Where is the Origin of Life on Earth?

[Music] it's my pleasure to introduce our very own Molly Bentley Molly will be moderating tonight's event and introducing our esteemed panel if Molly doesn't look familiar you will surely recognize her wonderful voice from the acclaimed radio show and podcast big picture science where Molly is the executive producer and co-host and please join me in welcoming Molly good evening the first question we always have to ask can you hear me it's the question we always ask in radio anyway when it comes to understanding the origin of life the questions are big and the answers are complex but luckily tonight we are joined by scientists who are experts at making complexity accessible they Deemer is a research professor of biomolecular engineering at the University of California Santa Cruz and Bruce Damer is an associate researcher in that department and they are here tonight to discuss their new model for the origin of life that it began not that it began in warm pools on land not in hydrothermal vents in the ocean that these warm pools on land are the most plausible site for life's origins and they will talk about how they're putting their ideas to the test in Western Australia their work which includes that of their colleague Tara Joe Kitsch was on the cover story of your 2017 August subscription of Scientific American mine is well-thumbed here Lynn Rothschild is a senior scientist at NASA Ames Research Center she's an astrobiologist she's a synthetic biologist and she will bring her she will provide an evolutionary biologist perspective on this subject within the framework of NASA's astrobiology program and we had the pleasure of interviewing Lynn recently for a show that we did on big picture science on extremophiles and she was terrific now we just have two other gentlemen to booked on the show about the origins of life and we'll be all set so in case you had any questions of whether or not these scientists are willing to sweat for the answers to these big questions consider this some of Bruce's fieldwork is in an active geothermal area of New Zealand called Hell's Gate David's is on a site in Lassen Volcanic National Park called bumpass hell and one of one of Lynn's projects for creating a novel organism that can endure extreme conditions is called hell's cell so please welcome these three scientists who are willing to endure what they're willing to endure to answer these questions please come up on the stage Lynn and linen David this so what I really would like to do is to show you one slide with a Hubble image of the galaxies and a bunch of arrows and say this is where life started end of story thank you very much and then we could you know we could all go out to dinner but it's not quite so simple and so what I'd like to do is give you a little bit of a perspective sort of leading up to the story that you're about to hear this is sort of an awkward panel I'm used to being in more of a debate format but unfortunately I I don't feel it I can't debate these two gentlemen because I'm actually a great admirer so that makes it totally boring evening for you but so I'm what I'll do is to give you more of an introduction so before we talk about where a life originated you do have to think a little bit about what is life and we could spend a lot of time thinking about it people tend to give definitions of you know commonalities in life on earth I like to think of it and maybe a little bit more philosophical point of view that life is an emergent process it's based on physical components but it's not just an object it would just be like a river isn't a river unless it moves and this includes fighting entropy just the way Schrodinger told us and his famous lectures and I believe was 1944 that life fights entropy so if you leave the kids room all neat and tidy and you come back in a month or maybe in a few hours I finally decide the other day that would you really need a clip of that scene in Mary Poppins you know singing and just run it backwards and that's entropy for you and life obviously has to fight entropy or else we wouldn't be here but of course we do have some physical components life as we know it is not just some sort of ethereal intellectual thing it's a physical instantiation and I believe very firmly that sort of ground zero is that life is based on organic carbon chemistry and that you need a solvent likely water and I'll go into that in a moment but you also need energy and you need time so there are a lot of reasons that I believe that carbon is really important but there are a lot of other elements that we need as well for various aspects of cells at least for life as we know it but I suspect these that you see here are ones that we would see over and over in life-forms anywhere you go we do happen to use a lot of metals it's critical to us people always ask which metals and I always tell them look on the back of a vitamin bottle and so I've provided a vitamin bottle for you you can run home and look again tonight water now there potentially other solvents besides water people have thought a lot about liquid ethane or methane which would then allow us to think about life on Titan it would be incredibly cool and there are a lot of people who would like to be sort of perverse about it but at the end of the day water it looks like it's a really great one it's very common in the solar system in the universe as a whole it's got a lot of great properties including the fact that it's less dense when it's frozen which allows you to have an ice cube in your gin and tonic floating around so you can prepare for summer otherwise it would just sink to the bottom but in a more serious way that also allows us to have ice-covered bodies like Europa this moon of Jupiter and in solidus a moon of Saturn that has liquid water underneath it rather than being frozen solid it also of course has a lot of great chemical properties including being liquid at a fairly high temperature how long does it take the life to originate people say oh it's got to be you know a long period of time you need to have a planet that's been stable for long periods of time what along does it take we have no idea I suspect that it's actually very quick once we have the building blocks built up whether it's you know was a three-day weekend at some point for a year or ten thousand years I don't know but I suspect it wasn't millions of years do you think about it we throw out these numbers like millions of years but as humans we think on a lifespan of about a hundred years so even a million year even a hundred year experiment would be almost beyond our comprehension anything more than a three year experiments beyond the comprehension of the funding agencies so I suspect that it actually was fairly quick but we only have one example we wouldn't know where did it originate which is the subject for tonight we don't really know that either was it off earth did life originate on Mars which should have been more Clement before the earth or were the building blocks produced off earth and came through meteorites and interplanetary dust particles and so on or maybe the whole thing happened on the earth maybe in a deep-sea vent in a hydrothermal vent or in Darwin's warm little pond or in some other surface area so that's talking about sort of the philosophical picture and then the individual building blocks but to go from there to an organism you have to start dealing with polymers and the big ones for life are lipids which of course form our membranes and they can form a biotic lien self-assemble you want to go do it at home you you know take water and vinegar or oil and vinegar and you shake it you've made your own little vesicles proteins amino acids are made a biotic li and we can make short peptides abiotic ly in various ways including shock synthesis which just means that if you've got these on a meteorite and they whack into the earth you can actually help produce smart proteins you can also have bases that are important for the nucleic acids found in abiotic settings but how do you go from there to nucleotides and how do you go from there to polymers and I'm sure that Dave's going to talk about it since he's done really the great work in that area