5 ms·

Can you elaborate on this further? Why don't the laws of probability apply to chemistry?

bediger4000 5y ago
They definitely do apply, but it's like laws of probability apply to gas dynamics: sure there's a very small, but not non-existent chance that all the air in your room will end up confined to the half you're not in. There's a very tiny probability that acetic acid in vinegar and sodium bicarbonate in baking soda won't combine. I suppose some extremely tiny fraction of the acid and baking soda I've mixed together in my life didn't react. But the probability is so tiny, it just doesn't matter: all my cookies and soda bread rose. Same with self replicating organic molecules - if you mix amino acids together, you're going to get some long strands virtually every time you try it because the probability of amino acids not reacting is very tiny. The probability of getting self-replicating strands approaches 1 after only a few trials. That is, your solution of amino acids would end up with some goop in it, some polymerized amino acid strands that had replicated themselves. This "what's the probability!?!?" category of anti-evolutionary arguments is just false. "If you put all the pieces of a car in a box and shook it, the probability of getting a car is zero!" True, but an inapplicable analogy to organic chemistry reactions. Intuition about probability leads you astray. Nuts have an extremely low probability of getting agitated into screwing themselves on a bolt. The chemicals relevant to life have an extremely high probability of reacting to form larger molecules.
- memling 5y ago
  That's an interesting point, thanks. Please pardon some ignorant questioning. How far down does this apply? E.g., do amino acids come basically for free in the same way? If not, what's the bootstrapping process like, and how random is it? How many steps do you have to take from self replication to functional cells? That chemical reactions are quite deterministic makes sense to me, but I don't quite understand how one gets from chemistry to biology.
  - yamrzou 5y ago
    Good question, I wonder the same. If I may add, how far does this apply when getting from biology to consciousness, i.e from functional cells to general intelligence, as seen in living organisms and humans?
  - carbonguy 5y ago
    I'm not the parent commenter, but I studied biochemistry and find abiogenesis to be a particularly fascinating topic, so I'll take a crack at answering your questions: > How far down does this apply? E.g., do amino acids come basically for free in the same way? Broadly, I think it is fair to say that many molecules that we associate with biological processes (e.g. amino acids, nucleotides, simple alcohols, etc.) do come "for free" in the sense that there are known pathways for these molecules to be produced in the absence of living organisms. The Miller-Urey experiment is probably the most well-known proof of concept of this idea, though it's debated how well the experimental conditions correspond with "the real world." > ... [W]hat's the bootstrapping process like, and how random is it? If I understand you correctly, here you're asking "what does it take to get from prebiotic organic molecules to living organisms?" And that is a fascinating question that has, to my mind, several possible answers, though ultimately I think the answer is "we don't know." One very suggestive paper I read describes the bootstrapping process as a "surface metabolism" [1] that succeeds through several epochs before eventually producing free-floating lipid-membrane-enclosed micelles containing complex organic molecules and a rudimentary metabolism - i.e. protocells. However, the IIRC paper falls short of explaining how these protocells can then start to independently reproduce. One hypothesis I recall from David Deamer is that hydration/dehydration cycles in shallow pools promote complex organization of simpler protomolecules into structures we typically associate with living organisms [2]; in other words, given the protobiomolecules mentioned above, certain environmental conditions encourage [proto]cell formation. So, to answer your question (I think), there are many good candidates for the "bootstrapping process" and while there is randomness involved, it turns out that certain environmental conditions that were present on the early Earth (as well as currently!) tended to promote complex molecular formation. > How many steps do you have to take from self replication to functional cells? Not many; I would say that if you have something that looks like a cell and reproduces itself, it's a "functional cell." Personally, I think from that point we are at an, if not the, "origin of life," and understand in broad strokes "what happens next" - ever-more-refined single-celled organisms, multi-cell aggregates becoming "true" multi-celled organisms, and so on. Let me know if you're curious about any other aspect of this topic and I'll try to provide more info! [1] https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC373159/ https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC373159/ [2] https://www.liebertpub.com/doi/10.1089/ast.2019.2045 https://www.liebertpub.com/doi/10.1089/ast.2019.2045

