Why Do Cats Purr?
Cat Purring starts in the brain and then it usually travels down neural pathways into the larynx (throat) and the diaphragm causing oscillations. These oscillations move air across the larynx and cause a vibration which is what we audibly hear as the purr.
Through these oscillations, interestingly enough, there are about 250 vibrations per second! We have been able to determine the levels of purring due to the hertz, pathways and emotions that create these vibrations leading to different types of purring.
It all comes down to emotion communication. For example, Queen cats (mother) will communicate with their newborn kittens by purring. Since the kittens do not have their eyes open, this is how the mother lets them know that they are near them. Kittens also begin to purr early in their life to communicate with their litter mates that it is time to eat.
Purring in adult cats is typically a content expression of emotion. Along with their body posture communicating that they are comfortable and happy, purring also lets us know this.
Cats are so unique for so many of their features but mostly due to their purring.