Question: How do YOU think life started?

Keywords: ,

  1. Some time around 3.9 to 3.5 billion years ago, the first molecule that could replicate itself came into existence, and that was the beginning of life. We don’t know yet exactly what the molecule looked like or how it arose; these are really hard questions to answer, and we won’t have a better idea until we can reliably reproduce the beginning of life in the lab. Even then, it’s possible that we’ll only know one way that life might have started, not the specific one that actually occurred; we’ll need to spend a long time collecting evidence to sort out how likely the possibilities are.

    I know a few of the potential ways that this could have happened, but they’re pretty complicated and it would take me a long time to go into them here. What I can tell you, though, is that when life began, it began under conditions that you wouldn’t recognize today. 3.5 billion years ago the Earth was a much different place. The ground was just starting to firm up (the earth had been largely molten lava before that), the atmosphere had little or no breathable oxygen in it (if it was present, it was probably trapped as water vapour or bonded to iron) and may have had many things in it that would be toxic to breathe, etc. There were probably oceans, but conditions would have been wild.

    In these conditions, somehow the first replicator (molecule that could replicate itself) showed up. It probably began as a chance event when the right building blocks (amino acids) came together in the right way. The basis for this is buried in biochemistry that I don’t fully understand, but there’s a lot of plausible ways for this to happen. You’ll also hear about the possibility that these amino acids may have come from outer space on comets that hit the earth early in its formation; this is possible, because there’s reason to believe that these building blocks can form out in space. This is an exciting idea if true, because it’s another reason to believe that life would be common throughout the universe.

    I hope that helps a little bit; this is a really deep topic and there’s a lot to read about it, but it’s definitely an exciting question!


  2. Dear Sarahb; I am a biochemist. While I teach biochemistry on how life works, there is a bit about how life started. To make the long story short, the biochemistry text book mention about Dr. Stanley Miller who simulated ‘the ancient(primordial) atmosphere’ . He did make some amino acids and nucleotides from ammonia, CO2, H2O under electric power instead of thunder and lightening. What he showed was chemical reactions and it is not any evidence of how life started. Nowadays deep sea theral crater is suggested as the site of ‘beginning of life’.The begining of life can only be suggested, so called hypothesis.

    The basic unit of life is ‘Cell’ . The simplest cell like bacteria is composed of cell membrane, genetic information(DNA mostly), ribosome and cytoplasm; made of protein, lipid, carbohydrate, nucleic acid(DNA and RNA), vitamin, minerals, etc. Collection of amnio acids doesn’t make protein by itself, nucleotides doesn’t make itself into DNA or RNA. And where did the ammonia, H2O and CO2, lightening, etc come from? ‘Big Bang’ from a small dot? Where did the small ‘dot’ come from? Everything assumes preexisting something!

    The 2nd Law of Physics/Thermodynamics states that entropy(randomness) increases”. Bunch of amino acid can’t go into ordered protein by random collision no matter how much time is given. Same as nucleotides can’t be ordered into DNA or RNA. In opposite, as time passing, the proteins and nucleic acids decomposes into its molecules and atoms, according to 2nd law of physics.

    When you see an artifical silk flower, you know that somebody has made it, even though you do not know the name of the maker. I think same is true for the real flower with fragrance. We only know that any human being can’t make real flower, though.

    About 2 weeks ago, my mother passed away and I was at her death bed. Before and after her last breath, she was physiically same. Minute ago she was breathing and alive, minute later she was without breath and was dead. If she could decide herself life or death, she would have chosen to live with us. It was not her decision. That is why we, Koreans, say ‘Life’ is to live by order(higher authority). I am saying that life and death are not of our choice, nor random happening, neither by an accidenet, etc.

    To be honest with you as a scientist, I think ‘Start of Life’ whether indidual or at the very beginning, can be explained only as creation by Creator.

    Thank you for asking this important question.


  3. Well, if you really want to know, I believe God created the world, all the animals and us! When that happened, I don’t know. How long the process of creation took, I don’t know. I do believe in evolution and can see that humans, animals and plants adapt to their environment, but I don’t believe it all started with a big bang.