C I'd I I would have cited your work even if you weren't on stage DNA is not so easy I sort of joke that it's not deoxyribonucleic acid it probably just stands for do not ask so I think at that point I really would like to turn the stage over to the next speaker Thank You Lynn that said it all are there any questions no it's more than that I'm going to give you three big points in three slides they the organizers asked us to limit our talk to three slides and that's a very good idea believe me a frank excellent idea because that really focuses our attention of us and of you so three major things that you'll want to understand if you're going to understand what Bruce is going to say a little bit later the first one is that there are two kinds of water on the earth there's the 99% and the 1% something like the distribution of wealth you know then the 99% is in that little inset up to the right and that's sea water the ocean is 99% of the water on the earth it's salty it's got calcium and magnesium in it it's hard water it's a neutral pH a little bit up around close to pH eight which is just a bit on the alkaline side it was probably more acidic the time that life began but what you see coming out of the floor of the ocean there is a what we call a hydrothermal vent an alkaline Ida thermal vent this is a white smoker that was discovered in the 2000 air or maybe 10 or 15 years ago and this came along after the discovery of black smokers so isn't it interesting that we have these two kinds of smokers going on down in the floor of the ocean all the time the black smokers are loaded with metallic minerals and they produce a black deposit that can rise up many tens of meters off the floor of the ocean due to this uprising from hot water heated by magnetic basically heat related to volcanic action going on under the seafloor this is a little bit different the white smokers are caused by a chemical reaction called serpentinization seawater reacts with certain minerals in the seafloor and it produces a very alkaline a flood if we put a pH meter into that who'd be up around pH 10 it's a very Outland compared to the seawater at pH 8 in fact so the white is in fact minerals calcium and magnesium minerals that are carbonates and this stuff comes up and produces this mineral white smoke that you can see there when the black smokers were discovered it was amazing there was life there here we are really deep in the ocean takes the Alvin submersible to get down to it to look around down there and there was it was abundant life so Jack Corliss visited us just what the last year I guess came by Jack Corliss was in this submersible and 1977-78 as I recall he was down there was among the first people to see him john byrne rust then of at university of washington took notice of that and he got together with jack and a graduate student a couple of other people they said maybe life began there if life is there now maybe life could be there at the beginning and other people then took this up as an explanation of the origin of life and they're still working on this so there are colleagues we even see them at meetings we invite them to our meetings in fact to tell us so for what progress they've been made but we have another idea I'm a biomolecular engineer by just definition with what I do at UC Santa Cruz but before that I'm what's called a biophysicist and there are there are things that go on in life that are not chemical they are physical and one of these is the selfless M of membranes these are the boundaries around every living cell nothing tells a membrane how to make itself it's as spontaneous as the soap bubbles that we've all blown in our life so well if you've never seen what is truly miraculous nothing holds it together except some very weak forces between the lipid like molecules that form the bubble the same sort of microscopic bubbles are in fact the boundaries of all the trillion cells and every human body in this room so keep that in mind self-assembly is another lesson I want you to take home self-assembly does not work very well in seawater we discovered that 20 years ago and published a paper on it it startled everybody because you know everybody said well heck life must begun in the ocean together there's so much water there's just a little bit of fresh water you know the lakes and ice packs and less stuff like that but in fact we said that the calcium and the magnesium in seawater inhibits the formation of membranes and if you're gonna have a hub cell you're gonna have to have a membrane to keep everything in place so that is the biophysicist viewpoint and that got me started on the line of researchers finally led to this concept we're developing now and that is that life did not begin in the ocean but fresh water hot springs such as bumpass hell that is right up here in Mount lassen but some people in this room have visited it I've been been to Kamchatka twice there's another place that we've done worked bruce has traveled down to new zealand to another hot spring and we can make things happen in hot spring environments that simply can't happen in an ocean environment so what you're gonna hear tonight is the next point and that is self-assembly could I have the next slide actually it's not a slight as a video does this run can you get that to run what you're seeing here is what I see under the microscope off to the left is some dried phospholipid that's the stuff that makes membranes so it's and all the membranes of every living cell on earth it's been dried down in a microscope slide and I've added water off to the right the water penetrates into the lipid of multi-layers that's actually a multi-layered structure in the dry lipid and as it penetrates this swells and turns into these long tubules that come out that you're seeing and the tubules then are not not stable and they break up into the membranes that you see falling off that dry lipid so that is what self-assembly looks like I was so interested in that that I asked could self-assembly appear on the early Earth was there anything there that could help self-assembly of membranes for the first forms of cellular life happen well we extracted a meteorite and we're going to hand around a sample of the Murray meteorite that we just extracted a little while ago you're going to smell an aroma that is five billion years old this is older than the earth because it was synthesized in the molecular cloud that gave rise to our solar system and then it was on little tiny particles we call the interstellar dust that made the asteroids the asteroids collide pieces of the asteroid come to earth and form in meteorites and that's what you're smelling I put some of that stuff if I put a head in water to this you would see this happening it forms membranes five billion years old and we were easily able to make membranes and get the membranes to encapsulate stuff and that's the other thing that we have to think about we're gonna make membranes but how does stuff get caught inside and that brings us to the last point that I want to make next slide these are membranes a phospholipid with a difference I have put what we call monomer and just a quick little explanation a monitor is something that makes a polymer if your chemist you know those words very easily a monomer for instance is an amino acid and a protein is a polymer a nucleotide is a monomer of nucleic acids like DNA and RNA and the nucleic acids are polymers so these are the two primary polymers of all life on earth proteins and nucleic acids and we don't know where they came from that's one of the big caps in our understanding of the origin of life where do they come from I put this lipid in with the monomers of ribonucleic acid it's one of our nucleic acids that we use I put this mixture through a wet/dry cycle such as we see in the volcanoes that are all over the earth you know as I say I've been to a dozen volcanoes in my time and everywhere I go we see rain bringing in precipitation fresh water not saltwater and we see evaporation causing Easter dry out and as it dries out anything in solution becomes very concentrated and begins to react those monomers that I put into this system of membranes see those big red bubbles there that red stuff is