>"The existence of life is no mystery or lucky break, he told Quanta in 2014, but rather follows from general physical principles and “should be as unsurprising as rocks rolling downhill.”"
This makes sense. Life exists here on earth, I believe it got here through natural processes, and so it seems that life should be expected in the right circumstances.
But this begs the question, has life arisen independently from other existing life in the last 4 billion years? All known life shares the same fundamental genetic code and appears to descend from a single common ancestor. Are we to believe that the founder population of all life on earth, from which the GCA hailed, is the only instance of life on earth arising directly from inanimate matter? Or has life arisen independently between 4 billion years ago and now, just to be out-competed by existing life forms? Or were conditions just right 4 billion years ago to allow for the spontaneous generation of local-entropy reducing molecular agents (which evolved into life), and ever since conditions have been wrong for the generation of life?
If self-replicating organisms did spontaneously emerge multiple times in history (which is possible, although I think many, including England, overestimate the statistical likelihood of complex things coming together so perfectly), they were likely eaten immediately by more refined life forms.
I never understood this line of thinking (it kind of reminds me of the sci-fi trope of the killer virus from outer space). In order for two life forms to be able to interact significantly at a bio-chemical level (let alone eat each other), one would imagine their bio-chemistry would have to be highly compatible. That seems unlikely of lifeforms arising from independent abiogenesis events.
> That seems unlikely of lifeforms arising from independent abiogenesis events.
Not at all, you're presuming there are many different ways life could work, that might not be the case at all. It's entirely possible there's only one or very few possible recipes for life so no matter how many abiogenesis events occur, they produce the same kind of life.
A simple analogy, wood burns, fire is fire, you don't expect every different occurrence of fire in nature to produce a new and incompatible type of fire. Life could be the same, it could be that anywhere carbon based life forms it's basically the same basic recipe and thus biologically compatible with all other forms of carbon based life.
> It's entirely possible there's only one or very few possible recipes for life so no matter how many abiogenesis events occur, they produce the same kind of life.
Presumably this is even MORE likely if the independent lifeforms both emerged in similar physical & chemical environments.
Is this necessarily true though? Abiotic synthesis of amino acids is a thing. Might Organism T1 and Organism T2 still be composed of similar basic building blocks, even if they don't share organic ancestry?
The vast majority of life on Earth has been wiped out simply because other life created inhospitable conditions for them. Even if multiple events created life, if the wrong life is created, it will die.
Also I don't understand how the straightforward rebuttal to Jeremy England's thesis is addressed:
Since the primordials soup times, we also have energy hitting inanimate matter. On this planet. And also we have the other planets in our solar system. Why aren't we finding lots of bacteria being spontaneously generated everywhere?
The world is absolutely crawling with bacteria and fungi that will consume any precursors or early proto-life. RNA and protein sequences are delicious. Anything new is going to just get immediately eaten by the better adapted more advanced lifeforms that are everywhere, even in the deep crust, in arctic ice, and in the deepest parts of the ocean. There are no sterile places left.
It isn't that a novel form of primitive life arises then gets eaten; the building-blocks necessary for a novel form of life to arise get eaten before those building-blocks have much chance of interact at all. From what we can tell it would probably take many millions of years of chemical interactions in the appropriate conditions after being seeded with carbon-based molecules from comet/space impacts (since carbon compounds seem to be relatively common).
It seems likely that life will spread and adapt somewhat quickly since it is usually easier to find new resources than enter an arms-race over existing resources. That leaves a very narrow window of time (in evolutionary terms) for life to arise >1 time independently then evolve enough to be on equal footing with the other form(s).
It also seems far more likely that if this very rare event takes place one of two things happen:
1. One form of life has a head-start in the arms race and overtakes the other, completely wiping it out
2. The two forms of life are compatible enough to exchange genetic material because they evolved from the same raw building blocks deposited on the planet; though it mostly fails to produce viable offspring in a few cases the forms successfully cross and the new third form of life successfully outcompetes its progenitor forms.
As for Mars, it seems likely that life never evolved there at all.
The next best explanation seems to be life never got beyond single-cell organisms and struggled to eek out a short existence. Before Mars dried out and/or the massive hemisphere-shattering impact struck and erased what traces of life once existed.
I was going to post something similar to xenadu02's, but logged back on to find his post already there, so let me tackle a different point.
The simplest bacteria today are amazing organisms. They have cell membranes, which separate the protoplasm of the cell from the outside the world, and only selectively let some molecules through. They contain a blueprint to produce catalysts for a variety of chemical pathways; they can store energy in chemical form and use that energy to catalyze these reactions. The can break down complex molecules into simpler molecules and reuse these building blocks for their own purpose. They can move, to seek out new food sources. They can produce toxins that interfere with the chemical pathways of other cells, killing them.
But when we talk about abiogenesis, we aren't talking about the spontaneous generation of a cell. We're talking about the spontaneous generation of a single molecule, or a small set of molecules, probably proteins (amino acid chains) that, in the presence of proper raw material (amino acids) will tend to act as a catalyst for the formation of more of itself.
That's it; the reaction does not even have to be fast or obvious, even. If it takes years for the molecule to catalyze its replication, that's fine. Everything on top of that comes down to evolution, the slow development of a new trait - cell ways, a genome separate from the cell machinery, the ability to metabolize organic molecules into raw materials, locomotion - over millions of years.
So in addition to xenadu's point, there's also this: the abiogenesis of new self-replicating molecules could still be happening today, and we'd probably never know. The objects in question are too small, and the time scales involved are too large.
> has life arisen independently from other existing life in the last 4 billion years?
It depends on how you define life. If viruses are a life form then you have one. If self-replicating meta-structures composed of multiple different species interacting such as lichen count as separate life forms made of other life then that might count too.
On the more far-out side of theoretical biology people have proposed culture/memes and the modern high-tech economy as a new form of life that has emerged from previous life. If solar power (or fusion) becomes ubiquitous and it learns to recycle nearly all its waste it will become an ecologically self-sufficient form of life, and if AI ever gets good enough to have machines designing and producing machines it could "fork" and become a completely independent form of life.
Viruses are completely dependent on the rest of life, and so was their origin. They use the same DNA, RNA and proteins as everything else. They certainly didn't arise independently.
A universal common ancestor does not imply that there was only one organism at that time. All humans share a common female ancestor dubbed Mitochondrial Eve. [0] She was not the only woman in the world when she was alive.
