1 00:00:00,720 --> 00:00:10,759 [Music] 2 00:00:15,959 --> 00:00:13,770 so yes thank you thank you for the 3 00:00:18,480 --> 00:00:15,969 opportunity to talk here and I'm 4 00:00:20,550 --> 00:00:18,490 actually very happy to be following Hong 5 00:00:22,769 --> 00:00:20,560 Yang's a very excellent talk I think it 6 00:00:24,720 --> 00:00:22,779 builds a just a perfect bridge from the 7 00:00:27,420 --> 00:00:24,730 beautiful talks about metabolism and 8 00:00:29,460 --> 00:00:27,430 metabolic pathways this morning towards 9 00:00:32,609 --> 00:00:29,470 the ways in which I would like to think 10 00:00:34,439 --> 00:00:32,619 a little bit about metabolism and I 11 00:00:36,750 --> 00:00:34,449 should mention that I'm gonna be talking 12 00:00:39,689 --> 00:00:36,760 about a story an evolutionary story that 13 00:00:42,539 --> 00:00:39,699 plays out much more recent than origin 14 00:00:44,549 --> 00:00:42,549 so several billion years later but I 15 00:00:46,259 --> 00:00:44,559 think it's very relevant because you 16 00:00:48,090 --> 00:00:46,269 know of course if there are physical 17 00:00:49,979 --> 00:00:48,100 laws physical principles that are 18 00:00:52,439 --> 00:00:49,989 governing the emergence of life they 19 00:00:56,430 --> 00:00:52,449 don't go away once life is there right 20 00:00:57,689 --> 00:00:56,440 and so studying evolution in intractable 21 00:00:59,160 --> 00:00:57,699 systems that are playing out more 22 00:01:03,030 --> 00:00:59,170 recently can actually help us think 23 00:01:05,460 --> 00:01:03,040 about what those principles are and so 24 00:01:06,870 --> 00:01:05,470 you know so we but but in doing that I 25 00:01:08,910 --> 00:01:06,880 think it's important for us to think 26 00:01:10,590 --> 00:01:08,920 about finding the correct sort of 27 00:01:12,990 --> 00:01:10,600 reference frames to be thinking about 28 00:01:15,990 --> 00:01:13,000 evolution that are compatible to asking 29 00:01:17,750 --> 00:01:16,000 how we ask questions about emergence and 30 00:01:20,640 --> 00:01:17,760 so you know in Hong Kong stock talk 31 00:01:21,780 --> 00:01:20,650 focused on ideas of information flow and 32 00:01:24,030 --> 00:01:21,790 how that relates to population dynamics 33 00:01:26,730 --> 00:01:24,040 and I want to sort of talk a little bit 34 00:01:31,890 --> 00:01:26,740 more about mass and energy flows and 35 00:01:36,980 --> 00:01:31,900 sort of at that level so in in my work 36 00:01:40,230 --> 00:01:36,990 in in in general I'm interested in 37 00:01:43,410 --> 00:01:40,240 metabolic evolution I study metabolism 38 00:01:44,460 --> 00:01:43,420 in general and one of the things one of 39 00:01:47,760 --> 00:01:44,470 the most interesting things actually 40 00:01:49,290 --> 00:01:47,770 about metabolism to me is that it's not 41 00:01:51,380 --> 00:01:49,300 just a system but it's actually also a 42 00:01:53,940 --> 00:01:51,390 lens through which we can study 43 00:01:55,590 --> 00:01:53,950 organisms and it's because metabolism 44 00:01:58,410 --> 00:01:55,600 express itself at many different scales 45 00:02:00,690 --> 00:01:58,420 for within living systems so at the 46 00:02:03,090 --> 00:02:00,700 lowest level metabolism is basically 47 00:02:06,149 --> 00:02:03,100 chemical reactions like organic 48 00:02:09,300 --> 00:02:06,159 chemistry catalyzed by small metals and 49 00:02:11,100 --> 00:02:09,310 enzymes and cofactors if we zoom out to 50 00:02:13,110 --> 00:02:11,110 the Seiler level metabolism is now 51 00:02:14,940 --> 00:02:13,120 networks of that kind of chemistry that 52 00:02:17,730 --> 00:02:14,950 cells use to take in their environmental 53 00:02:18,930 --> 00:02:17,740 inputs and recreate themselves if you 54 00:02:20,910 --> 00:02:18,940 keep zooming out to the level of 55 00:02:22,800 --> 00:02:20,920 ecosystem the tablets in manaus network 56 00:02:24,480 --> 00:02:22,810 so that kind of networks where does it 57 00:02:26,160 --> 00:02:24,490 media it's not just the growth of cells 58 00:02:27,660 --> 00:02:26,170 but also the interactions the social 59 00:02:29,910 --> 00:02:27,670 interactions and the trophic exchanges 60 00:02:32,160 --> 00:02:29,920 between cells and if you keep zooming 61 00:02:33,720 --> 00:02:32,170 out at the global scale the metabolic 62 00:02:35,699 --> 00:02:33,730 activity of all cells on earth together 63 00:02:38,250 --> 00:02:35,709 is what's mediating the global elemental 64 00:02:41,520 --> 00:02:38,260 cycles but the key point is that all of 65 00:02:43,080 --> 00:02:41,530 these scales is the same chemistry right 66 00:02:45,270 --> 00:02:43,090 and so metabolism provides kind of a 67 00:02:49,050 --> 00:02:45,280 lens to be thinking about how we link up 68 00:02:51,150 --> 00:02:49,060 things like pathway innovations to 69 00:02:52,470 --> 00:02:51,160 adaptive radiations to be Co system 70 00:02:55,260 --> 00:02:52,480 restructuring and to global 71 00:02:56,250 --> 00:02:55,270 biogeochemical perturbations and the 72 00:02:57,870 --> 00:02:56,260 other thing in there is that because 73 00:03:00,180 --> 00:02:57,880 we're thinking at the level of chemistry 74 00:03:01,320 --> 00:03:00,190 again and this you know comes back to 75 00:03:03,000 --> 00:03:01,330 sort of some of the other themes we've 76 00:03:04,740 --> 00:03:03,010 been talking about before it allows us 77 00:03:07,850 --> 00:03:04,750 to think about metabolic or evolutionary 78 00:03:11,940 --> 00:03:07,860 change in terms of shifts between 79 00:03:13,590 --> 00:03:11,950 regimes of chemical dynamics and sort of 80 00:03:15,949 --> 00:03:13,600 you know in a sort of a physical way of 81 00:03:20,250 --> 00:03:15,959 thinking about evolution in that sense 82 00:03:22,170 --> 00:03:20,260 so the the system I'll be talking about 83 00:03:24,210 --> 00:03:22,180 in trying to build up some of these 84 00:03:27,240 --> 00:03:24,220 ideas you know was introduced by Hong 85 00:03:28,530 --> 00:03:27,250 Kong it's this cyanobacteria that lives 86 00:03:31,800 --> 00:03:28,540 in the surface oceans called 87 00:03:33,930 --> 00:03:31,810 prochlorococcus it's one of the most 88 00:03:38,280 --> 00:03:33,940 abundant cell cell living organisms on 89 00:03:39,810 --> 00:03:38,290 earth you know it lives between sort of 90 00:03:41,550 --> 00:03:39,820 these bands here everywhere out in the 91 00:03:45,150 --> 00:03:41,560 open ocean and form sort of a planet 92 00:03:46,770 --> 00:03:45,160 wrapping population of cells there's you 93 00:03:49,319 --> 00:03:46,780 know several times ten to the twenty 94 00:03:51,960 --> 00:03:49,329 seven of these cells on earth and they 95 00:03:53,610 --> 00:03:51,970 they form a sizeable fraction of primary 96 00:03:55,350 --> 00:03:53,620 productivity and photosynthesis on earth 97 00:03:57,420 --> 00:03:55,360 they're part of what's known as the 98 00:03:58,530 --> 00:03:57,430 marine pico center bacteria where 99 00:04:00,539 --> 00:03:58,540 together with their sister lineage 100 00:04:02,610 --> 00:04:00,549 marine cynical caucus they fix something 101 00:04:05,069 --> 00:04:02,620 like a quarter of all co2 in the oceans 102 00:04:07,440 --> 00:04:05,079 so really it's a it's a cellular system 103 00:04:08,699 --> 00:04:07,450 but it's also a planetary system right 104 00:04:09,930 --> 00:04:08,709 and so when we think about the evolution 105 00:04:11,039 --> 00:04:09,940 of the system it's also interesting to 106 00:04:13,020 --> 00:04:11,049 sort of think about and keep in mind 107 00:04:14,850 --> 00:04:13,030 what happens to the planet where the 108 00:04:17,779 --> 00:04:14,860 system switches on and comes on law 109 00:04:19,800 --> 00:04:17,789 comes on line and Earth history 110 00:04:21,120 --> 00:04:19,810 so there's several things about the 111 00:04:22,980 --> 00:04:21,130 system that make it very appealing for 112 00:04:25,200 --> 00:04:22,990 studying evolution ever studying 113 00:04:28,710 --> 00:04:25,210 metabolism one of the things is that as 114 00:04:30,240 --> 00:04:28,720 I mentioned you know it has very ways in 115 00:04:31,740 --> 00:04:30,250 which its ecology and the relationship 116 00:04:34,140 --> 00:04:31,750 between ecology and phylogeny are very 117 00:04:34,710 --> 00:04:34,150 well understood so if you go out into 118 00:04:35,910 --> 00:04:34,720 the open 119 00:04:37,500 --> 00:04:35,920 motioning you look by depth oh you'll 120 00:04:38,970 --> 00:04:37,510 see is that the population separates 121 00:04:42,000 --> 00:04:38,980 into a sort of layered population 122 00:04:43,560 --> 00:04:42,010 structure where the more the deepest 123 00:04:45,600 --> 00:04:43,570 branching populations live at the bottom 124 00:04:46,980 --> 00:04:45,610 of the euphotic zone where light energy 125 00:04:48,660 --> 00:04:46,990 is low energy concentrations are 126 00:04:51,120 --> 00:04:48,670 elevated whereas the most recent 127 00:04:52,470 --> 00:04:51,130 branching organisms lineages live at the 128 00:04:54,900 --> 00:04:52,480 top where light energy is abundant 129 00:04:55,980 --> 00:04:54,910 nutrient concentrations are low right so 130 00:04:57,810 --> 00:04:55,990 you have this sort of central light 131 00:05:00,000 --> 00:04:57,820 nutrient gradient that organizes the 132 00:05:01,350 --> 00:05:00,010 system and so what I set out to do is to 133 00:05:03,150 --> 00:05:01,360 see how does the metabolism of this 134 00:05:04,530 --> 00:05:03,160 system change along that gradient and 135 00:05:06,990 --> 00:05:04,540 what does that tell us about the 136 00:05:08,580 --> 00:05:07,000 evolution of the system as a whole and a 137 00:05:09,960 --> 00:05:08,590 lot of what I'm talking about you know 138 00:05:12,360 --> 00:05:09,970 is in if you want to read about it in 139 00:05:16,470 --> 00:05:12,370 this paper that came out earlier this 140 00:05:18,780 --> 00:05:16,480 past year right and so to look at this 141 00:05:20,240 --> 00:05:18,790 question I'm thankful to Donato for 142 00:05:23,040 --> 00:05:20,250 already introducing this idea earlier 143 00:05:24,150 --> 00:05:23,050 but so to do that I've you know used 144 00:05:26,240 --> 00:05:24,160 this system which have been trying to 145 00:05:28,770 --> 00:05:26,250 push now for the last several years 146 00:05:30,420 --> 00:05:28,780 where basically you integrate metabolic 147 00:05:31,710 --> 00:05:30,430 Network instructions with phylogenetic 148 00:05:33,990 --> 00:05:31,720 instructions to build trees of 149 00:05:35,580 --> 00:05:34,000 functional metabolic networks so the way 150 00:05:37,500 --> 00:05:35,590 this works is let's say you have some 151 00:05:39,420 --> 00:05:37,510 something Eric that you're interested in 152 00:05:41,250 --> 00:05:39,430 where you know these nodes are molecules 153 00:05:42,570 --> 00:05:41,260 and the links are reactions and in black 154 00:05:44,880 --> 00:05:42,580 are all the parts that are universal so 155 00:05:46,620 --> 00:05:44,890 everyone has them and let's say that you 156 00:05:47,820 --> 00:05:46,630 know that within that clade or in that 157 00:05:50,610 --> 00:05:47,830 that group you're looking at there's 158 00:05:52,409 --> 00:05:50,620 three known alternatives a pink pathway 159 00:05:54,240 --> 00:05:52,419 yellow path in a blue pathway which you 160 00:05:57,090 --> 00:05:54,250 then do is take all the genomes in that 161 00:05:58,830 --> 00:05:57,100 plate or in that phylum and look at the 162 