The purring of cats is something we find very appealing.
They are able to vibrate their vocal chords as they breathe in and out to produce that rhythmic vibration we call a purr, in a similar way to human speech.
Research suggests a cat can purr in different ways and for various reasons.
Kittens are born blind and deaf and they begin purring after just a few days to attract their mother’s attention at feeding time. Cat owners are often treated to a coercive display of purring around dinner time.
Cats can manipulate their purr. Researchers found that, when purring to solicit food, there is a concealed cry within their purr similar to the cries of a human baby. This triggers a nurturing response in their human owners.
Cats often purr when people stroke them so we associate purring and the cat’s pleasure. They may also be trying to encourage further interaction as if to say ‘please continue to stroke me’. But the benefit is not all one way. The purring of a cat has a calming effect on people and cat owners, for example, have a 40% lower risk of having a heart attack.
We usually associate purring with contentment However, even though it takes energy, many cats purr when they get hurt or are in pain. So what makes the effort worth it? The purr generates strong frequencies between 25 and 150 Hz. Various researchers have shown that sound frequencies in this range are optimal for pain relief and can improve bone density and promote healing of bones and muscles.
In general, the easiest way tell why your cat is purring is to check their body language and the context. If the purring is first thing in the morning maybe they’re simply asking to be fed. If you just returned from a day at work they may be saying hello.
And if they are sitting on your lap purring contentedly? Hey, don’t overthink it, just relax and enjoy the moment.
For more reading, try this New Scientist article Why do cats purr?