She says there's also a hunting meow and a kind of trilling meow mother cats use with their kittens. So meows are a versatile form of communication. Purring, on the other hand, is simply a sign of comfort. Dr. Houpt says that unlike meowing or human speech, purring isn't the result of air passing over the vocal cords. It's a vibration of the larynx that resonates down to the windpipe and into the diaphragm.
Kittens use it to communicate quietly with their mothers while they're nursing.
And that's probably why it continues to be a behavior that they show when they are comfortable. If we use it on the show you'll get a purr-fect Science Update mug. For the American Association for the Advancement of Science, I'm Bob Hirshon. To listen to back archives, visit the Science Update website. All rights reserved.