1 00:00:14,480 --> 00:00:12,170 [Music] 2 00:00:18,029 --> 00:00:14,490 thanks everybody for coming it's my 3 00:00:21,690 --> 00:00:18,039 great pleasure to talk to you today 4 00:00:23,580 --> 00:00:21,700 about some questions so I want to tell 5 00:00:26,370 --> 00:00:23,590 you briefly three things about my talk 6 00:00:29,130 --> 00:00:26,380 one is that it's the top with the 7 00:00:31,589 --> 00:00:29,140 longest title so it's going to be a 8 00:00:33,299 --> 00:00:31,599 little bit complicated the second is I 9 00:00:35,070 --> 00:00:33,309 think my talk is the first one that 10 00:00:38,610 --> 00:00:35,080 doesn't have any movies in it so sorry 11 00:00:41,070 --> 00:00:38,620 about that but please hold on and the 12 00:00:45,780 --> 00:00:41,080 third is that my talk really is a talk 13 00:00:47,400 --> 00:00:45,790 about questions that we're yet to define 14 00:00:49,139 --> 00:00:47,410 exactly what the answers to these 15 00:00:52,740 --> 00:00:49,149 questions are but I would like to 16 00:00:54,389 --> 00:00:52,750 introduce to you today a set of ways of 17 00:00:56,880 --> 00:00:54,399 thinking about life that might help us 18 00:00:59,400 --> 00:00:56,890 address questions concerning how it 19 00:01:02,549 --> 00:00:59,410 started and what the early evolution of 20 00:01:04,020 --> 00:01:02,559 this biological system was like so Jim 21 00:01:06,900 --> 00:01:04,030 already showed us a picture of a cell 22 00:01:09,630 --> 00:01:06,910 here is another picture of a cell in 23 00:01:12,570 --> 00:01:09,640 this case it's not a real cell 24 00:01:14,699 --> 00:01:12,580 it's a beautiful watercolor painting 25 00:01:16,199 --> 00:01:14,709 that was made by David Goodsell who is 26 00:01:19,440 --> 00:01:16,209 at the Scripps Institute in California 27 00:01:21,690 --> 00:01:19,450 and as Jim mentioned the cell is 28 00:01:23,460 --> 00:01:21,700 incredibly complicated it's beautifully 29 00:01:26,219 --> 00:01:23,470 complicated I would say since I'm a 30 00:01:28,710 --> 00:01:26,229 biologist this particular cell has one 31 00:01:30,900 --> 00:01:28,720 single membrane here and it has all of 32 00:01:32,880 --> 00:01:30,910 these green bits inside of it these are 33 00:01:34,859 --> 00:01:32,890 proteins that are inside of the membrane 34 00:01:36,990 --> 00:01:34,869 and it's covered with this hairy stuff 35 00:01:38,730 --> 00:01:37,000 on the outside and that hairy stuff is a 36 00:01:41,160 --> 00:01:38,740 way for the cell to communicate with 37 00:01:43,050 --> 00:01:41,170 other cells in the environment and then 38 00:01:46,559 --> 00:01:43,060 in the inside are these protein machines 39 00:01:49,290 --> 00:01:46,569 and information units that Jim already 40 00:01:51,330 --> 00:01:49,300 introduced and so in addition to asking 41 00:01:53,969 --> 00:01:51,340 the question of how these types of 42 00:01:55,949 --> 00:01:53,979 molecules originally came together and 43 00:01:58,320 --> 00:01:55,959 resulted eventually into the formation 44 00:02:01,020 --> 00:01:58,330 of a cell we have very fundamental 45 00:02:04,320 --> 00:02:01,030 questions left to address concerning the 46 00:02:05,520 --> 00:02:04,330 early evolution of life and how are we 47 00:02:07,619 --> 00:02:05,530 going to think about that early 48 00:02:09,930 --> 00:02:07,629 evolution life comes in many shapes and 49 00:02:13,830 --> 00:02:09,940 sizes it does many many things on the 50 00:02:16,050 --> 00:02:13,840 planet if we went outside today and 51 00:02:18,300 --> 00:02:16,060 started collecting cells or not even 52 00:02:19,710 --> 00:02:18,310 outside from this from this room we 53 00:02:21,510 --> 00:02:19,720 would be able to find cells of many 54 00:02:23,790 --> 00:02:21,520 different shapes and many different 55 00:02:25,500 --> 00:02:23,800 sizes some 56 00:02:27,720 --> 00:02:25,510 time's rarely they become in these 57 00:02:29,460 --> 00:02:27,730 fantastic star shapes sometimes they 58 00:02:31,050 --> 00:02:29,470 look like little salt crystals and they 59 00:02:32,760 --> 00:02:31,060 were originally mistaken to be salt 60 00:02:35,040 --> 00:02:32,770 crystals because they're so square in 61 00:02:37,860 --> 00:02:35,050 shape most of the cells that we know 62 00:02:39,510 --> 00:02:37,870 from our biology books and most that we 63 00:02:41,610 --> 00:02:39,520 