    The human body is sooooo complex and the processes in a single cell are so complex, I cannot believe it all started with a few molecules bumping into each other.


  4. After much reading and thinking, (because I’ve never really considered this question) I think I agree with the current hypothesis that Steven was discussing. I did find a cool article ( about when life possibly began as well.

    I think that there is still a long way to go until its figured out….if it ever is! Scientists will probably be able to replicate the different theories in a lab to figure out which makes the most sense – but we may never know for sure 🙂


  5. I strongly agree with what Steven has said in his answer and comment, that life probably began around 3.5 billion years ago, when the first replicating molecules were formed from a combination of primordial soup containing various building blocks (such as amino acids, long-chain carbon molecules, etc.) and some form of catalyst, like a large charge lightning strike. I’m using the generally accepted definition of ‘Life’ as a self-sustained and replicating chemical system capable of undergoing evolution.

    Scientists are still trying to work out how this all happened, and there is some pretty complex biochemistry involved, a lot of which I don’t understand. Scientists who work on this problem have a number of experiments that they can perform, replicating what we thing conditions were probably like 3.5 billion years ago, with similar molecules, and seeing if they can create replicating molecules like RNA or DNA. These was actually a competition run last year, called the “Origin of Life Challenge”, where groups could put forward their proposal of how life started, and how they would test their hypothesis. The proposals had to answer some very specific questions, which you can read all about here:

    As you can see, the questions get to the very heart of the question you asked, but in even more detail!

    You can read about the teams that won, and how they plan to use science to investigate the questions here:



  1. I feel compelled to address some of the things that Soon has said here, because she has unfortunately confused religion and science in her answer, and she has also made some errors of science fact. This is going to be a little long, but it’s important to straighten this out. If you get bored, there’s a great paragraph towards the end with giraffes in it, and you can get the main point of all this in the last two paragraphs. 🙂

    Let’s start with the errors in science fact. First, the beginning of life is a difficult topic to study. It’s very far in the past (billions of years ago), and the evidence of it is hard to find. But while it’s difficult to study, it’s not impossible, and we do know a number of things about it. For instance, we know when it it’s likely to have occurred, which as I said above is between 3.9 to 3.5 billion years ago. How do we know this? A couple of ways. There’s tiny microfossils and stromatolites (rock formations built up partially from thing films of microbes) from about 3.5 billion years ago which means that life had to have begun somewhere before 3.5 billion years ago. Our current best guess from the geological evidence is that things before 3.9 billion years ago were too unsettled for life to have begun much before that. So, that leaves a time period of about 400 million years (a really long time, much longer than humans have been around!) for life to have gotten its act together.

    But the actual beginning of life, the origins of the first cells from nothing but basic chemistry, is still a mystery. This is not a bad thing! The most exciting part of science is when we’re faced with a question that we don’t yet have an answer to. Soon’s answer makes this sound like a bad thing; we don’t know yet exactly how the amino acids turned into proteins, we don’t know how exactly how RNA or DNA started (though we have some good ideas!). It might have been in a way similar to Stanley Miller’s experiment, which showed an important step in a possible way to get complex molecules from simpler ones. It might also have been in a deep sea vent. We don’t know yet, but we’re working on it and debating it and testing it. This doesn’t mean, however, that there isn’t a scientific answer to these questions; we don’t need God to fill in the blanks, as she suggests at the end of her answer. This is actually a kind of logical mistake – or ‘fallacy’ – called the God of the Gaps fallacy. It’s the mistake of assuming that because there’s things we don’t know about yet, that we need God to explain them.

    Soon’s final sentences of that paragraph also dismisses the Big Bang. She says:

    ‘Big Bang’ from a small dot? Where did the small ‘dot’ come from? Everything assumes preexisting something!