Regarding the latter half of this article, I see no reason why there is a need to distinguish information processing from evolution -- it just so happens that complex self-replicating structures can compete better when they respond to information, and so they are evolutionarily favored.
The real challenge is modeling evolution mathematically. I don't see why Darwinian evolution is often considered a property of life, as opposed to life being the prime example of the fundamental, logical algorithm of evolution. That is, any self-replicating, changing system will tend toward competitiveness in its environment.
> Since then, England, a 35-year-old associate professor at the Massachusetts Institute of Technology, has been testing aspects of his idea in computer simulations.
Claiming life was created because a computer said so will convince no one requiring physical proof. The bar for evidence is too low with this experiment.
But it could at some point provide the key ingredients and conditions to replicate it. Lacking a laboratory of Earth's scale one could use supercomputing (at some point, we're not there yet) to figure out necessary and sufficient conditions, after which hopefully any chemistry student could replicate in the lab with that knowledge. Seems sci-fi now, but I could imagine this happening in a few decades.
Forgive me if I'm dense, but I read the article twice and don't see how this is anything more than a well known fact getting some science journalism coverage to seem important. Is the big news here that someone in physics has applied a crude model to the very well understood theory of abiogenesis? We've literally ran this experiment in vitro. With real chemicals.
I'm not sure how the entropic basis of the theory provides any insight beyond 'capacity for work can generate things that have capacity for work', which we knew. The big question isn't, and wasn't, whether a system with primordial chemicals could generate self-replicating reactions and structures - you could figure that out by looking in a mirror.
It's what those primordial cycles actually were.
Edit: Looks like the dude's former supervisor working in chem isn't full of shit like the rest of the article is: Shakhnovich said, but “Jeremy’s work represents potentially interesting exercises in non-equilibrium statistical mechanics of simple abstract systems.” Any claims that it has to do with biology or the origins of life, he added, are “pure and shameless speculations.”
TLDR - might be interesting in niche modeling field, but has nothing to do with origins of life.
There's no well understood theory of abiogenesis. For something to be a theory it must be supported by repeatable experiment and/or repeatable observation. The difference between hypothesis and theory is very important.
There are many good hypotheses on abiogenesis but until someone demonstrates rudimentary repeatable abiogenesis in the lab without "hand-holding" interventions then it's not a theory. (Or alternately finds a way to observe strong evidence for abiogenesis and how it occurred in the fossil record in a reproducible way that is specific enough to rule out other explanations for the same data.)
Your general description is correct, but your specific application is not; because you've implicitly in the latter limited empirical confirmation such as to juatify the label theort to direct observation or indirect observation that admits no other explanation. Neither is required, and the latter would move it beyond theory to irrefutable fact, as an observation “that is specific enough to rule out other explanations”, obviously, rules out all other explanations.)
That's not correct. There's no scientific theory of abiogenesis, because we haven't elucidated the entire pathway and developed falsifiable methods of determining which of the various models is correct, but there certainly is a theory of abiogenesis.
In fact, the theory is so well developed that there isn't really a competing scientific explanation to explain how life ultimately arose other than through abiogenesis. The area of research has been fairly fertile, to the point that many of the findings in that field have spun off into their own areas of research, from their original pursuit of the origins of life.
>to the point that many of the findings in that field have spun off into their own areas of research, from their original pursuit of the origins of life.
That sounds fascinating. Can you give some examples?
If there is no scientific theory of abiogenesis then there can be no theory so well developed that there is no competing scientific explanation. If it isn't science in the first place, it can't be science in the second place.
Abiogenesis and evolution as complementary ideas and its competition of intelligent design are philosophical standpoints attempting to portray themselves as science. They are metaphysical.
A simple example of one of the current evolutionary ideas is that there is much "junk" dna within each lifeform. If this is so, then with the current technology, we should be able to edit this "junk" dna out of the chromosomal dna structure and still be able to have fully viable lifeforms that breed true and are fully compatible for the pre-edited lifeforms. if there is 80% "junk", we should be able to edit this 80% out with no ill side-effects. If it turns out that we can't edit this "junk" out without causing non-viability or ill side-effects that that dna was not "junk" in the first place.
Over all the hundreds of millions of species existing on this planet, we should be able to find all sorts of species that are in transition forms (having partially functional organs or forms) today. You can make all sorts of claims about what has happened in the past, especially when you cannot actually test those living organisms in the lab.
That isn't true. Feel free to tell me what the alternative theories that constitute competition to abiogenesis. The alternatives are pretty much 1) a deity or 2) some mythical life force assembled things.
Abiogenesis has a ton of evidence behind it, but we do not have the entire chain of conditions and reactions required to go from primordial molecules to actual fact. Much in the same way that 'AI' vanishes, as we develop evidence and establish facts that support abiogenesis, they become standard biology, chemistry or physics.
Compare the argument for abiogenesis in the 1800s to the one today. We've discovered the mechanism for generating our species from single celled life forms, we've determined that RNA have intrinsic catalytic ability, we've developed robust theories of non-equilibrium reaction processes.
As for your statement about junk DNA, you have a very limited understanding of what that actually refers to. Junk DNA refers to non-coding dna. We know those areas can influence chromatin structure, contain regulated control sequences which influence gene expression, contain splicing sequences, etc.
As for your last paragraph, you make it very clear you don't understand the subject you're talking about. I suggest doing more than reading pop science books and picking up a volume on molecular biology. It will clear up what I imagine are a legion of misconceptions you have about what we know.
What is not true? You made one statement then you made a contradictory statement.
It matters not that neither of the alternatives that you supplied are palatable to your thinking processes. You cannot prove the veracity of your belief system by any scientific method as they are metaphysical in nature.
As I pointed out above, try listen to James Tour and you will see much of your "ton of evidence" is really evidence. It is conjecture and may have some evidential value, but on the basis of actual processes, the "evidence" just doesn't stack up.
We have in no way discovered the mechanism for turning single celled lifeforms into our species. If we had, we should have no problems in doing this from any sample of single cell lifeforms other than our own. We can't and we don't.
I don't consider any of the dna to be junk. I am using the definitions as promulgated by those who ascribe to the idea of "junk" dna. By your own definition as given above, this means that the relevant "junk" dna is not "junk".
