1 00:00:04,040 --> 00:00:06,280 This says geology bites with Oliver. 2 00:00:06,280 --> 00:00:11,160 Strimple stromatolites are thought to represent evidence 3 00:00:11,160 --> 00:00:15,720 for life on Earth as far back as about 3 1/2 billion years ago, 4 00:00:16,200 --> 00:00:19,560 which would be far and away the oldest life we know about. 5 00:00:20,520 --> 00:00:24,640 They are the LED structures left behind in rocks by the interplay 6 00:00:24,640 --> 00:00:27,920 between communities of microbes and their environment. 7 00:00:28,930 --> 00:00:31,690 But the interpretation of these structures as biological in 8 00:00:31,690 --> 00:00:35,410 origin is controversial, and several non biological 9 00:00:35,410 --> 00:00:38,610 mechanisms have been proposed that can generate stromatolite 10 00:00:38,610 --> 00:00:42,050 shapes. Martin van Kralendonck has 11 00:00:42,050 --> 00:00:45,730 devoted his long and prolific research career to the study of 12 00:00:45,730 --> 00:00:49,650 the early Earth. One major theme of his work has 13 00:00:49,650 --> 00:00:53,730 been to use detailed mapping and lab research to develop 14 00:00:53,730 --> 00:00:57,210 geological models for the environments of Earth's oldest 15 00:00:57,210 --> 00:01:00,280 fossils. This has helped establish the 16 00:01:00,280 --> 00:01:03,160 biological origin of many ancient fossils. 17 00:01:03,920 --> 00:01:07,560 His recent work on a newly discovered find of exceptionally 18 00:01:07,560 --> 00:01:11,600 well preserved 3 1/2 billion year old sedimentary rocks in 19 00:01:11,600 --> 00:01:16,320 the pillbrocratin of WA has provided the strongest evidence 20 00:01:16,320 --> 00:01:19,480 to date. The structures of this great age 21 00:01:19,680 --> 00:01:22,960 were indeed produced by the earliest forms of life. 22 00:01:24,450 --> 00:01:27,530 Martin van Crellendonck is a professor in the School of 23 00:01:27,530 --> 00:01:31,210 Biological, Earth and Environmental Sciences at the 24 00:01:31,210 --> 00:01:36,370 University of NSW in Sydney. Martin van Crellendonck, welcome 25 00:01:36,370 --> 00:01:39,050 to Geology Bites. Hello Oliver, it's a pleasure to 26 00:01:39,050 --> 00:01:40,490 be here and nice to have a chat with you. 27 00:01:41,090 --> 00:01:45,610 What do stromatolites look like? Stromatolites look like layered, 28 00:01:45,610 --> 00:01:51,050 wrinkly structures in rocks that are different from their 29 00:01:51,050 --> 00:01:54,470 surrounding geology. Their structures preserved as 30 00:01:54,470 --> 00:01:58,830 fossils, just like a fossil elephant bone or a trilobite, 31 00:01:59,270 --> 00:02:02,950 that are preserved in rocks and then surrounded by the 32 00:02:02,950 --> 00:02:07,510 geological matrix, the sandstone, the silt, the shale, 33 00:02:07,510 --> 00:02:11,150 the shirt, which is made by processes that don't involve 34 00:02:11,150 --> 00:02:14,670 life. And they're entombed within that 35 00:02:14,670 --> 00:02:18,790 matrix for, in some cases, many billions of years. 36 00:02:19,110 --> 00:02:21,790 So roughly how big are the structures that you're talking 37 00:02:21,790 --> 00:02:24,560 about? Stromatolites can be very large 38 00:02:24,560 --> 00:02:26,960 indeed. They could be up to 5 meters 39 00:02:26,960 --> 00:02:31,440 high, and they look like rocket cones and some exposures. 40 00:02:31,440 --> 00:02:34,720 They're packed side to side, but those are in slightly younger 41 00:02:34,720 --> 00:02:36,160 rocks than what we're talking about. 42 00:02:36,160 --> 00:02:40,240 Those are already 2 billion years old, but the very ancient 43 00:02:40,240 --> 00:02:41,960 ones, they're quite a bit smaller. 44 00:02:41,960 --> 00:02:45,360 They're about a centimeter scale to sometimes up to 30 45 00:02:45,360 --> 00:02:49,180 centimeters. But even 2.7 billion years ago, 46 00:02:49,180 --> 00:02:52,420 they're stromatolites that are the same height as me, almost 2 47 00:02:52,420 --> 00:02:55,100 meters tall. Before we talk about how 48 00:02:55,100 --> 00:02:59,380 stromatolite like structures can be formed biologically, how do 49 00:02:59,380 --> 00:03:02,580 proponents of a non biological origin explain them? 50 00:03:02,940 --> 00:03:05,660 So you have to be clear that stromatolites are regarded by 51 00:03:05,660 --> 00:03:07,540 the entire community as evidence. 52 00:03:07,990 --> 00:03:10,430 For life through much of the fossil records. 53 00:03:10,430 --> 00:03:12,990 So there are stromatolites that are living today. 54 00:03:12,990 --> 00:03:15,430 There's stromatolites that are a couple of million years old. 55 00:03:15,430 --> 00:03:18,670 There are stromatolites that are one and 2 billion years old, and 56 00:03:18,670 --> 00:03:22,590 nobody has any doubt that those are made by biology. 57 00:03:22,950 --> 00:03:26,710 It's really only the very most ancient ones, these ones that 58 00:03:26,710 --> 00:03:32,110 are 3.5 or beyond, because there is one claim in Greenland at 3.7 59 00:03:32,110 --> 00:03:36,670 billion years old, once they get to that great antiquity. 60 00:03:37,210 --> 00:03:40,290 People are a little bit more cautious just because the rocks 61 00:03:40,290 --> 00:03:44,930 are so old that in many cases they've had quite a long history 62 00:03:44,930 --> 00:03:49,050 of alteration movement, you know, by tilting and folding and 63 00:03:49,050 --> 00:03:51,690 cracking. And because the structures are a 64 00:03:51,690 --> 00:03:55,570 little bit more cryptic, people are rightfully cautious about a 65 00:03:55,610 --> 00:03:57,650 direct interpretation of biology. 66 00:03:58,130 --> 00:04:01,450 Extraordinary claims need extraordinary proof. 67 00:04:01,940 --> 00:04:07,220 That bar is raised for the most ancient type of life, to be able 68 00:04:07,220 --> 00:04:10,500 to really document very carefully that it was made by 69 00:04:10,500 --> 00:04:12,900 biology and not by something else. 70 00:04:13,220 --> 00:04:16,940 There have been proposals, and the main one is that they could 71 00:04:16,940 --> 00:04:21,740 just be the crusts of minerals that have accumulated over time. 72 00:04:22,220 --> 00:04:24,940 And we know that happens in a variety of different settings. 