Origins Lecture 5: Abiogenesis - Life from Chemistry and Geology

hello welcome to science Sunday today we're live-streaming from the sanctuary at D U you see due to the precautions established by the church all services forums and most church related activities have been postponed canceled or will be live-streamed we're supporting you and help you in this time and hope that you're doing well and thanks for joining us here today I'm Mike winter and along with Scott Thompson we host the science Sundays on 1st and 3rd Sunday's of the month and if you haven't seen us before we hope you become a regular participant and those of you that have been at a lot of our services our a lot of our activities welcome back we have science Sunday I want to thank this church community for the support that we receive we strive to make science Sunday representative of the principles of this church namely a free and responsible search for truth and meaning and also a realization of the interdependent web of life of which we are all apartment we think that that's important goal of this church and an important goal of each of us and I hope that you see that coming shining through as we as we present our topics thank you very much for being with us today supporting us supporting this church and for supporting science Sunday today I'd like to introduce Scott Thompson as he discusses the origins of life if you have questions the Scott is going to announce it a few times during the talk too but at T Scott at humanist chat dot org T Scott with the T and then two T's at the end humanists chat dot org you can send in questions and we'll do our best to answer all the questions that we thank you very much and with no further ado thanks Mike welcome to all of you science lovers those of you who are participating virtually live and those of you who might be seeing this later on you know previously in this series of lectures I've been talking about origins and we started at the very beginning which is the Big Bang and we talked about how matter conceivably and plausibly came into existence from the pure energy fields locked up in the processes of the Big Bang we talked about how that matter eventually turned into stars and how those stars are forges of creation in a scientific sense they create the heavier elements that have gone on to salt the universe with richness we've got carbon and nitrogen and oxygen and sulfur and iron and so on and so on and now the big question before us is once we get to the point where stars and planets are formed how does life plausibly arise so there are different sorts of questions all wrapped up in this one simple sounding inquiry how did life arise people have been thinking about this question probably ever since there have been people and there's been any number of explanations typically the explanations that preceded the Scientific Revolution were explanations based on mythology or some kind imagine the cosmology I'll talk a little bit about those later in the presentation but one of the wonderful things about science is that instead of saying that many of the things we behold in the natural world are the result of magic we can find plausible and in many cases verifiable and repeatable explanations for how the universe came to be the way that it is and this is now beginning to also address the question of how life came to be so I've talked before about the timeline of the universe and we're gonna start today talking about the formation of the earth which happened about 4.5 four point seven and seven billion years ago something like that and not too terribly long after that the the first hints that life existed is is to be found in the geologic record now the first sort of living things that we could expect on earth a couple of interesting points about that first it's not at all likely that the first sort of self-replicating metabolic information transforming and transmitting processes it's not at all likely that the first glimmerings of that kind of activity on planet earth would have been at all exactly like what we see today I mean by at all exactly I mean you know with nuclei cells with a nucleus and DNA and transcriptase and centrosomes that are involved in the splitting cells and all of this the complex machinery of even a single cell is expected to be far more advanced than anything was entailed in what's called a biogenesis which is life from nonliving matter life plausibly came from simple chemical and complicated chemical reactions in an environment that included a geology and a physical chemistry in an atmospheric chemistry and ocean chemistry that that are very different than we see today so we're going to talk about some of those plausibility x' however again it's not likely at all that we will find specific fossils but microbes don't fossilize very well and atoms doing their things well they don't leave any sort of fossils there's a little bit of an exception to that I'll talk about a little later which is not a direct fossil but an isotopic kind of residue in the fossil record now in order to continue our exploration of some of these topics we have to imagine ourselves at a different place in a different time so once again we're going to leverage our imaginary ship by part of this idea from Carl Sagan and Neil deGrasse Tyson they had a spaceship of the imagination I'm calling our spaceship of the imagination the daydream so we're gonna take our daydream we're gonna start off back at the time of the solar nebula and the pre solar nebula with planets including the earth and the moon first formed out of the dust and debris the silicates the iron the oxygen remember last time I said that the earth is mostly oxygen so that when you stub your toe you shouldn't worry about it most of what makes up a rock is oxygen but you lock that oxygen in a crystalline matrix and it becomes quite quite tough indeed but here we are hovering in our spaceship daydream over the the mass of the solar system and we see here an infant earth this infant earth has the first hints of confidence recall that last time