Verified answer

Aaahhhhhh - this is a question that still has no answer. It is an ongoing dilemma that has many theories.

It probably is not the vocal cords as cats can still talk and purr.

An interesting fact of purring is that it appears that cats purr when emotion is very high - they purr in joy ( as we all know ) but also purr when in pain.

A very interesting fact I read about a year ago is that seems the sound frequency of a purr appears to improve and speed up bone repair!! Fascinating.

Personally however I find it one of the most glorious sounds, especially when it is coming from the bundle in your arms or on your lap!!

No one knows for sure...they've been studying it for a while but no one knows. So your guess is as good as mine.

Did you know that cats can see color? They just don't care.

Noone really knows, but here is a link to read about it!