As for my last paragraph, it is a consequence of the evolutionary model. You can argue that it is not a consequence of the model but then you would be arguing against the evolutionary model itself. Since I took a great deal of interest in this area in my younger days and I would read as many of the published experiments as I could. What got me looking at this further was the discrepancy between the reported results of these experiments and the purported conclusions reached by the experimenters.
My last sentence is accurate, if you cannot test and reproduce the outcomes/results then it is just conjecture.
So with those comments, what is your background, interest and expertise in these areas?
I don't think an extended back and forth will be very fruitful at this time.
You have very large misconceptions about what we know, because you've approached the subject to look at a point of interest without understanding the context of the evidence we have. It's laudable that you're looking into things, but you have clear, demonstrable, gaps in your knowledge. It's as if you're trying arguing against the existence of rocks by pointing at pebbles and erosion while forgetting you're standing on a mountain littered with boulders.
I know this message must come off in an abrasive manner, and I do apologize. That isn't the intent. It is just difficult to show you precisely where you're wrong with the finite time I have available to me. I can't be your personal tutor for the natural sciences, but I feel an obligation to future readers to put your comments in context.
If you're serious about learning about the subject, pick up a molecular biology textbook and start reading, or audit a few 101 level courses at your local university. Molecular biology is great because you will get a huge bang for your buck in terms of understanding the natural world with your very first few classes!
It seems that the kolmogorov complexity of the simplest quines in most languages is relatively high. One would imagine that, in terms of chemistry, the kolmogorov complexity of something that can self-replicate and also evolve with mutations which do not prevent the replication from taking place over generations - ie resilience - is too high to have arisen by mere chance.
Be wary of anthropic bias. If this universe didn't happen to support life, then we wouldn't exist here to observe it. Perhaps there are other universes with different laws of physics, and we would exist in one of them instead. And even in our own universe, there are many trillions of planets. Yet we only know of one that has evolved life. The fact that we observe life here tells us nothing about how probable it is.
In fact as far as we can tell, life is extremely rare. We've only found one instance of it forming on it's own. And it can only exist in a very tiny space between the earths crust and the upper atmosphere (and only in very small quantities in most of that space.) We haven't found self replicating systems on other planets or deep within the earth.
So any theory that posits "life is an inevitable outcome of thermodynamics" is almost certainly wrong. It's a theory that can't be falsified, and has no predictive power. A more interesting theory would be one that can explain why our specific planet and our specific laws of physics support life. Why do exist here instead of somewhere else?
Yep it seems to be rare, thus falsifying the theory that England is developing.
And by the way, can't multiverse thinking be invoked pretty much anytime to explain anything?
"Oh we have fine tuning that is a knife's edge 1 part in 10 to the 127th"
"Yeah well maybe we have even more universes."
That's not real science. That's actually digging your heels in and saying "there is nothing beyond what we already found and understand". How will you go about testing this?
Anthropic bias doesn't explain anything. It just says that you can't use your own existence as evidence of something. Because if you didn't exist, you wouldn't be able to make the opposite argument. It's basically just a wider application of survivorship bias. It works whether or not there are actually other universes (although the existence of other universes definitely makes it more intuitive to understand.)
> In fact as far as we can tell, life is extremely rare.
As far as we can tell, right. Given our extremely narrowed view on the vast universe I'd say we've seen literally nothing yet. I'd not be surprised if life is not rare at all. It may only be rare in the tiny fraction of space that we know about.
When we first sent probes to other worlds, many people seriously expected to find life. The first astronauts on the moon were quarantined for weeks afterwards. Instead it seems like the vast majority of space is dead.
There may be lots of other planets like Earth, sure. But that's a very different claim than "life is an inevitable outcome of thermodynamics". At best it's "life is an inevitable outcome of very specific conditions that happened to exist on ancient Earth and Earth-like planets, under specific combinations of chemicals and temperature..." You need a lot more than just thermodynamics to have life.
It's probably entirely possible to create a self replicating machine using only components found on the surface of the moon. In fact that's been a serious research project of NASA for a long time. But such a machine will never form by chance, because the probability is so incredibly small. And so the moon is lifeless.
> and only in very small quantities in most of that space
It depends on how you define quantity. Total biomass may be low in proportion to crust, sure. But fully one fifth of the atmosphere is being maintained in a clearly unstable state (free oxygen!) by something. There's no way an alien would look at a spectrograph of our atmosphere and think anything but "it's alive".
As far as we can tell intelligent life is extremely rare. The not too distant universe could be well-populated with simple unicellular life (or just individual self-replicating molecules). It may be that self-replicating molecules form relatively easily but the jump to more complex life forms is exponentially more rare; but that would be more a question about the power of Darwinian selection than England's theory.
Also, England's theory never says "life is an inevitable outcome of thermodynamics," Jeremy England said that. There's a big difference. As it stands the theory says nothing about self-replication, it merely predicts chemicals forming seemingly-rare (with respect to the full chemical space) ordered structures. And his theory does have predictive potential and the simulated results in his PNAS paper support his predictions. It's certainly experimentally falsifiable: put a bunch of chemicals together that can form bonds, if you have an approximate understanding of the chemical space, you test apply an appropriate energy source, and see if the resulting chemicals occupy a surprisingly rare part of that space as predicted.
But I do agree that your question "Why do [we] exist here instead of somewhere else?" is one of the more interesting questions.
England's theory tells you that once you get close to a certain free energy basin you will access its optimal minimum. To my understanding it is silent about how you get "close enough"
Certainly not a complete picture. More of an unfinished amaetur impressionist water color.
But something along the lines of the dynamics seen in reaction diffusion systems.
Once you have a "metabolism" where interacting chemicals produce one another, you have a system that can sustain itself on it's reactants.
In a mess of random reactions, order will emerge through feedback effects, chemicals that are used up are used up, those that are replenished will increase in concentration.
Various regions will have different ratios, and different impurities giving a landscape in which versions of the metabolism may specialize or interact.
...
Some regions produce molecules that self assemble into things like walls and membranes.
...
RNA, likely around as a component the whole time, at some point it is specialized into an information medium role.
Stir continuously, simmer for 1-billion years or until it photosynthesizes.
Chance is not 'mere'. Whatever you think high complexity is, is just as well a low complexity to a different perspective. We are only slightly more remarkable than dirt, and over 4.5 billion years of chemical history, I don't see what you're basing your objection on.