in our prior lecture I talked about how the fluffy lightweight stuff that first comprised the infant earth would have through gravitational differentiation would have sort of bubbled up and floated to the surface and we call this lightweight fluffy stuff granite and then underneath the granite is a layer of hard dense basaltic Rock including something called olivine but our first few million years perhaps the first billion years of the history of Earth the earth was a very physically volatile place with lots of all volcanism island chains of granite formed by volcanoes that are moving about and rubbing into each other and building up the first proto continents and continental carks on the planet so it was a very different world that did not have oxygen in this atmosphere in fact it was what we might consider a hellish place there were meteors that were frequently bombarding the earth there was there were volcanoes that oceans were already even when the oceans first formed they were likely salty but they had very different chemistry than today they likely had a lot of dissolved iron in them and so it's very difficult for scientists to know exactly what the early Earth was like and this includes the early Earth that would have been the stage for the formation of self-replicating molecules so we're going to go instead of outside to roam around hellish Tundra we're gonna stay safely inside our imaginary spaceship daydream and we're gonna convene in a conference room where we get to see the the goings-on outside and speculate a little bit about what's plausible in terms of the science so here we are looking out a window at this landscape and imagine that we had all of the proper tools to do samplings of the ocean and the atmosphere and the earth one thing that we would find is that there is no soil soil is largely organic so the there might be clays due to weathering due to the friction between rocks as they slide together or as rocks fall down hill or as tectonic the the growing tectonic plates rub together etc as rain falls it was probably almost always and constantly raining on the early earth and this would have allowed the formation or facilitated the formation of clays and rock dust clay is essentially rock dust that can be wetted but no no soil for plants to grow no no dirt human beings were not formed from dirt nor was any other living thing originally because dirt itself didn't exist so when we talk about a simple life form and you imagine some of the simplest life forms that we know of today which is bacterium such as pictured in this slide you know even a bacteria is an incredibly complicated thing and every bacteria that's alive on earth today is the inheritor of billions of years of selective evolution so some bacteria had processes and metabolic processes and information transfer mechanisms and replication mechanisms that were significantly less efficient this is a highly plausible idea consistent with the evolution we see in macroscopic organisms and even the simplest bacteria and archaea that are around today like I said are vastly more complicated than we can expect the first prebiotic chemical operations to be or the first first things that we might call life and that's this gets us into the delineation between what is life and what isn't life one of the ways to simply deal with this problem is to say what life is a special thing a magical thing life was created maybe it was created by a who a Mazda or an has set or some other deity idea or maybe like some ancient traditions of the world life was created by the confluence of chaos and order in some kind of cosmic dance that gave rise to complexity and organization so these ideas which predate science are not on the face of it horrible ideas people have always been full of curiosity and lacking evidence and lacking the scientific method they invented stories some we would consider more many we would consider less plausible but everybody has tried to answer this question and today like I said in the modern era we're at least getting closer to be able to make some reasonable scientifically form speculations about these questions many of you might recall that back in the I think it was the 60s might been the 50s I don't have it written down the miller-urey experiment where a graduate student approached his professor who had already won the Nobel Prize yurei had already won won the Nobel Prize and Miller said you know I've got this crazy idea why don't we try to recreate the way that Earth's atmosphere and oceans were back several billion years ago and I don't know let's just run us park through it and see what happened and this famous Miller experiment called the miller-urey experiment was something kind of like that they took water and a kind of primordial soup Carl Sagan made that term famous and he took a primordial soup as was suspected at that time with with an atmosphere with methane and carbon dioxide and whatnot and all of these dissolved chemicals and they ran electrical sparks through this highly saturated atmosphere in a bottle set saturated with water and whatnot and after a few hours and certainly after a few days the clear water in one of the beakers had turned reddish and when they looked at that they found that it comprised a lot of amino acids and so since that time scientists have used telescopes and them the way that telescopes can look at the spectrum of light either emitted by hot molecules and atoms or reflected off of cooler molecule Adams's they've used this spectroscopic method and have found that these kinds of amino acid molecules and precursor mo courser molecules to things like lipids or fats these kinds of basic stuck together atoms of hydrogen and helium and sulfur and carbon na helium sorry hydrogen and oxygen and carbon etc these kinds of amino acids are everywhere that we look they're out in space they couldn't conceivably have come from Earth but they're out there now these aren't living things they're not living molecules but they are molecules relatively complicated molecules that are used ubiquitously by