ribonucleic acid we have made rnase under the conditions of wet dry cycling in volcanic freshwater pools and that is the fundamental thing that is different from other origins of life stories freshwater self-assembly polymerization by wet/dry cycles Bruce will now tell you about some of the implications from what I've just told you and where this all fits into the evolution of life on Earth so to get us started off I'm gonna hand out another wonderful artifact is this show-and-tell time this is kind of ground truth for us this is a three billion year old piece of rock that is basically constructed through the processes of life itself these ridges on here are something called stromatolite errs from at oolitic textures laid down by biofilms by basically microbial mat for thousands of years over tens of years to make this sample at a steamy stinky lake shore in the también and now it's called the tum viana in western australia and we picked this up during a field work about four three four years ago so what you're actually holding as I pass this around is actually our common ancestor which is microbial biofilms dominant in the fossil record for ninety percent of Earth's history so if we can start my slides shy to start them I can see sure okay so this is going to start with some hot sweaty fieldwork now we need the sound up okay there's no sound there we can get the sound this hot sweaty field work I can probably even just talk you through it so this is in New Zealand at the aforementioned bumpass hell where we took vials of reagents which included dried lipid and the monomers of RNA where we wet/dry cycled the reagents with actual acidic hot spring water at about pH 1.7 and I would basically hydrate these vials place them into this heat block directly into the hot spring and wait about thirty five minutes for them to dry and then to bake and in the baking phase the monomers of RNA are just sort of moving around in between the layers of lipid and forming RNA polymers and when we brought the the samples back from the lab or to the lab we found a really highly productive this is a very highly productive system we had predicted that well we would get just a few a few polymers maybe hardly to see because the natural system is is so complex and in the natural environment is so sort of molecule aggregating in a warm little pond and dr. Dana believes this to be much closer to the truth area we can show to our our colleagues into the world that we can self-assemble an important biopolymer of life called RNA in a hot spring pool that's cycling in the conditions that would have been around in the early earth on these big volcanic islands our colleagues are really gonna seriously look at doing more experiments and it'll create a whole movement the whole sort of paradigm shift in origin of life thinking back to Darwin's or little pond only now it's a cycling hot little pool Jaden McLeod local focus so the little thing that I was holding at the end there is called a fairy castle and we just drove about half an hour from Hell's Gate to a different hydrothermal system which was a sandbar where the hot spots have been coming up and been tracked for 50 years and stromatolites were being produced there in real time and that fairy castle is basically silica pulled out a solution around basically microbial communities which helped to form the actual structure and it was growing stromatolites in days to weeks in front of your eyes yeah which actually looked the same as the ones preserved in the ancient hot spring in the Pilbara that Tara dockage found that's the subject of this article so you can still see the process happening today that that when we go back and look as far back as we can get on evidence of for life on earth and these hot spring environments and other other aqueous environments we find microbial mats and they behave the same way back then so now what we're gonna look at this is just a peek at some of the product that came from from the rotorua experiment and we believe that this fibril imaged by atomic force microscopy by our colleagues and denmark is the RNA that dave was showing in the proto cells so that's the that's quite great length according to to a Haas and calm that's that's a thousand BER not a 300 more or 150 murder or 50 more that's a thousand base units in length so how does this all work well I'm a computer scientist by training and how many of you are self-described nerds in the room we we're at SR I the birthplace of modern visual computing with Doug Engelbart's group and Bill English and where the mouse was carved out of wood right so this is a hallowed ground an SR I back in the day in the 1950s would have been using computers that use punched paper tape or magnetic tape to drive them where programs are like cereal instructions well here's a metaphor from those days of computing for how can you write programs without a programmer how can you start boot up life itself from random sequences so if you were had a program a computer you wanted to program but you weren't allowed to do the programming you would set up just the conditions for programs to emerge and those conditions would start out with a taper paper tape puncher that punched random paper tape instructions random programs were that were read into a reader into a primitive computer this is one from my collection called an altair 8800 from the homebrew club which is just met down the road here that computer would be have a source of energy it would run these programs through a simple microprocessor and they would either crash or they would play again and I'll say for instance the program that did something lit up one of the diodes on the front of the Altair the great great kind of a function so over time what you do and then set up the system to take the programs that lit up diodes put them back into the puncher and punch random programs onto the end of them so you end up with program a B AC and AD and over trillions and quadrillions and zillion times you might evolve more programs which might evolve better computers I don't know if this one was that much better than an out era but then we got our laptops and we kept evolving and we got to our computers in our pockets and these days we pay engineers a lot of money to do this slightly more efficiently but this is the evolution of software and hardware together so where do we find this system in nature where do we find this system well as Dave was was indicating we find it in the polymerize earth at is all of that wonderful organics that you're smelling coming around coming in from not only from the sky but for meteoritic impacts from hydrothermal systems in the hot spring the monomers that build polymers in your polymerize er which is your paper tape puncher and the paper tape puncher of nature makes some paper tapes called polymers that are initially random and they go into our simple computer called a warm little cycling pool set up by this this gentleman Charlie Darwin and they are encapsulated in these membranous vesicles and called proto cells which are our little simple programs and they either pop or they do not they either survive the cycle of being in the pool to dry back down to be resynthesized again to go through the paper tape again or they don't and this is the evolution of software and hardware together so let's put this all together on the landscape we call this the hot spring origin of life and here's our Hadean landscape say 4.1 billion years ago you see the early solar system there's the Sun there and there's planets sweeping through the the disk of the dusty disk of the sort of protoplanetary disk of the solar system sweeping all this material up that we know is packed with organic compounds those compounds are are there for a lot of them synthesized in space like what you're smelling they rain down on the earth and accumulate they can accumulate in little pools on land whereas if they land in the bulk of the ocean they're lost for the use in prebiotic chemistry they're simply diluted so they can come into a number of pools so here's a little network of pools that we notice can have different PHS different temperatures different concentration abilities and they can mix across pools and you can see this