PURRING

[darren.naish@port.ac.uk]

How the thread wound round to this I have no idea, but, anyway, Dann 
Pigdon wrote..

> AFAIK only cats in the genus Felis pur. I don't think any of the
> Panthera do (I know that lions don't anyway). Nit picking, I know,
> but it's so rarely that I'm right about something, I'm trying to
> bring the percentage up to at least 51%.  :)

Nope. All cats purr - yes, even the big ones. A primary difference 
between _Panthera_ cats and all the others (there is no true big 
cat/small cat dichotomy as people use to think) is that _Panthera_ 
cats have a fully ossified hyoid which can only vibrate on 
exhalation. Therefore _Panthera_ cats only purr on out-breaths.

Other cats, in contrast, have an incompletely ossified hyoid which 
can vibrate both on exhalation and inhalation, viz. purring on in- 
breaths and out-breaths. In theory, therefore, if you hear purring 
but cannot see the purrer, you could work out if it was a _Panthera_ 
cat or not. This is why some zoologists believe that the Nunda 
(=Mngwa), a large grey cat from east Africa unknown from specimens, 
is a large _Profelis_ (golden cat). 

Purring, as a low-frequency noise that obscures the whereabouts of 
its origin, benefits mutual grooming and bonding in social cats when 
they den in obscured areas. One more thing: it is said that when you 
gently squeeze a cat's trachea, it will stop purring. This never 
works when I try it.

"To die would be the best adventure of all"

DARREN NAISH
darren.naish@port.ac.uk