David Krakauer: So of course it's great to introduce my colleague today, Eric Smith, and partly because he is not just a colleague, he is a friend of mine and he is a collaborator in the institute. And tonight's lecture, as you know, is in the topic of life, the inevitability of life and its origins in relation to Geochemistry. Now one of the unfortunate tendencies of the human mind is to think categorically, to think in terms of dichotomies, living, non living, conscious, not conscious good and evil. But of course the world is not categorical. It's more continuous. And of course this tendency to categorize extends to institutions departments, Physics Departments, Biology Departments, Literature Departments, Architectural Departments and for those of you who have been coming to these public lectures you will know that the Santa Fe Institute often stands in opposition to a rather simple minded categorization of the world, both institutional, intellectual and metaphysical. Now the topic of life of course derives some of its charge from the sort of categorical, dichotomist opposition it stands in relation to the inanimate world, to non life. And I want to read you a quick quote from Mary Shelley's Frankenstein; this is a preface that she wrote to the book in 1818. Many and long were the conversations between Lord Byron and Shelley, to which I was a devout but nearly silent listener, so presumably she couldn't get a word in. During one of these various philosophical doctrines were discussed and among others the nature of the principal of life. And whether there was any possibility or probability of it ever been discovered and communicated. Perhaps the corpse would be reanimated; galvanism had given a token of such things, galvanism of course being the application of current to muscles and their subsequent contraction. And of course there are other stories like the "The Golem". The golem is mentioned in the Talmud where Adam in fact was first a golem, made from dust and the famous golem of course in the famous golem of course at Prague, 16th century Rabbii Loew who constructed a creature to work on the Sabbath out of the mud of banks of the river Vltava IN Prague. And of course more recently computer viruses which some people think are alive. Now all of these narratives, Frankenstein viruses and the Golem, life springs from physical and chemical processes, doesn't spring from existing life. It's not like birth where living things borne living things. These are non living things borning living things. And at some point in the history of the earth presumably there was no biology. And some disposition to chemistry and physics gave rise to biology and the subsequent evolution of life. And these are things that Eric is going to talk about. Now that Eric has done his first share of raising disciplinary boundaries. He was an under grad at Caltech where he did his degree in mathematics and physics. He was then a post graduate student in Austin, Texas where he worked in string theory and quantum gravity. And then he was a post talk Texas and then Los Alamos before coming to the Santa Fe Institute. His interests include the emergence of life, that he will he talk about today, but they are not restricted to the emergence of life. He is also interested in the correspondences between the economic processes, physical processes, living processes, biological ones and also the connections between energy, information and computation. So in tonight's lecture Eric will ask with the contrary, I think to our intuitions, life may not be inevitable in the universe rather than rare, Eric.
Eric Smith: Thank you all for coming, David thank you. Wonderful introduction, it sets just exactly the right tone because in a subject where there has been too much over simplification, too much sound byte reporting I want to try to give you some sense of the richness and the beauty of the picture that comes up if we ask about the position of the life on earth. So let me stop this thing and good. So tonight I get to tell you some facts or some new ideas about the emergence of life on earth that I think will change what many of us have been told about whether we should think that life on earth is surprising or inevitable and how we should ask questions like this. At the same time as answering this question it should change our understanding of the position of the biosphere within the geological world and several important aspects of our position as people or as animals within the biosphere. So there are many different messages that all sort of inform each other. I want to set us tonight the task of answering four questions. First one, why is there life on earth at all as opposed to nothing or as opposed to an empty rocky planet? How and where did it originate, sort of obvious questions of mechanism. Why has life persisted? This is important because I think if we have a sensible understanding of how life emerged that must also make it sensible that life has stayed because the things that cause it to persist are the same things that caused it to emerge in the first place. So the questions must be asked and answered sensibly together. And then last of all, does the biosphere contain relics of emergence? So that by looking of what life is today we have a window that's informative about how it came into existence. Now before I can address any of these sorts of forward looking questions I have to address a question that has been a problem in this topic, which is whether science can say anything about these problems at all. And of course since I am here on the behalf of the institute talking to you about science you would think that this is a fore gone answer. But if