The mystery behind why cats really purr
<p>The purring cat is considered the perfect picture of contentment but there’s much more to purring than meets the ear.</p>
<p><strong>The mystery behind purring</strong></p>
<p>Just how cats purr has long stymied the scientific community because there’s no special apparatus in their body that enables them to purr. Most people agree now that purring begins at the brain – a repetitive neural oscillator triggers the laryngeal muscles (voice box) to twitch at the rate of 25 to 150 vibrations per second (Hz). This causes a sudden separation of the vocal cords, which allows cats to both inhale and exhale. Once the air hits the vibrating muscles, the feline purr is created.</p>
<p><strong>The original function for purring</strong></p>
<p>Purring is vital for newborn kittens. Born deaf and blind, they feel the soft vibrations of their mother’s purr which guides them to the protective warmth of her body. Kittens also communicate via purring, learning their first skill within a few days on the earth. They cannot meow and nurse at the same time so they can purr to let their mother know “all is well.” The mother reassures the kittens by purring back. This form of communication continues into their adult lives, and it’s why cats instructively purr when petted; they are signalling to you “all is well”.</p>
<p><strong>The healing powers of purring</strong></p>
<p>But cats also purr when they are frightened, distressed or threatened. Sick or injured cats purr too. Indeed, cats may purr while giving birth and often cats at the end of their life will purr. Animals experts believe purring could be a mechanism that helps cats rest, repair and calm itself.</p>
<p>Clinical trials of people receiving ultrasound treatments have proven that low-frequency ultrasound helps wounds and fractures heal faster. The low 25 Hz frequency of the cat’s purr could be a kind of built-in physical therapy for cats.</p>
<p><strong>The purr-suasive purrs</strong></p>
<p>While some purrs are barely audible unless you’re close to your cat, there are others which are very insistent purrs. Karen McComb from the University of Sussex in the UK decided to explore the characteristics of insistent purrs after wondering why her own cat was so annoying in the morning. Her study found that some cats had developed a special type of purr when they want human attention. They add to the basic low purr a high-frequency cry-meow that people find more annoying and urgent. Known as the “solicitation purr”, it is usually employed when cats want to be fed sooner rather than later.</p>
<p><strong>Purring is good for humans too</strong></p>
<p>Rebecca Johnson, director of the Research Centre for Human Animal Interaction, told Pet MD: “Purring is an auditory stimulus that people attribute to peacefulness and calmness.” Whether that’s actually true or not, it “gives us positive reinforcement for what we’re doing and can contribute to the whole relaxation effect when we interact with our cats,” she said.</p>
<p>We’re not arguing with that if we can pet our cats more!</p>
<p><em>Image: Getty Images</em></p>
