We always equate the purring of cats to feelings of happiness, friendliness, and contentment. It is almost equivalent to the soft bark of a dog that is so happy to see its owner. But then it would also not be right to think that a purring cat is always a friendly and happy cat. It could also be a sign that it is in distress, in pain, or hungry. Think of it this way: A person who laughs does not always mean he is happy. That’s the same thing with a feline purr. So, why do our feline friends purr? The things you’ll learn here may surprise you.
How a “Purr” Occurs
Everything starts in the cat’s brain. Something triggers the feline brain into sending electrical signals to the muscles of the larynx or voice box. The resulting contractions of these muscles lead to the creation of vibrations at a rate of between 25 and 150 per second. These vibrations separate the vocal cords at the same rate during both inhalation and exhalation. It is this passage of air through the vibrating vocal cords that produces the purring sound.
Since everything starts with the stimulation of the brain, the bigger question is what can “trigger” it? Looking for the answers to this question may be quite challenging, owing to the fact that no one has ever fully understood the inner workings of the feline brain. The best answers that we can provide come from observations and anecdotal evidence.
If a Cat Roars, Then It Cannot Purr
We said that the purring sound is the result of air passing through the vocal cords that are vibrating at a very rapid rate. Here’s one thing that should surprise you. Cats that roar cannot purr. Conversely, a feline that purrs can never roar.
The reason is simple. Cats that roar have a very different laryngeal anatomy. Instead of having an epihyal bone, these cats have a ligament that can stretch as far as the big cat can open its mouth. The greater the extension of this ligament, the deeper the sound that it produces. Moreover, the vocal cords of cats that roar are fleshy and unbroken. In other words, they are stiffer and do not produce vibrations that are critical in the production of the “purr” sound.
As such, lions, tigers, jaguars, and leopards can produce the loudest roar that can reverberate throughout their territory. However, as large and ferocious as these big cats are, they can never “purr”. On the other hand, domestic cats and other “small” cats can purr, but can never roar.
There is this theory that states big cats developed their ability to roar because of the very nature of their existence. Being top predators of the land, they had to move around a lot so that they can catch prey. Unfortunately, doing so leaves their territory exposed to other predators that might want to enter the scene. As such, roaring is the big cat’s way of announcing “hey, this is my territory”.
On the other hand, small cats tend to have a smaller “hunting” ground. They are more solitary, too. As such, they do not feel the need to compete with other cats for prey. Instead, they rely on their urine and other bodily scents to mark their territory.
Purring as a Cat’s Way to Get the Attention of Its “Mommy”
While big cats roar to “communicate”, small cats also “purr” to communicate. It may not be about their territory, but the message is something a lot closer to their hearts.
There are a few studies that show domestic cats purr as a means to appeal to the nurturing instincts of their mother figures. When cats purr in a particular way, they often produce the sound within the frequency range of about 220 to 520 hertz.
What is surprising is that the cries of human babies are also within this frequency range; between 300 and 600 hertz to be precise. This means cats are using the same sound frequency to appeal to the nurturing instincts of their human owners.
Come to think of it, a baby’s cry is enough to make a mother stop whatever she’s doing and go to the aid of her baby. The baby may be hungry, has soiled its diapers, is in pain, or needs some form of comforting. Whatever the reason is, a baby’s cry is enough to trigger the nurturing instincts in moms.
Hence, when a feline pet purrs, it is trying to appeal to your nurturing instinct. It is getting your attention. The cat wants you to pick it up and comfort it. Or, it may have learned in the past that purring is a nice way to tell you that it’s your pet’s meal time. Whatever it is, the sound of the purr is enough to get your attention.
Purring as a Kitten and Mother Cat’s Way of Conveying Contentment and Safety
While we’re already in the kitten-mother cat relationship, let’s expand a little bit. We know that a certain type of purring can mean that the cat is trying to get its owner to nurture it. However, there is another type of purring that communicates a message of being safe.
The first few days in a kitten’s life are dark and quiet; they come out into the world blind and deaf, that’s why. As such, they have to rely on the vibrations that their mommy produces for guidance. These vibrations serve as a homing beacon, a light tower at the edge of a treacherous seaside cliff. Kittens follow these vibrations so that they will feel the warmth of the mother cat and give them invaluable protection. It’s also what guides them to their meals.
By the time kittens reach two days old, they start purring back. They do this because they cannot produce the characteristic “meow” of a cat yet. This is comforting for the mother. It knows that its kittens are responding well to the nurturing that it provides. Kittens purr as a way of saying they are content, happy, and safe. Mommy cat purrs back, further reassuring the kittens.
Purring also helps protect kittens from predators that are more inclined to home in on the characteristic “cries” of young ones. Purring involves the production of vibrations, something that predators do not “consider” as a sign of prey.
Producing vibrations instead of sound is also beneficial for a cat that’s about to give birth. If it “meows” or produce other vocalizations, there is a good chance that predators might hear its cries. This is not only dangerous to the mother cat, but also to its newborn kittens. As such, it tries to purr instead of meow. Plus, it’s now known that purring can release endorphins. This can help alleviate pain associated with giving birth. It is also more reassuring for the newborn kittens, telling them that everything will be okay.
Purring as a Cat’s Way to Heal Itself
We mentioned above that purring can stimulate the release of feel-good endorphins. Whenever we talk about endorphins, we always think about painkillers and antianxiety agents. This can aid cats in alleviating pain and anxiety.
Clinical trials involving patients with fractures show that low frequency ultrasonic therapy can accelerate the process of bone repair and healing. Now here’s something that we’re sure will surprise you. There’s a certain type of purr that occurs in the low frequency range of about 25 to 100 hertz. Given that the human bone is denser than that of a cat, the implications to feline fractures are immense. It goes to show that purring can help cats reduce pain, promote healing, and provide an overall sense of wellbeing.
Check out our guide on Cat Window Perches for more info.
Purring as a Form of Feline Exercise
This may come as a surprise. Some cats purr in an effort to stimulate bone and muscle growth. It is their equivalent to weight-bearing exercises in humans. Most people may have a difficult time believing this but it does have clinical evidence in the human world.
Astronauts that NASA sends to space use vibration therapy to stimulate their muscles and prevent muscle atrophy. Because there’s no gravity in space, astronauts are not able to perform exercises in an efficient way as they would on Earth. Vibrations stimulate the muscles to maintain their tonicity and strength. Bones also get stimulated and prevent the resorption of bone minerals into the blood.
So you see, a cat purring does not always mean that it is happy to see you or that it’s time for its food. It may be purring because it is exercising its muscles. In a way, you can say that the cat knows more about exercises than some of us.
Cats purr for different reasons. It can be to convey happiness and contentment or as a sign of feeling safe. It can also mean that the cat is trying to heal or soothe itself. Some may also purr because they want to exercise. So, the next time your cat purrs, think of these reasons before jumping into a very common conclusion.