we pull some influential 20th century scientist, in particular biologist, the returns we get are a little bit surprising. So let me start with Stephen Jay Gould. I actually chose my talk title tonight as a response to Gould's very wonderful little book called "Wonderful Life". Many of you probably have read it and it had a big influence on me with my first exposures to biology and it's a really important work of this century. Gould chose the title for his book on the basis of Frank Capra's 1946 movie "It's a Wonderful Life" because he felt that the movie told exactly the story that he wanted to tell. It's a story that an individual's actions can have permanent and important consequences. And Gould's message about biology was that for the first time in science things that seemed to be accidental can have consequences that could last forever. So of course being Gould and fighting the last war against over simplification he states things in the strongest possible terms. Any replay of the tape would lead evolution down a path way radically different from the road actually taken. Now if you take this at face value or in the context of the book it makes it sound like accidence are all that matters, which kind of leaves us wondering what then is the role for science, not the same as in the other sciences may be. Gould of course worked with things that are big enough to see without a microscope and that can leave fossils. Let's go to somebody who works with things that are smaller. This is Jacques Monod, who the year I was born, 1965, won a Nobel Prize in physiology and medicine for his work on the regulation of cell machinery from the gene. Monod wrote a lasting influential book called "Chance and Necessity"; his concern was one that we have heard many times. A wish that people not imprint human notions of purpose on biological descriptions of how machinery works, and he was interested in arguing against two things in particular, the two ways people to tend to imprint purpose. One, vitalism would have been a claim that when matter becomes part of a living thing it's no longer the same as the other matter and we can understand it. The other animism, which says well, its all matter but it all has purpose from the beginning. I think Monod's point in arguing these was to try to bring biology closer together to the other sciences on the way they are understood. But of course Monod was primarily a guy who explains how machinery works. And how machinery works doesn't necessarily provide a good explanation of why it's there at all or how it got there. And so faced with this difficulty he makes a statement that if anything is even stronger than Gould's. He says the biosphere does not contain a predictable class of objects or events but constitute a particular occurrence compatible indeed with first principles but not deducible from those principles and essentially unpredictable. So he starts out trying to bring biology together with the other sciences and with this sort of encapsulating statement if anything it makes biology seem more remote from the other sciences and leaves us wondering what we can say. But the grand daddy of them all as far as strong statements is Francis Crick. Crick together with Jim Watson discovered the double helix structure of DNA and first realized that this was the molecule that could be responsible for heredity and the way it works. And Crick takes these sorts of accidentalist view point of Gould and Monod all way back to the beginning by associating the emergence of life with the emergence of something like DNA and heredity. So early you see him here; he is looking sort of appropriately like a sorcerer, presumably lecturing on the structure of the molecule that's a key to life itself. And I think a lot of people have to think of DNA in those terms and I going to try to push back a little against that tonight. But he refers to the emergence of life as a happy accident and a little bit later goes on to say "The origin of life appears at the moment to be almost a miracle. So many are the conditions which would have to have been satisfied to get it going". Now if there is one thing we know science does not claim to be able to talk about, it's miracles. So well this is not necessarily a logical impossibility. It seems like a very strange point of view for a scientist to be putting forward as a scientific conclusion because that amounts essentially to throwing up ones hands and saying, oh we can't say anything about that part. So if there is ambiguity and the public's understanding of what science has to say about the emergence of life, I think it would not be blamed on the public, may be we should start by looking at the things scientists have said. But if there is ambiguity it should be leading us to ask three important questions. As one of my favorite political commentators' says what were they thinking? Specifically what aspect of Biology are these people looking at that would cause them to draw such seemingly odd conclusions. For us what's important is is this really science, is this the nature of life that they were talking about or is it actually a nature of their point of view which might be narrow and might have left things out, because if it is just a prejudice that comes from not having looked at every thing and we can broaden our perspective a little bit, may be we can find that from a bigger perspective there is a story that's not all about accident, and that's truer to the nature of life, not necessarily to the history of science. So that's what the rest of tonight is supposed to be about. So what were they thinking? Most of us who have seen any thing about the history of life have seen a picture