London: It is a famous animal rivalry which inspired the cartoon series Tom and Jerry. However, there may be more than just a battle of wills at play when mice try to get away from cats, researchers have suggested.
An intricate process evolved over many years may be helping the rodents escape when they are caught, according to animal behaviour experts. Mice produce a sweat chemical that confuses cats, giving them enough time to plot their route to freedom, Professor Benjamin Hart, from the University of California’s School of Veterinary Medicine, said.
Scientists suggest that Jerry the mouse may get the better of Tom the cat because of a chemical “catnip”. Credit:AP
They secrete molecules, called lactones, which have a mesmerising effect on their feline captor similar to the effect of catnip, which contains a molecule called nepetalactone.
When cats smell catnip on the plant Nepeta cataria, a herbaceous member of the mint family native to Europe and Asia, this triggers the release of beta-endorphins, natural opioid chemicals produced in the body. They feel compelled to sniff, lick and chew the flowers and leaves – and even roll around, shake their heads and drool. This may explain why cats enjoy batting mice around and playing with them before eating them, as they are overcome by the catnip-like chemical in the mouse’s sweat.
The excitement usually lasts for around 15 minutes, and can then return again after an hour. During the 15-minute window, in which the cat’s usual predatory faculties are compromised, the mouse may be able to scurry away with relative ease.
Scientists suggest mice may have developed the ability to generate this sweat chemical due to evolutionary forces. The physiological process may have developed over many years as a way of helping them survive when they find themselves in the clutches of a ferocious cat.
Hart said: “Mice produce lactones in the skin, which are excreted when mice are stressed. I hypothesised that mice evolved an alteration in the lactone to resemble nepetalactone and evoke catnip reactions in cats. Because the catnip, nepetalactone, induces playful behaviour, this gives mice a chance to escape”.
Not all domestic cats succumb to the effects of catnip, with around three in 10 not responding to it. This means mice will not always be able to rely on their sweat chemical to stage an escape. However, big cats such as lions do appear to be susceptible to catnip – suggesting future studies may reveal their prey could also have developed an evolutionary generation of this chemical.
Scientists from the University of California previously found that the physiology of mice may play a role in not only how they respond to attacks from cats, but also how afraid they are of them.
Mice were able to permanently lose their innate fear of cats after they had been infected with the microscopic parasite Toxoplasma gondii, according to their study in the journal PLOS One. This is because the infection causes irreversible brain changes, the research found.
Cats often mark their territory with urine. When mice smell it, they take it as a warning that predators might be lurking. However, mice who were infected with the parasite no longer reacted fearfully when they smelled cat urine.
The Telegraph, London
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