would see if we started looking under a 64 00:02:44,880 --> 00:02:41,620 microscope today would be these rod 65 00:02:50,160 --> 00:02:44,890 shaped cells or these kind of sphere 66 00:02:51,360 --> 00:02:50,170 achill shaped cells and we're left with 67 00:02:53,580 --> 00:02:51,370 this question how did all of this 68 00:02:55,980 --> 00:02:53,590 diversity arise and what was early 69 00:02:57,600 --> 00:02:55,990 diversity like on the planet what were 70 00:03:00,270 --> 00:02:57,610 the early mechanisms for diversity 71 00:03:02,760 --> 00:03:00,280 generation and I want to make a point 72 00:03:04,260 --> 00:03:02,770 that the growth of the cell as we 73 00:03:06,930 --> 00:03:04,270 understand it today is intrinsically 74 00:03:09,120 --> 00:03:06,940 linked to the replication of DNA DNA 75 00:03:12,390 --> 00:03:09,130 being the informational polymer of the 76 00:03:14,220 --> 00:03:12,400 cell it's the way that cell cells are 77 00:03:17,550 --> 00:03:14,230 able to pass information from generation 78 00:03:19,890 --> 00:03:17,560 to generation and if we thought about a 79 00:03:22,140 --> 00:03:19,900 cell we can draw an outline around this 80 00:03:24,180 --> 00:03:22,150 DNA molecule we could think about that 81 00:03:26,460 --> 00:03:24,190 DNA replicating and then we would have 82 00:03:29,100 --> 00:03:26,470 two cells here and four cells and so on 83 00:03:31,280 --> 00:03:29,110 from a contemporary perspective of today 84 00:03:34,530 --> 00:03:31,290 one of the most fundamental notions of 85 00:03:36,660 --> 00:03:34,540 biology cells are the fundamental unit 86 00:03:37,800 --> 00:03:36,670 of biology on the planet today and all 87 00:03:41,310 --> 00:03:37,810 cells replicate and they replicate 88 00:03:43,020 --> 00:03:41,320 through this DNA process what I want to 89 00:03:45,210 --> 00:03:43,030 try to do today is try to ask the 90 00:03:48,180 --> 00:03:45,220 question what was it like before this 91 00:03:51,000 --> 00:03:48,190 nice clean DNA replication process and 92 00:03:52,790 --> 00:03:51,010 how do we think about that so again 93 00:03:55,370 --> 00:03:52,800 going back to diversity generation 94 00:03:58,080 --> 00:03:55,380 there's many types of cells many shapes 95 00:04:00,810 --> 00:03:58,090 of cells many types of metabolisms on 96 00:04:03,210 --> 00:04:00,820 the planet and all of this is going to 97 00:04:05,070 --> 00:04:03,220 be linked the generation of this type of 98 00:04:07,920 --> 00:04:05,080 diversity is linked to this fundamental 99 00:04:10,650 --> 00:04:07,930 process of DNA separation and 100 00:04:15,030 --> 00:04:10,660 replication followed by the packaging 101 00:04:16,830 --> 00:04:15,040 into new cells and sometimes when DNA is 102 00:04:18,390 --> 00:04:16,840 replicated there's a mistake that 103 00:04:21,110 --> 00:04:18,400 happens and this is what we usually 104 00:04:23,190 --> 00:04:21,120 refer to as a mutation but this is a 105 00:04:26,190 --> 00:04:23,200 really really fundamental part of 106 00:04:28,830 --> 00:04:26,200 biology in addition to self replication 107 00:04:30,390 --> 00:04:28,840 of DNA molecules we have to always 108 00:04:32,250 --> 00:04:30,400 understand that it's not perfect 109 00:04:34,320 --> 00:04:32,260 there's always mistakes that are made in 110 00:04:35,399 --> 00:04:34,330 this replication process but these 111 00:04:36,929 --> 00:04:35,409 mistakes 112 00:04:39,329 --> 00:04:36,939 English the word mistake has a kind of 113 00:04:41,369 --> 00:04:39,339 negative connotation mistakes are not a 114 00:04:44,429 --> 00:04:41,379 negative process in biological systems 115 00:04:46,979 --> 00:04:44,439 per se in fact when we look at the total 116 00:04:50,009 --> 00:04:46,989 biodiversity on the planet these 117 00:04:54,989 --> 00:04:50,019 mistakes which are accruing through 118 00:04:56,939 --> 00:04:54,999 history here are leading to diversity 119 00:04:59,669 --> 00:04:56,949 generation so all of the life that we 120 00:05:02,489 --> 00:04:59,679 see on the planet is in part a product 121 00:05:05,909 --> 00:05:02,499 of mistakes and so mistakes using that 122 00:05:08,909 --> 00:05:05,919 word is a little bit of a no-no maybe a 123 00:05:11,579 --> 00:05:08,919 mutation is a better word on the left 124 00:05:14,040 --> 00:05:11,589 I'm showing a plot that was generated 