in any hot spring you go to we call it nature's chemistry set so they really looked like an act like a chemistry set so within those pools they can get concentrated enough to come together to form more complex structures like membranes and like polymers so for example if this collection manages to find itself to cycling pool that's doing the thing that Dave is shown in the laboratory now we're showing in the field wet dry wet dry wet dry you can do amazing complex chemistry like we were doing in in Rotorua and so here's our cycling pool driven by a geyser that's pushing pulses of water into the pool and the key thing is it so regular you know like Old Faithful every 73 minutes or whatever it has been in the past it's so regular because if we're setting up in the lab to do an almost industrial scale chemistry to do away from equilibrium chemistry to to ratchet a system up we just do it on a repeated basis where you find that in nature with cycling hydrothermal geyser systems also through wet/dry cycling in dues in the day through periodic rainfall their cycles everywhere of wet and dry so what happens in this system is in in the dry phase you get these films that synthesize your polymers in the wet phase they're encapsulated they bud off their capsulated into trillions of compartments which is a each of each an experiment and combinatorial chemistry the ones that survive form these sludges in the bottom of the dish or the pool and that sludge is a combinatorial unit that we believe is the path to the Carl Woese concept of the progeny if you've studied his work over the years the progeny is described as the boot-up phase of life the unit that establishes the relationship between phenotype and genotype over time and allows the living cell to emerge from not individuals competing but from a network of collaborating protocells because in this period of history there's no wave there's no technology for cells to compete so they can't evolve strictly of the Darwinian system of linear descent because there's no species there's no ability to create offspring so it had to start with a network effect and this was Carl's intuition and in this 1977 paper the same year that Alvin discovered the hydrothermal vents so we believe that the progeny can emerge in these wet/dry cycling systems the protein note is an interesting thing it's basically like bathtub sludge you know we came from a very ignoble start in other words and but it has a property of distribution so these protocells or masses can flow into other pools they can dry down as films and blow in the wind akin to seeds or spores so they can populate a landscape why is that important because they can get into more than one environment so the eggs are out of one basket why is that important because they can develop polymeric evolutions in these cycling systems and then share them across the landscape that's exactly how life works today you know the seeds you know come from trees they flow into other environments as quickly as possible and and basically after the products of evolution are shared across a giant landscape including cultural and technological evolution so just finishing up here the protein oat being the unit of initial evolution becomes the microbial mat community so the origin of the microbial mat is a simpler form of community made out of proto cells so the cellular communities ancestor is a proto cellular community that's called the principle of continuity that was described by hands Mauro woods so just moving along toward the the life that Lin studies so we we would see these protocells form they would gradually get more function to get pores metabolism they would then learn how to capture sunlight maybe through delivered pigments and called polycyclic s-- and then gradually they would develop more autonomy over time learn how to divide we see their early life the rise of cell division that's a major challenge that's a major chasm to cross so you need a combinatorial a massive system to get to cell division once they have cell division then they have linear descent they have a system of hereditary heritable traits perhaps they've they've got an active photosynthetic system some kind of translation for proteins and they're becoming more robust and then they can adjust to the salty sea shore the very turbine environments of high tides and they must develop active membrane transport to deal with the the saltwater and so then you get back down to these these things which one of each you're holding in your hand so the top is the hot spring stromatolite discovered by Terra and his and her colleague Martin Van cran and Doc at 3.5 billion years this is Lakeshore stromatolite which your hope passing around fresh water and this is the marine stromatolites that are common in the fossil record that are ubiquitous in the fossil record in fact and that that had to adapt to much more extrema file conditions so really that's that's our entire story so we we hope you followed along with it and managed to hold the stromatolite and a final story for you this de rata light that you're passing around has been around the world twice it's been to Stephens Bay and the Galapagos where Darwin stepped ashore from the Beagle but the most interesting place it went was wet a workshop in New Zealand where Sir Richard Taylor delightedly the founder one of the three founders of Wetty grabbed it had it 3d scanned for their collection and it's in three movies as an easter egg and they named it precious because they made the Lord of the Rings films so it's called precious officially it's the most famous stromatolite on the planet and with that say yes precious must continue her journey around the planet so thank you very much [Applause] getting ready we have a just one small surprise there are three chairs out there the down underneath the chair there's a metal bar and there's a piece of paper taped to three chairs down there and that is that entitles you to a signed copy of David's new book just published assembling life which you can get at the table on your way out it's okay okay yeah hold up your hand if you have if you found okay we have one two one more one more and you know Dave you can you can say hi to him afterward okay we're going to let's get the discussion started because it's going to be brief we want to include some questions from the audience you know where to go when you have your questions but let me ask I don't say our panelists they're not really panelists but the scientists here some follow-ups so um Dave and Bruce the the work that you outlined here represents a new theory about where life originated although it's really an update on an old theory of course it was Darwin himself who I think in a 1871 suggested that it could be a little warm pond but there is a competing theory about how life got started there's more than one but one is that it was a hydrothermal vent and just a couple months ago I was down at JPL that at NASA where they reproduced the conditions of the ancient ocean in their lab and they successfully created amino acids and they're feeling like that is a very strong indication that they're on the right track so I'm wondering what is the crucial difference between these two theories I don't think it's just salt water and fresh water although that's actually that's part of it and are you suggesting that your theory replaces the hydrothermal vent theory well the way science works alternative hypotheses that's the best way to do science that way nobody's right or wrong what you're trying to do is to get weight of evidence you're testing these two hypotheses so that's what's happening we're testing the freshwater hypothesis but we're fortunate that we can visit places where we think our analogs of the original site of life's beginning on the earth read these freshwater volcanic conditions it's much harder to go down the Elven to test it there so what Lori barge is doing with Michael Russell is making a simulation of a hydrothermal vent by putting injecting a solution that will produce a mineral and within that mineral then they have added one extra compound which i think is pyruvic acid and not sure oh and with ammonia I'm getting kind of a booming quality is that okay okay yeah it was