something like this. We see many pictures of trees of life. Let me very briefly tell you what this is in case it's not familiar. Every name here at the end, elegant things like Methanosarcina and Entoameoba, these are big groups of organisms. The tree is basically much too small for me to be able to show individual organisms. And as we go down any of these lines what you are saying is that the history that led up to the organism as it is today. So when you see then two lines that become one line in the past the idea is that the two things that are different once had an ancestor and that was a single thing. So one could easily talk for days about just this tree, there is so much interesting to know about it. I will mention only a few things. One, this is a representation of data that says that every thing we know about in the earth is related to every thing else. And as far as we can tell everything that's around today came at some point from one single form that was a bottle neck from which the survivors descended. Now, to give you a sense of scale everything you can see without a microscope is these three little branches here, the plants, animals and the fungi. So the rest of what is alive in the world is individual cells. Now I couldn't make these dots small enough to only cover all of human history, so it's about ten times too big for that. And it's kind of a useful thing to give us a sense of what part people are in the natural world. And you know not only scientifically but also as human beings. But the thing that I really want to point to you about trees that's important is that the only time similarities and that's what these trees are, I should mention, the trees are trees of family resemblances. You see a trait that's in two things and not any where else. You infer that those two things, that the trait came from a time when two things were once a single population of organisms. Now the only way having the same trait implies that you are related to the others that have the trait, is it's that it's infinitely accidental. So this is the reason you can't use skin darkness to figure who is related to whom, because as soon as you move towards the equator you have to get darker to survive, you move away from the equator you have to get lighter to survive. So these things can change so fast and they can change in so many ways that they are not good guides to what is related to what. So the only time family resemblances imply a tree is when the change along these branches is in characters that are so rare that they are it's amazingly they ever occurred and if they are lost they are gone for ever. So the reason Gould sees accident is that Gould's life was understanding the structure and the relations of this tree which is the thing that emphasizes the accidental parts of life. But we still have to understand why anything about life is so accidental that it would make a tree that the family relations would be that. And to understand that we have to go down to the molecular level. So this is now the world of Crick and Monod. What Crick discovered with the double helix structure of DNA, was that you have a positive and a negative of the same information which can be split and copied with out being used up. And that's how changes can be passed on from a mother to a daughter when in the case of cells, the mother divides. Now at the same time either the positive or the negative can be used as a source of instructions to control the cell and that's how the hereditary information that's passed down is expressed in us. But the thing that's important here is this is like a company whose is commander only gives commands and never listens to feed back, the only way you know whether they were good ideas or not is whether the company lives or dies. This is what implies accident, because it says that it's only the accidental changes in the course of living or in the course of dividing that cause organisms to gradually change and then those changes are inherited and the only thing that determines what we see today is which changes live and which ones didn't. This is Darwin's idea. And of course what Crick and Watson recognized is that this is the molecular basis that gives substance to Darwin's empirical observations. But I will point out to you here; this is the description of life at the level of control and inheritance. And of course if we have you know a moment of common sense, we remember that there is more to life than control. And so what I want to do is now broaden the picture, ask what else is in life and then start to dig down on a different area that may be is more fruitful, okay. So what I want to show you here, life is not just one thing. It's not just one level of structure or just one kind of organization. Its many things and they are all different and they all work together. So just to kind of give you a lay of the land or review what some of them are and then I will tell you which one is I am going to focus on. First thing, life lives in the non living world of rocks in the atmosphere. And in the non living world your carbon comes in the form of carbon dioxide molecules mostly. That's why these little stunted butterflies are supposed to be, pictures of carbon dioxide. So the first thing life has to do is make carbon-carbon bonds which it does by making a certain set of small molecules, not many of these, about 250 and they are not very big, between five and twenty carbon atoms. So this is the whole structure of chemistry it is called core metabolism and that will be hero of our story tonight. But for a moment let me go on. You make little atoms, one carbon at a time, when you make big atoms you do some thing