00:06:01,170 --> 00:05:58,840 distribution of the genes encoding those 163 00:06:02,550 --> 00:06:01,180 pathways and so let's say that in you 164 00:06:04,469 --> 00:06:02,560 know in this case you see that the genes 165 00:06:05,940 --> 00:06:04,479 for the yellow pathway are universally 166 00:06:07,290 --> 00:06:05,950 distributed across your tree and across 167 00:06:09,180 --> 00:06:07,300 the roots and that implies that the 168 00:06:11,330 --> 00:06:09,190 yellow path is the ancestral pathway and 169 00:06:13,469 --> 00:06:11,340 that pink and blue were derived from it 170 00:06:15,150 --> 00:06:13,479 there's one additional key constraint 171 00:06:17,219 --> 00:06:15,160 which is that in going from yellow to 172 00:06:18,659 --> 00:06:17,229 say blue the first gained the blue 173 00:06:20,820 --> 00:06:18,669 pathway before you can lose the yellow 174 00:06:22,710 --> 00:06:20,830 pathway because you at first you lose 175 00:06:24,500 --> 00:06:22,720 the yellow pathway flows through the 176 00:06:26,640 --> 00:06:24,510 network is cut and the lineage dies off 177 00:06:29,010 --> 00:06:26,650 right and so what this then means is 178 00:06:30,240 --> 00:06:29,020 that you have now tree of phenotypes so 179 00:06:31,830 --> 00:06:30,250 these are all functional metabolic 180 00:06:33,030 --> 00:06:31,840 networks what you can do is you can 181 00:06:34,710 --> 00:06:33,040 start looking at the biochemical 182 00:06:36,540 --> 00:06:34,720 properties of the individual pathways to 183 00:06:38,640 --> 00:06:36,550 try to understand what drove the system 184 00:06:40,770 --> 00:06:38,650 from one state to another one so for 185 00:06:42,540 --> 00:06:40,780 example looking at differences in trace 186 00:06:44,400 --> 00:06:42,550 metal usages of the enzymes 187 00:06:46,080 --> 00:06:44,410 maybe there's oxygen sensitivities and 188 00:06:47,810 --> 00:06:46,090 the different enzymes maybe there's 189 00:06:49,640 --> 00:06:47,820 differences in ATP usages 190 00:06:50,780 --> 00:06:49,650 - in different pathways and by making 191 00:06:52,670 --> 00:06:50,790 these kind of comparison you can start 192 00:06:55,760 --> 00:06:52,680 to infer what was the evolutionary 193 00:06:57,640 --> 00:06:55,770 driving mechanism so taking this kind of 194 00:07:00,170 --> 00:06:57,650 approach and looking at prochlorococcus 195 00:07:02,210 --> 00:07:00,180 you see something very dramatic actually 196 00:07:04,310 --> 00:07:02,220 happens so what I've shown here is the 197 00:07:05,900 --> 00:07:04,320 metabolic core so this is the 198 00:07:07,510 --> 00:07:05,910 photosynthetic electron transport chain 199 00:07:10,070 --> 00:07:07,520 and this core carbohydrate metabolism 200 00:07:11,780 --> 00:07:10,080 this is where electrons and Co to come 201 00:07:13,970 --> 00:07:11,790 together to initiate all of biosynthesis 202 00:07:14,930 --> 00:07:13,980 and what happens actually in this part 203 00:07:16,640 --> 00:07:14,940 of the network is that you see the 204 00:07:17,990 --> 00:07:16,650 prochlorococcus forms of very unique 205 00:07:18,740 --> 00:07:18,000 lineages within the rest of 206 00:07:20,750 --> 00:07:18,750 cyanobacteria 207 00:07:23,600 --> 00:07:20,760 the whole metabolic core undergoes 208 00:07:25,640 --> 00:07:23,610 remodeling any way that is uncommon in 209 00:07:27,410 --> 00:07:25,650 the rest of santé bacteria so almost 210 00:07:29,630 --> 00:07:27,420 everything undergoes change you see path 211 00:07:31,850 --> 00:07:29,640 genes are being lost genes are being 212 00:07:33,080 --> 00:07:31,860 gained the stoichiometry is in the 213 00:07:35,140 --> 00:07:33,090 pigments of the photo systems are 214 00:07:37,460 --> 00:07:35,150 undergoing change so a lot is happening 215 00:07:38,900 --> 00:07:37,470 which already is telling you a lot right 216 00:07:40,520 --> 00:07:38,910 because this is where everything starts 217 00:07:42,740 --> 00:07:40,530 so change is not going to be easy 218 00:07:45,140 --> 00:07:42,750 so if you see change it's suggesting of 219 00:07:46,760 --> 00:07:45,150 a strong driving force and the other 220 00:07:48,950 --> 00:07:46,770 thing that we see as part of this change 221 00:07:50,600 --> 00:07:48,960 sort of surprisingly initially is that 222 00:07:53,090 --> 00:07:50,610 it seems to be adding what looked like 223 00:07:54,830 --> 00:07:53,100 electron drains in the network right so 224 00:07:57,110 --> 00:07:54,840 as system is evolving networks are being 225 00:07:59,090 --> 00:07:57,120 interrupted and it looks like Panthers 226 00:08:02,530 --> 00:07:59,100 are being added for excreting small 227 00:08:04,820 --> 00:08:02,540 organic carbon molecules out of the cell 228 00:08:07,070 --> 00:08:04,830 now that seems kind of like a surprising 229 00:08:09,290 --> 00:08:07,080 thing why would a assist to be evolving 230 00:08:11,660 --> 00:08:09,300 to burn energy out into the environment 231 00:08:14,330 --> 00:08:11,670 in that sense and so to try to make 232 00:08:15,860 --> 00:08:14,340 sense of this I took the information we 233 00:08:17,060 --> 00:08:15,870 know from metabolism and try to 234 00:08:19,160 --> 00:08:17,070 integrate it with everything else we 235 00:08:21,400 --> 00:08:19,170 know about the system so looking at the 236 00:08:23,930 --> 00:08:21,410 population structure genome evolution 237 00:08:26,030 --> 00:08:23,940 proteome evolution growth rate light 238 00:08:28,280 --> 00:08:26,040 physiology everything else that you know 239 00:08:29,450 --> 00:08:28,290 we can find and when you do that when 240 00:08:31,070 --> 00:08:29,460 you integrate all that information 241 00:08:32,750 --> 00:08:31,080 together it turns out that you can 242 00:08:35,000 --> 00:08:32,760 actually align all of the macroscale 243 00:08:37,670 --> 00:08:35,010 diversity within this system along a 244 00:08:40,070 --> 00:08:37,680 single physiological axis which is 245 00:08:42,100 --> 00:08:40,080 suggesting that over geologic time the 246 00:08:44,540 --> 00:08:42,110 system evolution is sort of steadily 247 00:08:47,060 --> 00:08:44,550 maximizing this one single physiological 248 00:08:48,830 --> 00:08:47,070 parameter which is the ratio of electron 249 00:08:51,080 --> 00:08:48,840 flux to the nutrient flux in the cell 250 00:08:52,580 --> 00:08:51,090 let me unpack that a little bit electron 251 00:08:54,110 --> 00:08:52,590 flux is just light intensity times 252 00:08:56,300 --> 00:08:54,120 absorption cross section times quantum 253 00:08:58,340 --> 00:08:56,310 efficiency and nutrient flux is the 254 00:09:00,890 --> 00:08:58,350 growth rate times the nutrient quota the 255 00:09:01,700 --> 00:09:00,900 number of atoms in a Cell and so you 256 00:09:04,130 --> 00:09:01,710 know I already mentioned 257 00:09:05,870 --> 00:09:04,140 you see this light level differentiation 258 00:09:08,150 --> 00:09:05,880 here so these see more light than these 259 00:09:10,070 --> 00:09:08,160 so that's you know driving an increase 260 00:09:11,990 --> 00:09:10,080 in electron flux but at the same time 261 00:09:13,280 --> 00:09:12,000 the the photosynthetic machinery is also 262 00:09:14,660 --> 00:09:13,290 undergoing change in a way that 263 00:09:17,150 --> 00:09:14,670 increases the absorption cross-section 264 00:09:19,670 --> 00:09:17,160 of the cells so the the the the 265 00:09:21,320 --> 00:09:19,680 stoichiometry and the pigments of the 266 00:09:23,390 --> 00:09:21,330 photo systems are being modified in such 267 00:09:25,190 --> 00:09:23,400 a way that they're also absorbing more 268 00:09:28,010 --> 00:09:25,200 of the light that they see of the blue 269 00:09:29,420 --> 00:09:28,020 the blue light and at the same time we 270 00:09:31,610 --> 00:09:29,430 see that the nutrient flux is steadily 271 00:09:33,320 --> 00:09:31,620 going down in this lineage so you see 272 00:09:35,660 --> 00:09:33,330 that the cells are getting smaller the 273 00:09:38,030 --> 00:09:35,670 membranes are going from phospholipid to 274 00:09:39,500 --> 00:09:38,040 sulfa lipids the genome and the proteome 275 00:09:41,990 --> 00:09:39,510 is streamlined in ways that save 276 00:09:44,150 --> 00:09:42,000 nitrogen and phosphorus as well and the 277 00:09:45,470 --> 00:09:44,160 changes to the the photostatic machinery 278 00:09:48,110 --> 00:09:45,480 and the metabolic network end up saving 279 00:09:50,150 --> 00:09:48,120 iron as well so what in fact we were 280 00:09:52,460 --> 00:09:50,160 seeing in the addition of these carbon 281 00:09:54,230 --> 00:09:52,470 excretion pathways is reflective of a 282 00:09:56,270 --> 00:09:54,240 more general process which is increasing 283 00:10:00,200 --> 00:09:56,280 the through flow of electrons through 284 00:10:01,790 --> 00:10:00,210 the system and sort of as a byproduct of 285 00:10:03,470 --> 00:10:01,800 that then ends up excreting some of 286 00:10:06,680 --> 00:10:03,480 these electrons into the into the 287 00:10:10,580 --> 00:10:06,690 environment now try to ask what that 288 00:10:11,900 --> 00:10:10,590 means right so what electrons do is they 289 00:10:14,750 --> 00:10:11,910 transfer energy from the environment 290 00:10:16,220 --> 00:10:14,760 into the cell so in fact what this is 291 00:10:17,270 --> 00:10:16,230 suggesting is that what's going on here 292 00:10:19,940 --> 00:10:17,280 is that evolution is steadily increasing 293 00:10:21,320 --> 00:10:19,950 metabolic rate of the cell and so the 294 00:10:22,610 --> 00:10:21,330 question then becomes why should 295 00:10:24,500 --> 00:10:22,620 evolution increased elie increased 296 00:10:28,580 --> 00:10:24,510 metabolic rate and excretion of organic 297 00:10:30,560 --> 00:10:28,590 carbon and so there's a couple of 298 00:10:32,990 --> 00:10:30,570 additional clues about the system that 299 00:10:33,800 --> 00:10:33,000 you know will help us understand why 300 00:10:35,720 --> 00:10:33,810 this might be 301 00:10:37,400 --> 00:10:35,730 and the main one here is that this 302 00:10:40,460 --> 00:10:37,410 highest metabolic rate phenotype 303 00:10:42,470 --> 00:10:40,470 actually lives in the highest surface 304 00:10:44,540 --> 00:10:42,480 layers environment where the light 305 00:10:46,550 --> 00:10:44,550 energy is most abundant and the nutrient 306 00:10:47,780 --> 00:10:46,560 concentrations are the lowest right so 307 00:10:50,590 --> 00:10:47,790 it suggests that there's a link between 308 00:10:52,850 --> 00:10:50,600 metabolic rate and nutrient acquisition 309 00:10:54,740 --> 00:10:52,860 and that's basically what we ended up 310 00:10:56,270 --> 00:10:54,750 arguing in in the paper which is that 311 00:10:59,330 --> 00:10:56,280 what's going on here is that evolution 312 00:11:01,370 --> 00:10:59,340 is reducing and as an ever more powerful 313 00:11:03,710 --> 00:11:01,380 vacuum cleaner if you will for sucking 314 00:11:05,870 --> 00:11:03,720 up the recalcitrant nutrients from the 315 00:11:07,940 --> 00:11:05,880 environment and as a sort of byproduct 316 00:11:09,680 --> 00:11:07,950 of that sort of exhaust of this more 317 00:11:12,860 --> 00:11:09,690 powerful engine excreting small organic 318 00:11:15,360 --> 00:11:12,870 molecules into the environment we 319 00:11:16,980 --> 00:11:15,370 formalize that a little bit more but 320 00:11:18,900 --> 00:11:16,990 making reversible Michaelis Menten 321 00:11:21,510 --> 00:11:18,910 enzyme kinetics and rewriting it