Why Do Cats Purr?

Cats purr when satisfied, in pain, giving birth and dying- indicating that they purr for a variety of reasons, whether they are stressed or happy.

Kittens that purr during nursing appear to be signaling that they are safe and healthy to their mother. Likewise, the mother may purr during nursing to help guide her kittens; it is also thought that purring is an essential part of mother-kitten bonding.

Research at the University of Sussex showed that cats are capable of masking a high-pitched cry within their purr that nears the frequency exhibited by the cries of human infants. This unique purr appears to be linked to the cat's desire to eat and is used to grab the attention of its human caretakers.

The origins of a purr are what set it apart from other vocalizations, in that these rhythmic vibrations are produced during the entire respiratory cycle, whereas other vocalizations are produced solely during an exhalation of breath.

The purr begins with a signal created by the neural oscillator, a cluster of neurons that intermittently fires and rests, which triggers the rapid oscillation of the larynx. These muscles are used to open and close the glottis, the folds that separate the vocal chords. These contractions vibrate the voice box during both inhalation and exhalation, allowing the purr to continue through a wide variety of circumstances.

While some believe that the purr may be used to signal good intentions, another purpose for the purr is almost universally accepted by veterinary authorities and experts. A cat's purr produces a therapeutic, analgesic and healing effect.

Most purring occurs at about 26 Hertz, a frequency which helps build bone density and promotes tissue regeneration, something normally only attained through high-impact exercise.

Currently, these healing vibrations are being explored for their possible benefits to humans.

Similarly, NASA has divulged some of its research into a Gravity Loading Countermeasure Skinsuit (GLCS) meant reduce or counteract the bone loss experienced by astronauts during long-duration spaceflights by using vibrations that operate similarly to a cat's purr.