125 00:05:16,589 --> 00:05:14,050 just last year from a group in the US 126 00:05:18,350 --> 00:05:16,599 and what this group was able to do was 127 00:05:20,609 --> 00:05:18,360 take the same type of organism and 128 00:05:23,519 --> 00:05:20,619 follow the number of mistakes or 129 00:05:25,019 --> 00:05:23,529 mutations over time and there's a couple 130 00:05:26,609 --> 00:05:25,029 there's a many many interesting things 131 00:05:28,739 --> 00:05:26,619 about this plot and we could spend a lot 132 00:05:30,809 --> 00:05:28,749 of time looking at it today even though 133 00:05:33,619 --> 00:05:30,819 the initial population or cell types 134 00:05:36,059 --> 00:05:33,629 were identical basically identical 135 00:05:38,699 --> 00:05:36,069 different bottles or different tubes 136 00:05:40,169 --> 00:05:38,709 started behaving differently and so even 137 00:05:42,509 --> 00:05:40,179 if we start with the same type of a 138 00:05:43,469 --> 00:05:42,519 system we get different results remember 139 00:05:46,079 --> 00:05:43,479 earlier this morning 140 00:05:48,839 --> 00:05:46,089 what Ramon taught us about the formation 141 00:05:50,519 --> 00:05:48,849 of planets and the universe if he starts 142 00:05:53,269 --> 00:05:50,529 a simulation again he gets a different 143 00:05:55,319 --> 00:05:53,279 set of planets out of here and this 144 00:05:56,790 --> 00:05:55,329 different behavior happening in 145 00:05:59,699 --> 00:05:56,800 different bottles tells us something 146 00:06:01,109 --> 00:05:59,709 about the way evolution works it works 147 00:06:03,149 --> 00:06:01,119 in a way that's not completely 148 00:06:05,399 --> 00:06:03,159 predictable these yellow ones started 149 00:06:07,409 --> 00:06:05,409 changing really really rapidly and then 150 00:06:10,319 --> 00:06:07,419 there was a group of cells here hiding 151 00:06:12,209 --> 00:06:10,329 behind this brown color are a number of 152 00:06:14,699 --> 00:06:12,219 different dots which represent different 153 00:06:17,369 --> 00:06:14,709 bottles and they were all behaving more 154 00:06:19,379 --> 00:06:17,379 similar to one another but so that the 155 00:06:21,419 --> 00:06:19,389 kind of result of this slide is that we 156 00:06:23,189 --> 00:06:21,429 can understand that there is diversity 157 00:06:27,569 --> 00:06:23,199 even when things appear to be the same 158 00:06:31,139 --> 00:06:27,579 and so over time the accumulation of 159 00:06:32,429 --> 00:06:31,149 these isotopes it does happen it doesn't 160 00:06:34,649 --> 00:06:32,439 happen to everybody but it does happen 161 00:06:39,119 --> 00:06:34,659 and it's fundamentally linked to this 162 00:06:41,189 --> 00:06:39,129 process of DNA replication so we're left 163 00:06:42,529 --> 00:06:41,199 with this question to try to think about 164 00:06:44,909 --> 00:06:42,539 how this happened on the early Earth 165 00:06:47,790 --> 00:06:44,919 today we have what's known as the 166 00:06:49,170 --> 00:06:47,800 central dogma of biology where DNA 167 00:06:51,090 --> 00:06:49,180 molecules make RNA 168 00:06:53,219 --> 00:06:51,100 molecules and then those go on to make 169 00:06:55,050 --> 00:06:53,229 these protein molecules these beautiful 170 00:06:57,600 --> 00:06:55,060 machines that Jim showed us these 171 00:06:59,279 --> 00:06:57,610 wonderful videos about this is kind of 172 00:07:01,499 --> 00:06:59,289 how we understand biology operating 173 00:07:04,680 --> 00:07:01,509 today we have an informational component 174 00:07:06,600 --> 00:07:04,690 we have a kind of intermediary between 175 00:07:08,520 --> 00:07:06,610 the information and the function and 176 00:07:11,490 --> 00:07:08,530 then we have this functional component 177 00:07:15,420 --> 00:07:11,500 which is most largely represented by 178 00:07:18,240 --> 00:07:15,430 proteins on the early Earth what could 179 00:07:21,600 --> 00:07:18,250 it have been could it have been proteins 180 00:07:24,390 --> 00:07:21,610 only could it have been RNA only could 181 00:07:25,439 --> 00:07:24,400 it have been DNA only could have been 182 00:07:28,439 --> 00:07:25,449 everything together 183 00:07:32,730 --> 00:07:28,449 I don't know and nobody nobody really 184 00:07:34,379 --> 00:07:32,740 knows for sure but one idea that I think 185 00:07:36,300 --> 00:07:34,389 makes a lot of sense and a lot