1 00:00:01,800 --> 00:00:04,320 Speaker 1: Welcome to brain Stuff, a production of I Heart Radio, 2 00:00:06,840 --> 00:00:10,920 Speaker 1: Hey brain Stuff, Lauren bog Obam Here. The long held 3 00:00:11,000 --> 00:00:14,000 Speaker 1: and much perpetuated belief that dogs have a sense of 4 00:00:14,000 --> 00:00:18,160 Speaker 1: smell superior to their trusty humans is total bunk, according 5 00:00:18,200 --> 00:00:22,840 Speaker 1: to a review published in the journal Science. The author 6 00:00:22,920 --> 00:00:27,760 Speaker 1: was Rutgers University sensory neuroscientist Dr John McGann, who sniffed 7 00:00:27,800 --> 00:00:31,479 Speaker 1: out the truth by reviewing years of prior olfactory related 8 00:00:31,520 --> 00:00:36,280 Speaker 1: research and comparing brain's responses to smelly stimuli in mice, dogs, 9 00:00:36,320 --> 00:00:40,640 Speaker 1: and humans. Before the article this episode is based on, 10 00:00:40,840 --> 00:00:44,160 Speaker 1: has to Work, spoke with McGann via email. He said, 11 00:00:44,680 --> 00:00:47,600 Speaker 1: when we started working with people, it was impressive how 12 00:00:47,640 --> 00:00:50,479 Speaker 1: excellent the human sense of smell really is. And I 13 00:00:50,520 --> 00:00:53,640 Speaker 1: started closely reading the many years of previous work on 14 00:00:53,680 --> 00:00:58,840 Speaker 1: the subject. So where did the idea of canines as 15 00:00:59,000 --> 00:01:02,560 Speaker 1: superior smeller has come from? McGann traced it back to 16 00:01:02,600 --> 00:01:06,160 Speaker 1: the works of one Paul Brokaw, a nineteenth century era 17 00:01:06,319 --> 00:01:11,440 Speaker 1: neuro anatomist. Brokaw dubbed humans as non smellers without any 18 00:01:11,440 --> 00:01:15,119 Speaker 1: sort of sensory testing to back that up. McGann wrote 19 00:01:15,120 --> 00:01:18,480 Speaker 1: in his review he believed that the evolutionary enlargement of 20 00:01:18,480 --> 00:01:21,600 Speaker 1: the human frontal lobe gave human beings free will at 21 00:01:21,640 --> 00:01:26,279 Speaker 1: the expense of the old factory system. Brokaw also noted 22 00:01:26,319 --> 00:01:29,160 Speaker 1: that other mammals feature old factory bulbs that are much 23 00:01:29,280 --> 00:01:31,520 Speaker 1: larger in proportion to the rest of their brains than 24 00:01:31,560 --> 00:01:35,200 Speaker 1: those in human beings. For example, of primates and humans 25 00:01:35,200 --> 00:01:37,920 Speaker 1: have an old factory bulb making up just zero point 26 00:01:38,040 --> 00:01:41,080 Speaker 1: zero one percent of the brain by volume, which compared 27 00:01:41,120 --> 00:01:43,760 Speaker 1: with two percent of the average mouse brain can seem 28 00:01:43,760 --> 00:01:46,960 Speaker 1: a little paltry, but this doesn't make humans any worse 29 00:01:47,040 --> 00:01:51,600 Speaker 1: at smelling. McGann explained, the human bulb is a very 30 00:01:51,640 --> 00:01:54,560 Speaker 1: small percentage of the human brain, which is part of 31 00:01:54,560 --> 00:01:57,200 Speaker 1: the origin of the myth that humans are bad smellers, 32 00:01:57,320 --> 00:02:00,680 Speaker 1: but it's actually quite large in absolute terms, much bigger 33 00:02:00,680 --> 00:02:04,720 Speaker 1: than a mouse, say. It's also richly interconnected with many 34 00:02:04,800 --> 00:02:07,840 Speaker 1: other brain regions that are larger and do more powerful 35 00:02:07,880 --> 00:02:12,280 Speaker 1: computations in humans. That's not to say that certain species 36 00:02:12,280 --> 00:02:16,600 Speaker 1: don't excel at identifying specific types of sense. However, in 37 00:02:16,639 --> 00:02:20,160 Speaker 1: the research, dogs were better at discerning between urins and 38 00:02:20,240 --> 00:02:24,880 Speaker 1: humans were better at differentiating between wines. Began wrote in 39 00:02:24,919 --> 00:02:28,400 Speaker 1: the review when an appropriate range of odors is tested. 