1 00:00:02,040 --> 00:00:09,920 Speaker 1: Welcome to brain Stuff from how Stuff Works. Hey, I'm 2 00:00:10,000 --> 00:00:13,119 Speaker 1: Christian Sagar and this is brain stuff. Let's get something 3 00:00:13,160 --> 00:00:16,680 Speaker 1: straight about cats right away from the beginning. Not all 4 00:00:16,720 --> 00:00:20,239 Speaker 1: cats can purr. In fact, there's two kinds of cats, 5 00:00:20,520 --> 00:00:24,040 Speaker 1: the ones that purr and the ones that roar. For instance, 6 00:00:24,160 --> 00:00:27,200 Speaker 1: none of the panther knee I subfamily of cats can 7 00:00:27,240 --> 00:00:32,400 Speaker 1: pur This includes lions, leopards, jaguars, and tigers, but boy 8 00:00:32,520 --> 00:00:35,640 Speaker 1: can they roar. The cats that can purr include our 9 00:00:35,680 --> 00:00:38,680 Speaker 1: common domestic cats, as well as big cats that can't roar, 10 00:00:38,840 --> 00:00:43,920 Speaker 1: like bob cats, cheetahs, lynxes, pumas, and wildcats. These are 11 00:00:43,920 --> 00:00:46,080 Speaker 1: the ones we care about, right because it feels like 12 00:00:46,120 --> 00:00:48,879 Speaker 1: they're sharing their contentment with us when they're happy, and 13 00:00:48,880 --> 00:00:52,519 Speaker 1: we're just playing fascinated with cats because well, you know 14 00:00:52,920 --> 00:00:56,520 Speaker 1: the Internet. But how did these non roaring cats actually 15 00:00:56,560 --> 00:01:00,480 Speaker 1: do the whole purring thing anyway? Well, the most accepted 16 00:01:00,520 --> 00:01:04,080 Speaker 1: idea is that a cat's brain signals the laryngeal muscles 17 00:01:04,120 --> 00:01:07,960 Speaker 1: in its voice box, so they vibrate. These muscles act 18 00:01:08,000 --> 00:01:10,920 Speaker 1: like a valve by opening and closing the glottis that's 19 00:01:10,959 --> 00:01:14,160 Speaker 1: the space between the vocal cords, and then allowing air 20 00:01:14,280 --> 00:01:17,759 Speaker 1: to flow past the cat's voice box. One reason we're 21 00:01:17,760 --> 00:01:20,160 Speaker 1: pretty sure this is how purring works is that cats 22 00:01:20,160 --> 00:01:24,959 Speaker 1: with laryngeal paralysis can't purr. What makes purring so distinctive 23 00:01:25,120 --> 00:01:28,640 Speaker 1: is that it works when cats are both inhaling and exhaling. 24 00:01:29,200 --> 00:01:31,360 Speaker 1: This is why it seems like they can just keep 25 00:01:31,440 --> 00:01:34,319 Speaker 1: purring forever. And while we have a pretty good idea 26 00:01:34,360 --> 00:01:38,679 Speaker 1: how purring works in the throat, scientists don't exactly a 27 00:01:38,080 --> 00:01:42,640 Speaker 1: dent agree on how cats initiate purring. Some believe it's 28 00:01:42,640 --> 00:01:46,520 Speaker 1: a voluntary act, initiated by their nervous system. This would 29 00:01:46,560 --> 00:01:49,200 Speaker 1: mean that cats only purr when they want to, but 30 00:01:49,360 --> 00:01:52,080 Speaker 1: other studies suggest that the pur signal comes from a 31 00:01:52,120 --> 00:01:56,240 Speaker 1: neural oscillator in the cat's brain. Still, another theory is 32 00:01:56,280 --> 00:01:59,280 Speaker 1: that purring is caused by the release of endorphins. When 33 00:01:59,320 --> 00:02:03,240 Speaker 1: cats experien it's either pleasure or pain. That's right. Cats 34 00:02:03,240 --> 00:02:06,360 Speaker 1: don't always purr when they're happy. Sure, we mostly hear 35 00:02:06,400 --> 00:02:09,240 Speaker 1: them do it when we're petting or feeding them and nursing. 36 00:02:09,320 --> 00:02:11,960 Speaker 1: Kittens pur to let their mothers know their well because 37 00:02:12,000 --> 00:02:14,440 Speaker 1: they can't me out and drink milk at the same time. 38 00:02:14,919 --> 00:02:16,560 Speaker 1: So purring is kind of a way for them to 39 00:02:16,600 --> 00:02:19,920 Speaker 1: bond with their mothers and say hey mommy, I'm I'm okay. 40 00:02:20,400 --> 00:02:24,960 Speaker 1: But purring communicates more than just happiness. Upset, injured, sick, 41 00:02:25,000 --> 00:02:28,560 Speaker 1: and even dying cats are known to purr. Female cats 42 00:02:28,600 --> 00:02:32,600 Speaker 1: sometimes per when they're delivering kittens. Animal behaviorists think that 43 00:02:32,680 --> 00:02:37,600 Speaker 1: these cats are purring under difficult circumstances because they're comforting themselves. 44 00:02:38,160 --> 00:02:41,800 Speaker 1: It's also possible that frightened cats per to communicate peaceful 45 00:02:41,840 --> 00:02:45,560 Speaker 1: intentions to signal that they won't attack. Older cats do 46 00:02:45,639 --> 00:02:48,560 Speaker 1: this sometimes when they approach younger cats to say hey you, 47 00:02:48,680 --> 00:02:53,000 Speaker 1: I'm friendly. There's another pretty awesome hypothesis about white cats purr. 48 00:02:53,520 --> 00:02:56,520 Speaker 1: The rapid opening and closing of their vocal cords creates 49 00:02:56,520 --> 00:02:59,880 Speaker 1: a sound somewhere between twenty and a hundred and fifty hurt. 50 00:03:00,639 --> 00:03:04,840 Speaker 1: These sound frequencies can both improve bone density and act 51 00:03:04,960 --> 00:03:08,799 Speaker 1: as a natural healing mechanism. There's evidence that shows purring 52 00:03:08,840 --> 00:03:13,360 Speaker 1: can repair bones, relieve pain, and even heal wounds. This 53 00:03:13,440 --> 00:03:16,400 Speaker 1: goes all the way back to an old veterinary legend 54 00:03:16,600 --> 00:03:19,000 Speaker 1: that if you place a disembodied cat in a room 55 00:03:19,000 --> 00:03:22,880 Speaker 1: with all of their body parts, they can reassemble their bones. Together. 56 00:03:23,560 --> 00:03:26,520 Speaker 1: So wait, if other cats can only roar and not 57 00:03:26,720 --> 00:03:29,240 Speaker 1: pur does that also mean they don't have these crazy 58 00:03:29,280 --> 00:03:36,440 Speaker 1: healing powers. Check out the brain stuff channel on YouTube, 59 00:03:36,520 --> 00:03:38,680 Speaker 1: and for more on this and thousands of other topics, 60 00:03:38,840 --> 00:03:52,520 Speaker 1: visit how stuff works dot com