The mysterious marvellous purr

The purr mecanism isn’t well known yet : we know purrs is a low frequency vibration (20 to 150 Hz) originated in the cat’s larynx, and that it can work both in inspirations and expirations, making the purr constant. We thought that activated vocal muscles were creating the purr. However a study published in 2023 shows purr can also happen passively, without neural input indicating that the activated vocal muscle are probably just an enhancement of the purr. So yeah. We go on the moon, build I, but even though we live with cats for nearly 10 000 years but we still are not sure how they purr ;)

But how?!

We don’t know how, but we have good theories on why. It is believed that purr is used in intraspecific (= cat to cat) communication, specially in kitten and mother relationship. Kittens learn to recognize their mothers’s purr and it plays a role in the emotional development and stability of the kittens. Kittens starts purring at 2 days old and purr is probably used to reassure both mother and kittens of eachother's presence. There is however no scientific consensus whether the purr is used to communicate between adult cats.

Communication purr

Yes, cats purr when they are happy and content. But purr can also express pain, stress and fear : your vet can vouch that a lot of cats purr while dying or are put to sleep. Purring is a self-soothing behaviour: probably linked to safe juvenile memories, it helps to reduce the stress. So how do you know if a cat is purring out of contentment or stress?
Well, as usual, behaviours should be interpreted as a whole and depend on the context : if your cat body is relaxed, slowly blinking or closed eyes, and shows no signs of stress, then this probably is a happy purr. If your cats eyes are wide open, pupils dilated, tail flinching, flatten or facing backward ears, then it is probably a distress purr. If you were petting your cat, it is time to stop.

Self-soothing:

Good news, purring also have benefits on humans -who said cats are selfish ?- Purrs have a soothing effect on us too, it helps lower the blood pressure and with mental health. For people who aren't lucky enough to live with a cat, you can actually find purr recording on internet to help you fall asleep or calm your anxiety down.

La ronronthérapie :

Next time someone asks you to do something while your cat is purring on your lap, just innocently answer : « Ah, I'd like to but I can’t stand up, I'm sorry : I am in a middle of a purr therapy »

Most felines -except for some species in the Pantherinea genra on which scientists still debate-, can create a vibration called a purr. Purrs are often interpreted by human as a sign of hapiness but purring is way more complicated than that and has several different purposes. Let’s deep into them.

Low frequencies vibrations are prooven to reduce blood pressure, lessen stress and even facilitate bones and other tissues regeneration. As the whole body of the cat vibrates while purring and the purr occurs in those healing frequencies, it isn’t far fetched to believe that purring has some self-healing benifits. Purring may help cats produce ocytocine and endorphine, and recover from injuries, isn’t it badass ? This ain’t magical though : contrary to the urban legend, cats do not always heal faster than dogs, neither have nine lives.

They do have a longer lifespan than dogs though, but other factors such as better genetic diversity, high pain tolerance or healthy grooming habbits might be also involved.

Sources:

https://www.youtube.com/watch?v=1fKkIJCoCR8&ab_channel=ThePurringJournal

https://effervesciences.info/index.php/2021/02/10/transformez-votre-portable-en-ronronnette/


C. T., Herbst., & al. (2023). Domestic cat larynges can produce purring frequencies without neural input. Current Biology, 33:4727-4732.e4. doi: 10.1016/j.cub.2023.09.014

David, Reby., Andrey, Anikin. (2023). 1. Vocal communication: The enigmatic production of low-frequency purrs in cats. Current Biology, doi: 10.1016/j.cub.2023.10.033

(2022). Corrigendum to ‘Recognising and assessing feline emotions during the consultation: history, body language and behaviour’. Journal of Feline Medicine and Surgery, 24:e678-e678. doi: 10.1177/1098612X221142200

K. McComb., & al. (2009). 7. The cry embedded within the purr. Current Biology, doi: 10.1016/J.CUB.2009.05.033

Elizabeth von Muggenthaler; The felid purr: A healing mechanism?. J. Acoust. Soc. Am. 1 November 2001; 110 (5_Supplement): 2666. https://doi.org/10.1121/1.4777098

R.C. de Lucenia & al. (2023) Role of the cat-human bond in supporting the tutors' mental health Brazilian Journal of Animal and Environmental Research DOI:10.34188/bjaerv6n2-055

Sollicitation purr

Self-healing vibrations:

Cats have exceptionnal adaptation skills and it seems their can adapt their communication to the audience. For example, adults cats’ meow are only directed at humans, cats do not meow to communicate with each other - they can however use other vocalisations-. Well, it works with the purr too : cats asking their human for food use a slightly modified purr. Called ‘sollicitation purr’, it is more high pitched, and is at a similar frequences than kittens' or babys' cry (520 Hz). In nature, adult cats find their own food, since we treat our cats like kittens by feeding them, they maintain their juvenile behaviour with us. The purr is discribed as less pleasant and more urgent than the usual purr by humans and is probably increasing the chances/speed of feeding. Even people not used to cats can ear the difference* and scientists speak of a « cry embeded in the purr ».

* Try it yourself: click here to listen to a normal purr and click here to listen to a sollicitation purr.

Lunarbaboon

Tigers, lions, panthers etc. can roar but they cannot purr.
Nobody is perfect.

jessiedoodles

To conclude, here is a piece of useless knowledge to shine (or not) in social events: did you know that cats never purr when sleeping? They might meow in their dreams but they never purr.
Well, now you do. You're welcome. ;)