an ammonium then add to the primary weak acid and makes glycine well glycine was made 1953 by Stanley Miller and no other amino acids as well elleny by sparking a mixture of gases that might have been around on the earlier so glycine is sort of a you know we've got that in hand it's in meteorites it's synthesized it's out into outer space we have radio telescopes looking and seeing an evidence of glycine outer space so glycine is a monomer that's been around the trick is to make it into a polymer let's let's leave that there because there's this is really a discussion that could go on for a while but that's excellent so we'll leave it at there are competing hypotheses there's competing hypotheses so Lin I wonder if you could address the implications of this new theory or hypotheses that and how it bears on the search for life elsewhere in the universe for example if life did begin in saltwater vents as suggested by hydrothermal vent Theory you're unlikely to find it on Mars for example so what is your reaction to to this proposal that life started in these freshwater pools what does that how does that bear on the bigger question well first of all I think there are having suggestions that there could be hydrothermal activity on neat the surface of Mars anyway I mean that there could have been yes so obviously well first of all you have to understand that conditions for the origin of life are not necessarily completely the same as the conditions for survival for life so for example we've got a great planet for humans right now it's about twenty twenty-one percent oxygen its room and so on but it'd be much more difficult for some of the prebiotic chemistry to occur in these conditions that are actually perfect for us and vice-versa I dare any of you to go to back to an anaerobic earth and survive it might be a little nasty and so you know you have to when you're looking for life you have to sort of have this time disjunct to wear my originate so beyond that you know clearly the implication is that you would want to find places that would have hydrothermal activity or you would want something where there's surface water now once you're starting to deal with surface though you have an extra complication which I don't think Dave or Bruce mentioned and that is that you then have radiation flux on the surface and that's sort of a mixed thing because ultraviolet radiation can create compounds but it can also destroy and so you have this sort of yin-yang balance and so if you've got a body that is absolutely bathed with a high level of radiation for example someplace like mercury that's close to the Sun or a moon that's very close to a planet very close to Jupiter and it's just getting you know bombarded with radiation then surface conditions may not be the best place so it does sort of provide extra implications in there where we might look for places that had the origin of life but as I said the conditions the origin of life are not always the same as the conditions for the survival so there could even be a multiplanetary things those hinting that you could have life originated on one planet and then go to another or there's a temporal aspect where it originates when the conditions are different and then they change to go through some sort of evolutionary cycle or maybe these are separated spatially so maybe you get the origin of life deep in a hydrothermal vent just it's the wrong thing to say soon between the two of them and then it moves out into could you also have a life originated twice on earth and in separate locations oh absolutely and that's actually something that I was going to ask Jane because a geyser is an essence a hydrothermal vent by the surface and so it's not clear to me since you're talking about splash zones but geysers why the two hypotheses actually couldn't be merged that you do get some production within a geyser for example and perhaps then the polymerization occurs in the splash zone but Bruce and I like about geysers but Bruce and I like about Bruce and I like about geysers is that it is a short term cycling and I visited the the original geyser in Iceland and that thing comes up every hour or so and and kids get under the plume because the hot water is cool by the time it comes down so I saw my little daughter get good and wet you know while this came down on her but the thing that hits hot rock and that is a wet/dry cycle so anything that came up that geyser water turns into a organic film on the mineral surfaces and that's where we see the reactions occurring that I talked to you about so if you just stick to hydrothermal yes geysers are a hydrothermal thing it's fresh water though much more diluted than seawater the problem with seawater is that you cannot have a cycle deep in the ocean obviously there's no way to get a wet/dry cycle and that makes a thermodynamic hurdle that the people promoting a merchants light down there they have to find a way to get around that you and I get around it by making activated monomers and that helps us make our polymers in an aqueous environment we don't know how to make activated monomers of course Darwin himself mentioned that was the problem with the warm little pond is that you have a dilution problem that you know you would have to create so much buildup of organic material if you are amortize you know over the whole ocean a key idea that underpins all this work that is maybe most obvious and a little bit elusive was laid out in the 1920s by scientists Oberon and Haldane that the early Earth was not the way that it is today and that the chemistry was different was probably different and that chemistry could have occurred then that just doesn't occur now so the question is do we understand what the conditions were of the early Earth in the scenario that you've put forth year and how do you recreate a lab experiment if you don't know what the original conditions were I think the we this is why Dave and I went to Western Australia with Martin Van cranny donk and Tara who we mentioned before and Malcolm Walter because we and Glynn you were there so we basically took a truck like bus contraption from Shark Bay which you were showing on the screen which has living stromatolites you can push your your fingers into the spongy sort of living surface of them and we went to the Pilbara where we could touch the stromatolites at the age of three point four eight billion years as far back as we've got well preserved earth's crust now the interesting thing is literally we can't look back much further because you don't have much surviving crust everything sort of reworked you have something in Greenland at about 2.7 billion years but it's very metamorphosed so as far back as we can look the conditions for those living communities seem pretty much the same as say an extremophile environment on earth now they use they leave the same storm at oolitic textures there obviously so there's there photosynthesizing cyanobacteria you know their colonies there their microbial mats so that's all we know but if you consider planetary formation we asked the geologists we asked them well how much land mass was there they said it wasn't granitic sort of tectonic plate landmass but there would have been a lot of volcanic land masses so the analogs being Kamchatka and places like like like the North Island of New Zealand or like Iceland would have existed there we would have had cycling systems we would have rainfall we would have had climate so we would have had geysers we would have had just as we would have had hydrothermal vents in the ocean we have hydrothermal systems on land in fact the whole earth was a gigantic hydro thermal cycling system at that time so we can only conjecture and guess but we think that by going to the analogs and doing the chemistry and getting the chemistry to work it's it's strongly plausible that this could be happening on an idea on an island during the Hadean epoch so that stromatolite where is that stromatolite now they don't walk away with it what's that back so some of the answers to the question I just asked you are in that that rock right there and they're in the what's called the rock record no the key there are many keys to this you talked about the the cycling of