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The metabolic science is really cool. The conclusion that life arose twice requires you to buy that proto-cells that grew on these vents and needed those metall

The metabolic science is really cool. The conclusion that life arose twice requires you to buy that proto-cells that grew on these vents and needed those metallic surfaces to survive didn’t count as “life”. Then, free living cells, bacteria and archea, could maybe be argued as having independent paths as they plugged the gaps in their metabolism independently. Same DNA/RNA, same proteins. Same broad rules of metabolism. Just some alternate paths through chemical space to plug in the metabolic gaps and get free from metal surfaces. To me, these are clearly not independent paths, but rather the branching of proto-life into two of the great kingdoms of life. It’s a stretch to call this two origins rather than a branching. Then a couple billion years later, one of em ate the other, and rather than destroy it, they both started a symbiotic relationship, and we were off to the eukaryotic race. This is all the same web of life. Not two independent streams.

ck2 2mo ago
the Great Oxidation Event caused all kinds of crazy stress = crazy mutations/adaptations where one eventually started our path * https://en.wikipedia.org/wiki/Great_Oxidation_Event https://en.wikipedia.org/wiki/Great_Oxidation_Event one of my absolute favorite PBS Space Time on the subject * https://www.youtube.com/watch?v=abvzkSJEhKk https://www.youtube.com/watch?v=abvzkSJEhKk
mycall 2mo ago
You would think there would be some isolated places where proto-life still exists for this to be true.
- Drakim 2mo ago
  Hash competition from life might cause them to go extinct, and even if it happens again it just gets out-competed to extinction fast.
  - giantrobot 2mo ago
    It could be happening on my kitchen counter right this very second. But my kitchen counter, despite a recent cleaning, is absolutely lousy with microorganisms. So the new proto-life is immediately starved or more likely eaten by existing life. There's very few places on Earth that has not been colonized by some sort of life so there's very few places a new form of life could form and succeed long enough to itself grow and spread without being starved or eaten.
- binaryturtle 2mo ago
  I always found it odd that there's only one single origin of life point or even just a single common ancestor considered in history. Shouldn't entirely new life develop all the time on earth? I mean the ingredients and building blocks are still there, the environmental situation still should work out, like availability of water, temperatures, etc. We should see a constant emergence of new life all the time. Why would that process stop, just because some other life already exists? Maybe we just can't detect this, because whatever new life happens to appear —more or less— resembles life that's already there.
  - altcognito 2mo ago
    It has to survive though in the sense that it has to live long enough for us to see it. If we think of life as "spontaneously" (roughly speaking) emerging from the right conditions reasonably rarely, it has to outcompete other existing life for some time. And then there's the chance that we might not recognize it as "new" at all.
    - tejtm 2mo ago
      A step further "novel" life (hence still simpler) made from the same raw materials as existing life would look exactly like decomposing existing life and be routinely scavenged for material.
  - Asraelite 2mo ago
    > Shouldn't entirely new life develop all the time on earth? The fact that it doesn't is a pretty simple solution to the Fermi Paradox.
    - antonvs 2mo ago
      It's probably unrelated to the Fermi Paradox. Life doesn't develop all the time on Earth largely because it's already developed. The conditions for that development are largely gone now, plus existing life easily outcompetes new life in general. This tells us nothing about the probability of the development of new life in an environment that doesn't already have life.
- randomImmigrant 2mo ago
  No, because conditions have changed markedly. For metals to act as catalysts, and replace some metabolic enzymes, they need to be in highly reduced conditions. This was true in early Earth, but about 2.5 billion years ago, we had the great oxygenation event, and over the next billion years free oxygen has gone up enough that you won’t find the reduced conditions where metal can take over the job of metabolic enzymes in much of Earth anymore. That is, what sustains today’s life prevents new proto-life for forming. You need to have the fancy gadgets life has today to continue to survive and replicate on Earth. Note though, it was other life forms that contributed to the great oxygenation event, too. This is all a continuous web.
  - foota 2mo ago
    Just curious, are there lifeforms today that rely on these metals to live in anaerobic environments? Maybe the hydrothermal vents that are talked about? Do you think complex life could develop (perhaps by moving backwards) in a way that they rely on an anaerobic metal-rich environment? I guess the oxidation event maybe was necessary for life to develop enzymes (since there wasn't sufficient evolutionary advantage for it to develop in an anaerobic environment?) but maybe something could go backwards? I'm just curious if there might be advantages for live in that sort of environment.
