WEBVTT 00:00:01.365 --> 00:00:04.837 I'm an ocean microbiologist at the University of Tennessee, 00:00:04.837 --> 00:00:07.294 and I want to tell you guys about some microbes 00:00:07.294 --> 00:00:10.624 that are so strange and wonderful 00:00:10.624 --> 00:00:14.451 that they're challenging our assumptions about what life is like on Earth. NOTE Paragraph 00:00:14.451 --> 00:00:15.904 So I have a question. 00:00:15.904 --> 00:00:18.971 Please raise your hand if you've ever thought it would be cool 00:00:18.971 --> 00:00:22.203 to go to the bottom of the ocean in a submarine? 00:00:22.623 --> 00:00:23.746 Yes. 00:00:23.746 --> 00:00:26.233 Most of you, because the oceans are so cool. NOTE Paragraph 00:00:26.233 --> 00:00:28.673 Alright, now, please raise your hand 00:00:28.673 --> 00:00:30.697 if the reason you raised your hand 00:00:30.697 --> 00:00:32.273 to go to the bottom of the ocean in the submarine 00:00:32.273 --> 00:00:34.414 is because it would get you a little bit closer 00:00:34.414 --> 00:00:38.001 to that exciting mud that's down there. 00:00:38.001 --> 00:00:39.576 Nobody. 00:00:39.576 --> 00:00:41.515 I'm the only one in this room. NOTE Paragraph 00:00:41.515 --> 00:00:43.624 Well, I think about this all the time. 00:00:43.624 --> 00:00:45.913 I spend most of my waking hours 00:00:45.913 --> 00:00:47.194 trying to determine 00:00:47.194 --> 00:00:49.775 how deep we can go into the Earth 00:00:49.775 --> 00:00:53.525 and still find something, anything, that's alive, 00:00:53.525 --> 00:00:55.977 because we still don't know the answer to this very basic question 00:00:55.977 --> 00:00:57.499 about life on Earth. NOTE Paragraph 00:00:57.499 --> 00:01:01.084 So in the 1980s, a scientist named John Parks in the UK 00:01:01.084 --> 00:01:02.822 was similarly obsessed, 00:01:02.822 --> 00:01:06.016 and he came up with a crazy idea. 00:01:06.016 --> 00:01:11.197 He believed that there was a vast, deep, and living microbial biosphere 00:01:11.197 --> 00:01:13.135 underneath all the world's oceans 00:01:13.135 --> 00:01:15.627 that extends hundreds of meters into the seafloor, 00:01:15.627 --> 00:01:16.909 which is cool, 00:01:16.909 --> 00:01:20.005 but the only problem is that nobody believed him, 00:01:20.005 --> 00:01:22.932 and the reason that nobody believed him 00:01:22.932 --> 00:01:28.135 is that ocean sediments may be the most boring place on Earth. 00:01:28.135 --> 00:01:31.460 There's no sunlight, there's no oxygen, 00:01:31.460 --> 00:01:33.023 and perhaps worst of all, 00:01:33.023 --> 00:01:34.751 there's no fresh food deliveries 00:01:34.751 --> 00:01:37.306 for literally millions of years. 00:01:37.306 --> 00:01:39.224 You don't have to have a PhD in biology 00:01:39.224 --> 00:01:42.595 to know that that is a bad place to go looking for life. NOTE Paragraph 00:01:42.595 --> 00:01:47.406 But in 2002, John had convinced enough people that he was on to something 00:01:47.406 --> 00:01:51.441 that he actually got an expedition on this drill ship 00:01:51.441 --> 00:01:53.297 called the Joides Resolution, 00:01:53.297 --> 00:01:56.616 and he ran it along with Bo Barker Jørgensen of Denmark. 00:01:56.616 --> 00:02:00.038 And so they were finally able to get some really good pristine 00:02:00.038 --> 00:02:01.684 deep sub-surface samples 00:02:01.684 --> 00:02:04.373 without contamination from surface microbes. 