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> All complex life on earth shares a common ancestor, a cell that arose from simple bacterial progenitors on just one occasion in 4 billion years. This strike

> All complex life on earth shares a common ancestor, a cell that arose from simple bacterial progenitors on just one occasion in 4 billion years. This strikes me as a commonly held but deeply flawed origin story, and a close read suggests Gates doesn't buy it either, but fell into the literary trap of writing it anyway. If we believe the first form of life occurred on the sea floor, why shouldn't we believe that new forms of life are spontaneously occurring on the sea floor all the time? By now the overwhelming majority of those new forms are probably eaten by an existing critter, but in the early days, there were many, many, many events. And, like he says, there were many, many times when one cell ate another cell. I rather doubt it only succeeded to result in eukaryotes once.

tokenadult 10y ago
The economical (Occam's Razor) explanation of the patterning of life on earth, based on genetic studies, is that all current living things share a common ancestor. That's what the quoted sentence says, and what you wrote doesn't show that the quoted sentence is a "deeply flawed origin story".
- niels_olson 10y ago
  Economy is not a fundamental principle of physical law. I recommend you try to work up from thermodynamics. Start by asking yourself how many molecules of water are in the ocean, and how frequently they vibrate.
  - snowwrestler 10y ago
    Didn't Feynman win a Nobel Prize for showing that particles are always most likely to take the most efficient path? Anyway, Occam's razor is about preferring theories, not physical laws. If two theories match a given set of observations, there is no objective reason to prefer one over the other. But it is easier to work with a simpler theory, so scientists prefer it out of self-interest. Put another way, if there is no way to distinguish between a LUCA and continuous abiogenesis that looks exactly like a LUCA, then there's no reason to care that continuous abiogenesis might be occuring. But if you believe there is a way to prove that continuous abiogenesis is occuring, then by all means conduct the observation and publish it.
    - niels_olson 10y ago
      > Nobel Prize for showing that particles are always most likely to take the most efficient path I only have a BS in physics, so do please correct me, but the path integral formulation of quantum mechanics helps predict particle behavior but doesn't say anything is most likely to happen all the time. Indeed, it requires considering how often very absurd things happen. > it is easier to work with a simpler theory, so scientists prefer it out of self-interest Thermodynamics is definitely simpler than any phylogenetic analysis trying to peer backward through a graph with many, many cycles in it. But thermodynamics requires accepting the possibilities of just how many times some very unlikely event might happen.
  - tokenadult 10y ago
    I simply meant that there are no data to show that any current living thing derives from a different earliest ancestor from all of the other currently living things. You are welcome to show me a counterexample if you know of one.
jerf 10y ago
If scientists are biased at all, they're biased against life being hard; generally the party line is that it is easy. The standard line is that life arose once because all the evidence seems to point to the fact that all observable life comes from the same line, not because they can't conceive of any alternative. It is still thought that there could be a slight possibility of a different life line still alive in some extreme environment, which we would have a hard time observing with our existing tools; e.g., if it was not built on DNA then some of the tooling we use to detect small amounts of otherwise-unknown life might not work. But to the best of my knowledge this is just speculation with no current concrete evidence.
civilian 10y ago
If you had read the book, you would know that Archaea and Bacteria both share some genes. Not many genes, but a few genes that are very fundamental. And not even the genes we were expecting to be the "minimum viable product" for life. Nick Lane thinks that the evidence is for there being a common ancestor between Archaea and Bacteria too. The genetic evidence backs it. Your intuition and suspicious about bias just don't matter. :) But, I think the mistake you're making is a misunderstanding of how long this early evolution takes, vs. how long it takes for life to spread around the ocean. Abiogenesis is probably much slower than the time it takes for a unicellular alkaline vent-dweller to occupy the globe. And, as far as eukaryotes go, keep in mind that there was about a billion years where there were only bacteria & archaea on the globe. A billion years! Why did it take so long to form a eukaryote then? It's because it's very x 10^9 unlikely to happen.
- red-indian 10y ago
  Horizontal gene transfer is well established. Existence of a small number of common genes between two species does not necessarily indicate a common ancestor.
  - niels_olson 10y ago
    It would seem to me that bacteriophages alone sort of ruin the idea of a phylogeny with a single root.
    - civilian 10y ago
      How so? I will happily agree that bacteriophages & HGT ruin the idea that phylogenetic tree can be a perfect tree-- our phylogenetic tree has many undirected cycles in it.
      - niels_olson 10y ago
        How would you reconstruct the phylogeny to see through that mess? We're not even talking about computational complexity yet. Simply, how do you see through a random number of random DNA fragments being inserted in random places of random genomes at random intervals over a billion years?
astazangasta 10y ago