in 322 00:11:22,800 --> 00:11:21,520 terms of nutrient concentrations and for 323 00:11:24,960 --> 00:11:22,810 those of you familiar with resource 324 00:11:27,500 --> 00:11:24,970 ratio theory from ecology it's sort of 325 00:11:30,269 --> 00:11:27,510 an extension of that to geologic time 326 00:11:31,980 --> 00:11:30,279 and when you do that then so now you see 327 00:11:34,230 --> 00:11:31,990 some of the terms we saw before the 328 00:11:35,550 --> 00:11:34,240 nutrient flux is the electron flux this 329 00:11:37,950 --> 00:11:35,560 is the efficiency of carbon fixation 330 00:11:39,780 --> 00:11:37,960 which then gives you the carbon flux the 331 00:11:41,970 --> 00:11:39,790 fraction of exterior carbon here in beta 332 00:11:43,530 --> 00:11:41,980 and the Delta G here is the free energy 333 00:11:47,250 --> 00:11:43,540 of the new update reaction what you can 334 00:11:49,110 --> 00:11:47,260 do is ask if selection is acting now on 335 00:11:51,390 --> 00:11:49,120 the nutrient concentration of the 336 00:11:52,980 --> 00:11:51,400 population at which they live favoring 337 00:11:55,110 --> 00:11:52,990 populations that can grow with lower 338 00:11:57,230 --> 00:11:55,120 nutrient concentrations what sort of 339 00:11:59,460 --> 00:11:57,240 cellular features will start to emerge 340 00:12:00,750 --> 00:11:59,470 and so you can see very quickly that 341 00:12:02,220 --> 00:12:00,760 what you would want to do is you would 342 00:12:04,170 --> 00:12:02,230 lower your nutrient your nutrient 343 00:12:06,329 --> 00:12:04,180 flux which is what we see happening in 344 00:12:08,310 --> 00:12:06,339 the system but a key point here is that 345 00:12:09,630 --> 00:12:08,320 as the nutrient concentrations drop and 346 00:12:11,790 --> 00:12:09,640 cells figure out way to grow at lower 347 00:12:13,380 --> 00:12:11,800 nutrient concentrations the free energy 348 00:12:15,180 --> 00:12:13,390 cost of the nutrient uptake reaction 349 00:12:17,130 --> 00:12:15,190 actually goes up so it becomes more 350 00:12:18,630 --> 00:12:17,140 thermodynamically uphill and so 351 00:12:19,949 --> 00:12:18,640 basically what I think is a good way of 352 00:12:22,560 --> 00:12:19,959 thinking about what the system is then 353 00:12:24,720 --> 00:12:22,570 telling us is that the way it sort of 354 00:12:26,790 --> 00:12:24,730 solves that problem is by driving using 355 00:12:29,190 --> 00:12:26,800 these excess electrons to drive the 356 00:12:31,829 --> 00:12:29,200 system into saturation and coupling that 357 00:12:34,560 --> 00:12:31,839 saturated state metabolism to that 358 00:12:36,210 --> 00:12:34,570 uphill a nutrient uptake reaction but 359 00:12:37,860 --> 00:12:36,220 that brings along with it a lot of extra 360 00:12:39,750 --> 00:12:37,870 carbon that the cell doesn't need and in 361 00:12:41,850 --> 00:12:39,760 fact it wants less of it and so the 362 00:12:44,640 --> 00:12:41,860 excreted carbon allows it to keep 363 00:12:46,410 --> 00:12:44,650 increasing this term of up here without 364 00:12:47,940 --> 00:12:46,420 increasing the overall parameter because 365 00:12:49,740 --> 00:12:47,950 it's actually kind of productive to 366 00:12:51,810 --> 00:12:49,750 increase this term so if you increase 367 00:12:53,130 --> 00:12:51,820 both the electron flux and the expiry of 368 00:12:56,579 --> 00:12:53,140 carbon fraction you can actually solve 369 00:13:00,660 --> 00:12:56,589 the whole problem then so what are the 370 00:13:03,300 --> 00:13:00,670 implications of this framework well it 371 00:13:05,880 --> 00:13:03,310 has a few things and the first thing 372 00:13:07,680 --> 00:13:05,890 that it says is that if you look at this 373 00:13:09,810 --> 00:13:07,690 you know population structure that we 374 00:13:11,370 --> 00:13:09,820 see in the excellent oceans implication 375 00:13:13,740 --> 00:13:11,380 is that the way that that came about is 376 00:13:15,120 --> 00:13:13,750 that you're at a sequence of innovations 377 00:13:17,519 --> 00:13:15,130 near the surface where an assessor 378 00:13:19,140 --> 00:13:17,529 ecotype was living in in a steady-state 379 00:13:20,910 --> 00:13:19,150 equilibrium with its environment an 380 00:13:22,860 --> 00:13:20,920 innovation comes in that enhances the 381 00:13:24,329 --> 00:13:22,870 energy flow through the system that 382 00:13:26,880 --> 00:13:24,339 begins to draw down the nutrient 383 00:13:28,380 --> 00:13:26,890 concentrations in the surface and then 384 00:13:30,570 --> 00:13:28,390 allowing a new 385 00:13:32,670 --> 00:13:30,580 to start expanding in and as the 386 00:13:34,440 --> 00:13:32,680 nutrient concentrations drop is in such 387 00:13:35,820 --> 00:13:34,450 eco type which was adapted to higher 388 00:13:37,950 --> 00:13:35,830 energy concentrations become restricted 389 00:13:39,480 --> 00:13:37,960 further than the wall or water column so 390 00:13:42,270 --> 00:13:39,490 basically evolution is sort of steadily 391 00:13:44,160 --> 00:13:42,280 bending this nutrient curve further and 392 00:13:45,630 --> 00:13:44,170 further down and compressing this 393 00:13:49,260 --> 00:13:45,640 population structure further and further 394 00:13:51,060 --> 00:13:49,270 down the water column what this also 395 00:13:53,280 --> 00:13:51,070 means then is that the implication of 396 00:13:55,170 --> 00:13:53,290 this is that prochlorococcus and you 397 00:13:57,990 --> 00:13:55,180 know on the file plan fin as well have a 398 00:13:59,010 --> 00:13:58,000 important role in shaping the chemistry 399 00:14:01,290 --> 00:13:59,020 in the in the extant 400 00:14:02,880 --> 00:14:01,300 oceans and indeed if you look at 401 00:14:05,130 --> 00:14:02,890 prochlorococcus distributions what you 402 00:14:07,290 --> 00:14:05,140 will see and this is from a transect 403 00:14:09,780 --> 00:14:07,300 your ship going across the whole 404 00:14:11,070 --> 00:14:09,790 atlantic is that and this is depth on 405 00:14:13,440 --> 00:14:11,080 this axis here what you'll see is that 406 00:14:15,900 --> 00:14:13,450 the prochlorococcus populations sort of 407 00:14:17,130 --> 00:14:15,910 retrace the nutrient minima right so 408 00:14:19,080 --> 00:14:17,140 everywhere from core caucuses the 409 00:14:20,220 --> 00:14:19,090 nutrient concentrations are lowest but 410 00:14:21,330 --> 00:14:20,230 it turns out that that's also the 411 00:14:23,820 --> 00:14:21,340 environment where the dissolved organic 412 00:14:25,680 --> 00:14:23,830 carbon levels are at their highest 413 00:14:27,270 --> 00:14:25,690 so dissolved organic carbon in the 414 00:14:29,910 --> 00:14:27,280 global ocean is everywhere sort of at 415 00:14:32,220 --> 00:14:29,920 around 40 micro molar except exactly in 416 00:14:33,780 --> 00:14:32,230 these drops subtropical service oceans 417 00:14:36,540 --> 00:14:33,790 where the concentration spikes up to 80 418 00:14:38,070 --> 00:14:36,550 or 100 micro molar now this of course 419 00:14:40,680 --> 00:14:38,080 has all kinds of implications for 420 00:14:42,300 --> 00:14:40,690 evolution at the ecosystem level right - 421 00:14:43,920 --> 00:14:42,310 both the drawdown of the nutrients dry 422 00:14:46,230 --> 00:14:43,930 as evolution and others but also the 423 00:14:48,750 --> 00:14:46,240 exclusion of organic carbon and to look 424 00:14:51,480 --> 00:14:48,760 at the impacts of that secondary step I 425 00:14:53,910 --> 00:14:51,490 looked at what happens in the metabolism 426 00:14:56,630 --> 00:14:53,920 of SAR 11 which is the most abundant 427 00:14:58,800 --> 00:14:56,640 heterotroph on the planet co-occurs with 428 00:15:00,870 --> 00:14:58,810 prochlorococcus in these environments 429 00:15:02,310 --> 00:15:00,880 and it's in fact almost a little bit 430 00:15:04,080 --> 00:15:02,320 more abundant prochlorococcus globally 431 00:15:06,000 --> 00:15:04,090 but they co-occur always in the same 432 00:15:07,770 --> 00:15:06,010 environment and if you do this kind of 433 00:15:09,930 --> 00:15:07,780 same sort of analysis that I did for 434 00:15:11,850 --> 00:15:09,940 prochlorococcus for SAR 11 what you'll 435 00:15:13,890 --> 00:15:11,860 see that again it's its metabolic core 436 00:15:16,140 --> 00:15:13,900 undergoes a global reorganization 437 00:15:18,420 --> 00:15:16,150 pathways being gained and lost and if 438 00:15:19,770 --> 00:15:18,430 you if you map that diversity on to its 439 00:15:21,810 --> 00:15:19,780 phylogeny what you'll see is that the 440 00:15:23,430 --> 00:15:21,820 metabolic core changes in a way that's 441 00:15:25,410 --> 00:15:23,440 complementary to that of prochlorococcus 442 00:15:27,090 --> 00:15:25,420 so all the pathways that emerges 443 00:15:29,580 --> 00:15:27,100 excretion pathways in prochlorococcus 444 00:15:31,890 --> 00:15:29,590 emerges uptake pathways and SAR 11 and 445 00:15:33,060 --> 00:15:31,900 there's also an excretion pathway that 446 00:15:34,710 --> 00:15:33,070 emerges in started I've been matching an 447 00:15:36,690 --> 00:15:34,720 uptake pathway in prochlorococcus 448 00:15:38,370 --> 00:15:36,700 they've kind of an emergence of free 449 00:15:40,950 --> 00:15:38,380 living mutualism between the two that 450 00:15:42,150 --> 00:15:40,960 you can start to see it even gets a 451 00:15:44,100 --> 00:15:42,160 little bit more interesting than that 452 00:15:46,110 --> 00:15:44,110 because if you look at the metabolic 453 00:15:47,550 --> 00:15:46,120 organization in this system and how 454 00:15:49,430 --> 00:15:47,560 prochlorococcus and started having 455 00:15:51,480 --> 00:15:49,440 interact and you compare that with how 456 00:15:53,610 --> 00:15:51,490 metabolism is distributed across the 457 00:15:54,990 --> 00:15:53,620 organelles of plant cells what you'll 458 00:15:57,990 --> 00:15:55,000 see is that they look like almost exact 459 00:15:59,639 --> 00:15:58,000 analogs of one another so up here is the 460 00:16:01,650 --> 00:15:59,649 ocean microbe community and down here 461 00:16:03,960 --> 00:16:01,660 are plant cells and what you'll see is 462 00:16:05,249 --> 00:16:03,970 that basically the same pathways that 463 00:16:07,769 --> 00:16:05,259 are being used for electron exchange 464 00:16:09,119 --> 00:16:07,779 between prochlorococcus and star 11 look 465 00:16:10,829 --> 00:16:09,129 very similar to the pathways that 466 00:16:13,470 --> 00:16:10,839 chloroplasts and mitochondria use to 467 00:16:15,179 --> 00:16:13,480 exchange electrons so in both cases we 468 00:16:16,980 --> 00:16:15,189 see intermediates of lower glycolysis 469 00:16:18,030 --> 00:16:16,990 and photorespiration sending electrons 470 00:16:19,800 --> 00:16:18,040 from the autotrophic to the 471 00:16:21,240 --> 00:16:19,810 heterotrophic side and in both cases 472 00:16:22,710 --> 00:16:21,250 intermediate from the citric acid cycle 473 00:16:25,019 --> 00:16:22,720 allow electron flow in the opposite 474 00:16:27,780 --> 00:16:25,029 direction but there are a lot more other 475 00:16:29,790 --> 00:16:27,790 similarities beyond that so for example 476 00:16:31,290 --> 00:16:29,800 it's known in ocean communities that you 477 00:16:32,939 --> 00:16:31,300 know prochlorococcus and some star 11 478 00:16:35,009 --> 00:16:32,949 have given up the ability to detoxify 479 00:16:37,949 --> 00:16:35,019 peroxide which is a byproduct of 480 00:16:39,569 --> 00:16:37,959 photosynthesis relying on co-occurring 481 00:16:42,090 --> 