00:02:04.373 --> 00:02:06.277 This drill ship is capable of drilling 00:02:06.277 --> 00:02:09.432 thousands of meters underneath the ocean, 00:02:09.432 --> 00:02:12.091 and the mud comes up in sequential cores, 00:02:12.091 --> 00:02:15.792 one after the other, long, long cores that look like this. 00:02:15.792 --> 00:02:19.656 This is being carried by scientists such as myself who go on these ships, 00:02:19.656 --> 00:02:21.994 and we process the cores on the ships and then we send them home 00:02:21.994 --> 00:02:24.742 to our home laboratories for further study. NOTE Paragraph 00:02:24.742 --> 00:02:29.722 So when John and his colleagues got these first precious 00:02:29.722 --> 00:02:31.674 deep sea pristine samples, 00:02:31.674 --> 00:02:32.446 they put them under the microscope, 00:02:32.446 --> 00:02:35.982 and they saw images that looked pretty much like this, 00:02:35.982 --> 00:02:38.189 which is actually taken from a more recent expedition 00:02:38.189 --> 00:02:40.693 by my PhD student Joy Buongiorno. 00:02:40.693 --> 00:02:43.005 You can see the hazy stuff in the background. 00:02:43.005 --> 00:02:45.814 That's mud. That's deep sea ocean mud, 00:02:45.814 --> 00:02:49.643 and the bright green dots stained with the green fluorescent dye 00:02:49.643 --> 00:02:53.373 are real, living microbes. NOTE Paragraph 00:02:53.373 --> 00:02:56.223 Now I've got to tell you all something really tragic about microbes. 00:02:56.223 --> 00:02:58.134 They all look the same under a microbe, 00:02:58.134 --> 00:03:00.104 I mean, to a first approximation. 00:03:00.104 --> 00:03:03.282 You can take the most fascinating organisms in the world, 00:03:03.282 --> 00:03:07.415 like a microbe that literally breathes uranium, 00:03:07.415 --> 00:03:09.760 and another one that makes rocket fuel, 00:03:09.760 --> 00:03:11.483 mix them up with some ocean mud, 00:03:11.483 --> 00:03:13.499 put them underneath a microscope, 00:03:13.499 --> 00:03:15.597 and they're just little dots. 00:03:15.597 --> 00:03:17.051 It's really annoying. 00:03:17.051 --> 00:03:19.426 So we can't use their looks to tell them apart. 00:03:19.426 --> 00:03:21.780 We have to use DNA like a fingerprint 00:03:21.780 --> 00:03:23.438 to say who is who. NOTE Paragraph 00:03:23.438 --> 00:03:26.382 And I'll teach you guys how to do it right now. 00:03:26.382 --> 00:03:29.536 So I made up some data, and I'm going to show you some data that are not real. 00:03:29.536 --> 00:03:31.900 This is to illustrate what it would look like 00:03:31.900 --> 00:03:35.749 if a bunch of species were not related to each other at all. 00:03:35.749 --> 00:03:38.964 So you can see each species 00:03:38.964 --> 00:03:43.387 has a list of combinations of A, G, C, and T, 00:03:43.387 --> 00:03:45.057 which are the four sub-units of DNA, 00:03:45.057 --> 00:03:48.802 sort of randomly jumbled and nothing looks like anything else 00:03:48.802 --> 00:03:51.345 and these species are totally unrelated to each other. 00:03:51.345 --> 00:03:54.814 But this is what real DNA looks like from a gene that these species 00:03:54.814 --> 00:03:56.677 happen to share. 00:03:56.677 --> 00:03:59.614 Everything lines up nearly perfectly. 00:03:59.614 --> 00:04:03.079 The chances of getting so many of those vertical columns 00:04:03.079 --> 00:04:06.019 where every species has a C or every species has a T 00:04:06.019 --> 00:04:09.321 by random chance is infinitesimal. 