WEBVTT 00:00:06.739 --> 00:00:08.217 "Hi, Bob." 00:00:08.217 --> 00:00:11.237 "Morning, Kelly. The tulips looks great." 00:00:11.237 --> 00:00:14.966 Have you ever wondered how your dog experiences the world? 00:00:14.966 --> 00:00:16.581 Here's what she sees. 00:00:16.581 --> 00:00:18.696 Not terribly interesting. 00:00:18.696 --> 00:00:22.266 But what she smells, that's a totally different story. 00:00:22.266 --> 00:00:25.381 And it begins at her wonderfully developed nose. 00:00:25.381 --> 00:00:28.400 As your dog catches the first hints of fresh air, 00:00:28.400 --> 00:00:34.725 her nose's moist, spongy outside helps capture any scents the breeze carries. 00:00:34.725 --> 00:00:37.465 The ability to smell separately with each nostril, 00:00:37.465 --> 00:00:39.099 smelling in stereo, 00:00:39.099 --> 00:00:41.797 helps to determine the direction of the smell's source 00:00:41.797 --> 00:00:44.265 so that within the first few moments of sniffing, 00:00:44.265 --> 00:00:48.291 the dog starts to become aware of not just what kind of things are out there 00:00:48.291 --> 00:00:50.695 but also where they're located. 00:00:50.695 --> 00:00:52.303 As air enters the nose, 00:00:52.303 --> 00:00:56.101 a small fold of tissue divides it into two separate folds, 00:00:56.101 --> 00:00:59.151 one for breathing and one just for smelling. 00:00:59.151 --> 00:01:01.140 This second airflow enters a region 00:01:01.140 --> 00:01:04.423 filled with highly specialized olfactory receptor cells, 00:01:04.423 --> 00:01:08.534 several hundred millions of them, compaired to our five million. 00:01:08.534 --> 00:01:12.391 And unlike our clumsy way of breathing in and out through the same passage, 00:01:12.391 --> 00:01:15.313 dogs exhale through slits at the side of their nose, 00:01:15.313 --> 00:01:19.491 creating swirls of air that help draw in new odor molecules 00:01:19.491 --> 00:01:24.148 and allow odor concentration to build up over mulitple sniffs. 00:01:24.148 --> 00:01:27.716 But all that impressive nasal architecture wouldn't be much help 00:01:27.716 --> 00:01:32.562 without something to process the loads of information the nose scoops up. 00:01:32.562 --> 00:01:36.996 And it turns out that the olfactory system dedicated to proessing smells 00:01:36.996 --> 00:01:42.655 takes up many times more relative brain area in dogs than in humans. 00:01:42.655 --> 00:01:44.487 All of this allows dogs to distinguish 00:01:44.487 --> 00:01:48.155 and remember a staggering variety of specific scents 00:01:48.155 --> 00:01:53.416 at concentrations up to 100 million times less than what our noses can detect. 00:01:53.416 --> 00:01:56.082 If you can smell a spritz of perfume in a small room, 00:01:56.082 --> 00:01:59.780 a dog would have no trouble smelling it in an enclosed stadium 00:01:59.780 --> 00:02:02.542 and distinguishing its ingredients, to boot. 00:02:02.542 --> 00:02:05.768 And everything in the street, every passing person or car, 00:02:05.768 --> 00:02:08.060 any contents of the neighbor's trash, 00:02:08.060 --> 00:02:09.568 each type of tree, 00:02:09.568 --> 00:02:11.556 and all the birds and insects in it 00:02:11.556 --> 00:02:15.830 has a distinct odor profile telling your dog what it is, where it is, 00:02:15.830 --> 00:02:18.977 and which direction it's moving in. 00:02:18.977 --> 00:02:21.161 Besides being much more powerful than ours, 00:02:21.161 --> 00:02:26.042 a dog's sense of smell can pick up things that can't even be seen at all. 00:02:26.042 --> 00:02:27.967 A whole separate olfactory system, 00:02:27.967 --> 00:02:31.506 called the vomeronasal organ, above the roof of the mouth, 00:02:31.506 --> 00:02:36.033 detects the hormones all animals, Including humans, naturally release. 00:02:36.033 --> 00:02:38.310 It lets dogs identify potential mates, 00:02:38.310 --> 00:02:41.550 or distinguish between friendly and hostile animals. 00:02:41.550 --> 00:02:44.250 It alerts them to our various emotional states, 00:02:44.250 --> 00:02:48.396 and it can even tell them when someone is pregnant or sick. 00:02:48.396 --> 00:02:51.117 Because olfaction is more primal than other senses, 00:02:51.117 --> 00:02:54.400 bypassing the thalamus to connect directly to the brain structures 00:02:54.400 --> 00:02:56.993 involving emotion and instinct, 00:02:56.993 --> 00:03:01.625 we might even say a dog's perception is more immediate and visceral than ours. 00:03:01.625 --> 00:03:04.165 But the most amazing thing about your dog's nose 00:03:04.165 --> 00:03:06.343 is that it can traverse time. 00:03:06.343 --> 00:03:09.340 The past appears in tracks left by passersby, 00:03:09.340 --> 00:03:11.977 and by the warmth of a recently parked car 00:03:11.977 --> 00:03:16.887 where the residue of where you've been and what you've done recently. 00:03:16.887 --> 00:03:18.807 Landmarks like fire hydrants and trees 00:03:18.807 --> 00:03:21.884 are aromatic bulletin boards carrying messages of who's been by, 00:03:21.884 --> 00:03:23.330 what they've been eating, 00:03:23.330 --> 00:03:25.198 and how they're feeling. 00:03:25.198 --> 00:03:26.771 And the future is in the breeze, 00:03:26.771 --> 00:03:31.386 alerting them to something or someone approaching long before you see them. 00:03:31.386 --> 00:03:33.841 Where we see and hear something at a single moment, 00:03:33.841 --> 00:03:38.092 a dog smells an entire story from start to finish. 00:03:38.092 --> 00:03:41.075 In some of the best examples of canine-human collaboration, 00:03:41.075 --> 00:03:44.414 dogs help us by sharing and reacting to those stories. 00:03:44.414 --> 00:03:47.368 They can respond with kindness to people in distress, 00:03:47.368 --> 00:03:49.131 or with aggression to threats 00:03:49.131 --> 00:03:51.928 because stress and anger manifest as a cloud of hormones 00:03:51.928 --> 00:03:54.507 recognizable to the dog's nose. 00:03:54.507 --> 00:03:55.792 With the proper training, 00:03:55.792 --> 00:03:58.196 they can even alert us to invisible threats 00:03:58.196 --> 00:04:00.925 ranging from bombs to cancer. 00:04:00.925 --> 00:04:03.180 As it turns out, humanity's best friend 00:04:03.180 --> 00:04:06.528 is not one who experiences the same things we do, 00:04:06.528 --> 00:04:11.762 but one whose incredible nose reveals a whole other world beyond our eyes.