They definitely do apply, but it's like laws of probability apply to gas dynamics: sure there's a very small, but not non-existent chance that all the air in your room will end up confined to the half you're not in. There's a very tiny probability that acetic acid in vinegar and sodium bicarbonate in baking soda won't combine. I suppose some extremely tiny fraction of the acid and baking soda I've mixed together in my life didn't react. But the probability is so tiny, it just doesn't matter: all my cookies and soda bread rose. Same with self replicating organic molecules - if you mix amino acids together, you're going to get some long strands virtually every time you try it because the probability of amino acids not reacting is very tiny. The probability of getting self-replicating strands approaches 1 after only a few trials. That is, your solution of amino acids would end up with some goop in it, some polymerized amino acid strands that had replicated themselves. This "what's the probability!?!?" category of anti-evolutionary arguments is just false. "If you put all the pieces of a car in a box and shook it, the probability of getting a car is zero!" True, but an inapplicable analogy to organic chemistry reactions. Intuition about probability leads you astray. Nuts have an extremely low probability of getting agitated into screwing themselves on a bolt. The chemicals relevant to life have an extremely high probability of reacting to form larger molecules.

memling 5y ago
That's an interesting point, thanks. Please pardon some ignorant questioning. How far down does this apply? E.g., do amino acids come basically for free in the same way? If not, what's the bootstrapping process like, and how random is it? How many steps do you have to take from self replication to functional cells? That chemical reactions are quite deterministic makes sense to me, but I don't quite understand how one gets from chemistry to biology.
- yamrzou 5y ago
  Good question, I wonder the same. If I may add, how far does this apply when getting from biology to consciousness, i.e from functional cells to general intelligence, as seen in living organisms and humans?
- carbonguy 5y ago
  I'm not the parent commenter, but I studied biochemistry and find abiogenesis to be a particularly fascinating topic, so I'll take a crack at answering your questions: > How far down does this apply? E.g., do amino acids come basically for free in the same way? Broadly, I think it is fair to say that many molecules that we associate with biological processes (e.g. amino acids, nucleotides, simple alcohols, etc.) do come "for free" in the sense that there are known pathways for these molecules to be produced in the absence of living organisms. The Miller-Urey experiment is probably the most well-known proof of concept of this idea, though it's debated how well the experimental conditions correspond with "the real world." > ... [W]hat's the bootstrapping process like, and how random is it? If I understand you correctly, here you're asking "what does it take to get from prebiotic organic molecules to living organisms?" And that is a fascinating question that has, to my mind, several possible answers, though ultimately I think the answer is "we don't know." One very suggestive paper I read describes the bootstrapping process as a "surface metabolism" [1] that succeeds through several epochs before eventually producing free-floating lipid-membrane-enclosed micelles containing complex organic molecules and a rudimentary metabolism - i.e. protocells. However, the IIRC paper falls short of explaining how these protocells can then start to independently reproduce. One hypothesis I recall from David Deamer is that hydration/dehydration cycles in shallow pools promote complex organization of simpler protomolecules into structures we typically associate with living organisms [2]; in other words, given the protobiomolecules mentioned above, certain environmental conditions encourage [proto]cell formation. So, to answer your question (I think), there are many good candidates for the "bootstrapping process" and while there is randomness involved, it turns out that certain environmental conditions that were present on the early Earth (as well as currently!) tended to promote complex molecular formation. > How many steps do you have to take from self replication to functional cells? Not many; I would say that if you have something that looks like a cell and reproduces itself, it's a "functional cell." Personally, I think from that point we are at an, if not the, "origin of life," and understand in broad strokes "what happens next" - ever-more-refined single-celled organisms, multi-cell aggregates becoming "true" multi-celled organisms, and so on. Let me know if you're curious about any other aspect of this topic and I'll try to provide more info! [1] https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC373159/ https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC373159/ [2] https://www.liebertpub.com/doi/10.1089/ast.2019.2045 https://www.liebertpub.com/doi/10.1089/ast.2019.2045