> The big question isn't, and wasn't, whether a system with primordial chemicals could generate self-replicating reactions and structures - you could figure that out by looking in a mirror.
OK, we knew that, but what are the precise conditions under which it is more or less likely to happen? Understanding that requires a mathematical theory of exactly how self-replicating patterns form under the laws of thermodynamics, which is what this line of work is aiming to provide.
It's a cute paper telling biochemists things they already knew. The biochemical sciences aren't discovering entropy for the first time.
The premise this work adopts doesn't add to our understanding of complex chemical systems. Believe me, there are plenty of computational chemists in the world.
> a system with primordial chemicals could generate self-replicating reactions and structures - you could figure that out by looking in a mirror
Only if you require no evidence, and no verifiable, independently confirmed experiments to back up your claim. What you said is basically the scientist's version of intelligent design at this point.
There have been plenty of experiments showing that the building blocks of life will spontaneously self-assemble under the right conditions. We have now confirmed that comets and other bodies in space contain complex molecules such as hydrocarbons.
There are also plenty of experiments demonstrating that certain structures self-assemble and even "replicate" (for some definition of replicate) under the right conditions, purely as a function of their molecular structure.
There is no conclusive proof... but certainly everything we've discovered to date supports abiogenesis of life given the right conditions and a few 100 million years for many trillions of attempts. It is likely that the first "life" wasn't life as we would define it, more like a prion: a self-replicating molecule built out of amino acids dumped on Earth from meteorite and comet impacts. The first true "life" was probably exceedingly simple and lived off chemical reactions around hydrothermal vents.
Go and listen to James Tour and his video on the problems of just getting the right pre-life chemical synthesis to occur. He is a organic chemist (one of the top in the world) and he talks about each of the incompatible processes between each step.
I would be more inclined to take his word for it than a biologist (of any stripe). Abiogenesis seems to be the least likely scenario in the formation of life (as in close to 0 as to make no difference) irrespective of the amount of time that is allocated.
> Abiogenesis seems to be the least likely scenario in the formation of life
Yet we know it happened, because life exists, and it didn't spring from magic so it must have sprung from non-life. Random chance is a hell of a search algorithm, abiogenesis is simply the inevitable outcome randomly trying every possible combination over hundreds of millions of years. There are no more likely scenarios.
Just because we know something is, does not mean know why. You make a very broad leap to say that there are only two possibilities - magic and abiogenesis - and that one of those possibilities doesn't exist.
There are three broad classifications of philosophical belief - the universe is all there is and there is no non-physical component, that the universe is and has a non-physical component (it is alive, etc) and that there is a creator who is separate from the universe and that creator made the universe.
Within that context, the three can be split into two variations, the universe (with or without a non-physical component) is eternal (steady state or cyclic) and an eternal creator who has made a finite lifespan universe.
Abiogenesis can arise in one of those three variations, in the other two, either the universe creates life as apart of its functionality (its non-physical attributes) or there is a creator that has designed and set in motion life.
Please note that abiogenesis is a completely different subject to any evolutionary model that people may subscribe to.
You can argue all you like about the variations above but you cannot use science to determine the "truth" of which variety you personally believe in. That is a metaphysical/philosophical/religious debate that is outside of the domain of science.
So, where does that leave us in this discussion? Well, it says that you have not given much thought to your point of view in such a way that you are able to logically argue its merit. In which case, I would suggest that you might like to flesh out your arguments because as they stand, the arguments you present are extremely weak and illogical.
I've given it plenty of thought, I simply don't subscribe to philosophical masturbation involving that which simply has no evidence of existing at all, the non-physical; there is no such thing, it's woo, nonsense, magic, unsupported by any evidence in all of history. Dualism is the view of an irrational mind.
You give equal weight to the possibility of an eternal universe or a created universe, this is simply illogical as there's no logical argument to be made for a creator that doesn't suffer from the fallacies of infinite regress and special pleading; the very idea of a creator is at its base irrational and illogical. Thus the entire fantasy of the creator can be ruled out leaving only the universe to contend with, and as there's no such thing as the non-physical that rules out the other path. Of the three possibilities you presented, two are magic, which I addressed originally.
This is not outside the domain of science, it is not a metaphysical/philosophical debate, it is very much firmly a matter of science and evidence. Abiogenesis happened, we can deduce that logically as a fact, we are here, there's really nothing to debate other than figuring out how it happened. So please don't talk to me about illogical while you posit illogical faulty arguments akin to magic; you have no logical leg to stand on.
Where does this leave us in this discussion, with me realizing you haven't yet grown beyond belief in magic and superstition making having a logical discussion all but impossible.
You are a large bag of molecules. You self replicate and generate a variety of structures. You are great evidence that complex systems arise out of simple phenomena. Wolfram's initial explorations dealt with this in particular. This is also the reason for developing systems like Conway's game of life. Simple rules. Complex outcomes.
The pumice stone you use to scrub yourself with has a particular distinctive pattern to it, not caused by life, but rather by volcanic and non-biological forces. When you wash your hands with soap and water in front of that bathroom mirror, the you construct a reversed lipid bi-layer, a self organizing structure that occurs as a result of polarity. This set of forces is the same as those that self-organizes your cell walls.
I think there's plenty of evidence. You just need to do a bit of learning to understand what you're seeing.
Here's a key paragraph that really walks back a lot of the language in the first half of the article. Here he's just stating physics may be much friendlier to the initial conditions for abiogenesis than previously believed:
“In the short term, I’m not saying this tells me a lot about what’s going in a biological system, nor even claiming that this is necessarily telling us where life as we know it came from,” he said. Both questions are “a fraught mess” based on “fragmentary evidence,” that, he said, “I am inclined to steer clear of for now.” He is rather suggesting that in the tool kit of the first life- or proto-life-forms, “maybe there’s more that you can get for free, and then you can optimize it using the Darwinian mechanism.”
I still like the article a lot, it gives the right amount of details to get me interested in the topic and starting a hunt for information on google scholar.
As a fair example of structure coalescing from randomness and simple physics,I have to hawk this* example called 'bloop' from my web 3d physics project. It is a cloud of gravitating bodies with a simple 'sticky' force between close neighbours, the strength of which varies like breeze. I find it reminiscent of the old 'bag in the wind' video.
