We all know this sound…
It’s a cat purring. But how and why do they make this sound?
The truth is, no one knows for sure, but there are quite a few theories as to why cats purr. It’s thought that kittens learn how to purr when they’re just a few days old. This early purring is a way for them to communicate to their mom that they’re close by and doing just fine.
In this way, purring also acts as a bonding mechanism between baby and mama cats. But, as we know, cats continue to purr as they grow older.
It’s thought that cats purr to express pleasure and contentment. Or as a general form of close communication, since purrs can’t travel very far.
And because purring usually occurs in close social situations like grooming or nursing.
But cats can also purr when they’re injured and in pain.
Research scientist and bio-acoustic specialist Dr. Elizabeth Von Muggenthaler suggests that the low frequency vibrations that purring produces act as a “natural healing mechanism”.
In this sense, it is also thought that purring can be a tool used by cats to calm themselves when they’re in a particularly stressful situation.
Some veterinarians have even observed cats lying next to each other purring when one is injured in a behavior known as “purr therapy”.
Dr. Von Muggenthaler also believes that purring may have bone healing properties. She found that cats purr in the range of 20 to 150 Hertz.
Which, according to the American Society for Bone and Mineral Research, is the frequency range that induces increased bone density.
The thinking behind this theory is that as cats spend time lying around waiting to hunt, purring stimulates their bones and prevents them from becoming weak or brittle.
Another theory suggests that cats purr to communicate peaceful intentions and to signal that they’re not going to attack.
Older cats, for instance, have been found to purr when approaching younger ones to communicate friendly intentions.
So there’s many reasons why cats purr, and each purr should be analyzed in context.
And it’s not just house cats.
Bobcats, pumas, and even cheetahs have been found to purr.
Meanwhile lions, leopards, jaguars, and tigers can’t. But they can roar.
In fact, early 19th century taxonomists thought that cats could either purr or roar, and split them into subfamilies along these lines. The purrers are grouped in the subfamily Felinae, and the roarers are in Pantherinae.
But today it’s believed that most cats—big and small—can purr, barring the exceptions I just mentioned.
But how do purring cats actually purr?
The most widely accepted idea is that a cat’s brain will signal to its laryngeal muscles in its voicebox to vibrate.
The muscles open and close the glottis, which is the space between the vocal cords, and allows air to pass through the voicebox and causes the purring sound.
One reason why researchers are confident that this is how purring works is because cats with laryngeal paralysis can’t purr.
But given the vast array of possible reasons cats purr, the jury’s still out on whether cats purr voluntarily or if it’s an involuntary reaction.
So the next time your cat purrs, listen closely. You might just learn something.