every form of life we've ever seen as is water so carbon water hydrogen sulfur nitrogen these atoms are everywhere in the universe we don't have to rely on some science fiction notion of silicon-based life because silicon tends to make much stronger bonds and look at the way quartz is silicon dioxide silicon and oxygen bind together so firmly that it's really hard to get any dynamic chemistry out of that duo but oxygen and carbon aren't quite as chummy as silicon and oxygen and so we can do some really complex chemistry with carbon so it's plausible that life in whatever form our living processes or proto living processes involve some chemistry involving hydrogen carbon carbon oxygen nitrogen the same sorts of atoms and molecules that are involved today and that we see with amino acids so Charles Darwin famously back in a letter to his friend Joseph hooker I believe in 1871 said said something very speculative now Charles Darwin lived at a time when nobody knew about genetics nobody knew about DNA that's not strictly true Mendel had done some of his experiments with peas and had found heritability and ideas that would eventually turn into ideas of genetics but Darwin very provably did not know about any of this so Darwin didn't know about DNA didn't know about the double helix it didn't know how cells worked he didn't know anything about ribosomes and transcriptase and all of these complicated processes within a cell but he did know that life was comprised of molecules and atoms of the regular kind of stuff we see around us every day and he speculated in this 1871 letter to Joseph Hooker that maybe somewhere on the early Earth and some warm little pond chemicals just pure chemicals came together in a way that they precipitated out of this muck and grabbed on to one another and started self-replication process and began the long chain of consequences that we call natural selection molecules that were more efficient at replicating themselves it would be really a stretch to call these living molecules but any molecule that would replicate itself more efficiently would become more prolific and higher concentration and molecules that were less efficient at replicating themselves so Darwin had this idea of a warm little pond with clément conditions where living living things might have gotten their start as self-assembling molecules and we'll see that this idea of the the prebiotic soup full of amino acids and lipids and whatnot is quite plausible again these chemicals are everywhere in the universe and they were everywhere on the prebiotic earth or at least in many places there were concentrations of these molecules quite plausibly on the prebiotic earth so if we look at the proverbial tree of life this is one of the representations of that tree that I prefer it's kind of a modern take on the idea and this shows that there are many sort of primary branches of this of this living population on planet Earth and the time as it were starts in the centre of this wheel and then as time progresses towards the edges of the wheel species evolve and change and isolated populations of species and micro environments like particular Pleasant Cove in an ocean or a macroscopic environment like an island that's become countenance that's become separated from other landmasses on earth the this idea of separating populations and subjecting different subsets of populations to different environmental constraints leads naturally to the idea of natural selection but at the center of this wheel something extraordinary happened and that's what we want to talk about today at the center of this wheel is something that biologists have called Luca Luca stands for the last Universal common ancestor and so back in the 70s or 80s and before there was this hypothesis that there was one living entity and from that one entity all the remaining organisms on earth have eventually evolved now the problem with that by the way I've had this call for two months I'm not I'm not particularly worried about it in any case if you try to zoom in in this Tree of Life to the to the to the root level as it were again this doesn't really look like that tree it's more wheeled you zoom in to the wheel of life at the very hub at the center instead of finding evidence of one single ancestor we find something quite different satisfying something quite different instead they find this tangled mess where it's not at all clear what the lineages that relates one microbe to another microbes that live in vastly different habitats may share some chemical properties some protein some biochemical pathways and their metabolism and yet they may have very distinct pathways and processes - and this gets to the idea that I'm not going to delve into too much today called horizontal gene transfer where if you're really tiny then you can learn tricks from your neighbors genetic tricks by exchanging little bits of your genome directly without going through sexual reproduction or cell division etc so this is evidence that at the very beginning life was exceptionally gregarious it was constantly exchanging bits of information and molecular processes and metabolites and if one plausibly gets rid of the notion of a cell wall even then you can imagine just little chemical replicators that are living in an environment where they exchange information fairly freely but in any case without having to dig back into some hypothetical microbial fossil record just looking at the microorganisms that are extent today we see evidence of horizontal gene transfer that completely obliterated this notion that there was a single primeval Luca organism that was the first living thing on earth there was a morass of chemical processes and biological proto biological processes and from this mass eventually at least one might successful microbe arised arose so here's this ancient question that has vexed philosophers and schoolchildren for Jenna which came first the chicken or the egg and according to the scientifically proven fact of Darwinian evolution something slightly different from a chicken laid an egg