hydration and and drying out that those but also it's the building of these of these polymers and we polymer just to define terms here a polymer defines a structure not the substance so the polymer is something that is a complicated molecule right it's but it can be of many different things so you can have one of DNA or you could have one of proteins and that's what you're looking at that's what's key about this hypothesis here is that it's a way to to create these building blocks of life it's not life itself as you said that's another jump but it's to create these precursor molecules is that right and what is it about this and you could just emphasize again about this the cycling of drying out and wetting and drying out that provides the necessary stresses so that those molecules come together okay that's probably me the chemist here every chemical reaction if it's going to happen has to have will be called Gibbs free energy it's uphill energetically and energy is given off as it goes downhill to equilibrium so when we have polymers made from monomers the reaction that makes the polymer is what we call a condensation reaction and we call it that because we're pulling water the water molecule out from between the two monomers to make a linkage between the two monomers so that that's what we call the dimer and that linkage there's only two primary mid linkages one is called an ester bond and everybody in this room has smelled an ester bond because you've opened a bottle of nail polish or polish remover that is ethyl acetate that's ethanol attached to acetic acid through an ester bond did the early Earth smell a little bit like nail-polish no it smelled like that meteorite yeah but you see the point being that this is a very simple bond to form so that RNA that I showed you up there it's held together by ester bonds and the reason we have to dry it out is to pull water away from it that's the energy we're putting into it we're heating it up a little bit we're also drying it out and that means that these molecules that are floating around instead of just floating around when they hit they can lose the water and the water goes away and they stay linked so that's really what polymerization is all about I want to ask question just a of Lin and Bruce and then invite you to come up and ask questions of your own don't be shy about that looks like we're a little shy about that come on up so so our it looks like RNA is it you said you created RNA and I want to ask Lin is that what is it that what is the advantage of RNA as it as an early molecule I mean why not just go right to DNA and say just a little bit of trouble what is it about RNA that makes it so feeling me as I think was mentioned earlier as organisms we need two things we need the physical body the phenotype but we need code we need some kind of genetic material to run the whole thing you know and give the instructions and the beauty of RNA is it's one-stop shopping it was discovered quite a while ago actually professors I had as an undergraduate was part of the Nobel Prize for this that RNA can actually have catalytic activity so in other words it can function like an enzyme which we thought up to then all enzymes were made of proteins but it also can carry genetic information now why not DNA first DNA is much more stable than RNA and so it makes much more sense but the way we make it in our cells and the way we think it would have been made prebiotic ly is that RNA is the precursor now it's not been said is actually I'm very bullish on the role of proteins in the origin of life and we sort of danced around the fact that their amino acids there they're actually easier to make prebiotic Li but there are also polymers well okay let me step back for a second and try to give an analogy for what they put so beautifully in case there's one person in the room who doesn't quite get it a monomer would be like a bead and a polymer would be like a string of beads so what he was talking about is when you start adding beads you give off water and so just think of it that way how do you go I was trying to describe some of how you would get these beads and then where Dave and Bruce have had these great insights is how to start to string those beads together and encapsulate those into the start of the body is that fair yeah okay one other question it's kind of a big one though but so I'll throw it to Bruce so is the idea here that you're trying to replicate how life could have started or are you trying to give us an answer how it did start so if we created an analogy like if you had a crime scene you could have a detective go and give you some theories for what happened but that's quite different from saying this is what did happen and which one are you going will you put your finger on it the subtitle of my book is not how did life begin but how can I like it begin and that's a very important difference in that verb right because we don't know we'll never know how life did begin because we're 4 billion years ago all this stuff was going on but we will know how life can begin if we can reproduce those processes in the laboratory or being enlightened by the results go out into New Zealand and make something happen there that looks like it's a step toward it even if that's not how life began here it's possible that whatever you're doing is how life began somewhere else and there's a wonderful project that we're initiating actually with Google called the Genesis Engine and it was came out of my PhD work about more than a decade ago and the idea is to use the power of Google's basically AI system to stand up a rapid simulator in software to try to penetrate through the darkness of this question and so what they're actually doing and we're writing the code right now is to simulate this polymer formation breakdown evolution system in software and then basically look drive it as hard as we can in the Genesis engine and look for the emergence of functions that we it's hard to see in the chemistry right now because chemistry takes so much time to do and you have to have the right parameters but the Google Genesis engine could see Oh a Porges formed in our artificial protocell and the poor are being there has let monomers into the proto cell during drying down which has now set up a catalytic activity which is now generating amplifying another simulated polymer in the system and watch this thing happening in silico and then go back to the lab into the field and say maybe a pore will emerge next if we do it with the right parameters so we can use computing this is my field and chemistry together and eventually we'll build the genesis engine which will literally run a robotic chemist off to the side with trillions and of little little vials maybe in microfluidics that will run the simulation run the actual chemistry do high-performance screening come back to the simulation run that run back this way and we can penetrate and and do a kind of an abiogenesis in silico and in vitro and it still only answers the question how life can begin looks like we have our own I don't know if you'd call it a monomer or poly mirror [Laughter] well it's pretty short so say it's of ma Tamir all right I like that Genesis engine I think I saw that Star Trek movie so this question is for the two of you let's say for the sake of argument that your theory is correct and furthermore that the only way life can emerge is in these pool scenarios and not in hydrants just for the sake of argument then are the various moons with oceans under ice sterile or doomed to be sterile is there some way that life could have emerged with your model in those scenarios and also could it have merged in pre-pre a greenhouse venus and mars so this gets to the implications for the searching for life elsewhere yeah this is the SETI Institute so I figured I would you know as I've written a paper exactly on that question it has to do with Enceladus Enceladus is a moon of Saturn and it's only 300 miles in diameter it has the ice coated surface but beneath the ice it looks like there's a liquid ocean when the Cassini mission flew past Enceladus they saw plumes of what looks like vapor coming out of the South Pole and the idea at the time the first thing you think of is