This theory is now widely questioned. I recommend this paper by W. Ford Doolittle on the subject: http://www.pnas.org/content/104/7/2043.short http://www.pnas.org/content/104/7/2043.short - also, "Uprooting the Tree of Life", http://www.ncbi.nlm.nih.gov/pubmed/10710791 http://www.ncbi.nlm.nih.gov/pubmed/10710791. Basically, the argument is that horizontal gene transfer must have been such a huge part of life at its inception that the notion of a "LUCA" is confused, and we must expect to find a disgusting mess at the root of the tree of life.
- danieltillett 10y ago
  Horizontal gene transfer is underestimated by biologists, but I am not sure in what sense LUCA is confused. I would not call the root of the tree of life a disgusting mess, just fuzzy.
  - astazangasta 10y ago
    If horizontal gene transfer was common and rampant at the outset of life, then a fundamental fact of evolutionary descent was not true at that point. This means there may NOT be a LUCA, but several progenitor organisms that each contributed to a portion of eventual life. E.g. there are four features ABCD. We may have descendants that are AB, BC, CD, AD, without having any creature that was ABCD.
    - danieltillett 10y ago
      Horizontal gene transfer is still rampant - actually it is a far better way to mix genes than sexual reproduction and it is probably why microbes rule the world. LUCA is an imaginary organism that captures the features that all known living organisms share - almost certainly the history of decent of each gene in modern organisms is different.
Symmetry 10y ago
>If we believe the first form of life occurred on the sea floor, why shouldn't we believe that new forms of life are spontaneously occurring on the sea floor all the time? I'd be very surprised if such spontaneous life could compete against life with millions of years of evolution behind it. As to eukaryotes, them arising seems to be a much more unlikely proposition so I'd be surprised if it happened more than once given that it took an order of magnitude more time to happen once the conditions were right. https://en.wikipedia.org/wiki/Timeline_of_the_evolutionary_history_of_life https://en.wikipedia.org/wiki/Timeline_of_the_evolutionary_h...
- niels_olson 10y ago
  Perhaps at a species level it may haven't happened many times, that is, a species of bacteria was ingested, or took harbor in, a larger cell. But if it worked once, it worked thousands if not millions of times.
pbhjpbhj 10y ago
I've thought this too - if the conditions for life existed at one point on the planet the chance they didn't exist at some other point seems infinitesimal. Down-thread someone argued that the subsequent genesis events would fail to produce new "roots" of the tree of living things. However, if the new roots fill a different niche (eg geographically), or quickly mutate to fill a different niche; or if the earlier roots evolved to higher forms that operate in a different niche then that objection doesn't seem so strong. Weigh that idea against the possibility of life elsewhere: if life only started once on Earth where the conditions for life to be created were perfect then the chances of life occurring elsewhere, life that follows the same forms at least, is surely so close to zero that we shouldn't ever expect to find extra-terrestrial life similar to forms on Earth? [It's not a watertight argument, I can see 2 flaws right off, but it's an interesting suggestion as a corollary to the "single terrestrial genesis event" idea.]
- deleted 10y ago
  [deleted]
geographomics 10y ago
https://en.wikipedia.org/wiki/Problem_of_induction https://en.wikipedia.org/wiki/Problem_of_induction
btilly 10y ago
If we believe the first form of life occurred on the sea floor, why shouldn't we believe that new forms of life are spontaneously occurring on the sea floor all the time? Once a cell has formed, through the miracle of exponential growth its descendants will quickly suck up available nutrients until you run out of some key nutrient, and then it can never happen again. Suppose that that formation of a viable cell was a 1 in a million year event. It would be essentially inevitable over a hundred million years. But the time from happening once to impossible is a lot, lot, lot less than a million years...
- niels_olson 10y ago
  > 1 in a million year event per what unit volume? Or unit surface area?
  - sampo 10y ago
    I think they mean per planet.
    - btilly 10y ago
      Yes, per planet.
CamperBob2 10y ago
If we believe the first form of life occurred on the sea floor, why shouldn't we believe that new forms of life are spontaneously occurring on the sea floor all the time? Many people don't seem to understand just how incredibly different the environmental conditions on Earth were when life was first ramping up. Those conditions not only no longer prevail, but the world is also full of competitors that weren't there in the beginning. Also, we probably haven't cataloged 10% of the life forms on our ocean floors yet. There's still a lot to learn, and there will be surprises.
- mentalpiracy 10y ago
  Glad you made this point. To expand on it a bit: Continuing abiogenesis may very well be occuring (in the very few locations that may still resemble the beginning), but at what complexity are we defining "life" when asking this question? Simple spontaneous assembly of RNA precursors? Something more fully fledged? In any case, the problem isn't even competitors that have evolved since then - it's the existence of complex metabolism. All of the "ingredients" you would need for abiogenesis to occur are now consumed by established organisms, ripping down the molecules for their own energy needs before they can catalyze into a more complex form. Life as we know it doesn't have room for the earliest products of abiogenesis anymore. Whatever form our earliest genetic ancestors may have taken, Earth's present-day micro-biosphere is simply too ubiquitous and too ravenous.