that inherited a mutation or that had its own mutation that made it a little different than its grandparent chickens or perhaps even its parent chickens and if you take this analogy back far enough chickens were at one point dinosaurs in fact all birds were dinosaurs and dinosaurs laid eggs so in terms of which came first the chicken or the egg well eggs predated chickens but if you want to have a chicken something that was a little different than what you might deem a chicken genetically speaking and maybe even physiologically speaking if you go back enough great-great-grandparents something a little different than a chicken laid an egg that became a chicken so depending on one's point of view you can provide a scientific answer to this in several different ways well there's a similar set of problems entailed in notions about the origin of life the question is we've got three significant pillars to the processes of life that are exhibited to this day and that involves an exchange of information the development of structure that allows an organism to thrive in a particular environment and to separate itself from that environment to provide a barrier between oneself and the other so that your your insights don't leak out so this idea of barriers and structures and internal structures and you know we have organs cells and even bacteria have organelles and then finally information structure and then tabble ISM you know how does a living thing extract information on so I extract energy from its environment and use that energy to derive the kind of nanomachines that biologically the biochemical nano machines that compel life to do its thing so information structure and metabolism harkening back to our chicken and egg question the relevant question is which of these came first and information transfer mechanisms such as DNA genes and DNA to RNA to proteins or was it a structured thing with cell walls and membranes and ribosomes and other specific structures or was it a metabolism thing where energy usually in the form of some kind of aqueous ion that is a electrical current drives biochemical processes well the scientists don't yet know the answer to this in a definitive way but there are certain contexts that they've imagined that would be plausible on a primitive earth that would combine more than one of these things in the same general location same ecosystem if you will so you know when we're talking about structure we've got cytoplasm x' ribosomes and and cells today have mitochondria etc and you know the kind of cell that goes into making you or I or a puppy dog or any other multicellular creatures phenomenally complex the complexity is evident also in its metabolism heard about the krebs cycle but there are thousands of chemical reactions entailed in releasing energy from different food sources molecular food sources in nature and then information processing as I alluded to you've got DNA transcribed by messenger RNA etc and I'll talk a little more about that in a minute but here's something very very interesting that scientists first noted at least fifty years ago and if you zoom in to what happens in a living cell whether it's a a relatively simple cell like a bacterium or a calm relatively much more complicated cell called a eukaryote which is kinds of cells that multicellular organisms have and some single-cell organisms but if you zoom in on the mechanisms of eukaryotes and bacteria and another whole class or kingdom of animals called the archaea and you look at the way that they do their chemical business at a microscopic level you find this amazing commonality within this you see that there is messenger RNA that carries information and this messenger RNA serves as a template and you have then these transport RNA that grab on to no asses within the cytoplasm of the cell or the environment of the cell and remember these kinds of amino acids are produced naturally through natural chemical processes they're so easily produced that they're produced in places where there can't possibly as far as we can extrapolate be living things like in the tail of a comet or in the dust around a baby star or in the laboratory creature of Miller or nur AIDS experiment so these transfer RNA have a particular chemical affinity for a particular amino acid and they grab them on and they fit like a lock into a key or a key into a lock on this messenger RNA and then this amazing little micro machine within every living cell called a ribosome takes this template of the messenger RNA which is a a encoding strand a strand of information encoding and it uses that to string together one after another of these transfer RNA that carry amino acids and this is the way a protein gets built but if you think carefully about this and notice what I've circled in this image you see that RNA is implicated again and again and again sure there's some DNA in a nucleus but it's plausible that RNA because it's so important to these functions that RNA is one of the fundamental characteristics of living things in that tangle of life I alluded to RNA is very very plausibly ubiquitous now one of the cool things about RNA is that it can do some chemical action on it on its own it can form enzymes it can form some structures that can operate on other molecules it's not as efficient at doing that as certain other protein based molecules but it can do a bit of it and here's a wonderful piece of proof that that's true the ribosome that takes messenger RNA and then facilitates the tacking on of transport RNA that pulls amino acids into a protein chain that ribosome is mostly made out of RNA now modern ribosomes in every creature that we've looked at also has some proteins tacked onto it but the operational bits the crunchy bits of the ribosome is made out of RNA the part that does the work is made out of RNA so this is a all a very good argument that there existed on the primeval earth this idea that's been called an RNA world and one of the things that's implicated in this notion is is that clay serves as a substrate before you have information