This warm and wonderful feeling of being snuggled close to mom, being safe and receiving meals on-demand, certainly explains the contentment aspect of the purr.
A Cat’s Purr Serves a Variety of Functions
The purr communicates several different emotional states. The one humans are most familiar with is that a purring cat is content and happy but in reality, cats purr for a variety of reasons and not all of them mean contentment.
The cat’s purr has been compared to the human smile. People smile for a variety of reasons. People smile when happy, nervous, unsure or when trying to make someone else feel comfortable. It’s that way with the purr as well. Cats may purr when happy but also they use it for self-soothing. Cats may purr in an attempt to soothe a potential opponent when they know there’s no means of escape. They may purr when nervous, sick, in pain or even when close to death. This makes sense because of the endorphin release.
Many cats really know how to maximize the purr to their advantage. A study at the University of Sussex in the UK identified that cats have developed a specialized purr referred to as a “soliciting purr.” The specialized purr includes cries at similar frequencies to a human baby cry. Cats seem to be able to ramp up the high frequency in order to get their human family members to feed them. Pretty smart, wouldn’t you agree?
Purring is also believed to be used by the cat for healing. Purrs vibrate at 25-150HZ which is also the frequency that assists in physical healing and bone mending. It may also be that purring during resting is a form of physical therapy to keep the cat’s bones strong since the frequency range of 25-150HZ increases bone density. So even as a cat is napping or resting, he might be keeping his bones strong and healthy and ready for the next opportunity to pounce on prey.
How Purring Helps Humans
We benefit as well when our cats purr. Just stroking a cat has been shown to lower blood pressure and stress. The sound of the cat’s purr near us usually makes us feel more relaxed since we associate purring with contentment. We begin stroking the purring cat and that exchange is very comforting.
What About Big Cats?
Large cats that roar, such as lions, don’t purr but cats who don’t roar can purr, such as cheetahs and bobcats. Cats that purr have a hard hyoid bone located in the throat. Cats that don’t purr have a more elastic hyoid bone. That flexibility of the bone enables roaring but not purring.