73 00:04:25,260 --> 00:04:28,420 We can see beautiful sometimes shrub like shaped mineral 74 00:04:28,420 --> 00:04:31,750 growths. Some beautifully layered smooth, 75 00:04:32,070 --> 00:04:35,350 some a bit more regularly textured, and those are 76 00:04:35,350 --> 00:04:39,150 structures that can sometimes look like stromatolites. 77 00:04:39,470 --> 00:04:42,590 So people are rightfully cautious to say, well, how can 78 00:04:42,590 --> 00:04:47,430 you absolutely determine that that structure is not a mineral 79 00:04:47,430 --> 00:04:49,830 crust without the influence of biology? 80 00:04:50,190 --> 00:04:52,070 That's a perfectly valid question. 81 00:04:52,070 --> 00:04:55,990 If you think about it, we as humans are living. 82 00:04:56,670 --> 00:05:01,390 But we're also a chemical system and we also produced minerals. 83 00:05:01,390 --> 00:05:04,830 So if you tap your teeth, you're tapping a mineral. 84 00:05:04,990 --> 00:05:08,150 We make minerals, we make bones, we make teeth, we make 85 00:05:08,150 --> 00:05:12,110 fingernails. And so that divide between life 86 00:05:12,590 --> 00:05:17,110 and just chemistry or just geology is in some cases really 87 00:05:17,110 --> 00:05:22,430 fine and really hard to define. What is the mechanism whereby 88 00:05:22,430 --> 00:05:25,550 these intricate layered structures, as much as 5 meters 89 00:05:25,550 --> 00:05:28,930 tall, can be formed by? Well, by biology? 90 00:05:28,930 --> 00:05:30,690 And what kind of biology? Yeah. 91 00:05:30,690 --> 00:05:33,330 So the great thing is that we have living remnants of these 92 00:05:33,330 --> 00:05:36,130 microbial communities that are still making stromatalites 93 00:05:36,130 --> 00:05:38,010 today. So we can study those and 94 00:05:38,010 --> 00:05:42,090 understand very clearly how these rock structures are formed 95 00:05:42,090 --> 00:05:45,570 because they are forming in front of our eyes today. 96 00:05:46,210 --> 00:05:49,930 So the most famous ones are in Shark Bay, WA and they're large 97 00:05:49,930 --> 00:05:54,290 structures up to a meter tall and they're made of rock. 98 00:05:54,780 --> 00:06:00,380 For 99% of the structure, they are made of rock, but the very 99 00:06:00,380 --> 00:06:03,460 top most layer is green and squidgy. 100 00:06:03,460 --> 00:06:07,180 And so if you press on it, it's a little bit slimy, it's goopy, 101 00:06:07,180 --> 00:06:09,980 it moves. So that's where we can see the 102 00:06:09,980 --> 00:06:12,020 life is. And of course when we take a 103 00:06:12,020 --> 00:06:15,020 microscopic view, we can see the microorganisms. 104 00:06:15,580 --> 00:06:20,860 But what these communities do is they make their structures in 105 00:06:20,860 --> 00:06:24,000 three different ways. One is that because they are a 106 00:06:24,000 --> 00:06:27,960 bit sticky, they actually trap sediment that's loosely in the 107 00:06:27,960 --> 00:06:29,800 water. Just think about the piece of 108 00:06:29,800 --> 00:06:32,840 sticky tape on your dining room table with the sticky side up. 109 00:06:33,240 --> 00:06:36,000 Any dust that's floating through the air will stick onto that 110 00:06:36,000 --> 00:06:37,960 sticky tape. And so stromadolites grow the 111 00:06:37,960 --> 00:06:40,280 same way. They trap and then they grow 112 00:06:40,280 --> 00:06:43,680 over and bind the sediment and make a layer that way. 113 00:06:44,040 --> 00:06:48,240 But they can do other things as well and because of their life 114 00:06:48,240 --> 00:06:52,740 force, their metabolism. They actually change a very 115 00:06:52,740 --> 00:06:58,500 small volume of seawater. They change its composition and 116 00:06:58,500 --> 00:07:01,540 seawater has dissolved minerals in it. 117 00:07:01,940 --> 00:07:05,740 When you evaporate the water, it leaves behind those minerals. 118 00:07:05,740 --> 00:07:09,140 And so limestone reefs are one example of that. 119 00:07:09,180 --> 00:07:13,140 Limestone is dissolved in water and we know that salt is 120 00:07:13,140 --> 00:07:17,340 dissolved in seawater and So what microbes can do is they 121 00:07:17,340 --> 00:07:20,140 change the composition of the seawater. 122 00:07:20,680 --> 00:07:24,000 And that will induce the precipitation of minerals 123 00:07:24,000 --> 00:07:26,960 behind. And the microorgans always stay 124 00:07:26,960 --> 00:07:30,840 one step above, they deposit the minerals below and they keep 125 00:07:30,840 --> 00:07:33,600 growing upwards. And so you build up these 126 00:07:33,600 --> 00:07:36,040 layered kind of apartment buildings, if you like from the 127 00:07:36,040 --> 00:07:40,320 ground floor up over time. And then the 3rd way is that you 128 00:07:40,320 --> 00:07:43,720 can get a biological mineral precipitation so. 129 00:07:44,150 --> 00:07:48,270 The presence of those microbes just induces the minerals to 130 00:07:48,270 --> 00:07:51,030 precipitate on them because they have a charged surface. 131 00:07:51,470 --> 00:07:54,150 So there's been interplay of three different mechanisms that 132 00:07:54,150 --> 00:07:58,230 allow for stromatolites to grow. Some only grow by trapping A 133 00:07:58,230 --> 00:08:01,350 binding sediment, some grow really primarily by 134 00:08:01,350 --> 00:08:04,030 precipitating materials as a result of metabolism. 135 00:08:04,550 --> 00:08:07,870 And then there's any combination in between, and that's caused 136 00:08:07,870 --> 00:08:10,270 some of the confusion in the geological literature. 