transfer from messenger RNA long strands of RNA that already have in for me so we're back to the chicken and egg thing it has been proven that if you have a moistened clay substrate and clay tends to build up in layers like sheets of paper layered on on top of each other in between the layers transfer RNA which are very simple little bits of RNA can grab on to these clay layers and form these these strings along with their attendant amino acid to conform these strings and you know happens billions and trillions of time in a suit it rhymes in a solution with the right prebiotic molecules and it's a leap of imagination but a justifiable one and a plausible one most scientists think to say that some of these chains these random chains of amino acids strung together by thermodynamic and chemical processes on a clay substrate by RNA some of these would have folded because when you string amino acids together that has a name a string of amino acids is called a protein and proteins but different amino acids have different residual charges positive and negative charges on them and these charges attract or repel other amino acids and it causes a string of amino acids to fold into complicated ways and those complications are part of building literally a machine out of protein so one plausibility is that this prebiotic world of moistened clay and biomolecule organic molecules that were not living things per se formed a dynamic place for the generation of random and much additional research is being done into that idea to try and see if there's a print preferential sort of protein or a selection mechanism that the molecules can undergo here's a little video clip of how a ribosome works how it gathers transfer RNA that are just floating around in the environment that have a little bit of amino acid attached and then uses our messenger RNA information strand as a template to string them up and the string them together in the right order a very very primitive machine in life in fact every single living cell whether it's a bacteria or an archaea or eukaryote again which makes up you and chickens and everything else everything has ribosomes in it in fact every cell of your body has about 100 million ribosomes so they're incredibly tiny little molecular machines even a bacteria or an archaea will have something like ten thousand ribosomes in it and because of differential processes in evolution one ribosome of one species is not identical to the ribosome of another but they're all constituted of RNA with more or less proteins tacked on to help improve their chemical efficiency amazing stuff and nowhere in this explanation is there a need for something magical speaking of magical one of the arguments that sometimes is levied against the notion of abiogenesis of life originating from chemical geological processes is the second law of thermodynamics alright and the second law of thermodynamics is used to say well you know you can never increase the complexity of a thing or you can never you can never increase the the energy of a thing an energy will tend to dissipate over time and through space and so the idea that you could collect energy into into a biomolecule that just that goes against the second law of thermodynamics well the second law of thermodynamics applies to the entire universe and one of the tricks that the universe plays with the laws of physics is that you can locally increase energy and diminish a related quantity called entropy which I'm not going to talk a lot about you can do that locally as long as your environment loses even more energy or creates even more colloquially I will call it disorder so think of it this way if you have a ball sitting on top of a hill there's a tendency because of the laws of nature specifically the law of gravity there's a tendency for that rock or ball to roll downhill and that's just the action of the law of nature and when the ball rolls downhill and hips bowling pin or a foot obviously it has energy energy of motion that it could potentially release but to get a ball or a boulder rolling downhill in the first place might be difficult you can imagine some jagged peaks like this this mountain peak now instead of thinking of this as literal mountains think of it as energy levels right there are energy levels associated with biochemical processes now what if I take this mountain range as it were this says this graph of energy levels and I tilt it a little bit but when I tilt it if you'll notice there's still a tendency for the energy to decrease or diminish as you traverse the range each one of the troughs is lower than the preceding trough but there's this little spike of energy preventing a chemical process from taking advantage of that and rolling rolling easily downhill and this this idea is in tail than many natural processes where you get the evolution I'm sorry that's a probably a poor use of the term where you get the creation of structure because of energetically favorable processes dissipative structures and one example is a hurricane a hurricane has a lot more structure than just a single puffy cloud might have but this is an emergency because of the energetic thermodynamics of what's called a dissipative structure nature often finds a way to take advantage of energy gradients including thermal gradients and it typically does this in a structured and organized way these patterns that evolve naturally shouldn't use that word these patterns that occur naturally because of thermodynamic and physical processes are everywhere we see spiral galaxies we see spiral hurricanes we see mud cracks that look like their patterns laid down by a contractor building an interesting mosaic third floor we even see pattern earth in the form of circles of stone we're freezing and thawing cycles differentiate the heavier lighter stones from that I'm sorry heavier larger stones from the smaller and lighter stones so this kind of pattern earth arises naturally circles formed on earth through no magic whatsoever it's just thermodynamics doing its thing but to overcome one of these humps requires