    There’s two parts to this. The first is whether the Big Bang occurred, a fact about which there seems to be some confusion around here. That the Big Bang happened is well-established. We know this because we can look out into space and see the way the galaxies are moving away from each other, which is only explainable by an expanding universe. An expanding universe only comes form a universe that was once smaller in the past. We see radiation in the night sky that is predicted by the Big Bang theory. It’s also consistent with what we know of physics. (I’ve drawn on this source for some of the physics and astronomy here). We have a lot of strong evidence for the Big Bang theory, evidence that would convince any court. Natasha says that she doesn’t ‘believe’ that in the Big Bang, but unfortunately it doesn’t really matter what she believes. Scientific truth doesn’t depend upon belief to be true. Gravity works whether you believe in it or not, evolution happened and is happening whether you believe in it or not, and the Big Bang happened whether you believe in it or not. We know this because of the evidence that we have collected over centuries of asking questions. That doesn’t mean that Soon or Natasha are wrong for believing in God, just that their belief in God isn’t relevant to science. Their belief is a personal matter, a religious matter to which they are more than entitled. But it doesn’t allow them to answer scientific questions with their religious beliefs.

    The second part is what happened before the Big Bang. That, we don’t know, because we can’t look past that point. But as I said in my answer above, we’re not without possible explanations. If you’re religious, though, God may be one of those explanations, but the problem is that ‘God did it’ is not a useful explanation. It doesn’t tell us anything about how it happened, and it only raises other questions, like ‘where did God come from, then?’

    Soon goes on to make a really simple error about the second law of thermodynamics. She says that the second law ‘states that entropy (randomness) increases’, but she left out a part: ‘entropy (randomness) increases in a closed system‘. What is entropy and what does this all mean? The physicist Brian Greene has a nice explanation of this, which I’ll try to simplify a little here. Entropy is a measure of disorder. Systems with higher entropy are messier. Your bedroom, for instance, might have high entropy! And left on its own, your bedroom will tend to higher levels of entropy (it will get messier over time). Soon is saying that it’s impossible for your room to go from higher entropy (messy) to lower entropy (clean and organized), in the same way that she claims it’s possible for amino acids to become proteins. Yet it’s clear that she’s wrong, because your bedroom does get cleaned, right? How does this happen? It’s because your bedroom isn’t a closed system. When you burn energy to clean your room, you are still increasing entropy in the universe (the energy you burn while cleaning is an increase in entropy) while you’ve made a local decrease in entropy (your bedroom is cleaner). In the same way, amino acids are free to organize into proteins without violating the second law of thermodynamics, because the sun is shining on the Earth and inputting energy just like you did when you cleaned your room!

    I’m really surprised that Soon used this argument, because it’s both very old (many decades, at least) and was proven wrong just about as long ago. But then, to be fair, her naxt paragraph uses something even older! When she discusses the silk flower, she’s actually using an argument that came from a guy named William Paley in 1802, called the watchmaker argument. The argument goes that because a silk flower or a watch looks like it was designed, it has to have a designer. The idea was that you wouldn’t expect a watch to just appear by random chance looking as though it was designed, so why would expect you expect life to either? But going from the artificial flower or the watch to ‘God must have made us’ is a creationist tactic that is flawed for many reasons. (This also isn’t an argument about how life began; it’s an argument about why life looks like it does now. In short, it’s not about the beginning of life, it’s about evolution, which is not the same thing).

    The simplest of these flaws is that we have a very clear explanation for why life looks like it does and how it arose: evolution! We know that evolution has occurred and is continuing to occur; this is a fact that is as well-established as gravity is. We can see it happening, we can see the evidence that it has happened, and we can make it happen ourselves. How evolution happens is what Darwin tried to explain, with his theories of natural selection (among others). Much of what Darwin wrote has been conclusively proven; some of what he wrote, such as how things are inherited from parent to child, was wrong because he didn’t know about things like genetics. And biologists like me are still working out a lot of the details of how evolution works, through the careful process of science.

    Another flaw comes from the fact that unlike the silk flower, life is often very badly designed. Have you ever seen a movie where someone choked to death? Have you ever wondered why we have a single pipe for food and air? Other mammals don’t have this problem; they have a better configuration of trachea and esophagus. Your cat or dog, for instance, isn’t going to choke to death on its food. But you could. Why? Because you can talk. It turns out that the evolved modifications to our bodies that gave us our speech facilities as language became important also created a situation where our food and air pipes crossed in a way that could kill us.