00:04:09.321 --> 00:04:14.178 So we know that all those species had to have had a common ancestor. 00:04:14.178 --> 00:04:16.213 They're all relatives of each other. NOTE Paragraph 00:04:16.213 --> 00:04:18.363 So now I'll tell you who they are. 00:04:18.363 --> 00:04:21.166 The top two are us and chimpanzees, 00:04:21.166 --> 00:04:25.524 which y'all already knew were related, because, I mean, obviously, 00:04:25.524 --> 00:04:29.071 but we're also related to things that we don't look like, 00:04:29.071 --> 00:04:33.469 like pine trees and giardia, which is that gastrointestinal disease 00:04:33.469 --> 00:04:36.409 you can get if you don't filter your water while you're hiking. 00:04:36.409 --> 00:04:39.762 We're also related to bacteria like e.coli 00:04:39.762 --> 00:04:43.304 and Clostridium difficile, which is a horrible, opportunistic pathogen 00:04:43.304 --> 00:04:45.073 that kills lots of people. 00:04:45.073 --> 00:04:49.271 But there's of course good microbes here, like Dehalococcoides ethenogenes, 00:04:49.271 --> 00:04:51.954 which cleans up our industrial waste for us. 00:04:51.954 --> 00:04:54.926 So if I take these DNA sequences, 00:04:54.926 --> 00:04:57.690 and then I use them, the similarities and differences between them, 00:04:57.690 --> 00:04:59.946 to make a family tree for all of us 00:04:59.946 --> 00:05:01.759 so you can see who is closely related, 00:05:01.759 --> 00:05:03.540 then this is what it looks like. 00:05:03.540 --> 00:05:06.071 So you can see clearly at a glance 00:05:06.071 --> 00:05:11.317 that things like us and giardia and bunnies and pine trees 00:05:11.317 --> 00:05:13.212 are all, like, siblings, 00:05:13.212 --> 00:05:16.383 and then the bacteria are, like, our ancient cousins. 00:05:16.383 --> 00:05:20.277 But we're kin to every living thing on Earth. 00:05:20.277 --> 00:05:22.918 So in my job, on a daily basis, 00:05:22.918 --> 00:05:27.583 I get to produce scientific evidence against existential loneliness. NOTE Paragraph 00:05:27.583 --> 00:05:30.248 So when we got these first DNA sequences 00:05:30.248 --> 00:05:34.532 from the first crews of pristine samples from the deep subsurface, 00:05:34.532 --> 00:05:36.169 we wanted to know where they were. 00:05:36.169 --> 00:05:38.957 So the first thing that we discovered is that they were not aliens, 00:05:38.957 --> 00:05:42.874 because we could get their DNA to line up with everything else on Earth. 00:05:42.874 --> 00:05:47.113 But now check out where they go on our tree of life. 00:05:47.113 --> 00:05:50.794 The first thing you'll notice is that there's a lot of them. 00:05:50.794 --> 00:05:54.256 It wasn't just one little species that managed to live in this horrible place. 00:05:54.256 --> 00:05:55.927 It's kind of a lot of things. 00:05:55.927 --> 00:05:57.621 And the second thing that you'll notice, 00:05:57.621 --> 00:06:03.682 hopefully, is that they're not like anything we've ever seen before. 00:06:03.682 --> 00:06:05.745 They are as different from each other 00:06:05.745 --> 00:06:08.494 as they are from anything that we've known before 00:06:08.494 --> 00:06:10.714 as we are from pine trees. 00:06:10.714 --> 00:06:13.919 So John Parks was completely correct. 