different. You stitch the little atoms together like beads on a necklace. And this is where you get the big molecules. The DNA and the proteins that can have tens or hundreds of thousands of atoms, in some cases even millions, of course that's not all. The big molecules have to be physically stuck together to make destructors of cells, that's a different organizational problem. Now for some living things that's as far as it goes, you are one cell and that's your life. For others, you get many cells that group together to make a plant or an animal. That's another problem of organization. For most of us we live in an ecosystem were we have relations to all the other organisms, that's another problem of co-ordination organization. And then the ecosystems together on the earth feed back and change its basic geological chemistry. So all this is going on, these things were very different in their dynamics. So we shouldn't be thinking that one idea of control explains all of them. And the remarkable thing is if we look at these things from the perspective of chance and necessity we find that in fact they lay at very different places. So the benchmark for what I will necessity is the chemistry of the rocks in the atmosphere and the oceans. On any planet like the earth it's going to be the same. There is not much that's accidental to it. It's very steady; we can predict what the minerals are. And we understand that with our science. Now at the opposite end of this is any individual species. The fact that there should happen to have a been a large flightless pigeon on Mauritius is an infinite accident. And the fact that it didn't survive unfortunately is the most likely thing. This is Gould's world of contingency, all the things that almost never were and never will be again. And here of course they are available. They fluctuate like crazy. This is the Doug Irvine's lecture a few months ago on extinctions. And we have a hard time predicting them. So this is Gould, Monod and Crick, their statements. But here is what's need, Biology is not all piled up against the contention end. If I ask about the small molecules here, these are almost as steady as the chemistry of the rocks. The same set of about 250 of them is in every living thing in the world and appears to have been in the same for all of history, almost 4 billion years. So it's like a feature of the Geosphere. DNA, well chemically DNA has been around probably since fairly close to the beginning and RNA even closer than that, but when this contains instructions for how to make these chemicals, the instructions can change all over the place, the chemicals do not change and the path ways do not change. So all of a sudden control is looking like may be it's not the most important thing. May be getting the answer is the important thing and you have some freedom in how you do with control. Cells - cells are fairly regular but there is a significant amount of variability in them over history. And ecosystem is if I could have drawn them should cover this entire span because the accidents of how we live together in an ecosystem are among the most fragile things that are parts of life. And yet the chemistry of ecosystems which is the chemistry of these molecules goes all the way back here to the oldest things we know. So in fact if we want to understand the predictable parts of life we should be looking at metabolism as the bridge between the rock chemistry and the early stages of life and the part that we can predict. But in order to do that we need a science of metabolism which is going to be different from the science of control. So let me start back looking at the things that are alive again, and show you how you would think about their organization in metabolic terms. It turns out two questions will answer a huge fraction of what you need to know. One is where you get your energy and the second is do you depend on other living things for your own survival? And there are two choices to each. So, biochemistry 101 in 30 seconds. All of life is driven by energetic electrons. And the only question about where you get your energy is where you get your electrons. There turn out to be two choices. There are molecules that release energy by giving electrons away and the metabolisms that run on that energy are what I call reductive here. And both of these are of that kind. And I will tell what they are in a minute. This little guy lives at almost the temperature of boiling water in volcanoes under the deep sea, this is botulism which when I was a kid was not a cosmetic, it was a deadly poison that you tried not to get into your canned goods. The other option besides reductive metabolism are oxidative metabolisms, where the energy comes form pulling electrons, the environment. Oxidative metabolisms are things like the Blue-Green Algae that give the ocean its greenish color and everything most people think about life is down in this corner. The animals, the plants, the fungi; everything big enough to see without a microscope. Now here is the interesting thing. The oxygen in the world, that is the foundation for these this way of life, was produced by living things; it was not always here. So this whole way of life didn't exist at the beginning of the world and didn't exist at significant complexity until quite late probably half of the age of the earth. Okay. Now the other distinction we can make is whether or not you need anything else in the world. There are organisms, both of these kinds which basically can do every chemical thing they need in a world with no other living thing. What a life it must be especially if you are just one cell, you know, no communication, no competition, but they