    There’s literally dozens of these sorts of examples of shockingly poor design in the human body and in all bodies throughout the animal kingdom (here’s just a few more of them. Soon says that the silk flower is evidence of a designer; science shows us that the bodies are evidence of evolution. Indeed, some of the body’s features are only explainable by evolution. There’s a great example of a nerve in the body called the recurrent laryngeal nerve that demonstrates my point. This nerve helps us swallow and speak, and it carries signals from the brain to the throat. But to do so, it first goes on a really long trip down into your chest and around your heart, then back up to your throat. This doesn’t really make any sense, from a design point of view: why such a long path to get from your brain to your throat? Why not simply go in a straight line from the head to the throat? It turns out that there’s a good reason for this, which has to do with evolution. In our ancestors (which were fish!), this nerve lined up with a blood vessel to the gills. This was a straight line, but as our bodies were remodelled by evolution over millions of years, the nerve moved with the blood vessel as it became part of the mammal heart and moved down the chest into the chest cavity. Unfortunately, the nerve had to remain connected to the throat, and so the nerve was stuck looping around the heart in an absurd way, so that now it’s stuck in this bad setup. And it gets worse, of course, because as the link above shows you, this same nerve shows up again and again in all of the life forms descended from those fishy ancestors; this is pretty much everything with four legs, including all of us mammals, and is exactly what we expect from evolution. Giraffes, for example, end up with a nerve that’s 15 feet long, running all the way down their necks and all the way back up. Evolution has to do the best it can with what it has and often ends up with really messy solutions, while a designer could have easily detached and then reattached the nerve and made things much cleaner.

    I could write entire books on all of the evidence that shows us how evolution occurred. Thankfully, I don’t have to because they’ve already been written! (A great book to try, if you want more, is a book called Why Evolution is True, by Jerry Coyne, who I referenced above for the RL nerve). One of the great things about studying science is that you get to go out and read about all of the amazing discoveries that thousands of scientists have spent their lives accumulating to help push our knowledge forward. I feel lucky every time I walk into a library.

    The main point here, though, is that the arguments that Soon has made here are all non-scientific arguments. They’re examples of a way of thinking called ‘creationism’, or ‘intelligent design’. Don’t let them fool you: intelligent design is just creationism in different clothes, and none of it is science. Creationism is not scientific because it makes no predictions about the world for us to test and it adds nothing to our knowledge of science. I’m not saying that Soon can’t hold beliefs about God. What I am saying is that they don’t belong in a conversation about science, and they shouldn’t be presented as if they are scientific thought. Religion can be an important part of your life even if you are a scientist (many scientists are, indeed, religious), but religion gives us no answers when it comes to science itself and it is not a valid way to answer scientific questions.

    Soon ends by saying that ‘as a scientist’, she thinks that the beginning of life is only explainable by a Creator (God). I’m here to tell you, though, that when she says that, she’s not saying it as a scientist. She’s saying it as a person with a religious belief, and when it comes to science, that’s not how we do things.


    • I do appreciate the long and sincere comments of Steven about my answer to the ‘beginning of life’ presented by Sarahb. I want to make it very clear that creation and evolution hypotheses are not to be put on the same time table.

      Science in short is a ‘logical thinking’. We are talking about the very beginning of life. The basic unit of life is cell. Cell is called a ‘microscopic universe’. It is small in size, bacteria in 2-3 micron in length but it as a life form is very very complex and complicated.

      The chemical reactions carried out by Dr. Stanley Miller(amino acids and nucleotides ssynthesized) is too far to be any evidence of the beginning of the life, cell. It is very unlogical to call it as an evidence of the beginning of life. The scientists who try to support it as ‘THE EVIDENCE’ know that and says ‘some way’, ‘not yet can be explained’.

      And Dr. Miller used all of his knowledge to design the experiment, he used a glass apparatus to carry out his experiment, he used pre-existing gases, and electricity, etc. The amino acids as the building blocks of proteins, the nucleotides for DNA and RNA never could come to exist by itself no matter how long, how many billions of years is given to it. I think he rather proved that nothing can come out of nothing!

      Making something out of nothing is properly called ‘Creation’. Making something from pre-existing something is called ‘development’ or ‘Evolution’ here, in our debates. I said that the beginning of life is explained by creation, logically, not by evolution. That is what I mean by the two hypotheses have different time table.