00:16:39,579 heterotrophs that do that function for 482 00:16:43,590 --> 00:16:42,100 them same thing in plant cells the 483 00:16:45,569 --> 00:16:43,600 chloroplasts and mitochondria don't do 484 00:16:47,249 --> 00:16:45,579 the the peroxidase reaction to the 485 00:16:49,590 --> 00:16:47,259 peroxide of translation direction itself 486 00:16:51,749 --> 00:16:49,600 that's done by the peroxisome you look 487 00:16:53,100 --> 00:16:51,759 at other enzymes or other genes within 488 00:16:54,749 --> 00:16:53,110 the photo cycle electron transport 489 00:16:56,340 --> 00:16:54,759 chains of actually the electron 490 00:17:00,030 --> 00:16:56,350 transport chains on both sides of the 491 00:17:01,559 --> 00:17:00,040 equation you see that the same genes are 492 00:17:03,780 --> 00:17:01,569 being added to the electron train 493 00:17:05,340 --> 00:17:03,790 transports in both systems that are 494 00:17:07,890 --> 00:17:05,350 draining electrons from the electron 495 00:17:09,809 --> 00:17:07,900 transport chain in both cases the same 496 00:17:11,549 --> 00:17:09,819 genes are being added if you look at the 497 00:17:12,720 --> 00:17:11,559 photosystems themselves and the first 498 00:17:14,909 --> 00:17:12,730 tech electron transport chains 499 00:17:16,470 --> 00:17:14,919 themselves you see below Karakas is 500 00:17:18,329 --> 00:17:16,480 somewhat unique amongst anti-bacterial 501 00:17:20,549 --> 00:17:18,339 for having chlorophyll a and B it has a 502 00:17:23,399 --> 00:17:20,559 tweak so geometry if it's photosystem 2 503 00:17:25,409 --> 00:17:23,409 to one it uses different pigments in a 504 00:17:26,720 --> 00:17:25,419 and B as I mentioned and all those 505 00:17:29,430 --> 00:17:26,730 features are similar to what plant 506 00:17:32,130 --> 00:17:29,440 chloroplasts do as well so if you zoom 507 00:17:33,690 --> 00:17:32,140 out then to this kind of eagle eye view 508 00:17:35,789 --> 00:17:33,700 of this and focusing on the metabolism 509 00:17:38,250 --> 00:17:35,799 it really kind of starts to look as if 510 00:17:40,409 --> 00:17:38,260 the global ocean in the in the tropical 511 00:17:41,930 --> 00:17:40,419 and sub-tropical surface oceans these 512 00:17:44,010 --> 00:17:41,940 communities are essentially 513 00:17:45,810 --> 00:17:44,020 free-floating chloroplasts and 514 00:17:47,190 --> 00:17:45,820 mitochondria sort of interacting with 515 00:17:49,770 --> 00:17:47,200 each other just like organelles and 516 00:17:52,080 --> 00:17:49,780 plant cells do or alternatively that a 517 00:17:55,500 --> 00:17:52,090 plant cells like a microscopic microbial 518 00:17:56,970 --> 00:17:55,510 ocean recapitulated cell 519 00:17:59,370 --> 00:17:56,980 but I think it also allows us to think 520 00:18:01,860 --> 00:17:59,380 about mutualism in a slightly different 521 00:18:03,900 --> 00:18:01,870 way because what these electron exchange 522 00:18:05,810 --> 00:18:03,910 pathways are doing is that what was 523 00:18:08,880 --> 00:18:05,820 initially otherwise going to be 524 00:18:10,860 --> 00:18:08,890 metabolic waste energetic waste now 525 00:18:13,770 --> 00:18:10,870 these exchange pathways are essentially 526 00:18:15,900 --> 00:18:13,780 recycling those electrons allowing the 527 00:18:20,820 --> 00:18:15,910 maximization of electron flux to proceed 528 00:18:24,270 --> 00:18:20,830 now at the community level where as the 529 00:18:26,220 --> 00:18:24,280 loss of these peroxide the toxification 530 00:18:27,720 --> 00:18:26,230 genes and the abundant components of the 531 00:18:29,490 --> 00:18:27,730 system and restricting them to the less 532 00:18:31,170 --> 00:18:29,500 abundant ones and the key point here is 533 00:18:33,810 --> 00:18:31,180 that these genes involve iron in their 534 00:18:36,630 --> 00:18:33,820 active site lowers the average iron flux 535 00:18:38,190 --> 00:18:36,640 of the of the components and so what I 536 00:18:40,530 --> 00:18:38,200 think this is saying is that in many 537 00:18:43,230 --> 00:18:40,540 ways mutualisms are sort of like a self 538 00:18:45,600 --> 00:18:43,240 amplifying feedback loop that that 539 00:18:47,850 --> 00:18:45,610 maximized the electron to nutrient flux 540 00:18:49,590 --> 00:18:47,860 at the ecosystem level sort of emerging 541 00:18:52,980 --> 00:18:49,600 from that same Drive operating at the 542 00:18:54,750 --> 00:18:52,990 lower level of organization so kind of 543 00:18:56,730 --> 00:18:54,760 coming back then sort of and zooming out 544 00:18:58,260 --> 00:18:56,740 to the to a sort of more general level 545 00:18:59,820 --> 00:18:58,270 but I think this is telling us then is 546 00:19:02,970 --> 00:18:59,830 that at the ecosystem level the way 547 00:19:04,790 --> 00:19:02,980 evolution operates is that ecosystems as 548 00:19:07,080 --> 00:19:04,800 a whole follow these sort of self 549 00:19:09,000 --> 00:19:07,090 amplifying and self-organizing 550 00:19:11,130 --> 00:19:09,010 evolutionary trajectories where 551 00:19:13,260 --> 00:19:11,140 innovations that increase the energy 552 00:19:14,880 --> 00:19:13,270 input into the system caused a drawdown 553 00:19:17,130 --> 00:19:14,890 of nutrients in the environment and an 554 00:19:19,530 --> 00:19:17,140 increase in this in the biomass tanning 555 00:19:21,420 --> 00:19:19,540 stock of the ecosystem but this is done 556 00:19:23,490 --> 00:19:21,430 by increasing the electron flux faster 557 00:19:25,860 --> 00:19:23,500 than the nutrient flux and so you have 558 00:19:27,330 --> 00:19:25,870 an increased amount of excess electrons 559 00:19:29,310 --> 00:19:27,340 sort of circulating through the system 560 00:19:31,020 --> 00:19:29,320 and those excess electrons then drive 561 00:19:32,130 --> 00:19:31,030 the organization and the emergence of 562 00:19:35,250 --> 00:19:32,140 higher levels of organization that 563 00:19:36,810 --> 00:19:35,260 continue that same sort of process and 564 00:19:38,400 --> 00:19:36,820 so the key point then is that if you 565 00:19:40,950 --> 00:19:38,410 look I think what this is saying is that 566 00:19:43,620 --> 00:19:40,960 if you look at evolution on geologic 567 00:19:45,480 --> 00:19:43,630 timescales it's not actually a zero-sum 568 00:19:48,090 --> 00:19:45,490 game is that what it's doing is it's 569 00:19:51,930 --> 00:19:48,100 promoting a more energetic or more 570 00:19:53,640 --> 00:19:51,940 massive and a more complex biosphere now 571 00:19:55,770 --> 00:19:53,650 this has then implications for thinking 572 00:19:57,840 --> 00:19:55,780 about Earth history as a whole so if you 573 00:20:00,600 --> 00:19:57,850 think but you know where oxygen in our 574 00:20:02,690 --> 00:20:00,610 atmosphere comes from this is sort of a 575 00:20:04,230 --> 00:20:02,700 simplified view of the carbon cycle 576 00:20:06,150 --> 00:20:04,240 photosynthesis balanced against 577 00:20:08,550 --> 00:20:06,160 respiration now of course this is 578 00:20:09,450 --> 00:20:08,560 ultimately the source of the oxygen but 579 00:20:10,740 --> 00:20:09,460 if these two process 580 00:20:13,470 --> 00:20:10,750 these are perfectly balanced you won't 581 00:20:15,840 --> 00:20:13,480 actually have free oxygen so you know 582 00:20:17,460 --> 00:20:15,850 for long over long timescales of history 583 00:20:18,840 --> 00:20:17,470 it's thought that the way we accumulate 584 00:20:21,389 --> 00:20:18,850 atmosphere and the oxygen is that a 585 00:20:23,630 --> 00:20:21,399 small fraction of that carbon ends up 586 00:20:26,580 --> 00:20:23,640 being buried inside of the Earth's crust 587 00:20:28,230 --> 00:20:26,590 so if you now think about this on top of 588 00:20:29,880 --> 00:20:28,240 this kind of evolutionary dynamic where 589 00:20:31,649 --> 00:20:29,890 you have these innovations that increase 590 00:20:33,930 --> 00:20:31,659 the global standing stock of organic 591 00:20:36,029 --> 00:20:33,940 carbon and you have sort of always a 592 00:20:38,250 --> 00:20:36,039 steady background burial rate of 0.1 593 00:20:40,049 --> 00:20:38,260 percent or so if you suddenly increase 594 00:20:42,029 --> 00:20:40,059 the total standing soft organic carbon 595 00:20:43,680 --> 00:20:42,039 and this relative flux increases the 596 00:20:47,700 --> 00:20:43,690 total absolute flux of organic carbon 597 00:20:50,450 --> 00:20:47,710 burial now so turns out that if you look 598 00:20:52,980 --> 00:20:50,460 at molecular clock analyses that 599 00:20:54,630 --> 00:20:52,990 prochlorococcus and the Marine Pico 600 00:20:56,730 --> 00:20:54,640 Center bacteria in fact all planktonic 601 00:20:58,440 --> 00:20:56,740 santé bacteria emerge sort of right 602 00:21:00,269 --> 00:20:58,450 around this time in the earth history 603 00:21:02,610 --> 00:21:00,279 here between half a billion and about a 604 00:21:04,680 --> 00:21:02,620 billion years ago when oxygen starts to 605 00:21:08,070 --> 00:21:04,690 rise in the atmosphere so down here just 606 00:21:10,080 --> 00:21:08,080 as a bit more general point this is sort 607 00:21:12,299 --> 00:21:10,090 of like a general view of the history of 608 00:21:14,669 --> 00:21:12,309 the earth oxygenation and you know a lot 609 00:21:17,100 --> 00:21:14,679 of people often focus on the great 610 00:21:18,930 --> 00:21:17,110 oxidation event here which is when santa 611 00:21:20,730 --> 00:21:18,940 bacteria are thought to have driven or 612 00:21:22,860 --> 00:21:20,740 been part of the driving mechanism of 613 00:21:24,690 --> 00:21:22,870 oxygenating the earth initially but 614 00:21:27,750 --> 00:21:24,700 almost that at least as interesting to 615 00:21:29,399 --> 00:21:27,760 me is the secondary rise of oxygen here 616 00:21:32,039 --> 00:21:29,409 at this period where oxygen goes from 617 00:21:34,230 --> 00:21:32,049 maybe about one percent up to starts to 618 00:21:35,490 --> 00:21:34,240 rise up towards modern levels and that's 619 00:21:38,850 --> 00:21:35,500 exactly around the time that these 620 00:21:40,320 --> 00:21:38,860 marine vintages start to emerge the 621 00:21:42,180 --> 00:21:40,330 question then is what can these lineages 622 00:21:44,370 --> 00:21:42,190 teach us about the oxygenation of earth 623 00:21:47,519 --> 00:21:44,380 beyond just increasing standing stock of 624 00:21:49,169 --> 00:21:47,529 organic carbon and to think about this 625 00:21:51,269 --> 00:21:49,179 it's useful to kind of briefly review 626 00:21:53,519 --> 00:21:51,279 what we know about ocean chemistry at 627 00:21:55,529 --> 00:21:53,529 that time I should say this is very hard 628 00:21:57,360 --> 00:21:55,539 to study and this is very hotly debated 629 00:21:59,730 --> 00:21:57,370 still but there appears to be at least 630 00:22:02,820 --> 00:21:59,740 some consensus that in the deep open 631 00:22:05,010 --> 00:22:02,830 oceans the at least the the deeper part 632 00:22:06,200 --> 00:22:05,020 of the water column remained anoxic well 633 00:22:08,940 --> 00:22:06,210 after the goe 634 00:22:11,430 --> 00:22:08,950 dominated by iron two-plus and may be 635 00:22:12,560 --> 00:22:11,440 sort of at these continental margins 636 00:22:14,909 --> 00:22:12,570 where there was higher productivity 637 00:22:17,010 --> 00:22:14,919 maybe there there was what's known as 638 00:22:19,409 --> 00:22:17,020 you zinnia driving abundant to sulfide 639 00:22:20,070 --> 00:22:19,419 ions and and whereas you know in the 640 00:22:22,730 --> 00:22:20,080 