of people 186 00:07:38,969 --> 00:07:36,310 agree it makes a lot of sense is that 187 00:07:42,150 --> 00:07:38,979 this RNA molecule might be a candidate 188 00:07:44,760 --> 00:07:42,160 to participate in the process of cell 189 00:07:47,550 --> 00:07:44,770 prett self replication and have some 190 00:07:50,400 --> 00:07:47,560 function attributed to it and this is 191 00:07:51,810 --> 00:07:50,410 this idea is really a result of a series 192 00:07:54,240 --> 00:07:51,820 of amazing discoveries that have 193 00:07:57,089 --> 00:07:54,250 happened over the last twenty years or 194 00:07:59,610 --> 00:07:57,099 so where people have found that indeed 195 00:08:02,790 --> 00:07:59,620 RNA molecules are possible of making 196 00:08:05,300 --> 00:08:02,800 themselves again and so they have an 197 00:08:07,770 --> 00:08:05,310 informational component inside of them 198 00:08:10,170 --> 00:08:07,780 because they're able to do things are 199 00:08:13,500 --> 00:08:10,180 able to catalyze chemical reactions or 200 00:08:16,439 --> 00:08:13,510 change the behavior of molecules we can 201 00:08:16,860 --> 00:08:16,449 assign a functional attribute to them as 202 00:08:19,350 --> 00:08:16,870 well 203 00:08:21,779 --> 00:08:19,360 and so RNA takes a special place in 204 00:08:23,640 --> 00:08:21,789 biology it's one of the only polymers 205 00:08:26,010 --> 00:08:23,650 that we know that has a both 206 00:08:28,980 --> 00:08:26,020 informational capacity as well as a 207 00:08:30,899 --> 00:08:28,990 functional capacity proteins we can't 208 00:08:32,399 --> 00:08:30,909 you can try to imagine how that would 209 00:08:33,659 --> 00:08:32,409 store information but it's a little bit 210 00:08:36,810 --> 00:08:33,669 more difficult and not straightforward 211 00:08:39,360 --> 00:08:36,820 and functionally DNA seems to be 212 00:08:42,089 --> 00:08:39,370 chemically almost inert it doesn't have 213 00:08:46,530 --> 00:08:42,099 this ability to hold on to molecules and 214 00:08:48,860 --> 00:08:46,540 change molecules in solution so this is 215 00:08:51,360 --> 00:08:48,870 kind of an idea for how early 216 00:08:53,880 --> 00:08:51,370 replication might happen on the earth 217 00:08:55,889 --> 00:08:53,890 this is a long polymer looks like a 218 00:08:57,300 --> 00:08:55,899 spaghetti noodle on here but we could 219 00:09:00,170 --> 00:08:57,310 imagine that it's actually made out of 220 00:09:03,030 --> 00:09:00,180 oligonucleotides all linked together in 221 00:09:06,420 --> 00:09:03,040 today's biology like I mentioned pre 222 00:09:08,449 --> 00:09:06,430 ously cell growth and proliferation is 223 00:09:11,370 --> 00:09:08,459 fundamentally linked to this process of 224 00:09:13,590 --> 00:09:11,380 duplicating the chromosome and that 225 00:09:16,980 --> 00:09:13,600 changes over time and that gives us this 226 00:09:19,650 --> 00:09:16,990 picture Jim showed earlier a picture 227 00:09:23,420 --> 00:09:19,660 drawn by Darwin who was one of the first 228 00:09:26,280 --> 00:09:23,430 people or two famously draw a 229 00:09:28,499 --> 00:09:26,290 phylogenetic tree which is a graphical 230 00:09:30,930 --> 00:09:28,509 way of depicting relationships in 231 00:09:34,559 --> 00:09:30,940 biology and here's a cartoon diagram 232 00:09:37,980 --> 00:09:34,569 another drawing that was drawn by a Ford 233 00:09:40,740 --> 00:09:37,990 Doolittle in 1999 and it shows this idea 234 00:09:42,780 --> 00:09:40,750 that sometime in the past here on the 235 00:09:45,269 --> 00:09:42,790 bottom would be in the past and the top 236 00:09:47,670 --> 00:09:45,279 would be going forward in time 237 00:09:50,490 --> 00:09:47,680 it shows the idea of diversification 238 00:09:52,199 --> 00:09:50,500 happening and that diversification again 239 00:09:54,930 --> 00:09:52,209 is linked to these mistakes these 240 00:09:57,660 --> 00:09:54,940 mutations that happen and as those 241 00:09:59,400 --> 00:09:57,670 mistakes or mutations happen we can kind 242 00:10:01,499 --> 00:09:59,410 of think about adding more colors or 243 00:10:04,170 --> 00:10:01,509 more diversity to life here so this is 244 00:10:06,509 --> 00:10:04,180 how life is evolving today and continues 245 00:10:10,530 --> 00:10:06,519 to evolve on the planet so how did that 246 00:10:13,110 --> 00:10:10,540 begin originally it's possible