Why can’t a domestic cat howl?

Domestic cats can dominate the sofa like lions dominate the savannah, but other than their size, there is another major difference: their vocalizations. While most big cats, such as lions and tigers, can roar to let all unfortunate souls know they’ve wandered into their territory, for comparison, house cats make the most frightening sounds when they want to throw up a furball under the bed in the middle of the night.

Keep reading this article to find out, why domestic cats can’t roar.

Either purring or roaring: you can’t have both

Their lack of this ability is related to the physiology of their vocal cords and throat. Because purring and howling are produced in different ways, these sounds are mutually exclusive. Cats that can howl cannot purr, and cats that can purr cannot roar. A purr is a unique sound that is only considered a true purr when the sound is made as the cat inhales and exhales. Examples of felines that can purr include the domestic cat, the lynx, the ocelot, the cougar and the cheetah as well.

“Roaring is much rarer among cats and evolved in a particular lineage of large cats” John Wible, curator of mammals at the Carnegie Museum of Natural History in Pittsburgh, explained to Live Science. These cats form the Panthera genus, which includes lions,  tigers, jaguars, leopards and snow leopards. There is one exception, however: the snow leopard may have lost their ability to roar according to Wible and a study published in the Journal of Anatomy.

Why domestic cats can’t roar

As in humans, the sounds made by cats come from the vocal cords, the larynx. The difference between purring and roaring cats starts here. Roars come from the flexible bones in the throat, the hyoid bones. The vocal cords of mammals are located in the throat, where air passing through them vibrates them to produce sounds. The hyoid bone and the vocal cords are two essential parts of the larynx that also provide vocalization in cats. “All mammals have bones in their neck close to the lower jaw that are the hyoid apparatus, and these bones have a connection to the base of the skull, either directly or via ligaments.” One major difference between roaring and purring species lies in the hyoid bone.

“The roarers have a unique arrangement for one pair of the bones of the hyoid apparatus, called the epihyoids. Rather than bone, the epihyoid is an elongated elastic ligament.” – explains Wible. The elastic cartilage allows animals to lower the vocal cords in the throat, producing a deeper sound.

In veterinary anatomy, the hyoid apparatus refers to the bones of the tongue – a pair of stylohyoids, a pair of thyrohyoids and the odd basihyoid – and the associated upper gular connective tissue. In humans, the single hyoid bone is the equivalent of the hyoid apparatus.

The mystery of purring

Another major difference between roaring and purring cats lies in the vocal cords themselves which are fundamental to purring. Purring is caused by the extremely rapid twitching of the vocalis muscle in the vocal cord. Roaring cats have longer, heavier, more flexible, fleshy, fatty layers in their vocal cords. This tissue is strong and flexible, allowing these big cats to produce a low-pitched howl. According to research published in the journal PLOS One in 2011, it prevents them from purring.

Whatever the evolutionary advantage of purring was – it must have been there for it to persist in felines after all these years – scientists are not yet sure what it was. Theories include the suggestion that purring is a healing or calming mechanism. But it could also help mask kittens’ meowing from predators.