Myth: The truth about lemmings

For this week's mythconception, Georgia Mills has been uncovering the dark past of a commonly-held belief about lemmings...

Georgia - Lemmings are, by all appearances unremarkable little rodents, but with a remarkable reputation for throwing themselves off cliffs. The legend goes that huge swarms of the hamster-like creatures commit mass suicide, either through said cliff jumping or from careering straight into the sea.

And it is true that Norwegian lemmings would suddenly appear in huge numbers every few years before suddenly they’d apparently be wiped out to near extinction before the cycle would repeat.

Back in the 1500s this lead to someone to speculate that lemmings popped into existence in storm clouds before falling to the ground. A contemporary challenged this nonsense. Of course they didn’t appear in mid-air, they blew in on the wind.

And one folk tale even had people believe that when individual lemmings got too angry they simply exploded.

And the theory that still sticks to this day was that for the greater good of the species when the population grew too big the altruistic lemmings would run, in hoards, off of cliffs and drown themselves.

It sounds unbelievable. And it should do as, evolutionary speaking, it makes absolutely no sense. A selfless and suicidal lemming would be taken out of gene pool, while a selfish lemming who didn’t follow the crowd would have lots of babies and reproduce successfully. The cliff jumping behaviour would die out.

But there’s a reason this paradoxical plunging is still so widely believed - it was actually caught on camera. In 1950 Disney filmed a documentary called White Wilderness, and they got some never before seen footage of some lemmings hurling themselves off a cliff to their doom. So… case closed?

Well, here’s the rub and this may be distressing to some listeners. It certainly distressed me that these lemmings didn’t jump - they were pushed. The producers having fallen for the legend themselves wanted to include it in their documentary, but after they couldn’t see it for real they imported a whole bunch of lemmings and threw them off the cliff themselves.

Apart from contributing to the untimely and unnecessary deaths of some of Mickey Mouse’s close cousins this Academy Award winning documentary cemented the lemming myth in people’s minds for many years. But the deception has been exposed and safely assuming they aren’t spontaneously appearing in clouds or exploding we still need to explain this sudden appearance and disappearance of these lemmings.

Even now, we don’t have the whole story but we have many parts of the puzzle. Norwegian lemmings are fast breeders; if the environment is forgiving the numbers will increase dramatically. And when it’s cold lemmings can survive underneath the snow where they can breed safely before suddenly appearing in spring as if from nowhere. And when there are too many lemmings their numbers will start to drop; they run out of food; they’re picked off by predators, and many of the infants are killed by males.

Plus, when it’s too crowded herds of lemmings will migrate to pastures new. This mass migration can involve travelling down steep hills or swimming across small bodies of water, and sometimes lemmings might fall or drown. But the ones that survive get back to their breeding in a brave new world.

So to summarise, a very dynamic population size has led to the many myths about lemmings. And while the odd calamities lemming might blunder off a cliff, or be thrown by TV producers, there’s zero evidence they’ve ever tried to kill themselves.