Most of us know that large wild cats, such as tigers, lions, jaguars, and leopards, can definitely roar. But did you know that because they can roar, they lack the ability to purr? Conversely, the domestic cats we know and love purr their hearts out, but they cannot roar.
The fact that our feline friends purr is one more reason to love them, but that doesn’t mean the mechanism is fully understood. A closer look at why cats purr, and how they do it, may generate an even greater appreciation for these amazing animals.
The Subtle Art
Cats purr for a variety of reasons. Most of the time, cat owners recognize purring when their cat appears happy, such as when they knead or during an extended snuggle session. But cats also purr when they are stressed out, afraid, or in pain.
The Purr Instinct
Inside a cat’s brain, a neural oscillator sends a message to the muscles surrounding the larynx in the throat. These muscles vibrate or twitch about 25-100 times per second. The vocal cords spread apart with each inhale and exhale, thus producing a purring sound. What’s more, purring occurs at certain frequencies that actually support bone growth and regeneration. Vibrations may also repair muscles, soothe aching tendons, and reduce swelling and pain.
In other words, cats purr to heal themselves, or make themselves feel better.
Not All Cats Purr
How come some cats cannot purr, but they can roar? It has to do with their anatomy. The U-shaped bone in the neck that supports the tongue is called a hyoid. Some evidence suggests that the hyoid of roaring cats is incompletely ossified, or turned into bone or bony tissue. Their larynxes aren’t rigid enough to create the purr. Purring cats, on the other hand, have completely ossified hyoids that helps them make the purring sound.
Alternatively, some experts believe that cats purr simply because of the neural oscillator that triggers the action and the sound, and not the hyoid.
Many Others Do, Too
Many other animals purr. Raccoons, bears, hyenas, guinea pigs, squirrels, foxes, badgers, lemurs, and even gorillas purr. Also, certain large wild cats like cheetahs, pumas and snow leopards are known to be purring cats rather than roaring cats.
Roaring cats have to move around a great deal in order to catch prey. By roaring, large cats stake out territory and warn those that threaten their community. Purring cats are much smaller and depend on scent-marking instead of roaring.
Cats Purr for People
There is reason to believe that cats purr to communicate with the people they live with. Hidden within this sweet sound can also be little cries or vocalizations that seem to trigger our nurturing instincts – frequencies of cat purrs are of a similar range to the cries of human babies. This, in turn, stimulates our own positive health properties, such as lowered blood pressure. Cat owners may be 40% less likely to have heart attacks than those that don’t experience the powerful nature of cats.