137 00:08:10,350 --> 00:08:13,710 How can we prove that these are made by life? 138 00:08:14,140 --> 00:08:18,420 If you can also have a biogenic mineral crust precipitation, so 139 00:08:18,420 --> 00:08:22,100 it is a tricky game. Are the labs analogous to growth 140 00:08:22,100 --> 00:08:25,180 rings and trees? Each successive wrinkle, if you 141 00:08:25,180 --> 00:08:28,100 like, in this tramatolite. It's very, very tempting to 142 00:08:28,100 --> 00:08:31,740 interpret the layers as annual growth links, but the reality is 143 00:08:31,740 --> 00:08:35,340 that a colleague of mine has sat on a beach in the Bahamas and 144 00:08:35,340 --> 00:08:37,539 watched tramatolites grow for years on end. 145 00:08:38,059 --> 00:08:40,940 And it turns out it's not very regular at all. 146 00:08:41,669 --> 00:08:44,950 That depends a lot more on changing environmental 147 00:08:44,950 --> 00:08:48,830 conditions and storm events turn out to be really important 148 00:08:48,950 --> 00:08:52,310 markers and then they grow very slowly and not much happens for 149 00:08:52,310 --> 00:08:55,350 a long time in between. So it's not as easy as saying 150 00:08:55,350 --> 00:08:59,150 their annual layers, but they do accrete over time if the 151 00:08:59,150 --> 00:09:01,030 conditions are right. Okay. 152 00:09:01,030 --> 00:09:06,470 So let's talk about the recent find of these exceptionally well 153 00:09:06,470 --> 00:09:09,990 preserved 3 1/2 billion year olds from Atalites. 154 00:09:10,640 --> 00:09:13,040 Where exactly were they found and what do they? 155 00:09:13,040 --> 00:09:15,960 Look like so. These ancient structures were 156 00:09:15,960 --> 00:09:19,960 found in the Pilbara region of WA, which is right up in the 157 00:09:19,960 --> 00:09:22,640 northwest corner of the continent, but they weren't 158 00:09:22,640 --> 00:09:24,920 recently discovered. They were actually found in the 159 00:09:24,920 --> 00:09:28,680 very late 1970s already, and they've been looked at for a 160 00:09:28,680 --> 00:09:32,600 long time using mostly just quite simple techniques. 161 00:09:32,600 --> 00:09:36,200 Their shape in the outcrops some thin slices of rocks. 162 00:09:36,780 --> 00:09:39,180 But it's only recently that we've been able to really 163 00:09:39,180 --> 00:09:43,860 penetrate deep inside them into fresh materials and that's the 164 00:09:43,860 --> 00:09:46,820 recent advances that have been made by our group. 165 00:09:47,500 --> 00:09:50,900 So all the previous studies have been worked on from surface 166 00:09:50,900 --> 00:09:54,060 deposits. And the problem is, is that the 167 00:09:54,060 --> 00:09:57,860 surface of the Earth is exposed to weathering. 168 00:09:58,300 --> 00:10:03,100 It's exposed to sun and rain and drying and oxygen. 169 00:10:03,990 --> 00:10:08,270 And in very old rocks, that causes the minerals to get 170 00:10:08,310 --> 00:10:10,990 altered by those surface processes. 171 00:10:10,990 --> 00:10:14,830 And so even though the textures are really well preserved at the 172 00:10:14,830 --> 00:10:19,070 surface, what made the minerals and what the fine kind of 173 00:10:19,070 --> 00:10:24,150 textures were preserved, we couldn't determine until we were 174 00:10:24,150 --> 00:10:28,550 able to retrieve samples of fresh, unaltered material from 175 00:10:28,550 --> 00:10:31,830 deep below the surface through diamond drilling. 176 00:10:32,390 --> 00:10:35,390 Just like the way that exploration companies will take 177 00:10:35,390 --> 00:10:38,310 a drill rig to explore for mineral deposits deep beneath 178 00:10:38,310 --> 00:10:42,870 the ground, my group in two different studies were able to 179 00:10:42,870 --> 00:10:47,350 take a drill into the Pilbra and penetrate below the level of the 180 00:10:47,350 --> 00:10:50,990 surface alteration and extract fresh materials. 181 00:10:51,390 --> 00:10:54,590 And it's by studying those fresh materials that we've learned so 182 00:10:54,590 --> 00:10:56,590 much more about these ancient structures. 183 00:10:56,870 --> 00:11:01,120 How do you know where to dig? Yeah, well, that takes a long 184 00:11:01,120 --> 00:11:02,720 time. So I've been chomping around 185 00:11:02,720 --> 00:11:05,680 that country for about 30 years now, and I'm finally starting to 186 00:11:05,680 --> 00:11:08,520 get a bit of understanding about it because you're right, there 187 00:11:08,520 --> 00:11:11,320 are places where the structures might be faulted away. 188 00:11:11,800 --> 00:11:14,800 And so one of the best places where we take visitors to come 189 00:11:14,800 --> 00:11:17,160 and see. We didn't drill there because 190 00:11:17,160 --> 00:11:20,000 there's a little fault structure and we weren't sure how deep it 191 00:11:20,000 --> 00:11:23,400 might have offset the units, so we went somewhere else where the 192 00:11:23,400 --> 00:11:25,400 conditions were much better preserved. 193 00:11:25,830 --> 00:11:30,150 And we were able to drill there first in 2007 and we retrieved 194 00:11:30,150 --> 00:11:33,550 really good materials. And then more recently in 2019, 195 00:11:33,550 --> 00:11:37,550 we drilled in that similar locality but in a couple of 196 00:11:37,550 --> 00:11:40,670 different places and we retrieved really good material. 197 00:11:40,670 --> 00:11:42,870 And listen, sometimes it doesn't always work out. 198 00:11:42,870 --> 00:11:45,910 One of our drill holes in 2019 completely missed. 199 00:11:46,390 --> 00:11:49,670 And another one got stuck in a fault that was full of clay and 200 00:11:49,670 --> 00:11:52,790 we lost the drill a stem. And you know, it's a risky 201 00:11:52,790 --> 00:11:55,230 business, but the success is worth the effort. 202 00:11:55,270 --> 00:11:59,110 And we got 3 drill holes that were really perfect right 203 00:11:59,110 --> 00:12:01,950 through the sequence. And we actually had one piece of 204 00:12:01,950 --> 00:12:04,550 drill core that we pulled out of the ground and it had 205 00:12:04,550 --> 00:12:06,870 stermatolites exposed on the edge of the core. 206 00:12:06,870 --> 00:12:08,350 We could see it come out of the ground. 207 00:12:08,350 --> 00:12:10,630 It was just incredible how far down was it? 208 00:12:11,120 --> 00:12:15,120 8090 meters down, the depth of alteration can extend down to 209 00:12:15,120 --> 00:12:18,200 about 70 meters. And so we purposely drilled down 210 00:12:18,200 --> 00:12:21,440 till about 80 or 90 meters to be below the effects of surface 211 00:12:21,440 --> 00:12:24,920 oxygen. So what exactly did you look at 212 00:12:24,960 --> 00:12:28,560 in these pristine rocks from this formation then that you 213 00:12:28,560 --> 00:12:31,680 were able to recover from the core to try and clinch the 214 00:12:31,680 --> 00:12:34,920 biological origin of these very, very ancient rocks? 