can do what none of the rest of us can do. These guys are called autotrophs, from the Greek roots meaning self-feeding. The alternative to being an autotroph is to be a heterotroph. You have to live in an ecology because you own chemistry is incomplete and you have to have the ecology providing things for you. And we of course are the ultimate heterotrophs, we need everything. But in fact, what I did here was a little bit of a slide of hand; I did the thing people always do. I looked at individual species and individual organisms, that wasn't the right thing to do it. It turns out to be a distraction. Because if I look at the ecosystem level, the whole ecology together, things become even simpler. By definition, every ecology because it's self contained has to do all of its own chemistry, so every ecology is autotrophic. The remarkable thing that you get form studying biochemistry is the knowledge that other than this division, there is essentially no variability at the ecosystem level in the chemistry of life, which means that I mean this is the Tolstoy quote, "All autotrophic ecosystems are essentially alike but every heterotrophic organism is heterotrophic in its own way". So if you are reductive ecology like one of these sulphur swarms that you get in volcanic hot springs then you are living off of electrons that come from the geochemical reactions. If you are an oxidative ecology, there is a little bit more variability, you are living ultimately off of the energy that comes from sunlight and the ability to produce oxygen. But here is some more remarkable thing. Chemically these things look like opposites, either the environment gives you electrons or it pulls them in. It turns out that in the structure of life this is not just an opposition, it's a hierarchy, because the universal chemistry that is in these guys is a subset of what's in these guys. Oxidative life is reductive life wrapped up in a space suite that's able to capture sunlight. So what that means is that even though on the earth today, there are environments with almost no oxygen down in the deep seas around volcanoes and environments with lots of oxygen like up here where we live. You can also look at this as a picture of back in time. Because back at the very beginning when there was not yet life to have made oxygen, the only kind of life there was the reductive life. And it, in these very simple organisms, basically building biomass is enough to be alive. This may have happened as long as almost four billion years ago within a couple of 100 million years of when the ocean stopped boiling off. So it basically was a snap of a finger. It happened as quickly as it could. Probably somewhat later and this is the biggest uncertainty in the talk. When this happened is unknown to a billion years or more. But at some point organisms started to realize that there was huge energy in the sunlight if they could capture it. And they started to couple that to building their core metabolism and they started producing oxygen. Took a long time though for the oxygen to build up and only when there was a lot did you start getting the things we think about as life, complex cell forms, multi-cell organisms all that stuff. Now here is the striking thing, oxygen when it first was introduced was a waste product. It was the worst poison for life than anything any of us have ever imagined. And yet this chemistry did not end, it was preserved and it has been preserved all the way up to the present. So I've just have thrown a huge amount of stuff at you in the five slides. I think maybe that's appropriate because life is complicated. And we said that if we want to avoid the mistakes of the past we don't want to oversimplify by ignoring things at the beginning. We want to look at it all and then we want to see what looks like it doesn't depend on chance and we want to let universality and stability be our guide. So we have been able to boil the story down to focusing on the core molecules of biochemistry and what we use to build our own biomass. So at this point we are still in the middle of a treasure hunt. We think we know what we are after but there hasn't been an ah-ha. That's for the next slide, but here is the cool thing. If you are to watch a movie, and one of the characters would open up a treasure map that has five arrows pointing to some place saying, "Here it is! This is it!" You would say, "Okay that's not a very subtle movie, what kind of character needs that?" What I am about to show you is that the map of biochemistry is a treasure map with five arrows pointing to, "Here it is!" and it's been known since the 1960s. But people only started to recognize what they were seeing within about the last 25 years. So this is what is universal about the way we build all of our bio-molecules. Biochemistry itself is not super complicated, if you ask what we are made of. We are made of five classes of things we know all of them because we have to eat them. Because you remember, I said, we are metabolically incomplete. So we need the fatty acids. Because otherwise we can't make cells, that's your olive oil. We need the amino acids which we know from meringue and marshmallow and things like that. That's the structure in the enzymes and all that good stuff. We need sugars, turns out they are probably more important for structure than they are for energy storage but we like them for the other thing. Very, very important set of about 20 to 30 little molecules which do all of our sort of superfine chemistry. Like the chlorophyll that allows plants to capture sunlight or the heme that allows us to do respiration. And then of course there are nucleic acids, the molecules of heredity. Now