A Game of Rat and Mouse

by Theodore Dalrymple (September 2014)

For the mouse is a creature of most excellent valour…

Is that not correct? A tiger needs no bravery, except perhaps in tackling another tiger, but a mouse takes its life in its paws every time it leaves its nest. They are not brave who know no fear, but those who fear and yet venture forth. The poem continues most movingly:

For the Mouse is a creature
Of great personal valour.
For the Mouse is of
An hospitable disposition.

No doubt strict biologists would deride these lines as absurdly anthropomorphic, but strict biologists have far greater difficulty in escaping from anthropomorphism and the language of intention than they usually acknowledge. The strictest Darwinists often speak as if Evolution were a person and instil it (or Him) with a purpose as well as a process. They would, perhaps, explain this lapse as being caused by a biologically-predetermined tendency for sapient beings to imbue the world, and therefore descriptions of the world, with intentionality, which it is the duty of scientific puritan to try to eliminate. I do not enter the argument as to whether they are right to want to do so, but only remark that people like Kit Smart, who express some affective kinship with mice, are likely to prove nicer people, and more amusing company, than those who see mice as automata.

I have also long been aware of the role of mice in spreading illness such as leptospirosis or Weill’s disease, also known as rat-catcher’s disease. But even when as a student I lived in close proximity to many mice, as measured by the number of their droppings, I resolved to do nothing about them, preferring rather to await the development of an illness and then treat it as leptospirosis (the principal danger of the disease lying in delayed diagnosis) rather than eliminate the mice wholesale.

Now voles are more akin to mice than rats, at least in my imagination. They are delightful creatures to look at and seem harmless. One of the most interesting books I have ever read is Charles Elton’s magisterial Voles, Mice and Lemmings: Problems in Population Dynamics. It was handsomely produced in 1942 by the Oxford University Press, and one is full of admiration that such scholarly work (admittedly the summary of many years’ study) should have continued in the midst of the great historical cataclysm. It is written in far more leisurely style than would be permitted today and describes the field vole, often called the field mouse. Here is the description of the vole:

[He] wears a livery entirely suitable to his surroundings: his coat is a short jacket of russet over a dull brown waistcoat; his clothing is completed by white small-clothes, altogether a fine costume for a life in the fields. He makes up for any poverty in his surroundings by an unquenchable activity. He takes no notice of the sun but works morning, noon, and night. With such incessant activity, and taste for almost every kind of crop, it is not surprising that the vole makes a success of life.

In fact the vole in Europe has long been an enemy of Man, for every few years his numbers increase explosively and destroy the crops for miles around:

It is an impressive picture of insurgent subterranean activity, of devastation breaking like a flood upon the crops. All man’s vigilance and care are taxed by the multitude of small, swift, flitting forms that infest the ground and devour all living plants. Poison, ploughing, fumigation, trenches, and prayers, all these can scarcely stop the destruction. Gérard [the author of a book about the fauna of his native region, Alsace] remembered an outbreak that happened in 1822, when he was a boy. In that year Alsace was absolutely in the power of mice. ‘It was a living and hideous scourging of the earth, which appeared perforated all over, like a sieve.’

Astonishingly to me, the author says of Aristotle’s ‘measure and balanced description of the rise and fall of a mouse [vole] population might be taken for a text of the present book’ – a book, incidentally of immense length. Aristotle, in the Historia Animalium, wrote:

 the destruction they cause, are beyond all telling. In many places their number is so incalculable that but very little of corn-crop is left to the farmer; and so rapid is their mode of proceeding that sometimes a small farmer will one day observe that it is time for reaping, and on the following morning, when he takes his reapers afield, he finds his entire crop destroyed. Their disappearance is unaccountable: in a few days not a mouse will be there to be seen.

According to Elton, a plague of voles struck Germany in 1917 and 1918, making food even scarcer, and thereby lessening Germany’s will and ability to continue the war. The voles it was that stabbed Germany in the back.

The sudden decline of vole populations that had equally suddenly exploded made the estimation of the efficacy of efforts to control vole plagues very difficult. Elton tells us:

 by outcry, and demands to Authority. Authority remembers its experts, or appoints some: they ought to know. The experts advise a Cure. The Cure can be almost anything: golden mice, holy water from Mecca, a Government Commission. A culture of bacteria, poison, prayers denunciatory or tactful, a new god, a trap, a Pied Piper. The Cures have only one thing in common: with a little patience they always work. They have never been known entirely to fail. Likewise they have never been known to prevent the next outbreak.

Here in essence is the problem that bedevils so much of our thinking: the grandiose assumption that because x was done before y happened, y happened because x was done. It has taken medical practitioners two millennia to free itself from this illusion.

Until I read Elton, I had assumed that H G Wells (whose genius is insufficiently appreciated) had invented, or foreseen, the idea of bacteriological warfare in his story The Stolen Bacillus, written in 1894. But it is possible that he was inspired by the experiments conducted in France by Jean Danysz, who in 1892 and 1893 tried to spread mouse typhoid among voles to control their numbers (Danysz himself had discovered the causative germ). The results were equivocal, partly because the experiments were insufficiently controlled and partly because Danysz sewed so much of his bait in the fields – bread soaked in culture of the germ – that it was uncertain whether an epidemic had been started among the voles, or they had simply each eaten of the bait individually and died of it in effect as of a poison. Danysz was also criticised because it was possible – indeed, so it eventually turned out – that the germ was potentially dangerous to man. To prove that it wasn’t, Danysz swallowed a whole beaker-full, repeating Pettenkofer’s famous attempted refutation of Koch’s discovery that the cholera vibrio was the cause of cholera. Both Pettenkofer and Danysz forgot that a necessary cause was not the same as a sufficient cause. Is there any of us who has never made the same mistake?

Charles Elton’s wonderful book, nearly 500 large and closely-printed pages long, remains, I suppose, largely undisturbed upon the shelves, where it is destined to remain until ‘de-accessioned,’ to use the euphemism of librarians more destructive of libraries than mere mice for the chucking out of books. At the end of his book, Elton makes an impassioned plea that the population dynamics of mice, voles and lemmings be understood ‘not for power alone, but on account of… the beauty of the unstable fabric of the living cosmos.’

To which we can only murmur both ‘Amen’ and ‘Fat chance!’ 

 

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