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
at Norton Sound
), and then died suddenly when the grass grew in spring.
This was refuted by the natural historian Ole Worm
, who first published dissections of a lemming, and showed that lemmings are anatomically similar to most other rodents.
While many people believe that lemmings commit mass suicide
when they migrate, this is not the case. Driven by strong biological urges, they will migrate in large groups when population density becomes too great. Lemmings can and do swim and may choose to cross a body of water
in search of a new habitat
. On occasion, and particularly in the case of the Norway lemmings
in Scandinavia, large migrating groups will reach a cliff overlooking the ocean. They will stop until the urge to press on causes them to jump off the cliff and start swimming, sometimes to exhaustion and death. Lemmings are also often pushed into the sea as more and more lemmings arrive at the shore. 
The myth of lemming mass suicide
is long-standing and has been popularized by a number of factors. In 1955
, Carl Barks
drew a Uncle Scrooge
adventure comic with the title: The Lemming with the Locket
. This comic, which was inspired by a 1954 National Geographic
article, showed massive numbers of lemmings jumping across the Norwegian cliffs.
. The suicide myth was further propagated by Walt Disney
documentary White Wilderness
in 1958 which includes footage of lemmings migrating and running head-long over a ledge. An investigation in 1983 by the Canadian Broadcasting Corporation's Brian Vallee, showed that the Disney film makers faked the entire sequence using imported lemmings (bought from Inuit children), a snow covered turntable on which a few dozen lemmings were forced to run, and literally throwing lemmings into the sea to show the alleged suicides. 
This myth is also witnessed in a German film-- Der Kleine Eisbär
(lars, the polar bear)--in which a group of despondent lemmings are frequently jumping off various ledges.
Due to their association with this odd behaviour, lemming suicide is a frequently-used metaphor
in reference to people who go along unquestioningly with popular opinion, with potentially dangerous or fatal consequences. This is the theme of the video game Lemmings
, where the player attempts to save the mindlessly marching rodents from walking to their deaths.