there are 250 or 300 basic molecules that these are built up from. But here is the kicker. Every molecule in every living thing in all the world for all time has been synthesized from one of these 11 molecules in this cycle. Now when we were in high school a lot of us were taught about the Krebs' cycle. And of course there was the million dollar, billion dollar point here which was ignored and something of almost no importance that we were told. We were told that the Krebs' cycle is important because we use it to breakdown sugars to get energy. The Krebs' cycle is important because everything in the entire history of life has used it as the starting point to build every bio-molecule, no exceptions. We came along two and half billion - well single cells came along two and half billion years later and used it to get energy. But we are borrowers in that sense. So it may be obvious now that I think this is where life started. But now that we have this chemical framework, I can also tell you why I think life had to start this way which is a question that we can ask in chemistry in a way that we could not be for. So in Biology the struggle has always been when you think in terms of control, how do you how do you explain why something is there because when we think why is something there, we always think what is it good for. Well what is it good for, is a purpose based question and it's not clear that it came up because it was good for anything, it came up for a different reason. In chemistry we are not so susceptible to that error, because in chemistry we are used to saying what was it getting away from. So a new way to ask about why life emerged is to say what was wrong with a non living earth? What was so wrong that could have driven it to have to change and why was that change in the direction that led toward life and that's the thing that I think we can answer or that we can at least pose good questions to that are testable in the laboratory. So that's what I will tell you about in what's left. Turns out, what we appeal to for understanding is the thing that's the most familiar of all. If you put enough stress on something, it will break. And it turns out that the essential math and also the essential intuition I care about for the origin of life is the intuition of breakdown. Now the thing that might be non or sort of counter intuitive if you have been wondering about the origin of life. You don't normally think of the origin of life as the breaking of a lifeless earth. So the true things that I have to show you is there is more than one way for things to breakdown. And then second, some times the process of breakdown is a process of creating new structure and creating accident where there was only formlessness before. But you will be surprised, as familiar as crack propagation is to us, these other two facts about breakdown are equally familiar. One of them we know all the time because lightning of course is a breakdown of the atmosphere. It's not a mechanical breakdown but instead it's an electrical breakdown. The thing that we need if we want to understand why life emerged is to understand where the stress came from and why it results in one kind of breakdown instead of another. So if you want to understand lightning, you say that storm systems pull charges apart between the clouds and the ground. And that creates an electrical stress for the charges to try to recombine. The ordinary dry atmosphere which is the the preferred configuration can't do that transport but the creation of the plasma channel of the lightening bolt can do that transport and that's what sustains the plasma channel. Now we can't predict exactly the track it will take, that's contingent that's accidental. But we can very well predict the chemistry of this plasma channel. So the analogy here and it's better than an analogy, it's a scientific equivalence is that our biochemistry is like the altered state that is the plasma channel within the lightning bolt and it was driven into existence in something like the same way. Now lightening is not an ideal example here because it's gone in a short time and we don't think of it as lasting for very long. Even though on the scale of the processes that make it, it's plenty a long lived. But there are other examples. Hurricanes are another kind of a breakdown of the atmosphere. This is not a breakdown of the electrical structure of the atmosphere; it's the breakdown of the thermal structure. What I am showing you here is a set of hurricane tracks which you can see transporting heat out of the tropical oceans and into the temperate and polar upper atmospheres. This is what drives the hurricane system. As, of course, people now understand and appreciate in a way that they didn't a little while back. This is a channel that has the ability to pull in heat in order to reinforce its own structure and the wall storms of the hurricane are transporting that heat from the ocean to the upper atmosphere. But in order to do that they have to break the smooth layered structure that the atmospheric temperature usually has. So if we want to understand the emergence of life, was it a chemical breakdown, what we have to ask is where did that happen and what was the stress that would have caused it to happen? And now we are talking about stress in a chemical sense. So my friend and colleague Harold Morowitz who is much older than I also has an infinite gift for words. And he has recognized that's why he has written something like eight or nine books that are revered around the world and I recommend any of them to you. But he has recognized that theories of the origin of life can be divided into two categories. They are