40 00:02:28,720 --> 00:02:32,799 Speaker 1: Humans outperform laboratory rodents and dogs in detecting some odors 41 00:02:33,040 --> 00:02:37,360 Speaker 1: while being less sensitive to other odors. He notes that 42 00:02:37,440 --> 00:02:39,920 Speaker 1: humans are even capable of following scent trails in the 43 00:02:39,919 --> 00:02:44,559 Speaker 1: great outdoors. He said via email, it's difficult to make generalizations, 44 00:02:44,760 --> 00:02:46,600 Speaker 1: but I think it's fair to say that though the 45 00:02:46,680 --> 00:02:49,760 Speaker 1: human olfactory system is different than the rodent or dog 46 00:02:49,760 --> 00:02:55,120 Speaker 1: olfactory system, it's not worse than they are. And in 47 00:02:55,160 --> 00:02:58,480 Speaker 1: addition to being more powerful than you previously thought, the 48 00:02:58,560 --> 00:03:02,600 Speaker 1: human sense of smell is actually more important too. Smells 49 00:03:02,639 --> 00:03:06,120 Speaker 1: can cause us to recall specific associated memories and can 50 00:03:06,160 --> 00:03:10,920 Speaker 1: also elicit related behavioral and emotional responses. Personal odor can 51 00:03:10,960 --> 00:03:15,280 Speaker 1: also relate information about anxiety, stress levels, even reproductive status, 52 00:03:15,720 --> 00:03:18,639 Speaker 1: all things we once thought were only communicated by non 53 00:03:18,760 --> 00:03:24,160 Speaker 1: human animals. McGann said smell is underappreciated in our daily lives. 54 00:03:24,680 --> 00:03:27,280 Speaker 1: Most of the flavor of food is actually its smell 55 00:03:27,440 --> 00:03:29,560 Speaker 1: reaching the nose by going up through the back of 56 00:03:29,600 --> 00:03:33,680 Speaker 1: the throat. We're also beginning to understand that humans communicate 57 00:03:33,720 --> 00:03:37,880 Speaker 1: information about our genetics, diet, and emotional state through individualized 58 00:03:37,880 --> 00:03:44,880 Speaker 1: body odors that influence the behavior of other people, often subconsciously. Furthermore, 59 00:03:44,880 --> 00:03:47,920 Speaker 1: our sense of smell begins declining somewhere around the age 60 00:03:47,920 --> 00:03:51,880 Speaker 1: of sixty, and an improperly functioning olfactory system can be 61 00:03:51,920 --> 00:03:56,960 Speaker 1: a symptom of neurodegenerative diseases like Alzheimer's or Parkinson's. McGann 62 00:03:57,040 --> 00:04:00,880 Speaker 1: said loss of smell can thus be veried stressing for people, 63 00:04:01,280 --> 00:04:03,320 Speaker 1: which is one of the reasons I wrote this article 64 00:04:03,640 --> 00:04:06,600 Speaker 1: and to increase popular awareness of the importance of smelling 65 00:04:06,720 --> 00:04:10,440 Speaker 1: humans and hopefully encourage more emphasis on the development of 66 00:04:10,480 --> 00:04:18,239 Speaker 1: all factory medicine. Today's episode is based on the article 67 00:04:18,440 --> 00:04:20,960 Speaker 1: a human sense of smell is actually as good as 68 00:04:20,960 --> 00:04:23,160 Speaker 1: the dog's on house toff works dot com, written by 69 00:04:23,240 --> 00:04:26,080 Speaker 1: Leo Hoyt. Brain Stuff is production of I Heart Radio 70 00:04:26,160 --> 00:04:28,080 Speaker 1: in partnership with how stuff works dot Com, and it's 71 00:04:28,120 --> 00:04:31,520 Speaker 1: produced by Tyler Klang. Before more podcasts from my heart Radio, 72 00:04:31,800 --> 00:04:34,480 Speaker 1: visit the I heart Radio app, Apple Podcasts, or wherever 73 00:04:34,520 --> 00:04:35,920 Speaker 1: you listen to your favorite shows.