Sam: Welcome to the Sound of Science on WNIJ. I’m Sam Watt.
Jeremy: and I’m Jeremy Benson. We’re here from NIU STEAM to answer your questions about anything to do with science, technology, engineering, and math.
S: Jeremy, we have a cuddly question from Kim today. Kim wants to know how and why cats purr?
J: That’s a question that I have wondered myself. Our co-worker Kate has two cats at home, Betsy and Irma, and they purr so differently and at different times. Betsy purrs when you just glance in her direction and Irma really makes you work for a purr.
S: So are cats trying to communicate with you when they purr?
J: Well according to research, cats purr when they are happy and content but also when they’re scared or stressed out.
S: Wait, those are different types of situations -- why would they purr in both?
J: Researcher liken it to humans smiling when they are stressed or scared. We smile and laugh nervously to release tension, or to show others that we’re friendly. Cats do the same thing with purring. But purring might a role other than communication.
J: Purring occurs at a low audio frequency. It has been suggested that this can trigger the production of a hormone that relieves stress or reduces pain. This calming effect can be seen in humans as well! What’s more: Purring is even thought to help heal injuries – like broken bones!
S: Whoa, purring is serious business. How do cats control the frequency?
J: Cats vibrate their vocal chords very quickly so when then inhale and exhale the purring sound is created.
S: I saw a video of someone petting a cheetah and the cheetah was purring like crazy!
J: Big cats purr too! But only some big cats purr. As far back as the 1800s researchers knew that felines can either purr or roar, not both.
S: Really? Why’s that?
J: Scientist aren’t sure. They used to think it was a physical distinction, but that’s been debunked. What we do know is that cats that live in groups -- like a pride of lions -- roar to communicate and keep their family members safe. Cats that are solitary -- like ocelots or house cats -- don’t need to roar to communicate; but they can purr.
S: I think it’s cool that we’ve been living with cats for thousands of years and we’re still learning about them! Thanks Jeremy.
J: Keep those science questions coming to us at stemoutreach@niu.edu. This has been the Sound of Science on WNIJ.
Sam: Where you learn something new every day.
