WEBVTT 00:00:13.974 --> 00:00:16.411 Being human, 00:00:16.411 --> 00:00:21.076 we each view ourselves as a unique and independent individual, 00:00:21.076 --> 00:00:23.064 but we're never alone! 00:00:23.064 --> 00:00:26.956 Millions of microscopic beings inhabit our bodies, 00:00:26.956 --> 00:00:29.462 and no two bodies are the same. 00:00:29.462 --> 00:00:33.080 Each is a different habitat for microbial communities: 00:00:33.080 --> 00:00:35.319 from the arid deserts of our skin, 00:00:35.319 --> 00:00:38.106 to the villages on our lips, 00:00:38.106 --> 00:00:39.978 and the cities in our mouths. 00:00:39.978 --> 00:00:44.696 Even every tooth is its own distinctive neighborhood, 00:00:44.696 --> 00:00:50.326 and our guts are teaming metropolises of interacting microbes. 00:00:50.326 --> 00:00:52.866 And in these bustling streets of our guts, 00:00:52.866 --> 00:00:56.306 we see a constant influx of food, 00:00:56.306 --> 00:00:59.111 and every microbe has a job to do. 00:00:59.111 --> 00:01:01.947 Here's a cellulolytic bacteria, for example. 00:01:01.947 --> 00:01:04.837 Their one job is to break down cellulose, 00:01:04.837 --> 00:01:08.567 a common compound in vegetables, into sugars. 00:01:08.567 --> 00:01:11.690 Those simple sugars then move along to the respirators, 00:01:11.690 --> 00:01:13.955 another set of microbes that snatch up 00:01:13.955 --> 00:01:17.347 these simple sugars and burn them as fuel. 00:01:17.347 --> 00:01:19.813 As food travels through our digestive tract, 00:01:19.813 --> 00:01:23.716 it reaches the fermentors who extract energy from these sugars 00:01:23.716 --> 00:01:25.247 by converting them into chemicals, 00:01:25.247 --> 00:01:27.446 like alcohol and hydrogen gas, 00:01:27.446 --> 00:01:30.512 which they spew out as waste products. 00:01:30.512 --> 00:01:33.165 Deeper in the depths of our gut city, 00:01:33.165 --> 00:01:37.518 the syntrophs eke out a living off the fermenters' trash. 00:01:37.518 --> 00:01:39.589 At each step of this process, 00:01:39.589 --> 00:01:41.251 energy is released, 00:01:41.251 --> 00:01:42.776 and that energy is absorbed 00:01:42.776 --> 00:01:44.492 by the cells of the digestive tract. 00:01:44.492 --> 00:01:48.169 This city we just saw is different in everyone. 00:01:48.169 --> 00:01:52.130 Every person has a unique and diverse community of gut microbes 00:01:52.130 --> 00:01:55.032 that can process food in different ways. 00:01:55.032 --> 00:01:57.642 One person's gut microbes may be capable 00:01:57.642 --> 00:01:59.907 of releasing only a fraction of the calories 00:01:59.907 --> 00:02:03.113 that another person's gut microbes can extract. 00:02:03.113 --> 00:02:07.663 So, what determines the membership of our gut microbial community? 00:02:07.663 --> 00:02:10.661 Well, things like our genetic makeup 00:02:10.661 --> 00:02:13.073 and the microbes we encounter throughout our lives 00:02:13.073 --> 00:02:16.829 can contribute to our microbial ecosystems. 00:02:16.829 --> 00:02:19.073 The food we eat also influences 00:02:19.073 --> 00:02:21.275 which microbes live in our gut. 00:02:21.275 --> 00:02:24.354 For example, food made of complex molecules, 00:02:24.354 --> 00:02:25.213 like an apple, 00:02:25.213 --> 00:02:28.751 requires a lot of different microbial workers to break it down. 00:02:28.751 --> 00:02:30.858 But, if a food is made of simple molecules, 00:02:30.858 --> 00:02:31.951 like a lollipop, 00:02:31.951 --> 00:02:34.989 some of these workers are put out of a job. 00:02:34.989 --> 00:02:38.005 Those workers leave the city, never to return. 00:02:38.005 --> 00:02:40.623 What doesn't function well are gut microbial communities 00:02:40.623 --> 00:02:43.718 with only a few different types of workers. 00:02:43.718 --> 00:02:46.406 For example, humans who suffer from diseases 00:02:46.406 --> 00:02:49.016 like diabetes or chronic gut inflamation 00:02:49.016 --> 00:02:52.550 typically have less microbial variety in their guts. 00:02:52.550 --> 00:02:54.886 We don't fully understand the best way 00:02:54.886 --> 00:02:58.100 to manage our individual microbial societies, 00:02:58.100 --> 00:03:00.269 but it is likely that lifestyle changes, 00:03:00.269 --> 00:03:04.704 such as eating a varied diet of complex, plant-based foods, 00:03:04.704 --> 00:03:07.874 can help revitalize our microbial ecosystems in our gut 00:03:07.874 --> 00:03:10.813 and across the entire landscape of our body. 00:03:10.813 --> 00:03:13.291 So, we are really not alone in our body. 00:03:13.291 --> 00:03:17.126 Our bodies are homes to millions of different microbes, 00:03:17.126 --> 00:03:20.957 and we need them just as much as they need us. 00:03:20.957 --> 00:03:23.048 As we learn more about how our microbes 00:03:23.048 --> 00:03:25.319 interact with each other and with our bodies, 00:03:25.319 --> 00:03:27.546 we will reveal how we can nurture 00:03:27.546 --> 00:03:29.294 this complex, invisible world 00:03:29.294 --> 00:03:31.176 that shapes our personal identity, 00:03:31.176 --> 00:03:32.184 our health, 00:03:32.184 --> 00:03:33.945 and our well-being.