      As a scientist, not by my personal belief, I answered the question about the beginning of life by creation, for a life(cell) to come to exist from nothing. It is the only logical thinking!

      Darwin has nothing to say about the ‘beginning of life’, but a lot about thereafter, ‘Origin of species’. ‘Beginning of life’ and ‘Origin of species’ are two different stories, of two different time table, two different events, for sure.

      I do thank to Steven again for bringing up the interesting analogy of cleaning up of messy room, to explain the entropy. Yes, the messy room can be cleaned up, put into order for sure. However, it can not be cleaned up by itself, no matter how much time is given to it. It involves somebody to do the job. More than that, the messy room itself couldn’t be into exist by itself unless somebody made the mess;- papers, snack crumbs, books, pants, socks, etc. None of them could come into that space by itself for sure. That is my logic as a scientist. Thank you very much.


      • Soon almost seems to be saying that because Miller didn’t create an entire cell the first time he turned on his experiment, that it proves that life had to be ‘created’ (and, as she said in her previous answer, that this had to be done by a Creator, which is a distinctly religious position). I hope that’s not what she actually means, but it’s what her writing implies. And she’s being unfair to Stanley Miller, who was just trying to show a single step in the complex process that goes from the simplest chemical building blocks to the first simple forms of life; he succeeded quite well at what he set out to do, since he created at least 20 amino acids from simple chemical parts. It’s also important to note that these simple forms of life do not have to be cells as Soon implies, but could have been much simpler than that; any collection of molecules that has been created and is capable of replicating itself and changing over generations (descent with modification) is enough to start the process of evolution. Life doesn’t necessarily start with the cell!

        Meanwhile, nobody is saying that the Miller-Urey experiment is the only step needed to show the creation of life! And there’s a lot of other ways in which this occurred, which is why Miller’s work is only one piece of evidence, and why scientists are debating all of the possible ways that this could have happened and testing them. There’s still a lot that we don’t know here, which is what makes it an exciting thing to study. But Miller’s work is valid evidence, and I don’t understand why Soon insists that he proved ‘nothing from nothing’ or why she insists that complex molecules like DNA could never organize themselves without presenting an actual argument as to why they couldn’t. What she’s writing seems very much like an argument from incredulity: because she can’t imagine how these molecules like DNA could have come about, she presumes that they can’t and so we need a Creator (God) to do it. This is not a logical, or scientific way, of thinking. If we as scientists thought this way about all of our work, we would give up before we started!

        Regarding creation vs evolution, I brought up evolution because Soon used the example of the artificial silk flower – Paley’s watchmaker argument – as evidence of design. This is an argument that creationists use in reference to why they believe that evolution is false, not as to why they think that the beginning of life (‘abiogenesis’, in technical language) must be due to God. I also address it because in multiple chats Soon has said things like ‘Darwin was wrong’ or that we ‘didn’t evolve from monkeys’, and so I needed to deal with this directly as well. She is right, though, that in general the beginning of life (abiogenesis) and evolution are two separate things; I mentioned this myself, in my first comment.

        Finally, I don’t know what to do with her response on entropy. She’s right that that a messy room won’t be cleaned up by itself, which is why the input of energy from outside the system is required (i.e. someone has to expend energy cleaning the room; that’s one reason why you might want a snack after spending an afternoon cleaning your room!). That’s the point! The entropy in the room goes down while the total entropy in the universe still goes up. This is the same way in which life emerges: local entropy – disorder, messiness – is reduced when the molecules come together in a more complex form, like when amino acids combine into proteins, etc. While this goes on, input of energy from the sun (and other mechanisms) continues to increase the total entropy in the universe (because the sun is burning energy and increasing entropy while it shines on us). In this way – which I’ve grossly simplified, and I’d be happy to have a physicist chime in here – the second law of thermodynamics is satisfied, and the creation of life doesn’t pose a problem for physics or chemistry. The way that she’s using this argument is simply flawed, and it’s been known that this argument doesn’t work for many decades now.