that this 247 00:10:15,809 --> 00:10:13,120 cartoon diagram on the top would have 248 00:10:18,540 --> 00:10:15,819 been quite a bit more messy in a world 249 00:10:19,439 --> 00:10:18,550 that was made of RNA molecules that were 250 00:10:21,990 --> 00:10:19,449 self-replicating 251 00:10:25,829 --> 00:10:22,000 and part of this mess would be derived 252 00:10:28,920 --> 00:10:25,839 from the the non specificity of this 253 00:10:31,769 --> 00:10:28,930 replication apparatus and so we could 254 00:10:33,660 --> 00:10:31,779 think about what these messy early 255 00:10:37,590 --> 00:10:33,670 moments in time would be like in biology 256 00:10:40,290 --> 00:10:37,600 before life gained the capacity to to 257 00:10:43,590 --> 00:10:40,300 almost perfectly replicate we would have 258 00:10:46,110 --> 00:10:43,600 a situation where we wouldn't be able to 259 00:10:48,379 --> 00:10:46,120 draw nice clean relationships between 260 00:10:50,759 --> 00:10:48,389 different organisms shown on the top 261 00:10:54,059 --> 00:10:50,769 instead we would have more of this net 262 00:10:57,809 --> 00:10:54,069 or this web on the bottom let me point 263 00:11:00,269 --> 00:10:57,819 out here these arrows these arrows 264 00:11:02,100 --> 00:11:00,279 corresponds to gene sharing or the 265 00:11:04,740 --> 00:11:02,110 sharing of DNA between different 266 00:11:07,439 --> 00:11:04,750 organisms we can call this horizontal 267 00:11:09,210 --> 00:11:07,449 gene transfer and it happens a lot and 268 00:11:11,280 --> 00:11:09,220 it's a it's a mechanism of generating 269 00:11:12,660 --> 00:11:11,290 diversity but most of these lines are 270 00:11:14,970 --> 00:11:12,670 vertical and they don't have many 271 00:11:16,740 --> 00:11:14,980 horizontal lines going on between them 272 00:11:18,810 --> 00:11:16,750 in the past 273 00:11:21,180 --> 00:11:18,820 it's possible that things were quite a 274 00:11:24,420 --> 00:11:21,190 bit more messy in the sense that this 275 00:11:27,930 --> 00:11:24,430 was not replicating with as high as a 276 00:11:29,580 --> 00:11:27,940 fidelity and there was more mixing going 277 00:11:32,460 --> 00:11:29,590 on so this is gonna create an 278 00:11:34,260 --> 00:11:32,470 informational e very messy world so we 279 00:11:35,970 --> 00:11:34,270 have to face up to that this idea that 280 00:11:38,430 --> 00:11:35,980 maybe early life was doing information 281 00:11:41,310 --> 00:11:38,440 transfer in different different ways and 282 00:11:42,990 --> 00:11:41,320 so sometime in the past how can we 283 00:11:47,670 --> 00:11:43,000 imagine what this web would be like or 284 00:11:49,470 --> 00:11:47,680 this kind of messy area today we're kind 285 00:11:51,390 --> 00:11:49,480 of taught in our biology books that we 286 00:11:54,180 --> 00:11:51,400 can separate life and the types of life 287 00:11:56,160 --> 00:11:54,190 quite cleanly and indeed we can for 288 00:11:58,290 --> 00:11:56,170 today's biology today's biology is quite 289 00:12:00,030 --> 00:11:58,300 old it's probably been here for three 290 00:12:02,760 --> 00:12:00,040 and a half or four billion years and 291 00:12:05,520 --> 00:12:02,770 we've these vertical lines we can trace 292 00:12:07,470 --> 00:12:05,530 and we can draw a nice network like this 293 00:12:10,170 --> 00:12:07,480 but in the past how can we imagine that 294 00:12:12,060 --> 00:12:10,180 I want to introduce this concept of the 295 00:12:14,190 --> 00:12:12,070 progeny oak just kind of one of the key 296 00:12:16,410 --> 00:12:14,200 words of the talk that I'm getting here 297 00:12:18,960 --> 00:12:16,420 and it refers to a period of life of 298 00:12:23,070 --> 00:12:18,970 biological history where information 299 00:12:25,310 --> 00:12:23,080 transfer was not happening as cleanly or 300 00:12:28,320 --> 00:12:25,320 with the fidelity that it happens today 301 00:12:30,420 --> 00:12:28,330 instead there was massive gene sharing 302 00:12:31,200 --> 00:12:30,430 and the capacity for life to 303 00:12:34,640 --> 00:12:31,210 self-replicate 304 00:12:38,130 --> 00:12:34,650 was not as good as it was today and so 305 00:12:39,690 --> 00:12:38,140 here's contemporary biology somewhere in 306 00:12:41,730 --> 00:12:39,700 the past there would be a common 307 00:12:43,829 --> 00:12:41,740 ancestor but there's the possibility 308 