1 00:00:13,974 --> 00:00:16,411 Being human, 2 00:00:16,411 --> 00:00:21,076 we each view ourselves as a unique and independent individual, 3 00:00:21,076 --> 00:00:23,064 but we're never alone! 4 00:00:23,064 --> 00:00:26,956 Millions of microscopic beings inhabit our bodies, 5 00:00:26,956 --> 00:00:29,462 and no two bodies are the same. 6 00:00:29,462 --> 00:00:33,080 Each is a different habitat for microbial communities: 7 00:00:33,080 --> 00:00:35,319 from the arid deserts of our skin, 8 00:00:35,319 --> 00:00:38,106 to the villages on our lips, 9 00:00:38,106 --> 00:00:39,978 and the cities in our mouths. 10 00:00:39,978 --> 00:00:44,696 Even every tooth is its own distinctive neighborhood, 11 00:00:44,696 --> 00:00:50,326 and our guts are teaming metropolises of interacting microbes. 12 00:00:50,326 --> 00:00:52,866 And in these bustling streets of our guts, 13 00:00:52,866 --> 00:00:56,306 we see a constant influx of food, 14 00:00:56,306 --> 00:00:59,111 and every microbe has a job to do. 15 00:00:59,111 --> 00:01:01,947 Here's a cellulolytic bacteria, for example. 16 00:01:01,947 --> 00:01:04,837 Their one job is to break down cellulose, 17 00:01:04,837 --> 00:01:08,567 a common compound in vegetables, into sugars. 18 00:01:08,567 --> 00:01:11,690 Those simple sugars then move along to the respirators, 19 00:01:11,690 --> 00:01:13,955 another set of microbes that snatch up 20 00:01:13,955 --> 00:01:17,347 these simple sugars and burn them as fuel. 21 00:01:17,347 --> 00:01:19,813 As food travels through our digestive tract, 22 00:01:19,813 --> 00:01:23,716 it reaches the fermentors who extract energy from these sugars 23 00:01:23,716 --> 00:01:25,247 by converting them into chemicals, 24 00:01:25,247 --> 00:01:27,446 like alcohol and hydrogen gas, 25 00:01:27,446 --> 00:01:30,512 which they spew out as waste products. 26 00:01:30,512 --> 00:01:33,165 Deeper in the depths of our gut city, 27 00:01:33,165 --> 00:01:37,518 the syntrophs eke out a living off the fermenters' trash. 28 00:01:37,518 --> 00:01:39,589 At each step of this process, 29 00:01:39,589 --> 00:01:41,251 energy is released, 30 00:01:41,251 --> 00:01:42,776 and that energy is absorbed 31 00:01:42,776 --> 00:01:44,492 by the cells of the digestive tract. 32 00:01:44,492 --> 00:01:48,169 This city we just saw is different in everyone. 33 00:01:48,169 --> 00:01:52,130 Every person has a unique and diverse community of gut microbes 34 00:01:52,130 --> 00:01:55,032 that can process food in different ways. 35 00:01:55,032 --> 00:01:57,642 One person's gut microbes may be capable 36 00:01:57,642 --> 00:01:59,907 of releasing only a fraction of the calories 37 00:01:59,907 --> 00:02:03,113 that another person's gut microbes can extract. 38 00:02:03,113 --> 00:02:07,663 So, what determines the membership of our gut microbial community? 39 00:02:07,663 --> 00:02:10,661 Well, things like our genetic makeup 40 00:02:10,661 --> 00:02:13,073 and the microbes we encounter throughout our lives 41 00:02:13,073 --> 00:02:16,829 can contribute to our microbial ecosystems. 42 00:02:16,829 --> 00:02:19,073 The food we eat also influences 43 00:02:19,073 --> 00:02:21,275 which microbes live in our gut. 44 00:02:21,275 --> 00:02:24,354 For example, food made of complex molecules, 45 00:02:24,354 --> 00:02:25,213 like an apple, 46 00:02:25,213 --> 00:02:28,751 requires a lot of different microbial workers to break it down. 47 00:02:28,751 --> 00:02:30,858 But, if a food is made of simple molecules, 48 00:02:30,858 --> 00:02:31,951 like a lollipop, 49 00:02:31,951 --> 00:02:34,989 some of these workers are put out of a job. 50 00:02:34,989 --> 00:02:38,005 Those workers leave the city, never to return. 51 00:02:38,005 --> 00:02:40,623 What doesn't function well are gut microbial communities 52 00:02:40,623 --> 00:02:43,718 with only a few different types of workers. 53 00:02:43,718 --> 00:02:46,406 For example, humans who suffer from diseases 54 00:02:46,406 --> 00:02:49,016 like diabetes or chronic gut inflamation 55 00:02:49,016 --> 00:02:52,550 typically have less microbial variety in their guts. 56 00:02:52,550 --> 00:02:54,886 We don't fully understand the best way 57 00:02:54,886 --> 00:02:58,100 to manage our individual microbial societies, 58 00:02:58,100 --> 00:03:00,269 but it is likely that lifestyle changes, 59 00:03:00,269 --> 00:03:04,704 such as eating a varied diet of complex, plant-based foods, 60 00:03:04,704 --> 00:03:07,874 can help revitalize our microbial ecosystems in our gut 61 00:03:07,874 --> 00:03:10,813 and across the entire landscape of our body. 62 00:03:10,813 --> 00:03:13,291 So, we are really not alone in our body. 63 00:03:13,291 --> 00:03:17,126 Our bodies are homes to millions of different microbes, 64 00:03:17,126 --> 00:03:20,957 and we need them just as much as they need us. 65 00:03:20,957 --> 00:03:23,048 As we learn more about how our microbes 66 00:03:23,048 --> 00:03:25,319 interact with each other and with our bodies, 67 00:03:25,319 --> 00:03:27,546 we will reveal how we can nurture 68 00:03:27,546 --> 00:03:29,294 this complex, invisible world 69 00:03:29,294 --> 00:03:31,176 that shapes our personal identity, 70 00:03:31,176 --> 00:03:32,184 our health, 71 00:03:32,184 --> 00:03:33,945 and our well-being.