something called the activation energy just like you have to push a ball or a bowler to get started rolling downhill many of these chemical processes require a little bit of energy to be put in and then you get a lot of energy out of it that's called catalysis and get catalytic reactions and one of the ways that you can make a catalytic process happen is by putting in a lot of energy on another way that you can do it is that you can lower the activation energy if you wrap that hill in in something like I don't know something that's easier to climb right you put Romans on the hill instead of just a flat surface of granite if you put a few carved runs onto the hill it would be easier to climb it well in a roughly analogous way biochemistry can lower the activation energy required for a chemical to occur and in natural processes these catalysts molecules are called enzymes enzymes in biological processes are catalysts that facilitate other chemical reactions by changing the activation energy requirements and one of the cool things is that when you look at that energy of life the way metabolism happens in living things you find protons everywhere the cells of plants that do photosynthesis have chloroplasts and I'm not going to talk a lot about photosynthesis now but those same plant cells that have chloroplasts also have mitochondria mitochondria is called the battery of life because it literally builds up a charge on the inside of the mitochondria that's different from the charge on the outside it creates literally a battery and in order for that to happen protons must preferentially be put inside the mitochondria this happens by virtue of a kind of proton pump that is powered by chemicals and by naturally occurring chemicals by by the oxidation and reduction processes where oxygen might want to buy might have a tendency energetically to find with carbon and in the process give up a little bit of energy in the form of motion and this little bit of motion actually spins quite literally a motor inside of the mitochondria on the walls of the mitochondria so the mitochondria which are in nearly every living cell are actually festooned with little motors that are spun by burning the oxygen just like you burn a pile of leaves but in a very controlled manner such that about 88% efficiency of energy transfer happens now you'd think that life might use electrons we use electrons we use electrons to power computers and light bulbs and many other things so why is it that nature leverages protons instead of electrons for some of its most important power plants well there's some good plausible answers for that that I'll get into in a moment but first I want to talk about some key discoveries first amino acids form spontaneously I've already talked about that lipid spheres also form naturally from prolific free biologic processes and organic chemistry so little spheres like to see little droplets of oil forming little spheres in dishwater you can easily create conditions in a plausible prebiotic earth in an aqueous solution where little spheres self-contained environments form photosynthesis is not the oldest metabolic pathway photosynthesis is all about freeing up electron but those electrons are eventually used to power these proton pumps in mitochondria that exists in the cells of plants so it looks like proton motive note ility moving protons around is more fundamental than electron motility autocatalytic metabolic processes for processing hydrogen molecules h2 and co2 are found in all primitive organisms every organism on earth has some kind of metabolic process that entails co2 and hydrogen by the way you can get protons out of hydrogen by stripping their electrons off and then ribosomes are common to all living things finally protein a proton gradients and their movement across boundaries through molecular turbines drive all cellular energy you put all these things together and it makes you want to look for a place on earth where protons are naturally liberated and flow across membranes well that has been found today we call this the lost city this is a place on the floor of the ocean where alkaline vents spew out mineral rich water and mineral mineral Laden water and these alkali vents are warm snuggly they're not like volcanic vents in fact they're usually several miles removed from the actual spreading center where the tectonic plates are pulling apart than you've got magma and boiling water this is just warm water and interestingly enough the processes by which these minerals condense as they bubble up through the mantle form these chambered structures and these chambers have a size roughly about the same size they can be as small as a bacteria so you've got this chamber with with mineral particles on it and protons flowing through it and inside you've got this aqueous environment this seawater and on the on the primitive earth the seawater was a little different and had a lot of iron dissolved in it so the chemistry that happened on the primitive earth is likely a bit different than the chemistry happening on the modern earth where these are but this is a plausible environment for how life's biochemistry could have been jump-started by a natural flow of protons and one of the ways that these things form remember last time I talked about the mineral olivine that is part of the basaltic crust of the earth when you expose all of the seawater it naturally undergoes a chemical reaction that can after a series of events liberate these protons it's called serpentinization olivine turns into certainty so where on earth are these things well the first one was found in the Mid Atlantic about 10 miles away from a spreading Center since then there's been another one found but I believe it's up by Greenland but these things are enormous sort of chemical factories and even to this day microbes live there but we're not expecting brand-new biomolecules to be evolved there because the microbes that already lived there if they see a little bio a molecule with some potential energy in it they just gobble it right up so those