the Heaven theories and the Hell theories. You can already guess which one I like. But it turns out that this has a basis. They are distinguished according to where the energy comes from in the life forms that use it today. The Heaven theories are all of the theories whose energy ultimately comes from sunlight or starlight. The idea is that there is so much energy in this that it can do the chemistry of forming carboncarbon bonds. So it can produce the small molecules. This can happen on the surfaces of asteroids which then fall on the earth, can happen in the ices of comets. In some small amount the sunlight drives the weather system and a little bit of the energy from weather winds up in the lightening bolt and that can do a little bit of chemistry. This was what the Miller-Urey experiment showed that was so exciting to people and that got the origin of life started as a scientific question. And that all of these stories that have to do with the sort of sun light yielded chemistry are the things that we associate with the primordial soup. Now this appealed to people when there was no other idea in town but there are a lot of problems with it. Sun light is a tremendous energy source but it's not easy to use, because it tends to destroy things and so in fact it's much easier to understand the way sunlight is used today if that happened somewhat later on when there was already life in place with the complex ability to capture it. Another problem with the primordial soup is that you need to finish life before the soup is done. So you are on the clock, the idea is that, you know, in the classical scenarios heaven deposits organic materials on the surface of the ocean and accidental chemistry gives you a control mechanism and then you have the keys to life itself. The DNA or whatever, but then you have to build the whole life underneath of this before you have used all of the soup. So that's unappealing, the thing that to me is the biggest problem with these ideas is that in this chemistry there is no special place for the Biochemistry we see and there is no special reason to exclude all of the things that are not in our biochemistry. So it's not clear to me that this is very tightly coupled to who we are. And since the whole point of explaining biochemistry was that, that was the thing to be explained, I think we should expect a couple and that's where the Hell theory comes in. This is the theory particularly associated with hydrothermal vents. These can be volcanoes but they can be quieter things that involve magma and water under the deep ocean. There can be many different kinds, you can have these guys which are alkaline and which are full of carbon-dioxide but not too much metal, these are called white smokers and they occur in not the hottest places. These are about at the boiling temperature of water, a little bit cooler. These guys can be 600 degrees Fahrenheit or six or a 300 degree Celsius roughly and they thunder along at the bottom of the ocean. They are black because they are full of metal and Sulfur, they are full of carbon-dioxide, they are full of hydrogen in particular they are full of all of the chemicals that life needs to exist but they are not full of primordial soup. And oddly enough that turns out to be an advantage and I will show you why in the next slide. Oh I should mention to you that there are whole eco-systems that live down here. A little grey guy, that I told you can live all by itself with no other living thing they live down here, in this region and they do exactly the chemistry I am going to tell you. I think it was being done 4 billion years ago before there was life. If you want to understand what was wrong with the lifeless earth then you say, what was the problem? Here is the problem. The geo chemistry creates carbon-dioxide and it creates hydrogen. Now hydrogen has electrons that it can give to carbon or oxygen and if it were to give them so you put as many hydrogens as will fit around a carbon to make methane. You put as many hydrogens as will fit around an oxygen to make water that is the most energy that's available from this system. You look at this picture and you say well how hard it could be, well it turns out its very hard. It's harder than any non-living thing can do at an appreciable rate but living things do it with superb efficiency. So the pre - what life on earth is today doing, among other things, these geo-chemical processes are generating all this energetic stuff but it would build up and build up and build up in the absence of life. Life consumes it, provides this downhill run, to lower energy molecules. So the idea behind the lightning strike is that this stress when there was no life built up and built up and created a lightning strike through chemistry to make this possible. But what does that have to do with bio- chemistry, all I showed you was carbon-dioxide and methane. Here is a surprising thing that's a little different than we are used to thinking off. I told you that there are organisms that live in these hydrogen environments, the reducing environments that give electrons. They are doing this chemistry and they have essentially nothing more than bio-synthesis. Their energy capture is very limited, it's much less than a tenth of what any of us use up in the air breathing world. The surprising thing is that in order to get from here to here, the best way is to go through the molecules of life so what this picture is you can think of this as being the chemical equivalent of a ball rolling down a hill and it has the same mathematical meaning. What I am showing you here is the starting point when no chemistry has been done, the ending point when all of the