tokenadult 10y ago

The economical (Occam's Razor) explanation of the patterning of life on earth, based on genetic studies, is that all current living things share a common ancestor. That's what the quoted sentence says, and what you wrote doesn't show that the quoted sentence is a "deeply flawed origin story".

niels_olson 10y ago
Economy is not a fundamental principle of physical law. I recommend you try to work up from thermodynamics. Start by asking yourself how many molecules of water are in the ocean, and how frequently they vibrate.
- snowwrestler 10y ago
  Didn't Feynman win a Nobel Prize for showing that particles are always most likely to take the most efficient path? Anyway, Occam's razor is about preferring theories, not physical laws. If two theories match a given set of observations, there is no objective reason to prefer one over the other. But it is easier to work with a simpler theory, so scientists prefer it out of self-interest. Put another way, if there is no way to distinguish between a LUCA and continuous abiogenesis that looks exactly like a LUCA, then there's no reason to care that continuous abiogenesis might be occuring. But if you believe there is a way to prove that continuous abiogenesis is occuring, then by all means conduct the observation and publish it.
  - niels_olson 10y ago
    > Nobel Prize for showing that particles are always most likely to take the most efficient path I only have a BS in physics, so do please correct me, but the path integral formulation of quantum mechanics helps predict particle behavior but doesn't say anything is most likely to happen all the time. Indeed, it requires considering how often very absurd things happen. > it is easier to work with a simpler theory, so scientists prefer it out of self-interest Thermodynamics is definitely simpler than any phylogenetic analysis trying to peer backward through a graph with many, many cycles in it. But thermodynamics requires accepting the possibilities of just how many times some very unlikely event might happen.
- tokenadult 10y ago
  I simply meant that there are no data to show that any current living thing derives from a different earliest ancestor from all of the other currently living things. You are welcome to show me a counterexample if you know of one.

jerf 10y ago

If scientists are biased at all, they're biased against life being hard; generally the party line is that it is easy. The standard line is that life arose once because all the evidence seems to point to the fact that all observable life comes from the same line, not because they can't conceive of any alternative. It is still thought that there could be a slight possibility of a different life line still alive in some extreme environment, which we would have a hard time observing with our existing tools; e.g., if it was not built on DNA then some of the tooling we use to detect small amounts of otherwise-unknown life might not work. But to the best of my knowledge this is just speculation with no current concrete evidence.

civilian 10y ago

If you had read the book, you would know that Archaea and Bacteria both share some genes. Not many genes, but a few genes that are very fundamental. And not even the genes we were expecting to be the "minimum viable product" for life. Nick Lane thinks that the evidence is for there being a common ancestor between Archaea and Bacteria too. The genetic evidence backs it. Your intuition and suspicious about bias just don't matter. :) But, I think the mistake you're making is a misunderstanding of how long this early evolution takes, vs. how long it takes for life to spread around the ocean. Abiogenesis is probably much slower than the time it takes for a unicellular alkaline vent-dweller to occupy the globe. And, as far as eukaryotes go, keep in mind that there was about a billion years where there were only bacteria & archaea on the globe. A billion years! Why did it take so long to form a eukaryote then? It's because it's very x 10^9 unlikely to happen.

red-indian 10y ago
Horizontal gene transfer is well established. Existence of a small number of common genes between two species does not necessarily indicate a common ancestor.
- niels_olson 10y ago
  It would seem to me that bacteriophages alone sort of ruin the idea of a phylogeny with a single root.
  - civilian 10y ago
    How so? I will happily agree that bacteriophages & HGT ruin the idea that phylogenetic tree can be a perfect tree-- our phylogenetic tree has many undirected cycles in it.
    - niels_olson 10y ago
      How would you reconstruct the phylogeny to see through that mess? We're not even talking about computational complexity yet. Simply, how do you see through a random number of random DNA fragments being inserted in random places of random genomes at random intervals over a billion years?

astazangasta 10y ago

This theory is now widely questioned. I recommend this paper by W. Ford Doolittle on the subject: http://www.pnas.org/content/104/7/2043.short http://www.pnas.org/content/104/7/2043.short - also, "Uprooting the Tree of Life", http://www.ncbi.nlm.nih.gov/pubmed/10710791 http://www.ncbi.nlm.nih.gov/pubmed/10710791. Basically, the argument is that horizontal gene transfer must have been such a huge part of life at its inception that the notion of a "LUCA" is confused, and we must expect to find a disgusting mess at the root of the tree of life.