00:06:13.919 --> 00:06:19.071 He, and we, had discovered a completely new and highly diverse 00:06:19.071 --> 00:06:20.969 microbial ecosystem on Earth 00:06:20.969 --> 00:06:25.407 that no one even knew existed before the 1980s. NOTE Paragraph 00:06:25.407 --> 00:06:27.010 So now we were on a roll. 00:06:27.010 --> 00:06:30.637 The next step was to grow these exotic species 00:06:30.637 --> 00:06:33.846 in a petri dish so that we could do real experiments on them 00:06:33.846 --> 00:06:35.941 like microbiologists are supposed to do. 00:06:35.941 --> 00:06:37.674 But no matter what we fed them, 00:06:37.674 --> 00:06:39.322 they refused to grow. 00:06:39.322 --> 00:06:43.891 Even now, 15 years and many expeditions later, 00:06:43.891 --> 00:06:49.422 no human has ever gotten a single one of these exotic deep subsurface microbes 00:06:49.422 --> 00:06:51.212 to grow in a petri dish. 00:06:51.212 --> 00:06:53.385 And it's not for lack of trying. 00:06:53.385 --> 00:06:55.139 That may sound disappointing, 00:06:55.139 --> 00:06:57.132 but I actually find it exhilarating, 00:06:57.132 --> 00:07:00.787 because it means there are so many tantalizing unknowns to work on. 00:07:00.787 --> 00:07:02.842 Like, for instance, my colleagues and I got what we thought 00:07:02.842 --> 00:07:04.239 was a really great idea. 00:07:04.239 --> 00:07:07.216 We were going to read their genes like a recipe book, 00:07:07.216 --> 00:07:10.914 find out what it was they wanted to eat, and put it in their petri dishes, 00:07:10.914 --> 00:07:12.987 and then they would grow and be happy. 00:07:12.987 --> 00:07:14.404 but then when we looked at their genes, 00:07:14.404 --> 00:07:18.220 it turns out that what they wanted to eat was the food we were already feeding them. 00:07:18.220 --> 00:07:20.480 So that was a total wash. 00:07:20.480 --> 00:07:23.481 There was something else that they wanted in their petri dishes 00:07:23.481 --> 00:07:26.032 that we were just not giving them. NOTE Paragraph 00:07:26.032 --> 00:07:30.178 So by combining measurements from many different places 00:07:30.178 --> 00:07:31.205 around the world, 00:07:31.205 --> 00:07:34.807 my colleagues at the University of Southern California, 00:07:34.807 --> 00:07:36.706 Doug LaRowe and Jan Amend, 00:07:36.706 --> 00:07:41.504 were able to calculate that each one of these deep sea microbial cells 00:07:41.504 --> 00:07:44.941 requires only one zeptowatt of power, 00:07:44.941 --> 00:07:48.858 and before you get your phones out, a zepto is 10 to the minus 21, 00:07:48.858 --> 00:07:50.624 because I know I would want to look that up. 00:07:50.624 --> 00:07:52.271 Humans, on the other hand, 00:07:52.271 --> 00:07:55.098 require about a hundred watts of power. 00:07:55.098 --> 00:07:58.633 So a hundred watts is basically if you take a pineapple 00:07:58.633 --> 00:08:04.749 and drop it from about waist height to the ground 881,632 times a day. 00:08:04.749 --> 00:08:07.144 If you did that and then linked it up to a turbine, 00:08:07.144 --> 00:08:11.187 that would create enough power to make me happen for a day. 00:08:11.187 --> 00:08:14.021 A zeptowatt, if you put it in similar terms, 00:08:14.021 --> 00:08:18.253 is if you take just one grain of salt 00:08:18.253 --> 00:08:21.714 and then you imagine a tiny, tiny, little ball 00:08:21.714 --> 00:08:25.473 that is one thousandth of the mass of that one grain of salt 00:08:25.473 --> 00:08:28.139 and then you drop it one nanometer, 00:08:28.139 --> 00:08:32.177 which is a hundred times smaller than the wavelength of visible