modern water 641 00:22:24,560 --> 00:22:22,740 modern oceans they're largely 642 00:22:26,149 --> 00:22:24,570 and so the question is what controls his 643 00:22:28,789 --> 00:22:26,159 transition people have suggested several 644 00:22:30,320 --> 00:22:28,799 different negative feedbacks one is that 645 00:22:32,840 --> 00:22:30,330 the sulfide ions can react with 646 00:22:34,370 --> 00:22:32,850 molybdenum and sort of like because 647 00:22:36,380 --> 00:22:34,380 molybdenum has a central role in much of 648 00:22:38,120 --> 00:22:36,390 the nitrogen cycle can potentially 649 00:22:40,190 --> 00:22:38,130 impose some kind of nitrogen limitation 650 00:22:41,539 --> 00:22:40,200 on ocean primary productivity other 651 00:22:44,060 --> 00:22:41,549 people have talked about how iron 652 00:22:45,799 --> 00:22:44,070 two-plus can react with phosphate as a 653 00:22:47,299 --> 00:22:45,809 sort of a grip on the phosphate imposing 654 00:22:49,820 --> 00:22:47,309 phosphorus limitation on the ocean 655 00:22:51,500 --> 00:22:49,830 biosphere but the point is to get over 656 00:22:53,990 --> 00:22:51,510 both of those negative feedbacks you 657 00:22:56,360 --> 00:22:54,000 need to oxygenate the system right so to 658 00:22:57,590 --> 00:22:56,370 oxygenate you have to oxygenate which is 659 00:22:59,450 --> 00:22:57,600 kind of a hard thing to think about and 660 00:23:01,310 --> 00:22:59,460 so people have often argued or thought 661 00:23:03,470 --> 00:23:01,320 about what kind of perturbations might 662 00:23:04,370 --> 00:23:03,480 allow you to get past that system but 663 00:23:06,139 --> 00:23:04,380 what I like to think about is whether 664 00:23:07,430 --> 00:23:06,149 there are other feedback loops that may 665 00:23:10,070 --> 00:23:07,440 allow us to think about this in a more 666 00:23:12,110 --> 00:23:10,080 deterministic way and what I'd like to 667 00:23:14,750 --> 00:23:12,120 what I would like to pose is that iron 668 00:23:16,279 --> 00:23:14,760 actually provides such a mechanism and 669 00:23:19,190 --> 00:23:16,289 the way to think about this is that you 670 00:23:21,610 --> 00:23:19,200 know after the this period in Earth 671 00:23:23,990 --> 00:23:21,620 history you start to see that indeed 672 00:23:26,120 --> 00:23:24,000 molybdenum and phosphorus start to rise 673 00:23:28,190 --> 00:23:26,130 in the ocean the concentration start to 674 00:23:31,490 --> 00:23:28,200 rise which is good for primary 675 00:23:32,720 --> 00:23:31,500 productivity but iron actually drops by 676 00:23:34,340 --> 00:23:32,730 a few orders of magnitude and that's 677 00:23:36,919 --> 00:23:34,350 actually a problem because iron is 678 00:23:38,360 --> 00:23:36,929 central to photosynthesis right so if 679 00:23:39,919 --> 00:23:38,370 you are a forest that excel you have to 680 00:23:41,690 --> 00:23:39,929 figure out a way first to deal with a 681 00:23:43,519 --> 00:23:41,700 drop in iron before you can do 682 00:23:46,310 --> 00:23:43,529 photosynthesis in that dropped iron 683 00:23:49,009 --> 00:23:46,320 environment so to say that another way I 684 00:23:50,930 --> 00:23:49,019 think that ancestral oxygen like 685 00:23:54,320 --> 00:23:50,940 photosynthesis in the air Li has within 686 00:23:56,600 --> 00:23:54,330 it itself negative feedback loop where 687 00:23:58,759 --> 00:23:56,610 you know this is photosynthetic process 688 00:23:59,990 --> 00:23:58,769 here depends on iron and therefore 689 00:24:02,299 --> 00:24:00,000 depends on a flux of iron into the 690 00:24:03,289 --> 00:24:02,309 system but it produces a fox of oxygen 691 00:24:05,690 --> 00:24:03,299 which which sort of ends up 692 00:24:06,830 --> 00:24:05,700 extinguishing this flux of iron here so 693 00:24:08,629 --> 00:24:06,840 you have to figure out a way to deal 694 00:24:10,070 --> 00:24:08,639 with this negative feedback loop and if 695 00:24:11,779 --> 00:24:10,080 you look at what extent phytoplankton 696 00:24:14,029 --> 00:24:11,789 doing prochlorococcus do they do several 697 00:24:16,009 --> 00:24:14,039 things one is that they modify the 698 00:24:18,379 --> 00:24:16,019 stoichiometry of the system to minimize 699 00:24:19,940 --> 00:24:18,389 the usage of iron and what they do is 700 00:24:21,799 --> 00:24:19,950 also these they enhance the absorption 701 00:24:23,509 --> 00:24:21,809 cross section of these systems to make 702 00:24:25,639 --> 00:24:23,519 it more efficient which allows more 703 00:24:27,379 --> 00:24:25,649 oxygen production with less iron but the 704 00:24:29,029 --> 00:24:27,389 other thing that it does is that in the 705 00:24:30,590 --> 00:24:29,039 ocean today iron is actually not free 706 00:24:33,139 --> 00:24:30,600 it's bound to dissolved organic carbon 707 00:24:34,700 --> 00:24:33,149 which is exactly this and in fact the 708 00:24:35,690 --> 00:24:34,710 sorts of molecules that are being 709 00:24:38,919 --> 00:24:35,700 produced by 710 00:24:41,240 --> 00:24:38,929 our caucus these carboxylic acids so 711 00:24:42,649 --> 00:24:41,250 what you then have is within the 712 00:24:44,810 --> 00:24:42,659 metabolic evolution that we're sort of 713 00:24:47,269 --> 00:24:44,820 seeing in prochlorococcus is built in 714 00:24:48,830 --> 00:24:47,279 now a positive feedback loop where the 715 00:24:50,570 --> 00:24:48,840 increase of energy flow through the 716 00:24:53,000 --> 00:24:50,580 system is producing as a by-product 717 00:24:54,740 --> 00:24:53,010 these ligands which can bind iron and 718 00:24:56,419 --> 00:24:54,750 enhance their solubility and 719 00:24:58,940 --> 00:24:56,429 accessibility within this oxygenated 720 00:25:00,620 --> 00:24:58,950 environment and moreover this positive 721 00:25:02,690 --> 00:25:00,630 feedback loop is related to metabolic 722 00:25:04,669 --> 00:25:02,700 rate so as the energy flow as the 723 00:25:07,039 --> 00:25:04,679 metabolic rate increases this positive 724 00:25:08,960 --> 00:25:07,049 feedback loop gets strengthened and you 725 00:25:11,659 --> 00:25:08,970 can over help increasing you start to 726 00:25:13,100 --> 00:25:11,669 overcome this negative feedback loop so 727 00:25:15,259 --> 00:25:13,110 summarize then kind of you have these 728 00:25:17,480 --> 00:25:15,269 phytoplankton here which produce the OC 729 00:25:19,190 --> 00:25:17,490 which bind the iron to stabilize its 730 00:25:20,870 --> 00:25:19,200 abundance it's actually a secondary 731 00:25:23,450 --> 00:25:20,880 thing which is that those same iron 732 00:25:25,430 --> 00:25:23,460 ligands are known to be able to in other 733 00:25:27,919 --> 00:25:25,440 systems able to dissolve rock minerals 734 00:25:30,710 --> 00:25:27,929 and make iron and phosphorus accessible 735 00:25:32,120 --> 00:25:30,720 to life and if you look at where iron 736 00:25:35,750 --> 00:25:32,130 and phosphorous come from out in the 737 00:25:39,080 --> 00:25:35,760 deep open ocean with windblown dust is a 738 00:25:40,490 --> 00:25:39,090 major source of iron and phosphorus and 739 00:25:43,310 --> 00:25:40,500 so if you have this system here which is 740 00:25:45,740 --> 00:25:43,320 producing this excess DLC to stabilize 741 00:25:47,450 --> 00:25:45,750 iron it may not be able to just increase 742 00:25:49,340 --> 00:25:47,460 the accessibility that iron may actually 743 00:25:52,370 --> 00:25:49,350 be able to increase the supply of iron 744 00:25:54,950 --> 00:25:52,380 and phosphorous to the open ocean and of 745 00:25:57,019 --> 00:25:54,960 course at the same time as oxygenation 746 00:25:58,370 --> 00:25:57,029 proceeds those negative feedback loops 747 00:26:00,620 --> 00:25:58,380 that I was talking about before start to 748 00:26:01,730 --> 00:26:00,630 fall away and so the grip of iron even 749 00:26:02,840 --> 00:26:01,740 though you're increasing relatively 750 00:26:03,610 --> 00:26:02,850 speaking the abundance of iron it's 751 00:26:06,289 --> 00:26:03,620 still dropping 752 00:26:07,879 --> 00:26:06,299 allowing it to phosphorus to escape the 753 00:26:11,029 --> 00:26:07,889 grip of iron and increase in total 754 00:26:12,169 --> 00:26:11,039 abundance there's an additional thing 755 00:26:13,879 --> 00:26:12,179 here which is that the sort of 756 00:26:15,259 --> 00:26:13,889 conditions that are being promoted here 757 00:26:17,840 --> 00:26:15,269 which is this dynamic in which you're 758 00:26:19,490 --> 00:26:17,850 drawing down the nitrogen but you're 759 00:26:21,500 --> 00:26:19,500 increasing the bioavailability of 760 00:26:23,600 --> 00:26:21,510 phosphorus sorry of iron and 761 00:26:26,029 --> 00:26:23,610 specifically those are conditions that 762 00:26:28,070 --> 00:26:26,039 are favorable for nitrogen fixation high 763 00:26:29,720 --> 00:26:28,080 iron low nitrogen conditions are where 764 00:26:31,580 --> 00:26:29,730 you generally tend to see nitrogen 765 00:26:34,100 --> 00:26:31,590 fixation and so it's rather interesting 766 00:26:35,779 --> 00:26:34,110 that molecular clocks suggest that the 767 00:26:37,700 --> 00:26:35,789 planktonic cyanobacteria that you see 768 00:26:39,649 --> 00:26:37,710 out in the open ocean emerge right 769 00:26:42,500 --> 00:26:39,659 around at the same time that the open 770 00:26:43,940 --> 00:26:42,510 ocean sign of bacteria do so what this 771 00:26:45,649 --> 00:26:43,950 is then is sort of implying is that 772 00:26:47,180 --> 00:26:45,659 potentially the evolution and the 773 00:26:49,580 --> 00:26:47,190 expansion of these santé material out 774 00:26:51,230 --> 00:26:49,590 into the deep open ocean 775 00:26:53,000 --> 00:26:51,240 brought with it an increased supply of 776 00:26:54,799 --> 00:26:53,010 iron phosphorus and nitrogen out into 777 00:26:59,210 --> 00:26:54,809 the deep open ocean stimulating total 778 00:27:00,740 --> 00:26:59,220 ocean ecosystem productivity now if some 779 00:27:03,049 --> 00:27:00,750 of this sounds familiar to some people 780 00:27:04,850 --> 00:27:03,059 in the audience here it's because people 781 00:27:06,710 --> 00:27:04,860 have actually suggested very similar 782 00:27:09,370 --> 00:27:06,720 mechanisms for what plants did when they 783 00:27:11,870 --> 00:27:09,380 colonize the continents when plants 784 00:27:14,419 --> 00:27:11,880 experience a night of nutrient 785 00:27:16,880 --> 00:27:14,429 limitation they will excrete dissolved 786 00:27:18,560 --> 00:27:16,890 organic carbon from their roots which 787 00:27:20,810 --> 00:27:18,570 dissolves the rocks and releases iron 788 00:27:22,940 --> 00:27:20,820 and phosphorus to become accessible to 789 00:27:25,610 --> 00:27:22,950 those plants also stimulating nitrogen 790 00:27:27,649 --> 00:27:25,620 fixation in their roots and this you 791 00:27:29,240 --> 00:27:27,659 know is was argued to be a key part of 792 00:27:32,029 --> 00:27:29,250 what allowed these systems to expand 793 00:27:34,669 --> 00:27:32,039 onto land increasing the standing stock 794 00:27:37,850 --> 00:27:34,679 of carbon on land and in that process 795 00:27:39,260 --> 00:27:37,860 driving oxygenation and what I guess all 796 00:27:41,539 --> 00:27:39,270 I'm basically trying to say then is that 797 00:27:42,889 --> 00:27:41,549 you can you can argue a very similar 798 00:27:44,690 --> 00:27:42,899 kind of mechanism to what people have 799 00:27:46,340 --> 00:27:44,700 argued for plants happening out in the 800 00:27:47,990 --> 00:27:46,350 open ocean and this