215 00:12:35,400 --> 00:12:39,560 So on the surface, these stromatolites appear rusty red 216 00:12:39,560 --> 00:12:41,910 and black. And they're wrinkly, textured. 217 00:12:41,910 --> 00:12:45,070 And the wrinkly texture is the signature of biology, because 218 00:12:45,070 --> 00:12:47,790 that doesn't happen so easy with just geology. 219 00:12:48,070 --> 00:12:50,990 But then, at depth, these structures that looked exactly 220 00:12:50,990 --> 00:12:54,750 the same were bright yellow, made out of what's commonly 221 00:12:54,750 --> 00:12:58,550 known as fool's gold or pyrite, iron sulfide. 222 00:12:59,150 --> 00:13:02,310 And when that's exposed at the surface, the sulfur combines 223 00:13:02,310 --> 00:13:05,670 with oxygen and it weathers and it makes rust, basically. 224 00:13:05,670 --> 00:13:07,910 So we were looking at the rusted equivalents. 225 00:13:08,430 --> 00:13:10,470 And we couldn't see the fine scale texture. 226 00:13:11,310 --> 00:13:15,150 But down under the ground we found that perfectly preserved 227 00:13:15,150 --> 00:13:17,150 pyrite. And when we pulled those 228 00:13:17,150 --> 00:13:20,670 structures out, we could see these lovely little Dome shaped 229 00:13:20,670 --> 00:13:24,870 columns, in some cases only one centimeter high, but very 230 00:13:24,870 --> 00:13:29,950 clearly growing off of the ancient sea floor 3.5 billion 231 00:13:29,950 --> 00:13:32,470 years ago. And below that we could see 232 00:13:32,470 --> 00:13:35,070 ripples in the sandstone. You know, we could see where the 233 00:13:35,070 --> 00:13:38,290 beach environment was. We could really reconstruct the 234 00:13:38,290 --> 00:13:42,130 environment from these fresh materials, but most importantly 235 00:13:42,170 --> 00:13:45,450 to be able to look inside the layers. 236 00:13:46,290 --> 00:13:49,890 So remember when I talked about livingstromatolites at Shark 237 00:13:49,890 --> 00:13:53,010 Bay, how there's that sort of green squidgy layer at the top 238 00:13:53,010 --> 00:13:56,050 that's the growth material. Well, as the minerals 239 00:13:56,050 --> 00:14:01,130 precipitate, they sometimes grow around the organic matter that 240 00:14:01,130 --> 00:14:04,490 those communities produce and they trap it inside and. 241 00:14:04,960 --> 00:14:08,200 And a colleague of mine of Raphael Baumgartner devised the 242 00:14:08,200 --> 00:14:12,800 way of etching away some of the iron sulfide and revealing what 243 00:14:12,800 --> 00:14:17,080 was buried and tombed within the stromatolites and he found 244 00:14:17,080 --> 00:14:22,160 remnants of organic matter. And so that was a real aha 245 00:14:22,160 --> 00:14:26,360 moment, because if they were just non biological mineral 246 00:14:26,360 --> 00:14:29,040 crusts you wouldn't expect to see organic matter. 247 00:14:29,040 --> 00:14:32,400 It shouldn't be there. And so we found this material 248 00:14:32,520 --> 00:14:36,600 preserved inside the iron sulfide, this wrinkly lamination 249 00:14:36,600 --> 00:14:38,760 that made the structure of the stromatolites. 250 00:14:39,160 --> 00:14:42,440 And that was, Oh my goodness, there's something unexpected 251 00:14:42,440 --> 00:14:46,720 here in terms of a biology. But there's a feature that's 252 00:14:46,720 --> 00:14:50,080 consistent with these structures being made by ancient life. 253 00:14:50,240 --> 00:14:54,080 When you say organic matter, did you actually find biomolecules 254 00:14:54,080 --> 00:14:55,800 like lipids or something? No. 255 00:14:55,800 --> 00:14:59,640 So these very ancient rocks have been heated up by metamorphic 256 00:14:59,640 --> 00:15:02,880 processes, by temperatures, and really just heat coming through 257 00:15:02,880 --> 00:15:06,200 the crust for so long. So they've been up to about 300 258 00:15:06,200 --> 00:15:09,480 degrees Celsius. They've been cooked, and that's 259 00:15:09,480 --> 00:15:12,400 too hot for biomolecules to be preserved. 260 00:15:13,420 --> 00:15:17,060 What we did find were two features that were of great 261 00:15:17,060 --> 00:15:20,980 interest. One is that the type of carbon 262 00:15:21,060 --> 00:15:25,100 preserved in the rocks was consistent with that heating. 263 00:15:25,580 --> 00:15:28,340 One of the options that the skeptics would say is, oh, that 264 00:15:28,340 --> 00:15:31,580 organic matter could have been brought in later and has nothing 265 00:15:31,580 --> 00:15:34,740 to do with the material and the texture that you're looking at. 266 00:15:35,660 --> 00:15:37,860 But there were two features we could argue against that. 267 00:15:37,940 --> 00:15:41,140 One is that it had been heated to the same temperature as the 268 00:15:41,140 --> 00:15:43,260 rocks around, so we knew it was very early. 269 00:15:43,260 --> 00:15:45,980 It had to be there at the same time as the layers were formed. 270 00:15:47,100 --> 00:15:50,220 And the second was that the isotope ratio of carbon. 271 00:15:50,860 --> 00:15:54,620 So carbon forms in a couple of different types, 12 and 13 272 00:15:54,620 --> 00:15:57,860 carbon, the isotopes of carbon and. 273 00:15:58,260 --> 00:16:02,660 In just normal organic matter, that's fractionated at a certain 274 00:16:02,660 --> 00:16:05,780 degree, but then life changes that dramatically because it 275 00:16:05,780 --> 00:16:08,260 prefers the lighter carbon, the 12 carbon. 276 00:16:08,820 --> 00:16:12,540 And this organic matter, it turned out, was fractionated in 277 00:16:12,540 --> 00:16:15,980 the same way that life fractionates carbon down to 278 00:16:15,980 --> 00:16:19,580 about -27, -, 30 per mil. It's a very strong 279 00:16:19,580 --> 00:16:22,020 fractionation. And so again, that was 280 00:16:22,020 --> 00:16:25,760 consistent with life. The other really important 281 00:16:25,760 --> 00:16:29,760 textural observation was that there were no veins, so later 282 00:16:29,760 --> 00:16:33,040 cracks that could have allowed the caravan to come in. 283 00:16:33,520 --> 00:16:37,680 It actually sat within these very, very small, and I'm 284 00:16:37,680 --> 00:16:42,840 talking nanoscale here, so extremely tiny, much, much, 285 00:16:42,880 --> 00:16:45,760 much, much, much thinner than the width of a human hair. 286 00:16:45,760 --> 00:16:48,640 These kind of pores within the sulfur. 