light, 00:08:32.177 --> 00:08:34.870 once per day. 00:08:34.870 --> 00:08:38.528 That's all it takes to make these microbes live. 00:08:38.528 --> 00:08:44.306 That's less energy than we ever thought would be capable of supporting life, 00:08:44.306 --> 00:08:47.124 but somehow, amazingly, beautifully, 00:08:47.124 --> 00:08:49.230 it's enough. NOTE Paragraph 00:08:49.230 --> 00:08:52.608 So if these deep subsurface microbes have a very different relationship 00:08:52.608 --> 00:08:54.312 with energy than we previously thought, 00:08:54.312 --> 00:08:56.172 then it follows that they'll have to have 00:08:56.172 --> 00:08:59.096 a different relationship with time as well, 00:08:59.096 --> 00:09:02.095 because when you live on such tiny energy gradients, 00:09:02.095 --> 00:09:04.010 rapid growth is impossible. 00:09:04.010 --> 00:09:06.721 If these things ever wanted to colonize our throats and make us sick, 00:09:06.721 --> 00:09:09.183 they would get muscled out by fast-growing streptococcus 00:09:09.183 --> 00:09:11.774 before they could even initiate cell division. 00:09:11.774 --> 00:09:15.469 So that's why we never find them in our throats. 00:09:15.469 --> 00:09:19.887 Perhaps the fact that the deep subsurface is so boring 00:09:19.887 --> 00:09:22.450 is actually an asset to these microbes. 00:09:22.450 --> 00:09:24.641 They never get washed out by a storm. 00:09:24.641 --> 00:09:27.325 They never get overgrown by weeds. 00:09:27.325 --> 00:09:31.063 All they have to do is exist. 00:09:31.063 --> 00:09:33.782 Maybe that thing that we were missing 00:09:33.782 --> 00:09:36.877 in our petri dishes was not food at all. 00:09:36.877 --> 00:09:38.288 Maybe it wasn't a chemical. 00:09:38.288 --> 00:09:40.203 Maybe the thing that they really want, 00:09:40.203 --> 00:09:44.023 the nutrient that they want, is time. 00:09:44.023 --> 00:09:47.895 But time is the one thing that I'll never be able to give them. 00:09:47.895 --> 00:09:50.978 So even if I have a cell culture that I pass to my PhD students, 00:09:50.978 --> 00:09:53.550 who pass it to their PhD students, and so on, 00:09:53.550 --> 00:09:56.065 we'd have to do that for thousands of years 00:09:56.065 --> 00:09:59.495 in order to mimic the exact conditions of the deep subsurface, 00:09:59.495 --> 00:10:01.838 all without growing any contaminants. 00:10:01.838 --> 00:10:03.885 It's just not possible. 00:10:03.885 --> 00:10:07.020 But maybe in a way we already have grown them in our petri dishes. 00:10:07.020 --> 00:10:09.521 Maybe they looked at all that food that we offered them and said, 00:10:09.521 --> 00:10:11.272 thanks, I'm going to speed up so much 00:10:11.272 --> 00:10:13.628 that I'm going to make a new cell next century. 00:10:13.628 --> 00:10:14.858 Ugh. NOTE Paragraph 00:10:14.858 --> 00:10:16.000 (Laughter) NOTE Paragraph 00:10:16.000 --> 00:10:21.361 So why is it that the rest of biology moves so fast? 00:10:21.361 --> 00:10:23.100 Why does a cell die after a day 00:10:23.100 --> 00:10:25.817 and a human dies after only a hundred years? 00:10:25.817 --> 00:10:28.226 These seem like really arbitrarily short limits 00:10:28.226 --> 00:10:31.041 when you think about the total amount of time in the universe. 00:10:31.041 --> 00:10:34.140 But these are not arbitrary limits. 