is interesting 801 00:27:50,090 --> 00:27:48,000 because they happen sort of roughly in 802 00:27:51,919 --> 00:27:50,100 similar times in Earth history this is 803 00:27:53,149 --> 00:27:51,929 happening somewhere near the in the 804 00:27:55,700 --> 00:27:53,159 neoproterozoic towards the phanerozoic 805 00:27:57,529 --> 00:27:55,710 boundary starts to switch on this 806 00:27:59,240 --> 00:27:57,539 process starts to happen sometime in the 807 00:28:01,490 --> 00:27:59,250 early planet or zoic which is 808 00:28:02,630 --> 00:28:01,500 interesting because I was just trying to 809 00:28:04,159 --> 00:28:02,640 argue before that if you look at the 810 00:28:06,409 --> 00:28:04,169 metabolism of these systems they look 811 00:28:08,029 --> 00:28:06,419 like convergent evolution breaching the 812 00:28:10,880 --> 00:28:08,039 same kind of organization of their 813 00:28:12,620 --> 00:28:10,890 metabolism and in specifically having a 814 00:28:14,090 --> 00:28:12,630 sort of a high metabolic rate type of 815 00:28:16,340 --> 00:28:14,100 phenotype that is part of this expansion 816 00:28:18,380 --> 00:28:16,350 so it really starts to look then if you 817 00:28:19,460 --> 00:28:18,390 kind of look at this level that what's 818 00:28:21,409 --> 00:28:19,470 going on here is that you have now a 819 00:28:23,899 --> 00:28:21,419 process convergent biogeochemical 820 00:28:25,610 --> 00:28:23,909 evolution where photosynthesis oxygen 821 00:28:27,529 --> 00:28:25,620 'ok photosynthesis is sort of expanding 822 00:28:29,090 --> 00:28:27,539 away from these sort of somewhat 823 00:28:31,159 --> 00:28:29,100 protective environments new your 824 00:28:32,480 --> 00:28:31,169 continental boundaries where nutrient 825 00:28:34,639 --> 00:28:32,490 supplies may be a little bit more easier 826 00:28:36,080 --> 00:28:34,649 in some ways out into the deep open 827 00:28:38,210 --> 00:28:36,090 ocean and out onto the continents where 828 00:28:40,310 --> 00:28:38,220 nutrients are harder to access and that 829 00:28:41,899 --> 00:28:40,320 has a key part to do with why 830 00:28:44,750 --> 00:28:41,909 oxygenation is happening in this time in 831 00:28:46,549 --> 00:28:44,760 Earth history so stepping back then and 832 00:28:47,389 --> 00:28:46,559 looking at this sort of profile of Earth 833 00:28:49,730 --> 00:28:47,399 oxygenation 834 00:28:51,889 --> 00:28:49,740 it becomes very tempting to speculate 835 00:28:53,659 --> 00:28:51,899 that what's going on here is that around 836 00:28:56,480 --> 00:28:53,669 this time is when you see first an 837 00:28:58,610 --> 00:28:56,490 expansion of self damping Center 838 00:29:01,850 --> 00:28:58,620 bacteria in sort of slightly more 839 00:29:03,379 --> 00:29:01,860 protective environments but you know 840 00:29:05,029 --> 00:29:03,389 their self damping in that there's 841 00:29:07,579 --> 00:29:05,039 a limit to how much nutrients they can 842 00:29:10,399 --> 00:29:07,589 access and only as they start to invent 843 00:29:12,709 --> 00:29:10,409 a higher metabolic rate variants and 844 00:29:14,749 --> 00:29:12,719 these sort of higher power forms of 845 00:29:16,159 --> 00:29:14,759 oxygen ik photosynthesis can live expand 846 00:29:18,109 --> 00:29:16,169 away into these sort of harsher 847 00:29:19,699 --> 00:29:18,119 environments increasing the total 848 00:29:22,669 --> 00:29:19,709 standings of organic carbon and driving 849 00:29:26,329 --> 00:29:22,679 earth oxygenation and relating this back 850 00:29:28,369 --> 00:29:26,339 then to complexity also and thinking 851 00:29:29,749 --> 00:29:28,379 about biosphere complexity and thinking 852 00:29:32,419 --> 00:29:29,759 about this in the context of increasing 853 00:29:34,609 --> 00:29:32,429 biospheric energy flux right sort of 854 00:29:35,539 --> 00:29:34,619 around this time is when you sort of you 855 00:29:37,339 --> 00:29:35,549 know a lot of evidence is suggesting 856 00:29:39,979 --> 00:29:37,349 this is when eukaryotes start to come on 857 00:29:41,599 --> 00:29:39,989 the scene whereas after this period here 858 00:29:43,190 --> 00:29:41,609 is when you start to see multicellular 859 00:29:45,499 --> 00:29:43,200 large multicellular organisms start to 860 00:29:48,229 --> 00:29:45,509 come online so again thinking about 861 00:29:50,209 --> 00:29:48,239 increasing coupling the increase in mass 862 00:29:54,139 --> 00:29:50,219 energy and complexity of the biosphere 863 00:29:55,459 --> 00:29:54,149 and so just to end then which I always 864 00:29:56,779 --> 00:29:55,469 think it's kind of fun to think about is 865 00:29:58,039 --> 00:29:56,789 that if you start to think about the 866 00:30:00,529 --> 00:29:58,049 evolution of the biosphere through this 867 00:30:02,389 --> 00:30:00,539 lens it's actually not all that 868 00:30:03,859 --> 00:30:02,399 different from thinking about how human 869 00:30:07,129 --> 00:30:03,869 societies have evolved in the 870 00:30:08,899 --> 00:30:07,139 post-industrial age right so as we have 871 00:30:11,269 --> 00:30:08,909 invented ways of pulling evermore 872 00:30:14,479 --> 00:30:11,279 electrons out of the earth married 873 00:30:17,089 --> 00:30:14,489 electrons or electrons from from plants 874 00:30:20,119 --> 00:30:17,099 and so on we have increased the amount 875 00:30:22,190 --> 00:30:20,129 of artificial nitrogen fixation that we 876 00:30:23,719 --> 00:30:22,200 have been doing we are increasing the 877 00:30:25,999 --> 00:30:23,729 amount of phosphate that we are mining 878 00:30:27,379 --> 00:30:26,009 from our minerals on earth and we are 879 00:30:29,659 --> 00:30:27,389 also increasing the rate at which we are 880 00:30:31,609 --> 00:30:29,669 extracting metals from our planet and at 881 00:30:33,499 --> 00:30:31,619 the same time the energy increases not 882 00:30:34,969 --> 00:30:33,509 just the total energy consumption is not 883 00:30:36,859 --> 00:30:34,979 increasing is not only increasing but 884 00:30:38,419 --> 00:30:36,869 also per person is it increasing and 885 00:30:42,190 --> 00:30:38,429 this is corresponding with the 886 00:30:44,149 --> 00:30:42,200 population boom of our human societies 887 00:30:46,039 --> 00:30:44,159 corresponding with all of that increased 888 00:30:47,419 --> 00:30:46,049 energy flow through the system there's 889 00:30:50,629 --> 00:30:47,429 lots of innovations that are happening 890 00:30:51,739 --> 00:30:50,639 that are driving integration and the 891 00:30:53,509 --> 00:30:51,749 emergence of higher levels of 892 00:30:55,940 --> 00:30:53,519 organization with human societies as 893 00:30:57,649 --> 00:30:55,950 well so economies are ever more 894 00:30:59,810 --> 00:30:57,659 integrated or social structures are 895 00:31:01,399 --> 00:30:59,820 becoming more integrated and our 896 00:31:05,029 --> 00:31:01,409 political structures are becoming more 897 00:31:10,489 --> 00:31:05,039 integrated as well so you know it's sort 898 00:31:11,869 --> 00:31:10,499 of tempting then to think of the rostral 899 00:31:16,430 --> 00:31:11,879 revolution as a kind of a heterotrophic 900 00:31:17,210 --> 00:31:16,440 innovation in Earth history and you know 901 00:31:19,340 --> 00:31:17,220 this is a 902 00:31:21,710 --> 00:31:19,350 then also seen in the composition of the 903 00:31:23,930 --> 00:31:21,720 atmosphere right so you know a lot of 904 00:31:25,399 --> 00:31:23,940 people focus on the increase of co2 in 905 00:31:28,010 --> 00:31:25,409 the atmosphere which you know our 906 00:31:29,510 --> 00:31:28,020 burning of carbon is doing that but 907 00:31:31,820 --> 00:31:29,520 actually at the same time we're drawing 908 00:31:33,409 --> 00:31:31,830 down oxygen right through the burning of 909 00:31:35,330 --> 00:31:33,419 the carbon we're drawing down the oxygen 910 00:31:36,680 --> 00:31:35,340 now this is a very small amount on the 911 00:31:38,270 --> 00:31:36,690 total background of oxygen so you don't 912 00:31:41,480 --> 00:31:38,280 really register it all that much but 913 00:31:43,070 --> 00:31:41,490 nevertheless it's it is going on at the 914 00:31:46,490 --> 00:31:43,080 same time now we're on the verge of a 915 00:31:47,690 --> 00:31:46,500 human autotrophic innovation and sort of 916 00:31:50,120 --> 00:31:47,700 playing around we've been trying to 917 00:31:51,140 --> 00:31:50,130 invent artificial photosynthesis and so 918 00:31:52,520 --> 00:31:51,150 I think it's sort of interesting to 919 00:31:54,500 --> 00:31:52,530 think about what this all means for the 920 00:31:56,270 --> 00:31:54,510 Earth's system long-term this total 921 00:31:59,029 --> 00:31:56,280 increase in energy flux and pumping into 922 00:32:00,860 --> 00:31:59,039 the system what will that do so I'll 923 00:32:03,380 --> 00:32:00,870 leave it there and just put up the 924 00:32:04,580 --> 00:32:03,390 acknowledgments with all the people that 925 00:32:14,060 --> 00:32:04,590 have helped me in all of this and open 926 00:32:22,460 --> 00:32:14,070 it up for questions thank you okay 927 00:32:25,940 --> 00:32:22,470 questions for Reggie Thanks does really 928 00:32:28,149 --> 00:32:25,950 interesting talk I really like this idea 929 00:32:30,560 --> 00:32:28,159 of ecosystems being self amplifying 930 00:32:33,590 --> 00:32:30,570 self-organizing evolving trying to 931 00:32:36,380 --> 00:32:33,600 maximize like making more energetic 932 00:32:37,820 --> 00:32:36,390 biosphere have you thought about what 933 00:32:39,010 --> 00:32:37,830 this implies for the emergence of life 934 00:32:41,180 --> 00:32:39,020 on other planets 935 00:32:42,470 --> 00:32:41,190 specifically places like Mars and the 936 00:32:45,169 --> 00:32:42,480 idea that maybe you could have a 937 00:32:46,909 --> 00:32:45,179 biosphere that dies out and what the 938 00:32:49,399 --> 00:32:46,919 energy what that means about the energy 939 00:32:50,930 --> 00:32:49,409 availability on other planets that's 940 00:32:53,120 --> 00:32:50,940 interesting question I have not myself 941 00:32:54,140 --> 00:32:53,130 thought about that very much but that is 942 00:32:55,640 --> 00:32:54,150 an interesting question to think about 943 00:32:57,110 --> 00:32:55,650 what are the available energy supplies 944 00:33:01,430 --> 00:32:57,120 and how long do they remain available 945 00:33:03,350 --> 00:33:01,440 yeah and what it implies about what a 946 00:33:05,240 --> 00:33:03,360 biosphere ending might look like yeah 947 00:33:06,980 --> 00:33:05,250 which is something that people 948 00:33:08,299 --> 00:33:06,990 hypothesize could have had a ton Mars 949 00:33:10,220 --> 00:33:08,309 right yeah it's a good it's a good 950 00:33:11,240 --> 00:33:10,230 question I don't have great deep 951 00:33:13,390 --> 00:33:11,250 thoughts about that but it's good 952 00:33:19,799 --> 00:33:13,400 question 953 00:33:24,000 --> 00:33:22,200 that was lovely 954 00:33:25,590 --> 00:33:24,010 my question could become irrelevant 955 00:33:27,149 --> 00:33:25,600 based on this first answer 956 00:33:30,090 --> 00:33:27,159 prochlorococcus don't fix nitrogen 957 00:33:33,060 --> 00:33:30,100 correct right so so how does that fit 958 00:33:35,149 --> 00:33:33,070 into this and and maybe speculating why 959 00:33:39,539 --> 00:33:35,159 they don't fix the intrusion if their 960 00:33:42,210 --> 00:33:39,549 Optima you know right optimizing rates 961 00:33:46,019 --> 00:33:42,220 of production they've got all these