287 00:16:48,920 --> 00:16:52,880 And that showed again that the material was present as that 288 00:16:52,920 --> 00:16:56,800 pyrite was being precipitated, which we think was actually 289 00:16:56,800 --> 00:16:58,680 induced by the microbial activity. 290 00:16:59,160 --> 00:17:04,560 So that organic matter, then, is carbon, a certain kind of actual 291 00:17:04,560 --> 00:17:07,079 carbon that came out of this skeletons of these 292 00:17:07,079 --> 00:17:09,640 microorganisms? It's a material that's called 293 00:17:09,640 --> 00:17:14,960 kerogen and it's a complex mix of carbon bearing molecules, but 294 00:17:14,960 --> 00:17:17,920 it's attached to oxygen and hydrogen. 295 00:17:18,420 --> 00:17:21,020 And because it's been cooked up, it's quite a structured 296 00:17:21,020 --> 00:17:23,579 material. The most structured type of 297 00:17:23,579 --> 00:17:26,780 carbon is graphite that we use in our pencils, and that comes 298 00:17:26,780 --> 00:17:30,020 from much higher temperatures. That's got to be up at about 500 299 00:17:30,020 --> 00:17:32,780 degrees. But Keragen is an intermediate 300 00:17:32,780 --> 00:17:37,060 step. So there's no indications of the 301 00:17:37,060 --> 00:17:41,660 primary organisms, the microbes, because it's all been heated up 302 00:17:41,660 --> 00:17:46,020 so much, but it's the decayed remains of microbes. 303 00:17:46,620 --> 00:17:51,380 And a material that microbes make called extra polymeric 304 00:17:51,380 --> 00:17:56,700 substance EPS. And what that is, it's kind of a 305 00:17:56,940 --> 00:18:02,300 sugary goo that microbes make so that they can move around their 306 00:18:02,300 --> 00:18:04,820 environment. Microbes need to be able to move 307 00:18:04,820 --> 00:18:08,900 towards sunlight, towards food sources, and they do that by 308 00:18:08,900 --> 00:18:12,340 gliding through the sugary goo. This EPS. 309 00:18:13,140 --> 00:18:16,100 And in fact it turns out that in stromatolites. 310 00:18:16,550 --> 00:18:20,790 The EPS goo is actually much more in volume than the microbes 311 00:18:20,790 --> 00:18:23,510 themselves. They make quite a soup that they 312 00:18:23,510 --> 00:18:27,350 can move around in, and it's this soup that actually gets 313 00:18:27,350 --> 00:18:32,230 preserved most commonly. And when we dissolve that pyrite 314 00:18:32,230 --> 00:18:36,030 away with a little bit of nitric acid, where we found ropy 315 00:18:36,030 --> 00:18:39,710 remnants, sometimes curling back on itself and knotted and then 316 00:18:39,710 --> 00:18:43,950 breaking into strands all entombed within that pyrite. 317 00:18:44,750 --> 00:18:49,230 And that looks exactly like the EPS of modern microbial 318 00:18:49,230 --> 00:18:53,470 communities and it was that kind of feature that really sealed 319 00:18:53,470 --> 00:18:56,150 the deal. So in addition to the carbon, 320 00:18:56,150 --> 00:18:59,670 the kerogen being preserved in the pores, having the right 321 00:18:59,670 --> 00:19:06,390 carbon isotope value and then this rope remnant EPS, that was 322 00:19:06,390 --> 00:19:10,670 a triad that showed that yes, these were formed by biology. 323 00:19:11,270 --> 00:19:14,470 You also looked at the concentration of certain other 324 00:19:14,550 --> 00:19:16,790 trace elements in these formations, didn't you? 325 00:19:17,030 --> 00:19:19,950 That's. So we were able to take a very 326 00:19:19,950 --> 00:19:23,390 thin slice of one of these centimeter tall stromatolites 327 00:19:23,390 --> 00:19:27,270 down onto the synchrotron in Melbourne, which is a source 328 00:19:27,270 --> 00:19:30,150 that generates high energy particles. 329 00:19:30,230 --> 00:19:34,710 And we use the X-ray analytical facility and we were able to map 330 00:19:34,870 --> 00:19:37,710 changes in element concentrations through those 331 00:19:37,710 --> 00:19:41,970 layered pyrite stromatolites. And it turns out that pyrite can 332 00:19:41,970 --> 00:19:46,050 absorb different elements as it grows, and so it can be rich in 333 00:19:46,050 --> 00:19:49,250 arsenic. It can be rich in copper, zinc, 334 00:19:49,690 --> 00:19:53,010 lead, etc. And what we found was this very 335 00:19:53,010 --> 00:19:58,090 gorgeous microscale lamination of changes between arsenic rich 336 00:19:58,090 --> 00:20:02,330 pyrite, zinc rich pyrite and nickel rich pyrite. 337 00:20:03,210 --> 00:20:06,250 And the exciting thing there was that it demonstrated there were 338 00:20:06,370 --> 00:20:09,450 textures of the layering. That showed it wasn't just 339 00:20:09,490 --> 00:20:14,690 regular a biological growth, but highly irregular with cutoff 340 00:20:14,690 --> 00:20:18,890 structures, growths like you see in trees, some layers that grow 341 00:20:18,890 --> 00:20:21,410 regularly and then they get over printed by another layer, 342 00:20:21,850 --> 00:20:25,090 whereas middle growth is very simple and continuous. 343 00:20:25,090 --> 00:20:27,170 So there was a good textural contrast. 344 00:20:27,690 --> 00:20:31,490 But what we also know is that there's a very early type of 345 00:20:31,490 --> 00:20:36,690 primitive type of microbe that prefers using zinc and nickel, 346 00:20:37,450 --> 00:20:40,410 and those are called sulfate reducing bacteria. 347 00:20:40,890 --> 00:20:44,650 They take sulfate that's dissolved in the seawater in 348 00:20:44,650 --> 00:20:49,690 very early earth conditions and changing that to sulfide. 349 00:20:49,890 --> 00:20:56,570 So, so four goes to S2. Most of it binds with iron, but 350 00:20:56,570 --> 00:21:01,010 because microbes of that type need nickel and zinc, they leave 351 00:21:01,010 --> 00:21:03,530 behind traces of enrichments in nickel and zinc. 352 00:21:03,930 --> 00:21:08,280 And that was another smoking gun to say, wow, this fits exactly 353 00:21:08,280 --> 00:21:11,120 what we predict. And there it was, looking us 354 00:21:11,120 --> 00:21:12,960 straight in the face. It was very cool. 355 00:21:13,160 --> 00:21:16,120 Wow, so. These metals are byproducts or 356 00:21:16,120 --> 00:21:20,160 part of the metabolism of these anaerobic microbes. 