I come upon things like this while playing with and debugging different forces. One very early, imploding world with simple gravity, created a surprising 'aleph-like' blob of flickering shapely artifacts. It blew my socks off but it was before proper version control and I'd have to do archeology to recreate it. Better to keep improving the physics and see what can pop up next ...
> He further showed that this statistical tendency to dissipate energy might foster self-replication. (As he explained it in 2014, “A great way of dissipating more is to make more copies of yourself.”)
Then the atoms will become happy and try to do more of that to become more happy?
My BS detector is screaming loudly.
First, this stuff about the second law of thermodynamics leaves me cold:
> the second law of thermodynamics, which says that energy constantly spreads and the entropy of the universe always increases. (The second law is true because there are more ways for energy to be spread out among particles than to be concentrated, so as particles move around and interact, the odds favor their energy becoming increasingly shared.)
BS. That argument has a huge, hidden assumption, that we are looking at an inert gas in a bottle. So, there are no chemical reactions, etc. Then there are lots of possible configurations.
Try that with some sticky ping pong balls and soon will have just a solid clump with only configuration. Try that with a lot of billiard balls, and soon they will arrange themselves on the bottom of the container with a lot of hexagons and tetrahedra, that is, with a relatively few number of configurations.
So, to discuss how life began, let's f'get about the second law.
Instead, we know that we can cook chemicals and get amino acids. Why? Because get chemical reactions where the atoms stick together, and it would take energy to split them apart again. Then if we cook for a few hundred million more years, we can get a configuration that can consume energy from its environment and reproduce itself. Then we are off to the races because what took a billion years to do the first time now just takes the time to reproduce. Then with small errors in the reproduction process and lots of reproduction, we get forms of life that are better at extracting energy from the environment and reproduce faster; soon that life form becomes relatively common, in that sense, dominates. Eventually we get a very creative farmer and expert with domestic animals, stone, wood, and metal with a very fertile wife, and they have lots of kids who also do really well.
There are some questions and issues, but IMHO the model for the second law of inert atoms of a gas in a bottle is nearly irrelevant.
When I was in vegas, the thought occurred to me that cities were structures designed to dissipate economic energy.
Money flows into vegas through the big casinos and gradually works its way out through the rest of the city, forming vortexes and whirlpools of economic activity, of lower and lower intensity as you move out from the city center, until it gradually fades out into desert.
But the idea of wealth concentration that then tapers out as a function of distance from the city center bears at least a superficial resemblance.
Perhaps why one works and the other doesn't is that personal wealth accumulation IS like water: it'll get stuck in local maxima, etc - whereas city wealth accumulation is more like sand; as it piles on top you get landslides that distribute.
I wonder if there's a way to adapt this to AI / machine learning. To my uneducated eye, there's a distinct similarity between the "breaking and reforming" of [simulated] physical bonds, and the training of a neural net.
If you consider your training data (or other "external sensors") as the environmental forcing factors... do you process "information" instead of "energy"?
The article seems to suggest he's simulating a "soup" of many different molecules and seeing which combinations lead to sustained reactions. Nick Lane's book "The Vital Question" [1] discounts the primordial soup idea (that life arose in tidal pools or streams near volcanos due to the right chemical mixture being present in the water at that time) and suggests underwater alkaline hydrothermal vents as the location of the first formation of life. The hydrothermal vents produced (see also his recent paper [2]) alkaline fluids which mixed with acidic seawater within micropores provided by the geological structures of a particular type of vent. This, he hypothesises, led to proton gradients which are essential for life.
Of course, both these guys are experts at the top of their fields, at respected institutes. I possess neither of those qualities.
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[ 2.9 ms ] story [ 140 ms ] threadThis makes sense. Life exists here on earth, I believe it got here through natural processes, and so it seems that life should be expected in the right circumstances.
But this begs the question, has life arisen independently from other existing life in the last 4 billion years? All known life shares the same fundamental genetic code and appears to descend from a single common ancestor. Are we to believe that the founder population of all life on earth, from which the GCA hailed, is the only instance of life on earth arising directly from inanimate matter? Or has life arisen independently between 4 billion years ago and now, just to be out-competed by existing life forms? Or were conditions just right 4 billion years ago to allow for the spontaneous generation of local-entropy reducing molecular agents (which evolved into life), and ever since conditions have been wrong for the generation of life?
https://en.wikipedia.org/wiki/Abiogenesis
Not at all, you're presuming there are many different ways life could work, that might not be the case at all. It's entirely possible there's only one or very few possible recipes for life so no matter how many abiogenesis events occur, they produce the same kind of life.
A simple analogy, wood burns, fire is fire, you don't expect every different occurrence of fire in nature to produce a new and incompatible type of fire. Life could be the same, it could be that anywhere carbon based life forms it's basically the same basic recipe and thus biologically compatible with all other forms of carbon based life.
Presumably this is even MORE likely if the independent lifeforms both emerged in similar physical & chemical environments.
https://en.wikipedia.org/wiki/Great_Oxygenation_Event
The vast majority of life on Earth has been wiped out simply because other life created inhospitable conditions for them. Even if multiple events created life, if the wrong life is created, it will die.
Since the primordials soup times, we also have energy hitting inanimate matter. On this planet. And also we have the other planets in our solar system. Why aren't we finding lots of bacteria being spontaneously generated everywhere?
It isn't that a novel form of primitive life arises then gets eaten; the building-blocks necessary for a novel form of life to arise get eaten before those building-blocks have much chance of interact at all. From what we can tell it would probably take many millions of years of chemical interactions in the appropriate conditions after being seeded with carbon-based molecules from comet/space impacts (since carbon compounds seem to be relatively common).
It seems likely that life will spread and adapt somewhat quickly since it is usually easier to find new resources than enter an arms-race over existing resources. That leaves a very narrow window of time (in evolutionary terms) for life to arise >1 time independently then evolve enough to be on equal footing with the other form(s).
It also seems far more likely that if this very rare event takes place one of two things happen: 1. One form of life has a head-start in the arms race and overtakes the other, completely wiping it out 2. The two forms of life are compatible enough to exchange genetic material because they evolved from the same raw building blocks deposited on the planet; though it mostly fails to produce viable offspring in a few cases the forms successfully cross and the new third form of life successfully outcompetes its progenitor forms.
As for Mars, it seems likely that life never evolved there at all.