newly formed molecules don't have a chance to undergo evolution so three plausibly relatively straightforward steps to simple life a proton gradient across an inorganic substrate which could form a kind of cell in this case a geometric cell not a living cell simple dissipative structures involving biochemical metabolic pathways biochemistry does not necessarily involve life biochemistry is just any chemistry involving carbon so yeah biochemical pathways metabolic prime pathways that increase the entropy of the surrounding seawater while decreasing entropy locally these are all very plausible chemical reactions and then plentiful reactive precursors sheltered environment the natural proton gradient gradient emergent biochemistry was driven by thermodynamic processes to use ever more complex biochemistry to hasten thermodynamic and equilibrium so life actually contributes to the second law anytime you have a living thing it's dissipating energy into the environment more rapidly than energy would be dissipated if it just reflected off of rocks or off of ocean water so life accelerates the increase of entropy in the universe which is entirely consistent with the second law so one of the other important things that happen in the history of life was it at some point a prokaryote which is a different kind of chemical structure but many of the same biochemical processes including their ribosomes and whatnot a pro archaea ate a bacteria and it did not bacteria didn't die and the archaea didn't die Linda Margolis came up with this idea several decades ago and this is called symbiosis or some symbiogenesis I believe and the idea is that if you take the advantages that bacteria have some of the advantages that have evolved in an archaea and you combine them into a single entity you can end up with beginnings of what we call that eukaryotic cell or a complex cell from simpler beginnings this is all consistent with Darwin from simple beginnings ever more complex living things emerged naturally through natural processes now one plausible thing that could be true rather than these hydrothermal vents and the ocean even a primitive ocean that had a slightly different biochemistry one of the plausible things could be that life got its start on another planet and was transported in the form of bacteria really robust amount of bacteria that could survive outer space it was transported to the early Earth this might help answer the question about how it is that life got started so early on the earth when earth was still hellishly unpleasant with volcanoes and asteroids and tsunamis because of the asteroids and whatnot maybe life originated somewhere else and was transported here by meteorite you know we recently had a visitor Oh mwah mwah was a visitor from another solar system that came through here last summer came through our solar system so there's nothing unscientific about this explanation but one of the things it does is it just pushes the abiotic or prebiotic chemistry back to a different stage right it might happen somewhere else someone else but it's still the same prebiotic biochemistry so whether we're talking about it happening here on earth or plausibly answer around some distant star it's still the same natural biochemical processes there's no magic involved there's no need for throwing up our hands and surrender and saying that one of the most complicated things known in fact I would go so far as to say it is the most complicated subject known to humanity is biochemistry and expecting a simple answer to the most complicated thing we know a simple answer like it just happened that trivializes it and is an invitation for us to just walk away from the problem instead we can pick this problem apart piece by piece and little by little come to a plausible understanding of the way nothing more than nature and nature's rules and chemistry and geology and the atmosphere and the ocean conspired to make replicating molecules from nonliving amino acids and lipids and other obviously prebiotic molecules that have been incorporated into the every living thing we see around us today why don't we see new life springing up well I alluded to it earlier why don't we see life evolving from scratch somewhere maybe using slightly different amino acids and whatnot well because all of these molecules are yummy to bacteria and archaea so if they're yummy something's going to eat them we've had billions of years for bacteria archaea eukaryotes to proliferate on our planet and now if a novel pre biologic or nascent biologic process evolves to create some kind of long complicated sugar molecule something's going to need that sugar so that's one of the reasons why we see everything descended from what looks like a common ancestors because once one chemical process started undergoing Darwinian evolution it led to a proliferation of organisms that saturated the environment and close the door on any new emergence of life it's like imagine driving around in an ancient steam-powered automobile well nobody does that anymore because now we've got race cars and hybrid cars and steam power automobile just wouldn't have any role to play other than there's a novelty in our environment in our societies and once you get modern organisms using a replicatable efficient biochemistry and this happened billions of years ago once that happened we're off to the races and everything Darwin has taught us about the way natural selection works is relevant and perfectly competent to explain the variety of life we see in the around us finally here are some books that I've used to inform today's presentation I encourage you to check out from your library or purchase one or more of these books and I thank all of you for your attention and virtual attendance today and we'll be seeing you soon stay healthy and well

Channel: Prairie State Humanists

Views: 734

Rating: 4.652174 out of 5

Keywords: science, abiogenesis, origins, origin of life, first life, hwsc, humanism, science sunday

Id: T1ozxdqPMDM

Length: 57min 55sec (3475 seconds)

Published: Sat Apr 18 2020