if this is liquid water being exposed to the vacuum of outer space and maybe there's stuff in that plume that we'll be able to collect and see whether or not there is life somehow developing a Unseld Attis now in my paper however I explored these two hypotheses or we've been talking about and I said if it turns out that a fresh water ida thermal volcanic origin is correct then Enceladus might be habitable but lifeless okay because life cannot begin unless we have these acai coals on the other hand if Mike Russell and Laurie and nikoline and Bill Martin are right and life can be get advanced then the Enceladus plumes might be generated by serpentinization occurring in the rocky interior and this is sort of hot water coming up and we might expect to see some evidence of life in the plume when we fly a mission to it again so you know it's just opinion and plausibility my opinion is probably life could not develop on Enceladus but it might be delivered to Enceladus and just found a way to get the energy and nutrients to live there thank you and indeed it does have okay it has bearing on what what missions NASA decides to fly so the question so the research here on on earth has bearing on where we go in space yes so the question is could you have life appearing through one of these mechanisms and then failing appearing again failing again one of them begins to really succeed the next one you get another start but it gets wiped out because the first one could you talk about that that that's something that it's a combinatorial person I've thought about a lot that in fact did everyone hear the question ken ken light would life start and then fail and then start and then fail on the start and then fail and it's just an intuition but when I sort of visualize these landscapes with the fairly rapid start to to protocells which are able to do some kind of adaptation not divide they're not living cells the the fact that they can distribute widely across the landscape in our model means you can have multiple starts and failures because a pool a cycling pool may have a stable system for years to decades but it might dry up tomorrow so I might just intuitive strike on this is that in order for a combinatorial system that to generate complexity as massive as the first dividing cells when you think about the minimum cell you need that kind of multiple start and failure you need a huge pinprick system of starts and failures and you have to have the opportunity to fail many times and then to share innovations many times to cross the enormous thermodynamic sort of combinatorial barrier toward life you just need to have it so you have to have a landscape that can support massive failure and and mixing I'll mention that norm sleep here at Stanford and Harold more of its at a paper come out ten fifteen years ago fifteen twenty years ago called impact frustration of a origin of life and this is a serious paper because the earth was being hit by gigantic asteroid sized objects that we see the record of on the moon and some of those could have been so big that they literally sterilized the Earth's surface and therefore the hydrothermal life that was hiding deep in those hydrothermal vents might have been the survivors of this but again maybe not so that was a serious question and is still an open question it doesn't doesn't it also get to the the time skills involved that you have a lot of time to fail and start over and fail and start over again I know that Lynne has talked about this and in other talks right and actually say there there was a later paper by Steve Moises at Colorado and nobody's a reviewer saying that the earth never actually would have been sterilized during that period but trying to think the last question in analogy would be sort of like you've got a garage full of parts and you're trying to put together a bicycle and you know you get by by luck you get maybe a wheel in a handlebar and you know gee it doesn't really work with the seat on the ground so we'll take parts of it about apart but we could still reuse some parts and so on and I suspect there was a lot of that going on in the origin of life you know bits were reused because there really wasn't a concept of self versus other you know there was much more sharing of whatever molecules there were and I don't mean to make it sound like it was this Golden Age but I actually call it the orgy stage dry student spots but also you had a hundred million years to make that bicycle or the other okay yes little technical if you look at nucleic acids including RNA monomer they're aromatic heterocycles lots of nitrogen in there these are very complicated electronic structures and they act as catalysts now it seems to me that the origin of life and the origin of evolution are going to be pretty much the same thing and that it's not going to be proteins it's going to be things that are able to act as catalysts and also sort of act as genetic material so what's your opinion of the theories that involve polymeric heterocyclic aromatic compounds may I just request that you if you did not hear that if you could just summarize it and also we want to be slightly brief I want to get to the end of our of our chain here because we have a representative from the future generation who's going to answer all these questions for us someday okay I got the message be brief okay so your question has to do with complex head Recycling's like adenine just for example the one of the four bases of DNA and RNA okay and where did it come from and how did it get caught up in these reactions leading to the polymers I'm talking about there's a big gap in our understanding how to get from adenine to adenosine monophosphate which is a nucleotide actual monomer of RNA and we even know how that happened yet there's some guesses digs ear right here at Stanford again has made some of those reactions occur but we really don't know yet adenine though is easy five cyanides 5h CMS this was discovered way back in 1960 by John in row five cyanide consumer eyes you get an adenine when we analyze the carbonaceous meteorites we see adenine there we seek wanting we see a few other nucleobases so the bases themselves are easy in chemically since but getting those bases into a polymer that's hard we don't know how to do that you so you're a timescale of 10 to 100 million years for this process suggested since in the early days these life-forms won't have been vetted carnivore ISM or competition even that multiple biogenesis could have occurred at the same time on the planet because they wouldn't spread around now we have a million branches of the tree of life but we believe there's only one root is that correct or might there be more than one root the question whether or not there's more than one root to the Tree of Life there probably was more than one root but what happened was since all life as far as we know it on earth today comes from a common ancestor what is much more likely as it went through a bottles bottleneck and you know what we had a word sort of a Noah's Ark so that only a few things one or a few things were able to make it through this bottleneck and they're the ones that all life on Earth is now descended from but I do believe that there were lots of experiments see I did that there was only one way to to originate life I find very unlikely so that's so just the organism that went through the bottleneck is not necessarily the one that was the first organism speaking of that first organism do you think that any of the forms of life we can currently observe and some of them are pretty weird like prions are they even life right do you think that we have some idea what that original cell would look like compared to the simplest forms of life we see today would it be a lot more simpler or would it be more complicated I'm laughing because I have a new grad student who's actually working on prions and how they might be related to the origin of life so invite me back in about three years and we'll have some good data for you I'll be here I mean what is interesting and I will spill the beans a little bit is prions have been known as this infectious protein agents as disease-causing agents in mammals but they've since been discovered in yeast