The next best explanation seems to be life never got beyond single-cell organisms and struggled to eek out a short existence. Before Mars dried out and/or the massive hemisphere-shattering impact struck and erased what traces of life once existed.
The simplest bacteria today are amazing organisms. They have cell membranes, which separate the protoplasm of the cell from the outside the world, and only selectively let some molecules through. They contain a blueprint to produce catalysts for a variety of chemical pathways; they can store energy in chemical form and use that energy to catalyze these reactions. The can break down complex molecules into simpler molecules and reuse these building blocks for their own purpose. They can move, to seek out new food sources. They can produce toxins that interfere with the chemical pathways of other cells, killing them.
But when we talk about abiogenesis, we aren't talking about the spontaneous generation of a cell. We're talking about the spontaneous generation of a single molecule, or a small set of molecules, probably proteins (amino acid chains) that, in the presence of proper raw material (amino acids) will tend to act as a catalyst for the formation of more of itself.
That's it; the reaction does not even have to be fast or obvious, even. If it takes years for the molecule to catalyze its replication, that's fine. Everything on top of that comes down to evolution, the slow development of a new trait - cell ways, a genome separate from the cell machinery, the ability to metabolize organic molecules into raw materials, locomotion - over millions of years.
So in addition to xenadu's point, there's also this: the abiogenesis of new self-replicating molecules could still be happening today, and we'd probably never know. The objects in question are too small, and the time scales involved are too large.
It depends on how you define life. If viruses are a life form then you have one. If self-replicating meta-structures composed of multiple different species interacting such as lichen count as separate life forms made of other life then that might count too.
On the more far-out side of theoretical biology people have proposed culture/memes and the modern high-tech economy as a new form of life that has emerged from previous life. If solar power (or fusion) becomes ubiquitous and it learns to recycle nearly all its waste it will become an ecologically self-sufficient form of life, and if AI ever gets good enough to have machines designing and producing machines it could "fork" and become a completely independent form of life.
A universal common ancestor does not imply that there was only one organism at that time. All humans share a common female ancestor dubbed Mitochondrial Eve. [0] She was not the only woman in the world when she was alive.
[0] https://en.wikipedia.org/wiki/Mitochondrial_Eve
The real challenge is modeling evolution mathematically. I don't see why Darwinian evolution is often considered a property of life, as opposed to life being the prime example of the fundamental, logical algorithm of evolution. That is, any self-replicating, changing system will tend toward competitiveness in its environment.
Claiming life was created because a computer said so will convince no one requiring physical proof. The bar for evidence is too low with this experiment.
I'm not sure how the entropic basis of the theory provides any insight beyond 'capacity for work can generate things that have capacity for work', which we knew. The big question isn't, and wasn't, whether a system with primordial chemicals could generate self-replicating reactions and structures - you could figure that out by looking in a mirror.
It's what those primordial cycles actually were.
Edit: Looks like the dude's former supervisor working in chem isn't full of shit like the rest of the article is: Shakhnovich said, but “Jeremy’s work represents potentially interesting exercises in non-equilibrium statistical mechanics of simple abstract systems.” Any claims that it has to do with biology or the origins of life, he added, are “pure and shameless speculations.”
TLDR - might be interesting in niche modeling field, but has nothing to do with origins of life.
There are many good hypotheses on abiogenesis but until someone demonstrates rudimentary repeatable abiogenesis in the lab without "hand-holding" interventions then it's not a theory. (Or alternately finds a way to observe strong evidence for abiogenesis and how it occurred in the fossil record in a reproducible way that is specific enough to rule out other explanations for the same data.)
In fact, the theory is so well developed that there isn't really a competing scientific explanation to explain how life ultimately arose other than through abiogenesis. The area of research has been fairly fertile, to the point that many of the findings in that field have spun off into their own areas of research, from their original pursuit of the origins of life.
That sounds fascinating. Can you give some examples?
Abiogenesis and evolution as complementary ideas and its competition of intelligent design are philosophical standpoints attempting to portray themselves as science. They are metaphysical.
A simple example of one of the current evolutionary ideas is that there is much "junk" dna within each lifeform. If this is so, then with the current technology, we should be able to edit this "junk" dna out of the chromosomal dna structure and still be able to have fully viable lifeforms that breed true and are fully compatible for the pre-edited lifeforms. if there is 80% "junk", we should be able to edit this 80% out with no ill side-effects. If it turns out that we can't edit this "junk" out without causing non-viability or ill side-effects that that dna was not "junk" in the first place.
Over all the hundreds of millions of species existing on this planet, we should be able to find all sorts of species that are in transition forms (having partially functional organs or forms) today. You can make all sorts of claims about what has happened in the past, especially when you cannot actually test those living organisms in the lab.
Abiogenesis has a ton of evidence behind it, but we do not have the entire chain of conditions and reactions required to go from primordial molecules to actual fact. Much in the same way that 'AI' vanishes, as we develop evidence and establish facts that support abiogenesis, they become standard biology, chemistry or physics.
Compare the argument for abiogenesis in the 1800s to the one today. We've discovered the mechanism for generating our species from single celled life forms, we've determined that RNA have intrinsic catalytic ability, we've developed robust theories of non-equilibrium reaction processes.
As for your statement about junk DNA, you have a very limited understanding of what that actually refers to. Junk DNA refers to non-coding dna. We know those areas can influence chromatin structure, contain regulated control sequences which influence gene expression, contain splicing sequences, etc.
As for your last paragraph, you make it very clear you don't understand the subject you're talking about. I suggest doing more than reading pop science books and picking up a volume on molecular biology. It will clear up what I imagine are a legion of misconceptions you have about what we know.
It matters not that neither of the alternatives that you supplied are palatable to your thinking processes. You cannot prove the veracity of your belief system by any scientific method as they are metaphysical in nature.
As I pointed out above, try listen to James Tour and you will see much of your "ton of evidence" is really evidence. It is conjecture and may have some evidential value, but on the basis of actual processes, the "evidence" just doesn't stack up.
We have in no way discovered the mechanism for turning single celled lifeforms into our species. If we had, we should have no problems in doing this from any sample of single cell lifeforms other than our own. We can't and we don't.
I don't consider any of the dna to be junk. I am using the definitions as promulgated by those who ascribe to the idea of "junk" dna. By your own definition as given above, this means that the relevant "junk" dna is not "junk".
