1 00:00:01,800 --> 00:00:06,920 Speaker 1: Welcome to brain Stuff, a production of iHeart Radio. Hey, 2 00:00:06,960 --> 00:00:11,200 Speaker 1: brain Stuff, learn vogal bomb here. Have you ever wondered 3 00:00:11,240 --> 00:00:14,080 Speaker 1: why you seem to know a lot more elderly Chihuahuas 4 00:00:14,120 --> 00:00:18,119 Speaker 1: than aged Rottweilers. It's just a fact of life that 5 00:00:18,280 --> 00:00:22,320 Speaker 1: small dogs, if they escape disease or misadventure, live longer 6 00:00:22,360 --> 00:00:27,120 Speaker 1: lives than larger ones. This trend has puzzled veterinary researchers 7 00:00:27,200 --> 00:00:29,960 Speaker 1: for as long as we've been fussing over our faithful 8 00:00:30,000 --> 00:00:33,480 Speaker 1: four legged friends, and it's a mystery that hasn't been 9 00:00:33,560 --> 00:00:38,800 Speaker 1: definitively solved. Conventional wisdom in the animal world dictates that 10 00:00:38,920 --> 00:00:43,120 Speaker 1: between different species, larger animals live longer than smaller ones. 11 00:00:43,760 --> 00:00:47,120 Speaker 1: For example, an elephant can live into its seventies, while 12 00:00:47,159 --> 00:00:49,360 Speaker 1: a mouse might only have a year or two to 13 00:00:49,640 --> 00:00:53,680 Speaker 1: do its earthly business. However, the opposite seems to be 14 00:00:53,720 --> 00:00:58,000 Speaker 1: true within single species subsets, and although dogs come in 15 00:00:58,080 --> 00:01:01,080 Speaker 1: lots of shapes and sizes, they're all the same species. 16 00:01:01,880 --> 00:01:04,880 Speaker 1: The average lifespan for an enormous dog is around seven 17 00:01:04,959 --> 00:01:07,840 Speaker 1: or eight years, while a tiny dog can reliably live 18 00:01:07,840 --> 00:01:12,440 Speaker 1: to the ripe old age of fourteen or fifteen. The 19 00:01:12,560 --> 00:01:15,680 Speaker 1: popular adage that one human year is equal to seven 20 00:01:15,720 --> 00:01:19,280 Speaker 1: dog years isn't supported by modern science. Although it's easy 21 00:01:19,360 --> 00:01:23,399 Speaker 1: math and therefore sticks around. The truth is more complex. 22 00:01:24,040 --> 00:01:26,160 Speaker 1: In the first year of a dog's life, it generally 23 00:01:26,200 --> 00:01:29,040 Speaker 1: reaches the physical maturity of a fifteen year old human. 24 00:01:29,680 --> 00:01:32,920 Speaker 1: The second year adds another nine years, and after that 25 00:01:33,200 --> 00:01:36,640 Speaker 1: the rate of aging varies widely based on breed and size. 26 00:01:37,520 --> 00:01:40,320 Speaker 1: A small dog is considered senior at around age eight, 27 00:01:40,600 --> 00:01:43,520 Speaker 1: while a large dog hits old age around five or six. 28 00:01:45,040 --> 00:01:48,600 Speaker 1: Researchers know this, but they're not entirely sure why, and 29 00:01:48,760 --> 00:01:51,520 Speaker 1: to be fair, it probably involves a combination of a 30 00:01:51,520 --> 00:01:55,520 Speaker 1: lot of different factors. It turns out that a dog's 31 00:01:55,560 --> 00:01:58,720 Speaker 1: size isn't the only, or even the primary factor that 32 00:01:58,800 --> 00:02:03,000 Speaker 1: determines lifespan. Genetics and breeding also play a role, with 33 00:02:03,080 --> 00:02:06,600 Speaker 1: certain breeds being more vulnerable to certain life threatening or 34 00:02:06,800 --> 00:02:11,480 Speaker 1: life shortening diseases and conditions than others. Basically, although the 35 00:02:11,520 --> 00:02:14,200 Speaker 1: aging process for dogs is very different than it is 36 00:02:14,240 --> 00:02:19,720 Speaker 1: for humans, it's also very different. Among dogs. The features 37 00:02:19,760 --> 00:02:22,000 Speaker 1: that a dog has been bred for seemed to matter 38 00:02:22,160 --> 00:02:25,520 Speaker 1: more than size. There was a study published in April 39 00:02:26,240 --> 00:02:29,200 Speaker 1: two in the journal Nature based on a massive database 40 00:02:29,240 --> 00:02:32,240 Speaker 1: of veterinary records from the United Kingdom, and to keep 41 00:02:32,280 --> 00:02:35,840 Speaker 1: it simple, they looked at the lifespans of pure bred dogs. 42 00:02:35,880 --> 00:02:40,400 Speaker 1: Small jack Russell Terriers, and midsized Border collies differ substantially 43 00:02:40,480 --> 00:02:43,600 Speaker 1: in size, but according to the study, they live pretty 44 00:02:43,639 --> 00:02:48,960 Speaker 1: similar lifespans twelve point seven and twelve point one year's respectively. However, 45 00:02:49,320 --> 