cells and we're in archaea and we're we've got an awful lot of candidates among the bacteria so it's something that probably is very ancient and it does have some information and so on in it and again they there's no scenario I can think of that you wouldn't also make amino acids and peptides so I just absolutely believe that they are the missing piece to the story has an active mission to go to Europa Lander and actually sample the ice for salinity and so you know rocking in contact with water do you think that that's fundamentally going in the wrong direction or reserve I'm misunderstanding it by me but what that mission is trying to accomplish okay I'm not speaking on behalf you need to repeat that that's about the act okay about the sample though looking looking for life Europa I'm not here representing NASA tonight would you where's the microphone they don't know I'm here so this is my own you know opinion but years ago actually had another student from Stanford for his master's thesis we looked a bit about different chemical continua to see which ones would be most creative most stable situation for DNA and actually you do need a salinity that's not unlike the ocean today and in fact that's encapsulated in the cytoplasm of every cell and so that's what I find you know one of the disturbing parts about your theory why would all cells on earth have a salinity that roughly matches that of the ocean if they began in freshwater rather than in the ocean they don't okay we're going to the ocean is 600 milli molar salt sodium and chloride 10 milli molar calcium 55:53 milli molar magnesium those are some of the major cations okay your cells have one one-fourth of that amount of sodium chlorate they're 150 milli molar instead of 600 milli molar the calcium in your cells is nano molar that the calcium is a signal in the cells your magnesium of a 5 milli molar so it's a misnomer to think that our cells reflect the ocean we do have the same ions but at much lower concentrations yes we're converging on as a brackish where we're in the world or not on in the world was life most likely to form well well we can let's take the question to Mars which is kind of an interesting thing so when we fly our missions above Mars Mars is a really interesting place because it's like a it's like a mummy it's like preserved for billions of years when you look down on the surface of Mars because it lost its water so early on that that water wasn't there to degrade and whether the system so you're looking at a truly ancient world but all over Mars we find these evidence of there was a shallow ocean in the northern latitudes and hopefully in silica sort of pouring down the sides of volcanoes these these silicate minerals and the spirit rover actually found silica by dragging a bum wheel that wasn't turning anymore through the soil and it turned up the stuff that looked like snow you remember that but it was actually evidence of an old hot spring so in the last three years we've been part of the Mars 2020 landing site meetings and the question they had was where could life start on Mars and where should we go and look for the new Rover that's that's landing and we made the argument that where the rover turned up that white soil all the rocks around there is an old yellow stone old old hotspring so if we actually went back to a place like that broke the rocks we might find those textures of the rock that you just held if we really got lucky if if life could emerge in a hot spring environment and then when as Mars died at the surfaces that lost habitability and the water disappeared the life would escape down the plumbing into the hot wet rocks down below or it would be quite salty and that's where you'd find life on Mars down in those rocks you know why he doesn't answer your question I was gonna that's because we have a problem of plate tectonics so anywhere we pick on the earth today was not in that location four billion years ago is it is it more likely that I mean I'm pretty sure it is but is it more likely that life appeared first outside of our solar system ah this is this is a very intriguing theory and then the idea is that it was seeded the life came to earth is that the theory that you're thinking about I guess what I'm trying to say is since earth we haven't really found a planet yet that has human like life but so far as we know so is it more likely that since the universe is so big that there a life originated outside of what we know and then came here or there are multiple multiple just last week we're at a conference approaching that question and there are serious scientists now saying that it's quite possible that life began on Mars and we are all Martians afraid we have to leave it there because we are running out of time thank you getting that I'm getting the thank you very much you I hate to leave can you just ask one question quickly please thank you for your question very quickly I'm very curious about the organics the original organics of our starting life and if there is anything that would have been missing from that set of organics that started life what would be like possible that would have still could have started life and what was brought that made life happen on earth and if something like that could happen somewhere also can we start life from those original organics I'm going to thank you suggest that maybe that question because I don't know if that could be answered in a sentence or two that would perhaps we take it outside and you can answer the the question in the hall but thank you for that excellent question so I want it I just want to thank the audience for coming out today can I just say one thing before you close and that is our esteemed colleague Dave D Moore has a big birthday coming up next week and I do need the audience and singing but instead I'm just actually I'm a big believer in singing so ready [Music] thank you very much and the final the final thought is if that if Bruce and Dave are correct then life began on land and crawled into the sea not the other way around okay to be continued ellipses dot dot dot thanks everyone [Applause]

Channel: SETI Institute

Views: 47,860

Rating: 4.7474403 out of 5

Keywords: early earth, origin of life, astrobiology, biology, evolution

Id: oFSIT1KctRU

Length: 77min 3sec (4623 seconds)

Published: Wed May 15 2019

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[u/alllie]

To answer the iconic question “Are We Alone?”, scientists around the world are also attempting to understand the origin of life. There are many pieces to the puzzle of how life began and many ways to put them together into a big picture. Some of the pieces are firmly established by the laws of chemistry and physics. Others are conjectures about what Earth was like four billion years ago, based on extrapolations of what we know from observing Earth today. However, there are still major gaps in our knowledge and these are necessarily filled in by best guesses.

We invited talented scientists to discuss their different opinions about the origin of life and the site of life’s origin. Most of them will agree that liquid water was necessary, but if we had a time machine and went back in time, would we find life first in a hydrothermal submarine setting in sea water or a fresh water site associated with emerging land masses?

Biologist David Deamer, a Research Professor of Biomolecular Engineering at the University of California, Santa Cruz, and multi-disciplinary scientist Bruce Damer, Associate Researcher in the Department of Biomolecular Engineering at UC Santa Cruz, will describe their most recent work, which infers that hydrothermal pools are the most plausible site for the origin of life. Both biologists have been collaborating since 2016 on a full conception of the Terrestrial Origin of Life Hypothesis.

Lynn Rothschild, Senior Scientist at NASA’s Ames Research Center and Adjunct Professor of Molecular Biology, Cell Biology, and Biochemistry at Brown University, who is an astrobiologist/ synthetic biologist specializing in molecular approaches to evolution, particularly in microbes and the application of synthetic biology to NASA's missions, will provide an evolutionary biologist’s perspective on the subject.