As for my last paragraph, it is a consequence of the evolutionary model. You can argue that it is not a consequence of the model but then you would be arguing against the evolutionary model itself. Since I took a great deal of interest in this area in my younger days and I would read as many of the published experiments as I could. What got me looking at this further was the discrepancy between the reported results of these experiments and the purported conclusions reached by the experimenters.
My last sentence is accurate, if you cannot test and reproduce the outcomes/results then it is just conjecture. So with those comments, what is your background, interest and expertise in these areas?
You have very large misconceptions about what we know, because you've approached the subject to look at a point of interest without understanding the context of the evidence we have. It's laudable that you're looking into things, but you have clear, demonstrable, gaps in your knowledge. It's as if you're trying arguing against the existence of rocks by pointing at pebbles and erosion while forgetting you're standing on a mountain littered with boulders.
I know this message must come off in an abrasive manner, and I do apologize. That isn't the intent. It is just difficult to show you precisely where you're wrong with the finite time I have available to me. I can't be your personal tutor for the natural sciences, but I feel an obligation to future readers to put your comments in context.
If you're serious about learning about the subject, pick up a molecular biology textbook and start reading, or audit a few 101 level courses at your local university. Molecular biology is great because you will get a huge bang for your buck in terms of understanding the natural world with your very first few classes!
The main question for me is abiogenesis.
How did the first self-replicating things evolve?
It seems that the kolmogorov complexity of the simplest quines in most languages is relatively high. One would imagine that, in terms of chemistry, the kolmogorov complexity of something that can self-replicate and also evolve with mutations which do not prevent the replication from taking place over generations - ie resilience - is too high to have arisen by mere chance.
In fact as far as we can tell, life is extremely rare. We've only found one instance of it forming on it's own. And it can only exist in a very tiny space between the earths crust and the upper atmosphere (and only in very small quantities in most of that space.) We haven't found self replicating systems on other planets or deep within the earth.
So any theory that posits "life is an inevitable outcome of thermodynamics" is almost certainly wrong. It's a theory that can't be falsified, and has no predictive power. A more interesting theory would be one that can explain why our specific planet and our specific laws of physics support life. Why do exist here instead of somewhere else?
And by the way, can't multiverse thinking be invoked pretty much anytime to explain anything?
"Oh we have fine tuning that is a knife's edge 1 part in 10 to the 127th"
"Yeah well maybe we have even more universes."
That's not real science. That's actually digging your heels in and saying "there is nothing beyond what we already found and understand". How will you go about testing this?
>And by the way, can't multiverse thinking be invoked pretty much anytime to explain anything?
That's exactly the problem I've always had when it comes up.
But what if the target was there before? Then you have to explain how the arrow hit it so perfectly. There is a difference.
The difference is, is there anything special about the target's placement?
One can argue that alternative universes where soups of particles didn't give rise to life are all uninteresting.
You can of course say that life is needed to make the judgment for what is interesting.
But are you sure there is no sense in which the target can be said to have been painted before the arrow was fired? It all rests on that.
As far as we can tell, right. Given our extremely narrowed view on the vast universe I'd say we've seen literally nothing yet. I'd not be surprised if life is not rare at all. It may only be rare in the tiny fraction of space that we know about.
There may be lots of other planets like Earth, sure. But that's a very different claim than "life is an inevitable outcome of thermodynamics". At best it's "life is an inevitable outcome of very specific conditions that happened to exist on ancient Earth and Earth-like planets, under specific combinations of chemicals and temperature..." You need a lot more than just thermodynamics to have life.
It's probably entirely possible to create a self replicating machine using only components found on the surface of the moon. In fact that's been a serious research project of NASA for a long time. But such a machine will never form by chance, because the probability is so incredibly small. And so the moon is lifeless.
It depends on how you define quantity. Total biomass may be low in proportion to crust, sure. But fully one fifth of the atmosphere is being maintained in a clearly unstable state (free oxygen!) by something. There's no way an alien would look at a spectrograph of our atmosphere and think anything but "it's alive".
Also, England's theory never says "life is an inevitable outcome of thermodynamics," Jeremy England said that. There's a big difference. As it stands the theory says nothing about self-replication, it merely predicts chemicals forming seemingly-rare (with respect to the full chemical space) ordered structures. And his theory does have predictive potential and the simulated results in his PNAS paper support his predictions. It's certainly experimentally falsifiable: put a bunch of chemicals together that can form bonds, if you have an approximate understanding of the chemical space, you test apply an appropriate energy source, and see if the resulting chemicals occupy a surprisingly rare part of that space as predicted.
But I do agree that your question "Why do [we] exist here instead of somewhere else?" is one of the more interesting questions.
I expect chemical metabolisms pre-dated organisms, and purely metabolism based replicators pre-dated stored instruction replicators.
But something along the lines of the dynamics seen in reaction diffusion systems.
Once you have a "metabolism" where interacting chemicals produce one another, you have a system that can sustain itself on it's reactants.
In a mess of random reactions, order will emerge through feedback effects, chemicals that are used up are used up, those that are replenished will increase in concentration.
Various regions will have different ratios, and different impurities giving a landscape in which versions of the metabolism may specialize or interact. ... Some regions produce molecules that self assemble into things like walls and membranes. ... RNA, likely around as a component the whole time, at some point it is specialized into an information medium role.
Stir continuously, simmer for 1-billion years or until it photosynthesizes.
OK, we knew that, but what are the precise conditions under which it is more or less likely to happen? Understanding that requires a mathematical theory of exactly how self-replicating patterns form under the laws of thermodynamics, which is what this line of work is aiming to provide.
The premise this work adopts doesn't add to our understanding of complex chemical systems. Believe me, there are plenty of computational chemists in the world.
Only if you require no evidence, and no verifiable, independently confirmed experiments to back up your claim. What you said is basically the scientist's version of intelligent design at this point.
There are also plenty of experiments demonstrating that certain structures self-assemble and even "replicate" (for some definition of replicate) under the right conditions, purely as a function of their molecular structure.
There is no conclusive proof... but certainly everything we've discovered to date supports abiogenesis of life given the right conditions and a few 100 million years for many trillions of attempts. It is likely that the first "life" wasn't life as we would define it, more like a prion: a self-replicating molecule built out of amino acids dumped on Earth from meteorite and comet impacts. The first true "life" was probably exceedingly simple and lived off chemical reactions around hydrothermal vents.