energy has been extracted and across here is how far you have gone in transferring those hydrogens. It turns out that there are no ways through little molecules to go from here to here that are as energy efficient and simple as going through these molecules which are the ones in the cycle I showed you. You don't need to worry about the names but if you want to know why is there sugar? There is sugar because sugar is down hill from the stuff that makes sugar. If you want to understand why there is oil including petroleum, it's because oil is on the way to methane if you have enough hydrogen to make it. And so what I am telling you, the chemistry was doing here is exactly what these little guys are doing at the base of that hydro-thermal vent that I showed you. And incidentally if I had remembered to point it out on the tree you remember that some of the organisms seem to connect in very, very close to the route, unlike us, we are kind of connected way out here in the leaves. This is one of them. This connects all the way down at the bottom. Lives a few degrees below the boiling temperature of water, seems to have ancestors that could be at least 3 billion years old before it has a common ancestry with anything else. Thus this simple chemistry is completely self contained and does nothing else. So this is the kind of model we are looking at for the chemistry of the origin of life. Now you shouldn't believe me yet even if you might believe me in a minute because I just told you that all of this chemistry is hard. So where did any of this stuff come from if it's so hard to do and that's what special about the cycle at the core of bio-chemistry with all the arrows pointing to it. Because that cycle is the chemical equivalent of the hurricane so here is the cycle again I didn't know how to show it to you without making it sort of sleep inducing but this is actually the chemical diagram showing where carbon dioxides come in, where hydrogen come in, where waters are given off and so one and we go round and round the cycle and we go around it in this picture the same way as the hurricane goes around it. By the way, if you have kids in school and they come home telling you that the Kreb's cycle is a citric acid cycle turn, tell them wait till they grow up. Because this thing is called by some people the reverse citric acid cycle. This is the real citric acid cycle this was here four billion years ago. We run the reverse citric acid cycle. That came along only when there was oxygen much later. But the important thing about this cycle is this. The chemistry of these molecules is chemistry that's like fly paper. Its suited to take in a carbon dioxide or a hydrogen even if they couldn't react with each other and so as you go around the cycle the molecules get bigger and bigger and bigger as they take in carbon and when they get here they split and you get two molecules were before you had one. So now you can take in twice as much carbon and it splits again and now you can take at four times as much carbon. So this is like compound interest or like the chain reaction that was of course made famous by Los Alamos some decades ago, where the hair commercial where she told two people so on and so on. The thing that's important about these kinds of cycles is that even if you have only a very rare event, to form one of these molecules if you have self amplification that can cause all of your carbon and all of your energy flow to get sucked into one cycle just like you never find two hurricanes in exactly the same place because any one of them is pulling all of the local energy in, from the ocean where it is. So that's pretty much the story. I am not going to tell you that all of it is fact, that all of it's established, but of all it is experimentally testable. And there are several things that I think it allows us to think that are different than have been thought before, probably more common sense and maybe more useful. Metabolism first, not control first. Control is complicated if it had to come on a background of nothing that would seem like almost a miracle but it doesn't exist on a background of almost nothing today. It exists on a background of metabolism and metabolism is old. Life arose and persists in order to enable metabolism. This is the lightning strike argument, think about how different this is and the way we usually think. We usually think that metabolism exists in order to enable life, that's the sort of purpose oriented thinking. In the chemical domain you get a completely different idea of what life even is, life is what can be built out of those eleven molecules when you have this amplifying cycles spewing them out from geochemistry. We get, to me, the very pleasing idea that the emergence of life was a form of collapse. The important thing about this is that things do not come up off of the floor and rearrange themselves on the table. So if the transition from a non-living to a living earth was actually a collapse that enables us to understand why life has been so stable. Species go extinct, eco-systems rearrange, life has winked out, it's been continuous all the way back and the chemistry has been in variant. This is a sensible way to look at that and of course most of all the biosphere is no longer separate from the geo-sphere, not in our thinking not in our science, geo chemistry is in some sense the core of what we are and have always been and the rest of us as living things is built around it. So there is contingency that comes in later, there is all kinds of room for accident but this accident comes in once there is a significant amount of structure already in place. So thank you and it will be good to talk.
