this is from a book entitled
“ #Catwatching” by #DesmondMorris:
The answer seems obvious enough. A purring cat is a contented cat. This surely must be true.
But it is not. Repeated observation has revealed that cats in great pain, injured, in labor,
and even dying often purr loud and long (this I have experienced several times). These can
hardly be called contented cats. It is true, of course, that contented cats do also purr, but
contentment is by no means the sole condition for purring. A more precise explanation,
which fits all cases, is that purring signals a friendly social mood, and it can be given as a
signal tp, say, a vet from an injured cat indicating the need for friendship, or as a
signal to an owner, saying thank you for friendshp given.
Purring first occurs when kittens are only a week old and its primary use is when they are
being suckled by their mother. It acts as a signal to her that all is well and that the milk
supply is successfully reaching its destination. She can lie there, listening to the grateful
purrs, and know without looking up that nothing has gone amiss. She in turn purrs to her
kittens as they feed, telling them that she too is in a relaxed, cooperative mood. The use
of purring among adult cats (and between adult cats and humans) is almost certainly
secondary and is derived from this primal parent-offspring context.
An important distinction between small cats, like our domestic species. and the big #cats,
like #lions and #tigers, is that the latter cannot purr properly. The tiger will greet you with a
friendly “one-way purr” – a sort of splutter – but it cannot produce the two-way purr of
the domestic cat, which makes its whirring noise not only with each outward breath
(like the tiger), but also with each inward breath. The exhalation-inhalation rhythm of
feline purring can be performed with the mouth firmly shut (or full of nipple), and may
be continued effortlessly for hours on end if the conditions are right. In this respect small
cats are one up on their giant relatives, but the big cats have another feature that
compensates for it – they can roar, which is something small cats can
never do."