Go and listen to James Tour and his video on the problems of just getting the right pre-life chemical synthesis to occur. He is a organic chemist (one of the top in the world) and he talks about each of the incompatible processes between each step.
I would be more inclined to take his word for it than a biologist (of any stripe). Abiogenesis seems to be the least likely scenario in the formation of life (as in close to 0 as to make no difference) irrespective of the amount of time that is allocated.
Yet we know it happened, because life exists, and it didn't spring from magic so it must have sprung from non-life. Random chance is a hell of a search algorithm, abiogenesis is simply the inevitable outcome randomly trying every possible combination over hundreds of millions of years. There are no more likely scenarios.
There are three broad classifications of philosophical belief - the universe is all there is and there is no non-physical component, that the universe is and has a non-physical component (it is alive, etc) and that there is a creator who is separate from the universe and that creator made the universe.
Within that context, the three can be split into two variations, the universe (with or without a non-physical component) is eternal (steady state or cyclic) and an eternal creator who has made a finite lifespan universe.
Abiogenesis can arise in one of those three variations, in the other two, either the universe creates life as apart of its functionality (its non-physical attributes) or there is a creator that has designed and set in motion life.
Please note that abiogenesis is a completely different subject to any evolutionary model that people may subscribe to.
You can argue all you like about the variations above but you cannot use science to determine the "truth" of which variety you personally believe in. That is a metaphysical/philosophical/religious debate that is outside of the domain of science.
So, where does that leave us in this discussion? Well, it says that you have not given much thought to your point of view in such a way that you are able to logically argue its merit. In which case, I would suggest that you might like to flesh out your arguments because as they stand, the arguments you present are extremely weak and illogical.
You give equal weight to the possibility of an eternal universe or a created universe, this is simply illogical as there's no logical argument to be made for a creator that doesn't suffer from the fallacies of infinite regress and special pleading; the very idea of a creator is at its base irrational and illogical. Thus the entire fantasy of the creator can be ruled out leaving only the universe to contend with, and as there's no such thing as the non-physical that rules out the other path. Of the three possibilities you presented, two are magic, which I addressed originally.
This is not outside the domain of science, it is not a metaphysical/philosophical debate, it is very much firmly a matter of science and evidence. Abiogenesis happened, we can deduce that logically as a fact, we are here, there's really nothing to debate other than figuring out how it happened. So please don't talk to me about illogical while you posit illogical faulty arguments akin to magic; you have no logical leg to stand on.
Where does this leave us in this discussion, with me realizing you haven't yet grown beyond belief in magic and superstition making having a logical discussion all but impossible.
The pumice stone you use to scrub yourself with has a particular distinctive pattern to it, not caused by life, but rather by volcanic and non-biological forces. When you wash your hands with soap and water in front of that bathroom mirror, the you construct a reversed lipid bi-layer, a self organizing structure that occurs as a result of polarity. This set of forces is the same as those that self-organizes your cell walls.
I think there's plenty of evidence. You just need to do a bit of learning to understand what you're seeing.
“In the short term, I’m not saying this tells me a lot about what’s going in a biological system, nor even claiming that this is necessarily telling us where life as we know it came from,” he said. Both questions are “a fraught mess” based on “fragmentary evidence,” that, he said, “I am inclined to steer clear of for now.” He is rather suggesting that in the tool kit of the first life- or proto-life-forms, “maybe there’s more that you can get for free, and then you can optimize it using the Darwinian mechanism.”
[*] https://strainer.github.io/fancy/#12
I come upon things like this while playing with and debugging different forces. One very early, imploding world with simple gravity, created a surprising 'aleph-like' blob of flickering shapely artifacts. It blew my socks off but it was before proper version control and I'd have to do archeology to recreate it. Better to keep improving the physics and see what can pop up next ...
Then the atoms will become happy and try to do more of that to become more happy?
My BS detector is screaming loudly.
First, this stuff about the second law of thermodynamics leaves me cold:
> the second law of thermodynamics, which says that energy constantly spreads and the entropy of the universe always increases. (The second law is true because there are more ways for energy to be spread out among particles than to be concentrated, so as particles move around and interact, the odds favor their energy becoming increasingly shared.)
BS. That argument has a huge, hidden assumption, that we are looking at an inert gas in a bottle. So, there are no chemical reactions, etc. Then there are lots of possible configurations.
Try that with some sticky ping pong balls and soon will have just a solid clump with only configuration. Try that with a lot of billiard balls, and soon they will arrange themselves on the bottom of the container with a lot of hexagons and tetrahedra, that is, with a relatively few number of configurations.
So, to discuss how life began, let's f'get about the second law.
Instead, we know that we can cook chemicals and get amino acids. Why? Because get chemical reactions where the atoms stick together, and it would take energy to split them apart again. Then if we cook for a few hundred million more years, we can get a configuration that can consume energy from its environment and reproduce itself. Then we are off to the races because what took a billion years to do the first time now just takes the time to reproduce. Then with small errors in the reproduction process and lots of reproduction, we get forms of life that are better at extracting energy from the environment and reproduce faster; soon that life form becomes relatively common, in that sense, dominates. Eventually we get a very creative farmer and expert with domestic animals, stone, wood, and metal with a very fertile wife, and they have lots of kids who also do really well.
There are some questions and issues, but IMHO the model for the second law of inert atoms of a gas in a bottle is nearly irrelevant.
Money flows into vegas through the big casinos and gradually works its way out through the rest of the city, forming vortexes and whirlpools of economic activity, of lower and lower intensity as you move out from the city center, until it gradually fades out into desert.
The more interesting question is if, while tricling down, people improve their life quality.
Far from true.
But the idea of wealth concentration that then tapers out as a function of distance from the city center bears at least a superficial resemblance.
Perhaps why one works and the other doesn't is that personal wealth accumulation IS like water: it'll get stuck in local maxima, etc - whereas city wealth accumulation is more like sand; as it piles on top you get landslides that distribute.
If you consider your training data (or other "external sensors") as the environmental forcing factors... do you process "information" instead of "energy"?
Of course, both these guys are experts at the top of their fields, at respected institutes. I possess neither of those qualities.
[1] https://www.amazon.com/Vital-Question-Evolution-Origins-Comp...
[2] http://nick-lane.net/publications/origin-life-alkaline-hydro...