Monday, September 22, 2014

In support of lemmings

The article Retirement fund managers behave 'like lemmings' in today's FT caught my eye, not because of the subject matter, though retirement fund managers do indeed interest me, but because of the lemming analogy. 

Now, it is unclear whether the analogy is the FT's Chris Flood's or the Cass Business School's Professor David Blake, the writer of the report cited in the article. I suspect given the use of inverted commas in the headline it is Professor Blake's. Regardless, it is wrong. Lemmings do not herd. They do not en masse commit suicide by jumping over cliffs into the ocean. They never have and they never will.

The myth about lemmings originated from a 1958 Disney documentary 'White Wilderness'. The filmmakers could not understand why lemming populations occasionally exploded and just as quickly collapsed so made up the mass suicide story, staging the well-known scene in which hundreds of lemmings are seen running over a cliff. As the lemmings tumble, the narrator tells us that: 

"A kind of compulsion seizes each tiny rodent and, carried along by an unreasoning hysteria, each falls into step for a march that will take them to a strange destiny. That destiny is to jump into the ocean. They've become victims of an obsession — a one-track thought: 'Move on! Move on!' This is the last chance to turn back, yet over they go, casting themselves out bodily into space ... and so is acted out the legend of mass suicide."

The truth, as is often the case, is a little more mundane.

Population sizes of animals that are preyed upon like lemmings are described by the Lokta-Volterra equation. Without needing to get technical, what this means is that there are certain situations in which populations can explode in size, either because of short gestation periods, large number of offspring per birth, abundance of food, lack of predators or good weather. However, the environment of the animal in question may not be able to support a large population, either because of lack of food, poor weather, increase in predators etc, so numbers collapse.

Disney it seems did not know what explained the collapse of lemming populations so with the help of some imported lemmings, clever camera angles and turntables to induce the frenzied activity, came up with their own explanation.

It is possible of course that in citing lemmings Professor Blake meant that retirement fund managers were procreating like crazy but I doubt it.

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