357 00:21:20,400 --> 00:21:23,600 That's right, they need these trace metals to just enhance the 358 00:21:23,600 --> 00:21:27,200 chemical reactions between these major elements, sulfur and iron 359 00:21:27,200 --> 00:21:29,160 and stuff. So that's known by studying 360 00:21:29,160 --> 00:21:31,120 modern sulfate reducing bacteria. 361 00:21:31,400 --> 00:21:34,850 They always find enrichments of zinc and nickel and here we 362 00:21:34,850 --> 00:21:39,970 found them 3 1/2 billion years ago so. 3 1/2 billion years ago 363 00:21:39,970 --> 00:21:43,810 was before the Great Oxidation Event and when the Earth's 364 00:21:43,810 --> 00:21:47,210 atmosphere became rich in oxygen as it is today. 365 00:21:47,210 --> 00:21:52,970 And so did these early microbial communities then have different 366 00:21:53,290 --> 00:21:56,890 anaerobic metabolisms to those that are around today in Shark 367 00:21:56,890 --> 00:21:58,930 Bay. So that's something we're still 368 00:21:58,930 --> 00:22:02,210 trying to tease out of these ancient structures. 369 00:22:02,370 --> 00:22:06,650 It's very difficult to be able to prove a type of metabolism. 370 00:22:07,210 --> 00:22:11,130 Now we think that the zinc and the nickel combined with 371 00:22:11,130 --> 00:22:13,970 fractionated sulfur isotopes that previous groups have 372 00:22:13,970 --> 00:22:18,290 documented strongly suggests that there was sulfate reducing 373 00:22:18,290 --> 00:22:22,530 bacteria alive at that time. But there may have been other 374 00:22:22,530 --> 00:22:25,930 microbes present in those communities as well. 375 00:22:26,830 --> 00:22:30,350 And we think that because in modern environments, sulfate 376 00:22:30,350 --> 00:22:34,350 reducing bacteria are quite a small volume of the overall 377 00:22:34,350 --> 00:22:38,990 community within a stromatalite. And when I say a community at 378 00:22:38,990 --> 00:22:42,190 Shark Bay, there are more than 10,000 different types of 379 00:22:42,190 --> 00:22:46,710 microbes in a stromatalite, but there's usually one dominant 380 00:22:46,710 --> 00:22:50,670 type of bacteria. And in modern stromatalites, 381 00:22:50,670 --> 00:22:55,150 that's cyanobacteria, what used to be called blue-green algae. 382 00:22:55,550 --> 00:22:59,990 It's actually bacteria, and that harnesses light energy and it 383 00:22:59,990 --> 00:23:04,110 gives off oxygen as a byproduct. And they're the ones that 384 00:23:04,110 --> 00:23:07,230 changed our planet about 2 1/2 billion years ago to this 385 00:23:07,230 --> 00:23:09,430 beautiful blue marble that we live in today. 386 00:23:10,590 --> 00:23:13,830 But prior to that, there were almost certainly oxygenic 387 00:23:13,830 --> 00:23:17,030 photosynthesizers, as we call them, the cyanobacteria present, 388 00:23:17,390 --> 00:23:20,430 but we don't know how far back in time they went. 389 00:23:21,240 --> 00:23:24,680 And certainly in the very early Earth, there's no evidence for 390 00:23:24,680 --> 00:23:29,200 free oxygen in the atmosphere. And so the question is, what was 391 00:23:29,200 --> 00:23:31,920 the primary producer? What was the big volume of 392 00:23:31,920 --> 00:23:34,880 microbes that could build these structures that even though 393 00:23:34,880 --> 00:23:38,080 they're small at a microbial scale, are still very big, 394 00:23:38,080 --> 00:23:40,400 right? Like a microbe is maybe 10 395 00:23:40,400 --> 00:23:43,000 microns in diameter, 100 microns in diameter. 396 00:23:43,360 --> 00:23:46,360 And these stromatolites we're looking at are centimeters to 397 00:23:46,400 --> 00:23:49,320 some case, 30 centimeters. So that's a lot of microbial 398 00:23:49,320 --> 00:23:54,730 activity and we think, but we haven't been able to prove that 399 00:23:54,730 --> 00:23:58,530 there were probably anoxygenic photosynthesizers. 400 00:23:58,930 --> 00:24:02,530 So bacteria that had been able to harness the energy from 401 00:24:02,530 --> 00:24:06,970 sunlight but gave off a different byproduct from oxygen. 402 00:24:07,250 --> 00:24:10,130 It's actually a much more complicated metabolism to give 403 00:24:10,130 --> 00:24:15,050 off oxygen and to break those molecular bonds than it is by 404 00:24:15,050 --> 00:24:18,450 using photosynthesis to metabolize without producing 405 00:24:18,450 --> 00:24:21,970 oxygen, And that's known to be a much more primitive lineage. 406 00:24:22,170 --> 00:24:24,690 And so it's likely that there were an oxygenic 407 00:24:24,690 --> 00:24:27,810 photosynthesizers. But we haven't been able to show 408 00:24:27,810 --> 00:24:30,730 the definitive proof for that. And that might be beyond our 409 00:24:30,730 --> 00:24:33,330 science at the moment, something we're still working on. 410 00:24:33,730 --> 00:24:35,490 But it's. Interesting that, even though 411 00:24:35,610 --> 00:24:38,490 the conditions could have been radically different back then 412 00:24:38,490 --> 00:24:41,730 from what they are today and therefore that the Community. 413 00:24:42,180 --> 00:24:45,660 The population, if you like, of the microbes would be quite 414 00:24:45,660 --> 00:24:48,260 different from those that are around today in Shark Bay. 415 00:24:48,580 --> 00:24:52,380 Nonetheless, you have structures that are very reminiscent and 416 00:24:52,420 --> 00:24:55,620 morphologies that are very reminiscent of what we see 417 00:24:55,620 --> 00:24:57,380 today. So it's kind of interesting that 418 00:24:57,380 --> 00:25:01,500 the same microfilm and columnar branching and all the things 419 00:25:01,500 --> 00:25:05,380 that you described would be so closely analogous across the 420 00:25:05,380 --> 00:25:08,800 billions of years. I guess in some ways it's not so 421 00:25:08,800 --> 00:25:11,480 surprising because what stromatolites do is they 422 00:25:11,480 --> 00:25:15,160 actually of course they want to survive and out compete the 423 00:25:15,200 --> 00:25:17,440 other aspects of their environment. 