00:12:46,650 --> 00:12:43,839 that deep in time there would be this 309 00:12:48,630 --> 00:12:46,660 location or this phase of biological 310 00:12:52,200 --> 00:12:48,640 evolution that we could call the pro 311 00:12:53,490 --> 00:12:52,210 Jeannot - and that would be where this 312 00:12:56,160 --> 00:12:53,500 massive gene sharing going on 313 00:12:59,100 --> 00:12:56,170 information transfer is not happening 314 00:13:00,780 --> 00:12:59,110 as cleanly as it does today so let's 315 00:13:04,050 --> 00:13:00,790 work through this idea a little bit if 316 00:13:06,480 --> 00:13:04,060 we represent the diversity of life in 317 00:13:08,130 --> 00:13:06,490 this clean network here we could divide 318 00:13:11,010 --> 00:13:08,140 life that we see on the planet today 319 00:13:13,590 --> 00:13:11,020 between what karl was initially 320 00:13:16,560 --> 00:13:13,600 described as our key bacteria today we 321 00:13:18,420 --> 00:13:16,570 call them archaea we could also make a 322 00:13:21,000 --> 00:13:18,430 group that includes us and this bean 323 00:13:25,290 --> 00:13:21,010 sprout' here which we call eukaryotes 324 00:13:27,270 --> 00:13:25,300 and karl was is other group that he he 325 00:13:29,070 --> 00:13:27,280 and others discovered was what he called 326 00:13:30,329 --> 00:13:29,080 the you bacteria but we can call 327 00:13:34,619 --> 00:13:30,339 bacteria today 328 00:13:37,920 --> 00:13:34,629 our question is from where did this bean 329 00:13:40,230 --> 00:13:37,930 sprout really branch out and lead to the 330 00:13:42,749 --> 00:13:40,240 diversification of life that we see 331 00:13:44,790 --> 00:13:42,759 today could have been here and then 332 00:13:46,470 --> 00:13:44,800 diversity went in this direction could 333 00:13:49,199 --> 00:13:46,480 it have been here and diversity went 334 00:13:50,670 --> 00:13:49,209 that direction and this direction or 335 00:13:53,720 --> 00:13:50,680 could it have been somewhere in the 336 00:13:57,299 --> 00:13:53,730 middle where would that diversity 337 00:14:00,119 --> 00:13:57,309 generation take place from and what time 338 00:14:05,790 --> 00:14:00,129 on the earth would that be those are of 339 00:14:08,549 --> 00:14:05,800 questions so here's a diagram I made on 340 00:14:11,400 --> 00:14:08,559 my kitchen table trying to show you this 341 00:14:16,499 --> 00:14:11,410 idea in the past there would be some 342 00:14:18,749 --> 00:14:16,509 start of information transfer this might 343 00:14:23,189 --> 00:14:18,759 be something you might classify as the 344 00:14:24,869 --> 00:14:23,199 origin of life and diversity generation 345 00:14:26,369 --> 00:14:24,879 would start to happening as that 346 00:14:28,290 --> 00:14:26,379 information was passed along and 347 00:14:30,749 --> 00:14:28,300 propagated remember I said that a 348 00:14:33,329 --> 00:14:30,759 fundamental part of DNA replication is 349 00:14:36,660 --> 00:14:33,339 mistakes and those mistakes then go on 350 00:14:38,569 --> 00:14:36,670 to lead to diversity generation so this 351 00:14:41,249 --> 00:14:38,579 is always going to be happening and 352 00:14:43,319 --> 00:14:41,259 there's also always going to be lots of 353 00:14:44,549 --> 00:14:43,329 extinctions happening on the earth we 354 00:14:46,499 --> 00:14:44,559 don't really know how many different 355 00:14:48,480 --> 00:14:46,509 types of life have lived on the earth 356 00:14:50,069 --> 00:14:48,490 because we don't know how to accurately 357 00:14:51,329 --> 00:14:50,079 quantify the number of extinctions that 358 00:14:54,030 --> 00:14:51,339 have happened through the history of 359 00:14:55,829 --> 00:14:54,040 Earth but we could represent them on 360 00:14:58,919 --> 00:14:55,839 paper by having these terminal lines 361 00:15:00,449 --> 00:14:58,929 here there's another extinction here's 362 00:15:04,439 --> 00:15:00,459 some other extinction here's another 363 00:15:08,699 --> 00:15:04,449 extinction what we see today is kind of 364 00:15:11,610 --> 00:15:08,709 this highly evolved area which doesn't 365 00:15:14,549 --> 00:15:11,620 necessarily go that far back deep into 366 00:15:16,769 --> 00:15:14,559 the past so it's a huge challenge to try 367 00:15:21,569 --> 00:15:16,779 to gain insight into an area that we 368 00:15:24,179 --> 00:15:21,579 can't see so instead of this clean 