        I think that Soon is sincere in her beliefs, but despite her saying that she’s speaking as a scientist and that creation and evolution are separate, she’s still using arguments that come directly from religious creationists when asked a scientific question. The 2nd Law of thermodynamics, the argument from design (silk flower / watchmaker), even the argument from incredulity; these are all straight from the creationist playbook, and none of them belong in a scientific discussion about how life might have begun.


      • Dear Soon,

        The modern understanding of science is that all ideas have the possibility of being proved wrong. In the historical record, Netwon had some really good ideas about motion. At the time, every test seemed to agree with his ideas, but everytime someone did an experiment measuring forces, masses and acceleration, there was always the possibility that the test might measure that acceleration would not equal force divided by mass. For hundreds of years, no test could disprove Einstein’s ideas, but every test had the possibility of doing so. Eventually, at high velocities, it has been measured that acceleration does not equal force divided by mass — this is now demonstrated every single day at the Australian Synchrotron, which accelerates electrons to very high velocities.

        Many people have sincerely held beliefs that there is a Creator. Even Einstein’s work refers to a creator or supreme being. Belief is not necessarily science. Since there is no test that (depending on the results of the test) might possibly disprove the existence of a Creator, the question of whether a Creator exists is outside the realm of science. This does not say that the existence of a Creator is right or wrong, just that it is not a scientific belief.

        I am a chemist (chemical scientist) with a background in physical chemistry and statistical physics, and therefore will comment on the entropy issue.
        Firstly, it is a statistical arguement or proof that entropy tends to increase in a closed system. The work of Professor Evans (at ANU), and others, have shown that in some situations, it is possible for entropy to decrease in a closed system, but it is statistically very very unlikely.
        Secondly, if we take a bunch of pens and separate pen-caps in a container and shake and shake and shake, eventually, randomly, one pencap might potentially be shaken onto a pen. it may be unlikely, but it is possible.
        A collection of random atoms and molecules can assemble into more complicated structures; astrophysists and radioastronomers have detected amino acids and other molecules in other space, and the creation of these species is understood in terms of chemical reactions. Many people believed that random atoms and molecules can NOT assemble into amino acids and other molecules, that are essential for the creation of life. The significance of the Miller experiment is that it disproved this idea. No valid scientific test absolutely, beyond doubt, ever proves something; all valid scientific tests disprove something. So the conclusion from the Miller experiment is that under some circumstances, it is possible for random atoms and molecules to assemble into amino acids and other molecules, that are essential for the creation of life.

        Kieran Lim, chemical scientist


  2. Wow, I wonder how many of the target audience have read this far!

    I would just like to add my support to Steven – he has done a fantastic job of explaining and summarising what I understand is the current scientific consensus in a balanced and even-handed manner. I tip my hat to you, sir! Indeed I am a physicist, and I can confirm that everything he says about the second law of thermodynamics is true – I don’t think I can add much. The second law of thermodynamics says the entropy of a *closed* system cannot increase. The earth is an open system – it has energy input from the sun. If it were true that systems could not self organise, then we wouldn’t be able to have things as simple as air-conditioning or freezers. Ice couldn’t form in the Antarctic.

    It can be tricky separating assertions and opinions from science, which is why those that deny climate change get a lot of air time. I have respect for those that tackle these issues on behalf of science as a whole.


  3. Dear Steven, Kieran, and Matthew;

    I am very happy to have this space to communicate with you and I am honored to be in the position to reply and ask questions back and forth.

    Following is the quotation of what Steven has commented yesterday(5th of Sep., 2012) ….’And she’s being unfair to Stanley Miller, who was just trying to show a single step in the complex process that goes from the simplest chemical building blocks to the first simple forms of life; he succeeded quite well at what he set out to do, since he created at least 20 amino acids from simple chemical parts. …’

    That is exactly I am trying to point out to you and to the students. Dr. Miller was there to make the 22 amino acids(not 20 as I read! it migh increase in numbers though.) through the chemical reactions. Do you expect that ‘creation(Steven, you used the very word,’CREATed’)
    could have happened by itself from nothing? Is it logical? Is that thinking scientific?
    I am keep saying that(and it is not my own word!) science is a logical thinking.

    I should be ready for the chatting with the Riverside Girls.
    Thank you very much and see you later.