This is an infographic which explains definitively in my opinion why domestic cats purr from a behavioral standpoint. There has to be a reason which encompasses a spectrum of circumstances under which domestic cats purr. You can’t simply say that cats purr when content. They do but that’s part of the picture. The infographic provides you with the whole picture and I am thankful for it to Dr Desmond Morris who’ve I mentioned quite a lot because I rely on him quite a lot. His seminal book on cat behavior published 37 years ago is probably the first that really got to the bottom of subject. It is written by a man who truly understands animal and human behavior. And what is particularly great about the book is that it is not dressed up in fancy scientific language. It is written in his clean, clear and elegant style without frills and pretensions. Impeccable.
Remember not all cat species purr. They can either roar or purr but not both. One large cat that purrs is the retiring puma. A sweet cat that also meows. The mountain lion is a big cat physically and a domestic cat vocally.
Healing mechanism? Work in progress
There is a extra issue worth briefly touching on: it is said that the frequency of the purr helps to heal. This may be another reason why domestic cats purr when injured. A study (The felid purr: A healing mechanism? – 2001) found that all 44 felid participants, including domestic cats, produce strong frequencies between 25 and 150 Hz when purring, and these frequencies correspond to vibrational and electrical frequencies used in various forms of therapy for bone growth, pain, edema, muscle growth, joint flexibility, dyspnea, and wounds.
The fact that some of the frequencies produced by purring are specifically beneficial for bone growth and fracture healing (25 and 50 Hz) and for pain, edema, wounds, and dyspnea (100 Hz) suggests that purring may have an internal healing mechanism that helps cats recover faster and keep their muscles and bones strong when they are sedentary or injured. This is particularly true for domestic cats, servals, ocelots, and pumas, which produce fundamental, dominant, or strong frequencies at exactly 25 Hz and 50 Hz and have a strong harmonic exactly at, or within 2 Hz of 100 Hz.
While purring may not always indicate contentment, it is likely that the benefits of purring go beyond expressing pleasure and relaxation. However, more research is needed to fully understand the mechanism behind purring and how it benefits cats in different situations.
Solicitation purr
Cats are smart. Some have evolved a meow/purr to give their request for something an extra edge. And they’ve also included on occasions in a baby cry for added effect!