369 00:15:26,759 --> 00:15:24,189 relationship of drawing one beansprout 370 00:15:28,499 --> 00:15:26,769 or one source leading to the diversity 371 00:15:30,059 --> 00:15:28,509 that we see today I want to suggest to 372 00:15:31,619 --> 00:15:30,069 you that the past might have been a lot 373 00:15:33,329 --> 00:15:31,629 more complicated and it might have 374 00:15:38,490 --> 00:15:33,339 looked like this whole pack of beans 375 00:15:40,350 --> 00:15:38,500 that I incorporated into soup but here 376 00:15:42,020 --> 00:15:40,360 I'm using to display this complicated 377 00:15:44,270 --> 00:15:42,030 Network in the 378 00:15:46,190 --> 00:15:44,280 that may have been on the earth so we 379 00:15:49,040 --> 00:15:46,200 don't know exactly when life started and 380 00:15:51,140 --> 00:15:49,050 we don't know exactly how fast diversity 381 00:15:54,670 --> 00:15:51,150 was generated on the planet to lead to 382 00:15:58,010 --> 00:15:54,680 what we see today we don't know that 383 00:16:00,710 --> 00:15:58,020 life could have started relatively later 384 00:16:03,950 --> 00:16:00,720 probably not this late but I'll use this 385 00:16:06,710 --> 00:16:03,960 as a point just to draw some questions 386 00:16:10,130 --> 00:16:06,720 from you like life may have started here 387 00:16:11,450 --> 00:16:10,140 or a life may have started here and here 388 00:16:14,540 --> 00:16:11,460 on the bottom what I'm showing you is 389 00:16:16,010 --> 00:16:14,550 this kind of from you where we have the 390 00:16:18,590 --> 00:16:16,020 formation of the earth somewhere around 391 00:16:21,440 --> 00:16:18,600 here this is what Ramon was talking 392 00:16:23,840 --> 00:16:21,450 about here we are today so we don't know 393 00:16:25,430 --> 00:16:23,850 exactly where this tree where this 394 00:16:27,470 --> 00:16:25,440 diversity generation would have started 395 00:16:29,480 --> 00:16:27,480 it could have happened on another planet 396 00:16:31,790 --> 00:16:29,490 and that life could have came to this 397 00:16:33,380 --> 00:16:31,800 planet and just continued becoming more 398 00:16:36,050 --> 00:16:33,390 and more diverse or it could have 399 00:16:37,250 --> 00:16:36,060 happened later on our planet how are we 400 00:16:39,980 --> 00:16:37,260 going to get ourselves out of this 401 00:16:41,870 --> 00:16:39,990 problem this is difficult problem we can 402 00:16:44,630 --> 00:16:41,880 constrain some things on this planet by 403 00:16:46,910 --> 00:16:44,640 knowing something about like Ramon told 404 00:16:49,100 --> 00:16:46,920 us this moon-forming impact probably 405 00:16:50,960 --> 00:16:49,110 would have sterilized the planet the 406 00:16:52,850 --> 00:16:50,970 planet became so hot that it wouldn't be 407 00:16:55,580 --> 00:16:52,860 possible to have life as we would really 408 00:16:59,060 --> 00:16:55,590 accept it to be on the planet and on 409 00:17:01,640 --> 00:16:59,070 these molten Lakes we know that sometime 410 00:17:05,060 --> 00:17:01,650 after that relatively soon there were 411 00:17:06,530 --> 00:17:05,070 there was water on the planet so as far 412 00:17:09,110 --> 00:17:06,540 as we understand life today all life 413 00:17:11,300 --> 00:17:09,120 requires water on this planet so after 414 00:17:12,860 --> 00:17:11,310 the formation of water would it planet 415 00:17:15,860 --> 00:17:12,870 cooled down enough to have liquid water 416 00:17:18,199 --> 00:17:15,870 on it we would be able to say maybe life 417 00:17:20,540 --> 00:17:18,209 could be starting around here and so but 418 00:17:22,880 --> 00:17:20,550 there's a huge range of when cells that 419 00:17:26,360 --> 00:17:22,890 we could recognize today actually began 420 00:17:29,210 --> 00:17:26,370 and this range is so big that I would 421 00:17:30,800 --> 00:17:29,220 suggest that it's not really until later 422 00:17:32,260 --> 00:17:30,810 in evolution that we can be really sure 423 00:17:35,720 --> 00:17:32,270 that we have something that is 424 00:17:38,120 --> 00:17:35,730 recognizable as a cell today here I used 425 00:17:40,490 --> 00:17:38,130 the idea of having cyanobacteria which 426 00:17:43,910 --> 00:17:40,500 can acquire electrons from water and 427 00:17:44,960 --> 00:17:43,920 make oxygen as the strongest sign of 428 00:17:47,030 --> 00:17:44,970 life 429 00:17:49,880 --> 00:17:47,040 