00:10:34.140 --> 00:10:37.055 They're dictated by one simple thing, 00:10:37.055 --> 00:10:39.985 and that thing is the Sun. 00:10:39.985 --> 00:10:41.852 Once life figured out how to harness 00:10:41.852 --> 00:10:43.927 the energy of the Sun through photosynthesis, 00:10:43.927 --> 00:10:46.920 we all had to speed up and get on day and night cycles. 00:10:46.920 --> 00:10:50.266 In that way, the Sun gave us both a reason to be fast 00:10:50.266 --> 00:10:51.989 and the fuel to do it. 00:10:51.989 --> 00:10:54.689 You can view most of life on Earth like a circulatory system, 00:10:54.689 --> 00:10:56.803 and the Sun is our beating heart. NOTE Paragraph 00:10:56.803 --> 00:11:00.008 But the deep subsurface is like a circulatory system 00:11:00.008 --> 00:11:02.620 that's completely disconnected from the Sun. 00:11:02.620 --> 00:11:08.141 It's instead being driven by long, slow geological rhythms. 00:11:08.141 --> 00:11:10.996 There's currently no theoretical limit 00:11:10.996 --> 00:11:14.865 on the lifespan of one single cell. 00:11:14.865 --> 00:11:18.410 As long as there is at least a tiny energy gradient to exploit, 00:11:18.410 --> 00:11:22.582 theoretically, a single cell could live for hundreds of thousands of years 00:11:22.582 --> 00:11:26.287 or more, simply by replacing broken parts over time. 00:11:26.287 --> 00:11:30.483 To ask a microbe that lives like that to grow in our petri dishes 00:11:30.483 --> 00:11:35.343 is to ask them to adapt to our frenetic, Sun-centric, fast way of living, 00:11:35.343 --> 00:11:38.341 and maybe they've got better things to do than that. NOTE Paragraph 00:11:38.341 --> 00:11:39.575 (Laughter) NOTE Paragraph 00:11:39.575 --> 00:11:43.875 Imagine if we could figure out how they managed to do this. 00:11:43.875 --> 00:11:46.898 What if it involves some cool, ultra-stable compounds 00:11:46.898 --> 00:11:49.247 that we could use to increase the shelf life 00:11:49.247 --> 00:11:52.003 in biomedical or industrial applications? 00:11:52.003 --> 00:11:54.257 Or maybe if we figure out the mechanism that they use 00:11:54.257 --> 00:11:57.394 to grow so extraordinarily slowly, 00:11:57.394 --> 00:12:01.348 we could mimic it in cancer cells and slow runaway cell division. 00:12:01.348 --> 00:12:03.198 I don't know. 00:12:03.198 --> 00:12:05.926 I mean, honestly, that is all speculation, 00:12:05.926 --> 00:12:08.870 but the only thing I know for certain 00:12:08.870 --> 00:12:12.967 is that there are a hundred billion billion billlion 00:12:12.967 --> 00:12:17.286 living microbial cells underlying all the world's oceans. 00:12:17.286 --> 00:12:21.968 That's 200 times more than the total biomass of humans on this planet. 00:12:21.968 --> 00:12:25.470 And those microbes have a fundamentally different relationship 00:12:25.470 --> 00:12:28.056 with time and energy than we do. 00:12:28.056 --> 00:12:30.279 What seems like a day to them 00:12:30.279 --> 00:12:33.226 might be a thousand years to us. 00:12:33.226 --> 00:12:35.315 They don't care about the Sun, 00:12:35.315 --> 00:12:37.427 and they don't care about growing fast, 00:12:37.427 --> 00:12:41.118 and they probably don't give a damn about my petri dishes, 00:12:41.118 --> 00:12:45.416 but if we can continue to find creative ways to study them, 00:12:45.416 --> 00:12:52.231 then maybe we'll finally figure out what life, all of life, is like on Earth. NOTE Paragraph 00:12:52.231 --> 00:12:53.638 Thank you. NOTE Paragraph 00:12:53.638 --> 00:12:55.105 (Applause)