted by the natural historian Ole Worm, who accepted that lemmings could fall out of the sky, but claimed they had been brought over by the wind rather than created by spontaneous generation. Worm first published dissections of a lemming, which showed they are anatomically similar to most other rodents like voles and hamsters, and the work of Carl Linnaeus proved they had a natural origin.