in terms of something that we could file 430 00:17:51,800 --> 00:17:49,890 a genetically recognized today before 431 00:17:53,750 --> 00:17:51,810 this time we have little hints like 432 00:17:54,770 --> 00:17:53,760 these mounds of life these piles of 433 00:17:56,750 --> 00:17:54,780 cells but 434 00:17:59,660 --> 00:17:56,760 could we recognize those to be part of 435 00:18:03,050 --> 00:17:59,670 the Tree of Life maybe maybe not we have 436 00:18:04,520 --> 00:18:03,060 some signs of metabolism isn't the same 437 00:18:06,650 --> 00:18:04,530 type of metabolism that we see today 438 00:18:09,920 --> 00:18:06,660 maybe maybe not this is difficult 439 00:18:13,730 --> 00:18:09,930 question so we're left with a series of 440 00:18:15,290 --> 00:18:13,740 questions and our job is to try to dig 441 00:18:18,290 --> 00:18:15,300 through the evidence and try to come up 442 00:18:21,800 --> 00:18:18,300 with the best answer here and just 443 00:18:24,140 --> 00:18:21,810 briefly I want to talk about how we can 444 00:18:28,220 --> 00:18:24,150 start trying to constrain this one way 445 00:18:30,440 --> 00:18:28,230 is to use an energy perspective and like 446 00:18:32,510 --> 00:18:30,450 a chemist would like Jim would say that 447 00:18:34,280 --> 00:18:32,520 life's not too different from other 448 00:18:37,070 --> 00:18:34,290 chemical process here's a butane lighter 449 00:18:40,700 --> 00:18:37,080 it takes butane molecules and combines 450 00:18:42,080 --> 00:18:40,710 them with oxygen and it makes flames I'd 451 00:18:44,260 --> 00:18:42,090 like to introduce the concept to you 452 00:18:47,240 --> 00:18:44,270 that life is not so different from this 453 00:18:49,700 --> 00:18:47,250 in fact all life can be partly 454 00:18:52,280 --> 00:18:49,710 understood as an electronic process so 455 00:18:54,920 --> 00:18:52,290 for example our bodies today we're now 456 00:18:58,400 --> 00:18:54,930 taking electrons that were taking in my 457 00:19:00,710 --> 00:18:58,410 case from my tempura dawn that I had for 458 00:19:04,040 --> 00:19:00,720 lunch and I'm taking those electrons and 459 00:19:05,870 --> 00:19:04,050 my cells are allowing these electrons to 460 00:19:07,640 --> 00:19:05,880 flow through my cell and my cells are 461 00:19:10,100 --> 00:19:07,650 doing some work and that work I'm up 462 00:19:13,310 --> 00:19:10,110 here able to talk and so what we're 463 00:19:15,170 --> 00:19:13,320 going to try to do and our big challenge 464 00:19:18,350 --> 00:19:15,180 is to try to understand how to link 465 00:19:22,220 --> 00:19:18,360 energy and work processes in the cell 466 00:19:23,960 --> 00:19:22,230 with this informational history today we 467 00:19:25,700 --> 00:19:23,970 can understand energy processes on the 468 00:19:29,330 --> 00:19:25,710 earth but what were those energy 469 00:19:31,010 --> 00:19:29,340 processes like in the past combining 470 00:19:33,350 --> 00:19:31,020 these knowledge together the energy 471 00:19:34,520 --> 00:19:33,360 systems and the DNA systems gives us 472 00:19:36,530 --> 00:19:34,530 these different energetic and 473 00:19:38,030 --> 00:19:36,540 information fingerprints and it's these 474 00:19:39,500 --> 00:19:38,040 types of fingerprints that we're going 475 00:19:41,930 --> 00:19:39,510 to be able to use in the future to try 476 00:19:44,630 --> 00:19:41,940 try to define what early biological 477 00:19:47,420 --> 00:19:44,640 evolution was like we don't know what 478 00:19:48,530 --> 00:19:47,430 that would like look like exactly but 479 00:19:51,290 --> 00:19:48,540 it's probably going to be something 480 00:19:54,110 --> 00:19:51,300 complicated like this diagram which is 481 00:19:56,660 --> 00:19:54,120 shown in gray many possible paths of 482 00:19:59,090 --> 00:19:56,670 evolution and then in black just the 483 00:20:01,780 --> 00:19:59,100 types of life that we see today so our 484 00:20:05,450 --> 00:20:01,790 our grand challenge is to try to uncover 485 00:20:08,120 --> 00:20:05,460 this period of biological history for 486 00:20:09,800 --> 00:20:08,130 which we can't really see I hope 487 00:20:12,500 --> 00:20:09,810 to be able to tell you in five or ten 488 00:20:13,820 --> 00:20:12,510 years more about this area thank you 489 00:20:17,580 --> 00:20:13,830 very much 490 00:20:48,960 --> 00:20:34,270 [Music]