The secrets of a cat’s purr
As any cat owner will tell you, there’s nothing quite like snuggling up with a purring cat. There’s something very relaxing – almost hypnotic – about this very unique and frankly odd animal vocalisation. But what does it mean? And how, exactly do they do it? Well, it turns out that purring is a lot more complex than it might first seem – yet more proof (as if we needed it!) that our furry feline friends are very remarkable little animals indeed.
Let’s start with the easy bit – how they do it. Cats purr by using their laryngeal muscles to vibrate their vocal cords at a frequency of between 25-150 vibrations per second. When they breathe in and out, air passes over their vibrating vocal cords, creating the purring sound. If you listen closely to your purring cat, you may even be able to hear when your cat switches from breathing in to breathing out and back again. So it’s all very straightforward, right?
Not so fast, because now things begin to get a bit more complicated…
Why do cats purr?
The simple answer, as we all know, is that cats purr because they’re warm, cosy and content, preferably when curled up on a human’s lap. But is there more to it than that? Perhaps we can learn more if we first look at when cats purr.
When do cats purr?
While it’s true that they purr during moments of extreme relaxation, they also purr at times of great stress or pain, such as during a visit to the vet and even when giving birth.
Scientists now believe that cats purr as a way of calming themselves down, meaning they’re just as likely to do it in a stressful or painful situation as they are when melting into their owner’s lap. The low-frequency vibrations that purring creates inside the cat’s body help them to ease their breathing and soothe tension away. But there’s more – incredibly, scientists also believe that these vibrations can help heal injuries, repair and build muscles and even act as painkillers, which might explain why injured or sick cats choose to expend valuable energy on purring. It might also explain why cats have a tendency to recover quicker than dogs from surgery, and suffer fewer complications.
If purring is so healthy for cats, is it also healthy for me?
Yes! A long-term study carried out by the University of Minnesota Stroke Centre found that cat owners were less likely to die from cardiovascular disease compared to non-cat owners – and some people have suggested that exposure to purring might be part of the reason for this. Which leads us to an obvious question: if purring is so healthy, why don’t we humans do it? It’s clear that we’ve missed an evolutionary trick here, so instead we’ll just have to rely on our cat friends to keep us healthy.
What if my cat doesn’t purr?
Each cat purrs in a different way, and at a different volume. The world record for purring volume was set by a cat from the UK called Merlin, whose purr was recorded at 67.8 decibels – about the same as a vacuum cleaner! Other cats purr in almost complete silence, and the only way to tell they are doing it is by touching their neck or throat to feel the vibration. That said, there are some cats that don’t appear to purr at all, and, barring an injury to the vocal cords, scientists are still trying to understand why. Feral cats are more likely to be non-purrers than domestic cats, leading to a theory that feral cat mothers discourage purring in their kittens to stop them attracting predators.
Do cats purr for any other reason?
Scientists have identified a particular type of purring, known as the ‘solicitation purr’, that cats appear to use exclusively as a means of obtaining something from their human friends – either affection or food. The ‘solicitation purr’ is a like a cross between a meow and a purr, and is very close in frequency to the sound of a crying baby – a noise we are naturally programmed to respond to.
So there we have it – our cats are manipulating our emotions in order to get food…which will come as no surprise to anyone who’s ever owned a cat!