424 00:25:18,160 --> 00:25:21,040 Now in the very early Earth there were no competitors like 425 00:25:21,040 --> 00:25:25,320 crabs or snails or seashells that would eat them today, but 426 00:25:25,320 --> 00:25:27,720 they were competing against the environment. 427 00:25:28,040 --> 00:25:31,400 Their environment was introducing sediment into the 428 00:25:31,400 --> 00:25:34,000 area where they were trying to grow and sediment kills them 429 00:25:34,000 --> 00:25:35,320 off. If there's too much sediment, 430 00:25:35,320 --> 00:25:38,720 they can't grow, and so stromatolites compete against 431 00:25:38,720 --> 00:25:42,520 this by growing upward to stay above the sea floor. 432 00:25:42,680 --> 00:25:47,240 And so that kind of aspect is common throughout time. 433 00:25:47,800 --> 00:25:52,120 If you only cover a flat surface, you can only grow so 434 00:25:52,120 --> 00:25:54,570 much. Just like humans build apartment 435 00:25:54,570 --> 00:25:58,090 buildings to fit more people into a small area, so 436 00:25:58,090 --> 00:26:00,810 stromatolites grow upwards because they're increasing their 437 00:26:00,810 --> 00:26:04,210 surface area can fit more microbes into that volume of 438 00:26:04,210 --> 00:26:06,690 space. It's just a common survival 439 00:26:06,690 --> 00:26:09,650 technique. And so it's maybe not surprising 440 00:26:09,650 --> 00:26:13,050 that even the oldest remnants of life show that battle to 441 00:26:13,050 --> 00:26:14,930 survive. You've. 442 00:26:14,930 --> 00:26:19,170 Been heavily involved in the search for life on Mars with the 443 00:26:19,410 --> 00:26:21,810 Curiosity and Perseverance Rovers. 444 00:26:22,450 --> 00:26:26,250 Is that because if there was one's life on Mars, it might 445 00:26:26,250 --> 00:26:28,890 have resembled to rescue stromatolites? 446 00:26:28,890 --> 00:26:32,970 Or because we think that Mars may once have had an environment 447 00:26:32,970 --> 00:26:35,050 similar to that of the Archaean on Earth. 448 00:26:35,650 --> 00:26:37,930 It's for both of those reasons all of us. 449 00:26:37,930 --> 00:26:40,330 We have an example of 1 here on Earth. 450 00:26:40,850 --> 00:26:43,930 Everything that we do in our exploration for the search of 451 00:26:43,930 --> 00:26:47,970 life elsewhere is based on our understanding of early life on 452 00:26:47,970 --> 00:26:51,570 Earth, particularly around Mars. Because Mars is a smaller 453 00:26:51,570 --> 00:26:55,760 planet, it became geologically dead much earlier in its 454 00:26:55,760 --> 00:26:58,400 history. Most of the rocks exposed on the 455 00:26:58,400 --> 00:27:01,640 surface of Mars are between 4:00 and about 3 billion years. 456 00:27:02,160 --> 00:27:07,040 And so really the Pilbara in WA, one of the few places on the 457 00:27:07,040 --> 00:27:10,880 globe that has rocks 3 1/2 billion years with evidence of 458 00:27:10,880 --> 00:27:15,120 life, is the place that everybody goes to, to not only 459 00:27:15,120 --> 00:27:18,480 see the textures that life preserved, but also to 460 00:27:18,560 --> 00:27:20,920 understand the habitats where life lived. 461 00:27:21,570 --> 00:27:24,770 If you have a whole planet to explore, like Mars, where would 462 00:27:24,770 --> 00:27:28,010 you go to maximize your chance of success, to look for life? 463 00:27:28,450 --> 00:27:32,170 And so a large part of the study that my group has done is to 464 00:27:32,170 --> 00:27:35,690 understand the environments where life flourished on early 465 00:27:35,690 --> 00:27:38,050 Earth. And one of the exciting things 466 00:27:38,050 --> 00:27:41,090 is that we look at the Dresser Formation, these ancient 3.5 467 00:27:41,090 --> 00:27:46,130 ones, but they're also Stromatal likes at 3.4, at 3.35, and 468 00:27:46,130 --> 00:27:49,130 through the geological record we can build up a picture of where 469 00:27:49,130 --> 00:27:51,800 life lived. What's extraordinary is that if 470 00:27:51,800 --> 00:27:56,320 you talk about older than 3 billion, there are many 471 00:27:56,560 --> 00:28:00,040 different niche spaces or environments where we find 472 00:28:00,040 --> 00:28:03,560 evidence for ancient life. And that's incredible. 473 00:28:03,600 --> 00:28:08,200 It just documents that life got started on Earth very early and 474 00:28:08,200 --> 00:28:12,160 diversified into these different environments, also very early. 475 00:28:13,130 --> 00:28:15,570 And that gives us hope about searching for life on Mars, 476 00:28:15,570 --> 00:28:17,770 because Mars had that short history. 477 00:28:18,050 --> 00:28:21,330 But if life got started on Earth and diversified very early, well 478 00:28:21,330 --> 00:28:24,490 maybe it got started on Mars and was able to gain a foothold in 479 00:28:24,490 --> 00:28:27,890 that very early record. So people come to look for the 480 00:28:27,890 --> 00:28:30,890 geological traces. What should we be looking for on 481 00:28:30,890 --> 00:28:32,810 Mars? What's the guide in terms of the 482 00:28:32,810 --> 00:28:36,450 textures and the fabrics and the environments, rock types? 483 00:28:36,930 --> 00:28:39,410 But then also what kind of habitat? 484 00:28:39,890 --> 00:28:44,580 So would you go to a flowing river or a quiet lake or a delta 485 00:28:44,860 --> 00:28:48,900 or a deep sea hydrothermal vent or a shallow caldera, where 486 00:28:48,900 --> 00:28:51,100 would you look? So you've got all those choices 487 00:28:51,580 --> 00:28:54,580 and our group has brought planetary investigators through 488 00:28:54,580 --> 00:28:57,300 the Pilbara so that they can really see that evidence for 489 00:28:57,300 --> 00:28:59,420 themselves. So we've had a little bit to do 490 00:28:59,420 --> 00:29:01,940 with site selection and understanding textures and what 491 00:29:01,940 --> 00:29:04,420 the search strategy should be if. 492 00:29:04,860 --> 00:29:10,260 Microbial life does indeed go back to 3 1/2 billion years ago. 493 00:29:11,140 --> 00:29:14,340 Do you think it was somehow facilitated by some particular 494 00:29:14,340 --> 00:29:16,340 change in the environment at that time? 495 00:29:16,340 --> 00:29:19,460 Or do you think there was no particular reason for the 496 00:29:19,460 --> 00:29:22,660 emergence of life at that