free 962 00:33:48,090 --> 00:33:46,029 electrons yeah why not yeah it's a good 963 00:33:50,789 --> 00:33:48,100 question and I can't actually say that I 964 00:33:52,019 --> 00:33:50,799 have a immediately a very good answer to 965 00:33:56,220 --> 00:33:52,029 you but it's kind of interesting that in 966 00:33:58,080 --> 00:33:56,230 general nitrogen fixation and the major 967 00:34:00,899 --> 00:33:58,090 primary productivity are off are often 968 00:34:03,509 --> 00:34:00,909 separate processes same on on land right 969 00:34:05,279 --> 00:34:03,519 like they're plants do this this you 970 00:34:07,799 --> 00:34:05,289 computation but it's then the microbes 971 00:34:10,530 --> 00:34:07,809 in their roots that are doing the 972 00:34:11,639 --> 00:34:10,540 nitrogen fixation I don't know I think 973 00:34:14,310 --> 00:34:11,649 it might have something to do with 974 00:34:16,409 --> 00:34:14,320 specialization and optimizing of the 975 00:34:19,290 --> 00:34:16,419 relative supply do you need obtuse it of 976 00:34:21,659 --> 00:34:19,300 the two things and how the the problem 977 00:34:23,940 --> 00:34:21,669 is an ecosystem perhaps better solved by 978 00:34:25,740 --> 00:34:23,950 having more abundant of your primary 979 00:34:27,720 --> 00:34:25,750 producers and a slightly lower abundance 980 00:34:29,159 --> 00:34:27,730 of your nitrogen fixers and that's sort 981 00:34:31,290 --> 00:34:29,169 of like a slight more optimal solution 982 00:34:32,579 --> 00:34:31,300 in that sense but but it's great I 983 00:34:34,950 --> 00:34:32,589 haven't really like thought that through 984 00:34:36,869 --> 00:34:34,960 with at the molecular sort of network 985 00:34:39,359 --> 00:34:36,879 level how those trade-offs would come 986 00:34:41,550 --> 00:34:39,369 into play but it is interesting that you 987 00:34:43,470 --> 00:34:41,560 know the two cysts the two groups are 988 00:34:45,599 --> 00:34:43,480 expanding into the open ocean sort of 989 00:34:47,430 --> 00:34:45,609 like kind of in the same timeframe so 990 00:34:48,990 --> 00:34:47,440 looking at that more closely and looking 991 00:34:50,820 --> 00:34:49,000 at their metabolic networks and that 992 00:34:52,440 --> 00:34:50,830 their distribution so I might be able to 993 00:34:58,770 --> 00:34:52,450 like get a better answer to your 994 00:34:59,460 --> 00:34:58,780 question right so that's kind of what I 995 00:35:01,290 --> 00:34:59,470 was trying to say with the 996 00:35:03,450 --> 00:35:01,300 specialization right so prochlorococcus 997 00:35:05,220 --> 00:35:03,460 fiercely and furiously trying to 998 00:35:08,280 --> 00:35:05,230 optimize the acquisition of nutrients 999 00:35:10,020 --> 00:35:08,290 and somehow if you draw the nitrogen 1000 00:35:12,120 --> 00:35:10,030 down to the lowest possible level and 1001 00:35:13,650 --> 00:35:12,130 you're best at that that that means that 1002 00:35:16,470 --> 00:35:13,660 ultimately the ecosystem will supply the 1003 00:35:18,150 --> 00:35:16,480 nitrogen to you right so the other other 1004 00:35:20,040 --> 00:35:18,160 cells will be doing the Nitro fixation 1005 00:35:27,870 --> 00:35:20,050 and eventually it'll make its way back 1006 00:35:40,030 --> 00:35:37,270 yes for the for the second oxygenation 1007 00:35:42,010 --> 00:35:40,040 event yeah the one and a half billion 1008 00:35:44,200 --> 00:35:42,020 year lag between the first and the 1009 00:35:45,400 --> 00:35:44,210 second is that essentially just waiting 1010 00:35:46,660 --> 00:35:45,410 for the innovation of high-powered 1011 00:35:48,520 --> 00:35:46,670 metabolism to come or do you think there 1012 00:35:50,079 --> 00:35:48,530 was another trigger that drove that 1013 00:35:52,210 --> 00:35:50,089 that's actually a really great question 1014 00:35:55,150 --> 00:35:52,220 and something that I like to think about 1015 00:35:57,309 --> 00:35:55,160 a lot right the question is why is there 1016 00:35:58,540 --> 00:35:57,319 this gap here why does one happen here 1017 00:36:00,520 --> 00:35:58,550 and then why does this happen to you why 1018 00:36:02,859 --> 00:36:00,530 does it happen sooner what what is the 1019 00:36:04,120 --> 00:36:02,869 reason for that so one possibility could 1020 00:36:06,609 --> 00:36:04,130 do that it has to do with the nature of 1021 00:36:09,400 --> 00:36:06,619 innovation and the exploration of you 1022 00:36:11,470 --> 00:36:09,410 know a mutation or landscapes of things 1023 00:36:12,849 --> 00:36:11,480 something along those lines I don't 1024 00:36:15,059 --> 00:36:12,859 actually necessarily think that that's 1025 00:36:17,319 --> 00:36:15,069 the main reason I think there are 1026 00:36:19,740 --> 00:36:17,329 potentially triggers in your system that 1027 00:36:22,030 --> 00:36:19,750 have may have something to do with it so 1028 00:36:23,859 --> 00:36:22,040 but exactly how that works that's a very 1029 00:36:25,329 --> 00:36:23,869 much of an open question and so one 1030 00:36:27,339 --> 00:36:25,339 thing that we need to do is to try to 1031 00:36:29,490 --> 00:36:27,349 like actually resolve the timescales of 1032 00:36:31,270 --> 00:36:29,500 when these these divergences of 1033 00:36:33,490 --> 00:36:31,280 prochlorococcus plus and if your 1034 00:36:34,960 --> 00:36:33,500 partners and subgroups are happening and 1035 00:36:36,250 --> 00:36:34,970 sort of get that finer and try to line 1036 00:36:38,770 --> 00:36:36,260 that up with what's going on in the 1037 00:36:40,120 --> 00:36:38,780 earth system at that time but there's a 1038 00:36:42,120 --> 00:36:40,130 few other things that are happening in 1039 00:36:44,349 --> 00:36:42,130 the earth system that might provide some 1040 00:36:45,730 --> 00:36:44,359 constraints to where we should be 1041 00:36:48,579 --> 00:36:45,740 looking for an answer one is that 1042 00:36:50,020 --> 00:36:48,589 there's a supercontinent Rodinia that's 1043 00:36:52,750 --> 00:36:50,030 sort of breaking up right around this 1044 00:36:53,920 --> 00:36:52,760 time right and this is so these these 1045 00:36:56,319 --> 00:36:53,930 marine center bacteria are coming from 1046 00:36:58,450 --> 00:36:56,329 freshwater ancestors and the breakup of 1047 00:37:00,790 --> 00:36:58,460 Rodinia is of course greatly expanding 1048 00:37:02,290 --> 00:37:00,800 the sort of coastline space and the 1049 00:37:04,329 --> 00:37:02,300 interface between freshwater marine 1050 00:37:06,460 --> 00:37:04,339 water so it's maybe increasing the the 1051 00:37:08,920 --> 00:37:06,470 probabilities of going from freshwater 1052 00:37:11,230 --> 00:37:08,930 to saltwater environments 1053 00:37:12,760 --> 00:37:11,240 there's also global glaciation events 1054 00:37:14,740 --> 00:37:12,770 that go on in this time in this 1055 00:37:16,480 --> 00:37:14,750 timeframe where it's thought that I sort 1056 00:37:19,270 --> 00:37:16,490 of covers much of the planet if not all 1057 00:37:22,210 --> 00:37:19,280 how does that relate to all of this you 1058 00:37:23,500 --> 00:37:22,220 know is that potentially triggering some 1059 00:37:25,960 --> 00:37:23,510 of these transitions some of these 1060 00:37:27,849 --> 00:37:25,970 evolutionary divergences or is there 1061 00:37:29,800 --> 00:37:27,859 some other causal mechanisms going on 1062 00:37:32,410 --> 00:37:29,810 here so I think by trying to actually 1063 00:37:34,480 --> 00:37:32,420 integrate what we know from geology with 1064 00:37:35,960 --> 00:37:34,490 what we see in the genomic record will 1065 00:37:41,690 --> 00:37:35,970 help us constrain that 1066 00:37:45,320 --> 00:37:41,700 much better I'm interested in the you 1067 00:37:50,900 --> 00:37:45,330 know the oxygenation but the events are 1068 00:37:55,040 --> 00:37:50,910 exotic and if so you said there you know 1069 00:37:58,970 --> 00:37:55,050 the the new more efficient mechanism Evo 1070 00:38:00,680 --> 00:37:58,980 and making a positive feedback but you 1071 00:38:03,440 --> 00:38:00,690 know we geologists said you know before 1072 00:38:07,130 --> 00:38:03,450 the the second rise of oxygen billion 1073 00:38:10,190 --> 00:38:07,140 years is nothing happened right so so my 1074 00:38:13,880 --> 00:38:10,200 question is what do you think prohibited 1075 00:38:16,640 --> 00:38:13,890 the new innovations before the these two 1076 00:38:20,180 --> 00:38:16,650 events I guess then in a way the the 1077 00:38:22,670 --> 00:38:20,190 speculation what prevented the the 1078 00:38:24,050 --> 00:38:22,680 innovation is in a way I think similar 1079 00:38:26,630 --> 00:38:24,060 to what we were just talking about what 1080 00:38:28,220 --> 00:38:26,640 triggered the innovation so it's a good 1081 00:38:30,620 --> 00:38:28,230 question I don't actually have a 1082 00:38:32,300 --> 00:38:30,630 particularly good answer for you but I 1083 00:38:34,430 --> 00:38:32,310 should also mention about you know 1084 00:38:35,839 --> 00:38:34,440 episodic and about oxygen rise this is 1085 00:38:38,089 --> 00:38:35,849 not somehow this sort of like click 1086 00:38:39,740 --> 00:38:38,099 switch is on here right so you see 1087 00:38:41,900 --> 00:38:39,750 actually perturbations in the carbon 1088 00:38:44,060 --> 00:38:41,910 cycle that extend back to about a 1089 00:38:46,220 --> 00:38:44,070 billion years or so before you really 1090 00:38:47,720 --> 00:38:46,230 start to see the rise of oxygen and then 1091 00:38:49,280 --> 00:38:47,730 when oxygen starts to rise it's not like 1092 00:38:51,560 --> 00:38:49,290 it's suddenly at very high levels it's 1093 00:38:53,210 --> 00:38:51,570 you know ever new evidence sort of is 1094 00:38:54,770 --> 00:38:53,220 continuously now suggesting that oxygen 1095 00:38:56,450 --> 00:38:54,780 doesn't really start to rise towards 1096 00:38:58,490 --> 00:38:56,460 moderate levels until actually well 1097 00:38:59,720 --> 00:38:58,500 after this boundary it may be somewhere 1098 00:39:01,310 --> 00:38:59,730 between three and four hundred million 1099 00:39:02,599 --> 00:39:01,320 years or so so really trying to 1100 00:39:05,540 --> 00:39:02,609 understand what are the sequences of 1101 00:39:07,040 --> 00:39:05,550 innovations you know across that whole 1102 00:39:08,660 --> 00:39:07,050 period and how does that relate to 1103 00:39:10,130 --> 00:39:08,670 what's going on in the earth system is a 1104 00:39:11,570 --> 00:39:10,140 much better understanding of how the to 1105 00:39:18,079 --> 00:39:11,580 line up or needed to be able to answer 1106 00:39:20,329 --> 00:39:18,089 that question well thank you very much 1107 00:39:22,310 --> 00:39:20,339 for the talk I'm probably just gonna go 1108 00:39:23,900 --> 00:39:22,320 back to something that you said at the 1109 00:39:26,839 --> 00:39:23,910 very beginning I probably tried to 1110 00:39:29,240 --> 00:39:26,849 capture again towards the end I guess do 1111 00:39:31,220 --> 00:39:29,250 you believe that I mean you talked a lot 1112 00:39:33,589 --> 00:39:31,230 about positive and negative feedbacks 1113 00:39:36,050 --> 00:39:33,599 actually as a possible way of interpret 1114 00:39:37,460 --> 00:39:36,060 well not a possible way as the way of 1115 00:39:40,460 --> 00:39:37,470 interpreting what's going on in 1116 00:39:43,070 --> 00:39:40,470 different phases and yeah you also 1117 00:39:45,290 --> 00:39:43,080 mentioned that you know you were not as 1118 00:39:46,880 --> 00:39:45,300 close to the origins