danieltillett 10y ago
Horizontal gene transfer is underestimated by biologists, but I am not sure in what sense LUCA is confused. I would not call the root of the tree of life a disgusting mess, just fuzzy.
- astazangasta 10y ago
  If horizontal gene transfer was common and rampant at the outset of life, then a fundamental fact of evolutionary descent was not true at that point. This means there may NOT be a LUCA, but several progenitor organisms that each contributed to a portion of eventual life. E.g. there are four features ABCD. We may have descendants that are AB, BC, CD, AD, without having any creature that was ABCD.
  - danieltillett 10y ago
    Horizontal gene transfer is still rampant - actually it is a far better way to mix genes than sexual reproduction and it is probably why microbes rule the world. LUCA is an imaginary organism that captures the features that all known living organisms share - almost certainly the history of decent of each gene in modern organisms is different.

Symmetry 10y ago

>If we believe the first form of life occurred on the sea floor, why shouldn't we believe that new forms of life are spontaneously occurring on the sea floor all the time? I'd be very surprised if such spontaneous life could compete against life with millions of years of evolution behind it. As to eukaryotes, them arising seems to be a much more unlikely proposition so I'd be surprised if it happened more than once given that it took an order of magnitude more time to happen once the conditions were right. https://en.wikipedia.org/wiki/Timeline_of_the_evolutionary_history_of_life https://en.wikipedia.org/wiki/Timeline_of_the_evolutionary_h...

niels_olson 10y ago
Perhaps at a species level it may haven't happened many times, that is, a species of bacteria was ingested, or took harbor in, a larger cell. But if it worked once, it worked thousands if not millions of times.

pbhjpbhj 10y ago

I've thought this too - if the conditions for life existed at one point on the planet the chance they didn't exist at some other point seems infinitesimal. Down-thread someone argued that the subsequent genesis events would fail to produce new "roots" of the tree of living things. However, if the new roots fill a different niche (eg geographically), or quickly mutate to fill a different niche; or if the earlier roots evolved to higher forms that operate in a different niche then that objection doesn't seem so strong. Weigh that idea against the possibility of life elsewhere: if life only started once on Earth where the conditions for life to be created were perfect then the chances of life occurring elsewhere, life that follows the same forms at least, is surely so close to zero that we shouldn't ever expect to find extra-terrestrial life similar to forms on Earth? [It's not a watertight argument, I can see 2 flaws right off, but it's an interesting suggestion as a corollary to the "single terrestrial genesis event" idea.]

deleted 10y ago
[deleted]

geographomics 10y ago

https://en.wikipedia.org/wiki/Problem_of_induction https://en.wikipedia.org/wiki/Problem_of_induction

btilly 10y ago

If we believe the first form of life occurred on the sea floor, why shouldn't we believe that new forms of life are spontaneously occurring on the sea floor all the time? Once a cell has formed, through the miracle of exponential growth its descendants will quickly suck up available nutrients until you run out of some key nutrient, and then it can never happen again. Suppose that that formation of a viable cell was a 1 in a million year event. It would be essentially inevitable over a hundred million years. But the time from happening once to impossible is a lot, lot, lot less than a million years...

niels_olson 10y ago
> 1 in a million year event per what unit volume? Or unit surface area?
- sampo 10y ago
  I think they mean per planet.
  - btilly 10y ago
    Yes, per planet.

CamperBob2 10y ago

If we believe the first form of life occurred on the sea floor, why shouldn't we believe that new forms of life are spontaneously occurring on the sea floor all the time? Many people don't seem to understand just how incredibly different the environmental conditions on Earth were when life was first ramping up. Those conditions not only no longer prevail, but the world is also full of competitors that weren't there in the beginning. Also, we probably haven't cataloged 10% of the life forms on our ocean floors yet. There's still a lot to learn, and there will be surprises.

mentalpiracy 10y ago
Glad you made this point. To expand on it a bit: Continuing abiogenesis may very well be occuring (in the very few locations that may still resemble the beginning), but at what complexity are we defining "life" when asking this question? Simple spontaneous assembly of RNA precursors? Something more fully fledged? In any case, the problem isn't even competitors that have evolved since then - it's the existence of complex metabolism. All of the "ingredients" you would need for abiogenesis to occur are now consumed by established organisms, ripping down the molecules for their own energy needs before they can catalyze into a more complex form. Life as we know it doesn't have room for the earliest products of abiogenesis anymore. Whatever form our earliest genetic ancestors may have taken, Earth's present-day micro-biosphere is simply too ubiquitous and too ravenous.