00:02:52,919 Speaker 1: flat faced breeds like pugs and French bulldogs were found 46 00:02:52,919 --> 00:02:56,560 Speaker 1: to have much lower life expectancies due to breathing problems, 47 00:02:56,600 --> 00:03:00,240 Speaker 1: a disease, and difficulty giving birth. The French bull dogs 48 00:03:00,280 --> 00:03:03,920 Speaker 1: life expectancy is only four point five years, and none 49 00:03:03,919 --> 00:03:06,320 Speaker 1: of the other flat faced breeds, no matter how small, 50 00:03:06,680 --> 00:03:09,040 Speaker 1: were found to have an average lifespan of more than 51 00:03:09,080 --> 00:03:15,160 Speaker 1: seven point eight years. Okay, but why might size matter. 52 00:03:16,480 --> 00:03:18,880 Speaker 1: It might have to do with how long it takes 53 00:03:18,880 --> 00:03:21,720 Speaker 1: a dog to become full grown and the difference in 54 00:03:21,800 --> 00:03:25,440 Speaker 1: size between its puppy body and its adult body. It 55 00:03:25,560 --> 00:03:29,200 Speaker 1: seems that growing very large, very quickly takes time off 56 00:03:29,280 --> 00:03:33,400 Speaker 1: of a dog's overall life span. Take, for example, a 57 00:03:33,440 --> 00:03:36,320 Speaker 1: Great Dane. In the first two years of their life, 58 00:03:36,360 --> 00:03:39,000 Speaker 1: they reach their full size, which can be over thirty 59 00:03:39,400 --> 00:03:42,320 Speaker 1: or eighty centimeters tall, and some a hundred and seventy 60 00:03:42,320 --> 00:03:45,960 Speaker 1: five pounds around eighty kilos. That's a lot, and it 61 00:03:46,000 --> 00:03:51,040 Speaker 1: apparently takes a toll. Large breeds die of cancer more 62 00:03:51,080 --> 00:03:54,640 Speaker 1: often than small breeds, a trend that researchers believe has 63 00:03:54,680 --> 00:03:56,840 Speaker 1: to do with how quickly they grow in their first 64 00:03:56,920 --> 00:04:00,600 Speaker 1: year of life. With all that rapid expansion, it possible 65 00:04:00,600 --> 00:04:04,040 Speaker 1: that abnormal cell growth is more likely, or because their 66 00:04:04,080 --> 00:04:06,400 Speaker 1: lives play up more quickly, that they succumb to the 67 00:04:06,440 --> 00:04:10,040 Speaker 1: diseases of old age earlier than say a chihuahua. It 68 00:04:10,160 --> 00:04:12,520 Speaker 1: takes a chihuahua about ten to twelve months to grow 69 00:04:12,560 --> 00:04:15,800 Speaker 1: to full size, but that size usually maxes out at 70 00:04:15,840 --> 00:04:19,640 Speaker 1: only about eight inches or fifteen centimeters tall and six pounds, 71 00:04:19,720 --> 00:04:23,200 Speaker 1: which is just under three kilos. It's just not as 72 00:04:23,279 --> 00:04:26,040 Speaker 1: taxing on the body to become a full grown chihuahua 73 00:04:26,279 --> 00:04:30,679 Speaker 1: as it is to become a complete great dane. Finally, 74 00:04:31,000 --> 00:04:35,240 Speaker 1: lifestyle and access to veterinary care can affect longevity, and 75 00:04:35,400 --> 00:04:37,520 Speaker 1: these factors can depend on the role of the dog 76 00:04:37,560 --> 00:04:41,640 Speaker 1: within the family. For example, toy dogs may be pampered 77 00:04:41,680 --> 00:04:46,880 Speaker 1: more than larger breeds given their lap friendly size. And 78 00:04:47,200 --> 00:04:50,040 Speaker 1: all of this isn't just important in terms of figuring 79 00:04:50,040 --> 00:04:52,360 Speaker 1: out how we might all spend more time with our 80 00:04:52,400 --> 00:04:57,000 Speaker 1: beloved companions a dog. Research is also important because dogs 81 00:04:57,040 --> 00:05:00,320 Speaker 1: die of the same illnesses that humans do, including answer 82 00:05:00,480 --> 00:05:04,600 Speaker 1: heart disease and diabetes, and so as usual, learning more 83 00:05:04,640 --> 00:05:12,840 Speaker 1: about them may help us learn more about ourselves. Today's 84 00:05:12,880 --> 00:05:15,240 Speaker 1: episode is based on the article the longest living dog 85 00:05:15,279 --> 00:05:18,120 Speaker 1: breeds are tiny, but Why on how stuff works dot Com, 86 00:05:18,160 --> 00:05:21,200 Speaker 1: written by Jesslyn Shields. Brainstuff this production of I Heart 87 00:05:21,240 --> 00:05:23,360 Speaker 1: Radio in partnership with how stuff works dot Com, and 88 00:05:23,400 --> 00:05:26,440 Speaker 1: it's produced by Tyler Clang. For more podcasts, my heart 89 00:05:26,480 --> 00:05:29,200 Speaker 1: Radio is the I heart Radio app, Apple Podcasts, or 90 00:05:29,240 --> 00:05:30,960 Speaker 1: wherever you listen to your favorite shows.