of life as you 1119 00:39:48,690 --> 00:39:46,890 could have being but do you believe that 1120 00:39:50,970 --> 00:39:48,700 there is a chance we could 1121 00:39:53,430 --> 00:39:50,980 be able like to capture like some sort 1122 00:39:55,859 --> 00:39:53,440 of like list of invariant properties 1123 00:39:57,870 --> 00:39:55,869 like related to either positive or 1124 00:40:01,230 --> 00:39:57,880 negative feedback or a combination or 1125 00:40:03,150 --> 00:40:01,240 both double allows us like to go back 1126 00:40:06,599 --> 00:40:03,160 and say well yeah once you find that 1127 00:40:09,150 --> 00:40:06,609 sort of I don't know interaction of 1128 00:40:11,130 --> 00:40:09,160 whatever components we are talking about 1129 00:40:16,710 --> 00:40:11,140 then there is a chance that something 1130 00:40:18,780 --> 00:40:16,720 interesting is emerging yeah so I don't 1131 00:40:20,460 --> 00:40:18,790 know this is you know answering 100 sent 1132 00:40:22,859 --> 00:40:20,470 directly your question but the question 1133 00:40:24,060 --> 00:40:22,869 of trying to look for general principles 1134 00:40:25,230 --> 00:40:24,070 that are coming from what we see in 1135 00:40:28,500 --> 00:40:25,240 evolution and try to think about 1136 00:40:31,500 --> 00:40:28,510 emergence I think you know this this 1137 00:40:34,050 --> 00:40:31,510 might be one place where we can think 1138 00:40:35,640 --> 00:40:34,060 about that right because what I'm what 1139 00:40:37,470 --> 00:40:35,650 I've been trying to say here or what I 1140 00:40:40,050 --> 00:40:37,480 was trying to say here is that this sort 1141 00:40:41,760 --> 00:40:40,060 of excess electrons flowing through the 1142 00:40:44,370 --> 00:40:41,770 system and causing a bill about 1143 00:40:46,290 --> 00:40:44,380 potential essentially that then leads to 1144 00:40:48,000 --> 00:40:46,300 an emergence of a feedback loop between 1145 00:40:50,250 --> 00:40:48,010 autotrophs and heterotrophs 1146 00:40:51,660 --> 00:40:50,260 that sort of like continues that process 1147 00:40:53,040 --> 00:40:51,670 but it's a sort of a higher level of 1148 00:40:56,130 --> 00:40:53,050 organization of that kind of dynamic 1149 00:40:58,440 --> 00:40:56,140 that actually fits in a general sense 1150 00:41:00,000 --> 00:40:58,450 with you know some people like to think 1151 00:41:01,829 --> 00:41:00,010 about the emergence of metabolism in 1152 00:41:03,420 --> 00:41:01,839 very similar ways right where you have 1153 00:41:06,599 --> 00:41:03,430 an autocatalytic 1154 00:41:09,150 --> 00:41:06,609 and a proto metabolism with ever longer 1155 00:41:10,829 --> 00:41:09,160 self amplifying feedback loops that sort 1156 00:41:13,410 --> 00:41:10,839 of like defined overall structure 1157 00:41:15,960 --> 00:41:13,420 metabolism growing out and growing away 1158 00:41:17,730 --> 00:41:15,970 from prebiotic chemistry and so i would 1159 00:41:20,849 --> 00:41:17,740 say that those kinds of thinking fit 1160 00:41:22,319 --> 00:41:20,859 nicely with each other and and actually 1161 00:41:25,200 --> 00:41:22,329 coming back to the discussion about 1162 00:41:27,930 --> 00:41:25,210 autotrophs and heterotrophs well right 1163 00:41:29,280 --> 00:41:27,940 which is in this case you know I'm 1164 00:41:30,599 --> 00:41:29,290 talking about innovations on the 1165 00:41:32,819 --> 00:41:30,609 autotrophic side but also on 1166 00:41:34,440 --> 00:41:32,829 heterotrophic side and those need not 1167 00:41:36,720 --> 00:41:34,450 happen ever concurrently there may be 1168 00:41:38,849 --> 00:41:36,730 delays between them right just as we 1169 00:41:41,520 --> 00:41:38,859 were talking about the emergence of rtca 1170 00:41:42,750 --> 00:41:41,530 and OTC a and harder choking heterotroph 1171 00:41:44,760 --> 00:41:42,760 e and what does how what happened before 1172 00:41:46,890 --> 00:41:44,770 the luca and so on it could very well be 1173 00:41:48,300 --> 00:41:46,900 and in fact i personally like the idea 1174 00:41:51,089 --> 00:41:48,310 that in the evolution of these 1175 00:41:53,190 --> 00:41:51,099 ecosystems and of the biosphere that you 1176 00:41:55,050 --> 00:41:53,200 have lags between autotrophic and 1177 00:41:56,579 --> 00:41:55,060 hydrophobic innovations and that there 1178 00:41:58,260 --> 00:41:56,589 might be some connections between those 1179 00:42:00,450 --> 00:41:58,270 legs and the perturbations that we see 1180 00:42:01,319 --> 00:42:00,460 in the carbon cycle right so you'll see 1181 00:42:03,420 --> 00:42:01,329 periods in the 1182 00:42:05,910 --> 00:42:03,430 carbon cycle where for tens of millions 1183 00:42:10,109 --> 00:42:05,920 of years maybe it sort of looks with a 1184 00:42:12,299 --> 00:42:10,119 plus positive carbon isotope skew and 1185 00:42:13,680 --> 00:42:12,309 then there's a massive perturbation 1186 00:42:16,709 --> 00:42:13,690 towards negative then it goes back to 1187 00:42:18,779 --> 00:42:16,719 positive and so I think it's at least 1188 00:42:20,819 --> 00:42:18,789 interesting to ponder whether there 1189 00:42:22,289 --> 00:42:20,829 could be a role in all of that for 1190 00:42:24,420 --> 00:42:22,299 delays between autotrophic and 1191 00:42:26,249 --> 00:42:24,430 heterotrophic innovations and given that 1192 00:42:28,049 --> 00:42:26,259 in the extant biosphere if that if 1193 00:42:29,789 --> 00:42:28,059 there's any merit to such an idea there 1194 00:42:32,039 --> 00:42:29,799 appeared to be as possible at least to 1195 00:42:33,839 --> 00:42:32,049 have substantial lags in time between 1196 00:42:35,549 --> 00:42:33,849 autotrophic and heterotroph innovations 1197 00:42:37,410 --> 00:42:35,559 that becomes interesting to think about 1198 00:42:39,120 --> 00:42:37,420 then in the context of early eco systems 1199 00:42:40,739 --> 00:42:39,130 and what kind of lag might you have 1200 00:42:42,809 --> 00:42:40,749 between autotrophic and hydrophobic 1201 00:42:44,279 --> 00:42:42,819 innovations and what does that make us 1202 00:42:50,549 --> 00:42:44,289 think about the boundary of the Mucca 1203 00:42:55,380 --> 00:42:50,559 for example hi thanks for the great talk 1204 00:42:57,839 --> 00:42:55,390 so my question is a little bit more on 1205 00:43:00,329 --> 00:42:57,849 the kind of sociological speculative 1206 00:43:02,069 --> 00:43:00,339 sites so in particular about the very 1207 00:43:06,120 --> 00:43:02,079 last part of your talk which I find very 1208 00:43:07,949 --> 00:43:06,130 interesting so yeah we see we've seen 1209 00:43:11,670 --> 00:43:07,959 this very disturbing exponential growth 1210 00:43:14,849 --> 00:43:11,680 in all kinds of sociological and sort of 1211 00:43:22,789 --> 00:43:14,859 economic metrics which of course is not 1212 00:43:26,189 --> 00:43:22,799 sustainable in the long term and and so 1213 00:43:29,249 --> 00:43:26,199 yeah basically if it carries on the 1214 00:43:32,400 --> 00:43:29,259 earth collapses but there is an 1215 00:43:38,779 --> 00:43:32,410 alternative which which we see hints of 1216 00:43:41,430 --> 00:43:38,789 right now and that is if we instead of 1217 00:43:43,289 --> 00:43:41,440 generating tons of entropy from our sort 1218 00:43:47,309 --> 00:43:43,299 of metabolic activity and traveling 1219 00:43:50,640 --> 00:43:47,319 around using fossil fuels etc if instead 1220 00:43:53,039 --> 00:43:50,650 we we get our sort of our enrichment 1221 00:43:57,569 --> 00:43:53,049 from just engaging with digital 1222 00:43:59,999 --> 00:43:57,579 technology if you extrapolate forward 1223 00:44:01,410 --> 00:44:00,009 you have this of dystopian vision where 1224 00:44:03,180 --> 00:44:01,420 in the future you know we're just kind 1225 00:44:05,430 --> 00:44:03,190 of in the matrix we're asleep all the 1226 00:44:07,650 --> 00:44:05,440 time being pumped with whatever 1227 00:44:09,689 --> 00:44:07,660 nutrients we need but we we live our 1228 00:44:13,499 --> 00:44:09,699 lives to the full in some digital world 1229 00:44:15,270 --> 00:44:13,509 because right now we all kind of feed 1230 00:44:17,310 --> 00:44:15,280 off social media and 1231 00:44:19,230 --> 00:44:17,320 social media feeds off content generated 1232 00:44:20,880 --> 00:44:19,240 in the real world but it wouldn't be 1233 00:44:23,370 --> 00:44:20,890 difficult for all that content to be 1234 00:44:24,660 --> 00:44:23,380 generated also in the digital world at 1235 00:44:27,270 --> 00:44:24,670 which point you don't need to engage 1236 00:44:30,390 --> 00:44:27,280 with the real world at all and so this 1237 00:44:32,820 --> 00:44:30,400 so this sort of dire vision on the one 1238 00:44:35,250 --> 00:44:32,830 hand it's kind of it's a bit scary but 1239 00:44:36,900 --> 00:44:35,260 it does solve this I mean the entropy 1240 00:44:38,430 --> 00:44:36,910 produced from just manipulating all 1241 00:44:40,740 --> 00:44:38,440 those bits would probably be less than 1242 00:44:42,330 --> 00:44:40,750 like 10 billion people flying all around 1243 00:44:46,860 --> 00:44:42,340 the world and that kind of thing right 1244 00:44:49,410 --> 00:44:46,870 so so might save planet Earth and it 1245 00:44:56,010 --> 00:44:49,420 might also explain Fermi's paradox did 1246 00:44:57,690 --> 00:44:56,020 so I think as speculation on that end is 1247 00:45:00,330 --> 00:44:57,700 a little bit beyond me to be able to 1248 00:45:02,520 --> 00:45:00,340 judge that but there is an interesting 1249 00:45:04,980 --> 00:45:02,530 point actually coming up coming back to 1250 00:45:08,340 --> 00:45:04,990 what we were just talking about general 1251 00:45:10,800 --> 00:45:08,350 ideas and general principles and you 1252 00:45:12,270 --> 00:45:10,810 know what I was what in a way what I was 1253 00:45:16,020 --> 00:45:12,280 trying to think about or trying to argue 1254 00:45:18,120 --> 00:45:16,030 here and maybe this relates a little bit 1255 00:45:20,130 --> 00:45:18,130 to what you're talking about is these 1256 00:45:22,800 --> 00:45:20,140 higher levels of organization that start 1257 00:45:25,710 --> 00:45:22,810 to emerge and increase metabolic rate at 1258 00:45:27,660 --> 00:45:25,720 the ecosystem level there's actually an 1259 00:45:29,400 --> 00:45:27,670 interesting way to think here about the 1260 00:45:31,740 --> 00:45:29,410 balance between maximizing rate and 1261 00:45:33,900 --> 00:45:31,750 maximizing efficiency mm-hm right so 1262 00:45:35,580 --> 00:45:33,910 overall you're still maximizing rate but 1263 00:45:37,500 --> 00:45:35,590 these innovations that produce higher 1264 00:45:38,990 --> 00:45:37,510 levels of organization are in a way 1265 00:45:41,610 --> 00:45:39,000 increasing the efficiency of the system 1266 00:45:43,140 --> 00:45:41,620 right and so that then drives down the 1267 00:45:45,420 --> 00:45:43,150 amount of waste that you're producing 1268 00:45:47,610 --> 00:45:45,430 and so on and so you know perhaps in 1269 00:45:49,740 --> 00:45:47,620 thinking about human societies things 1270 00:45:51,720 --> 00:45:49,750 like emergence of recycling for example 1271 00:45:54,120 --> 00:45:51,730 would be one example of that but so 1272 00:45:56,610 --> 00:45:54,130 maybe you know our complexification are 1273 00:46:01,380 --> 00:45:56,620 sort of of our social systems maybe that 1274 00:46:03,030 --> 00:46:01,390 increases our efficiency actually all 1275 00:46:08,380 --> 00:46:03,040 right so we're at time so let's thank