time? And if we just keep on looking, 497 00:29:23,140 --> 00:29:26,900 we might find still earlier life, perhaps going back to near 498 00:29:26,900 --> 00:29:30,580 the time the Earth first cooled enough to generate a hospitable 499 00:29:30,580 --> 00:29:32,980 environment nearer to 4 billion years ago. 500 00:29:33,500 --> 00:29:36,140 I would love that to be the case, Oliver, don't get me 501 00:29:36,140 --> 00:29:38,860 wrong. But unfortunately the history of 502 00:29:38,900 --> 00:29:43,410 Earth was that it had a very hot and almost cauldron like 503 00:29:43,410 --> 00:29:47,290 beginning. And it's only until about 3.5 504 00:29:47,290 --> 00:29:50,210 billion years ago that you get very well preserved ancient 505 00:29:50,210 --> 00:29:52,810 rocks. So there are older rocks on 506 00:29:52,810 --> 00:29:57,810 Earth going back to about 4.03 billion, but they've been really 507 00:29:57,810 --> 00:30:00,250 cooked up. They've been brought down deep 508 00:30:00,250 --> 00:30:02,250 into the crust. They've been heated to 509 00:30:02,330 --> 00:30:05,730 temperatures above their melting point and then swirled around by 510 00:30:05,730 --> 00:30:08,920 tectonic movements. And there's almost no primary 511 00:30:08,920 --> 00:30:12,160 information left in the textures of the rocks, which is so 512 00:30:12,160 --> 00:30:14,520 critical for understanding early life. 513 00:30:15,280 --> 00:30:18,440 So the Pilgrim is one of these sort of geological anomalies, 514 00:30:18,520 --> 00:30:21,920 just one of these fortunate places that have survived intact 515 00:30:21,920 --> 00:30:24,000 basically from 3 1/2 billion years ago. 516 00:30:24,680 --> 00:30:27,640 Most of the rest of the world, and we've looked now across a 517 00:30:27,640 --> 00:30:30,520 lot of the rest of the world, has rocks that are either 518 00:30:30,520 --> 00:30:33,720 younger or older but more strongly deformed. 519 00:30:34,820 --> 00:30:37,180 And as I mentioned earlier, there is a record. 520 00:30:37,180 --> 00:30:40,700 In fact, there's two different records of ancient life from 521 00:30:40,740 --> 00:30:46,500 West Greenland in rocks that are 3.7 billion years old, and there 522 00:30:46,500 --> 00:30:50,140 are little isolated pockets within that otherwise kind of 523 00:30:50,140 --> 00:30:54,020 soupy mess where there are preserved some primary textures. 524 00:30:54,420 --> 00:30:57,700 Now the community is not convinced by these older records 525 00:30:57,700 --> 00:31:01,420 because it doesn't have all the different arguments like we've 526 00:31:01,420 --> 00:31:03,100 described for the Dresser formation. 527 00:31:03,690 --> 00:31:06,130 They have one or two features that are really compelling. 528 00:31:06,650 --> 00:31:10,530 But because they're so heated and these are up to about 505 529 00:31:10,530 --> 00:31:14,210 fifty degrees, they've got some big metamorphic minerals growing 530 00:31:14,210 --> 00:31:17,210 around them. People are less convinced of the 531 00:31:17,210 --> 00:31:19,450 fact that these were made by biology. 532 00:31:20,330 --> 00:31:23,490 I am personally 100% convinced because I've been there. 533 00:31:23,490 --> 00:31:25,690 I've seen them. I understand that setting. 534 00:31:26,130 --> 00:31:31,170 And so getting that record of life back to older periods in 535 00:31:31,170 --> 00:31:33,610 the geological record is really difficult. 536 00:31:34,090 --> 00:31:38,250 And you mentioned about life emerging at 3.5. 537 00:31:39,210 --> 00:31:42,530 So that story I just recounted actually suggests that life 538 00:31:42,530 --> 00:31:46,210 probably emerged much earlier, but we just don't have a record 539 00:31:46,210 --> 00:31:48,690 of it. And that's also part of the 540 00:31:48,690 --> 00:31:51,770 exciting reason for going to Mars, because it doesn't have 541 00:31:51,770 --> 00:31:53,610 that young history of cooking things up. 542 00:31:53,730 --> 00:31:57,570 We can actually see a bit of our own early history on Mars 543 00:31:57,850 --> 00:32:01,910 because it was frozen in time. And so there's value in going 544 00:32:01,910 --> 00:32:04,990 back to Mars to learn about what our early Earth might have 545 00:32:04,990 --> 00:32:08,190 looked like, and perhaps even get a better record of where 546 00:32:08,190 --> 00:32:11,350 life might get started if it ever gained a foothold on Mars. 547 00:32:11,990 --> 00:32:14,470 You're. Not suggesting a common origin 548 00:32:14,470 --> 00:32:16,550 of life between here and Mars, are you? 549 00:32:17,030 --> 00:32:19,750 No, that's just that. Both planets probably had a 550 00:32:19,750 --> 00:32:23,620 similar very early start, and on Earth that early start has been 551 00:32:23,620 --> 00:32:27,100 erased by younger events. But on Mars that's been 552 00:32:27,100 --> 00:32:30,180 preserved, and so we might just be able to go and see what 553 00:32:30,180 --> 00:32:34,220 happened in parallel there. So yeah, if we go and find signs 554 00:32:34,220 --> 00:32:38,060 of ancient life on Mars, that might be a separate beginning. 555 00:32:38,500 --> 00:32:41,460 That would have huge implications for our 556 00:32:41,460 --> 00:32:44,820 understanding of the universe if it happened on 2 planets next 557 00:32:44,820 --> 00:32:46,100 door to each other, Oh my goodness. 558 00:32:46,100 --> 00:32:48,940 Just imagine how much life might be out there in the universe. 559 00:32:49,020 --> 00:32:52,230 Unbelievable. Martin van Kerennock, thank you 560 00:32:52,230 --> 00:32:54,750 very much. It's my great pleasure to talk 561 00:32:54,750 --> 00:32:57,550 to you, Oliver, and thanks for the opportunity to talk about 562 00:32:57,550 --> 00:33:00,670 stromatolites. To see pictures and 563 00:33:00,670 --> 00:33:06,070 illustrations that support this podcast, go to geologybytes.com, 564 00:33:06,670 --> 00:33:09,950 where you'll also find transcripts and a subject matter 565 00:33:09,950 --> 00:33:14,310 index of all the episodes there. You can also give me feedback, 566 00:33:14,310 --> 00:33:18,070 which I welcome, as well as sign up to get my emails about new 567 00:33:18,070 --> 00:33:18,790 episodes.