    - randomImmigrant 2mo ago
      There could be deep subsurface microbes that are exposed to both pure metal and anoxic conditions that are similar, but note, it’s not “metal or protein” for catalysis. Many protein catalysts have metals incorporated. What proto life did, it seems, was completely depend on metal surfaces to speed up some reactions. But that’s messy. The same metal can’t distinguish different components, so there would be competition for these surfaces, even within the same “cell”. That’s not ideal. Enzymes are much more specific. You can actually sequester different reactions. And once you have life that’s learned to do that, it will out compete any proto life like matter that may access such environments. Anaerobic microbes have enzymes also. So don’t think that reducing conditions mean no enzymes. It’s merely that in reduced conditions, you have metal that’s not oxidized available for early life -like goo to make use of. Over time, once this life learns to make newer and newer enzymes, the need to be metal dependent went away. Somewhat separately, you also had some of this lineage learn to photosynthesize, and that lead to bulk oxygen in the atmosphere, and that was initially catastrophic, then highly beneficial because oxygen based chemistry is way more energetic than anaerobic chemistry. It would be wrong to think of either condition as “better” though. They’re different. They force different tradeoffs. And both demand fine balance and dependence on the environment, eventually.
- wwarner 2mo ago
  Maybe, or maybe it was eaten into extinction.
- EA-3167 2mo ago
  Geology over large time-scales is profoundly unforgiving.
- culi 2mo ago
  Coacervates, liposomes, acetogenic precursors, etc are all commonplace and could be considered proto-life. Some scientists have even argued that viruses are proto life. Prions (misfolded proteins that can self-replicate) and plasmids (non-chromosomal DNA strands that play a major role in horizontal gene transfer) are also candidates for proto-life that blur the line between living and non-living
- andrewflnr 2mo ago
  For what it's worth, metals are still critical catalysts all over biology, they just tend to be encapsulated in biomolecules.
VLM 2mo ago
"proto-cells that grew on these vents and needed those metallic surfaces to survive didn’t count as “life”" What makes that argument extremely weak is analogies with contemporary obviously living animals. For example, humans are not alive, because we get 100% of our vitamin D ascorbic acid by scavenging from the environment, along with a handful of other animals that presumably evolved in an extremely vitamin C rich environment. If any animal, including humans, ever evolve a new ability to internally synthesize vitamin C from glucose like every other animal, then given that there were non-synthesizer animals in their ancestry who we arbitrarily define as not-alive aka dead, then we could say that life evolved twice. Note that humans could be defined as dead because we can't synthesize our own oxygen and have to scavenge 100% of it from the environment using lungs and so forth. If you pencil whip the English language hard enough, anything with lungs or stomachs is not alive. A similar line of argument would lead to all saprophytes not being alive, which is pretty ridiculous. Wood eating mushrooms are not alive because they rely on the environment to provide all their wood dietary needs. Yeah OK whatever.
- randomImmigrant 2mo ago
  No it’s not that simple. We don’t fall dead the moment we don’t get vitamin D. We can stay alive long enough to get more. That wouldn’t have been the case in these early beings, that were simply not capable of doing anything without these metals.
tshaddox 2mo ago
> The conclusion that life arose twice requires you to buy that proto-cells that grew on these vents and needed those metallic surfaces to survive didn’t count as “life”. Well, sure. For it to ever be possible to say "life arose more than once," one must decide where the boundary between life and non-life is. After all, every precursor of life arose all at once, in the Big Bang!
- randomImmigrant 2mo ago
  Hardly. There are nucleic and amino acids pretty much in every star system, we now know. But not during the big bang. Theres a lot of intermediate stages before stars are young enough to have the mix of chemicals to give rise to these precursor chemicals to life. Its stages, but it’s a bit hard to say “early stage was a single origin, then we count each bifurcated radiation as a separate start point”. Why not call it convergent evolution, which it would be, over a very long time period?
  - cubefox 2mo ago
    The Big Bang is the precursor to everything, including to nucleic and amino acids.
neuralkoi 2mo ago
The paper claims LUCA doesn't count as life because it still depended on its environment to metabolize. It's kind of interesting that there's parasites that arguably don't meet this definition either. Looking it up: Chlamydia can't reproduce independently; relies on its host's metabolism. Microsporidia can't make ATP on its own. Are these "life"?
- randomImmigrant 2mo ago
  The difference is more on survival. A closed loop metabolism is indeed a good boundary marker. Viruses would fail this. But many have “closed but for a few critical dependencies”, and the argument here is that when life depended on metals like this, it’s more critical dependencies than closed loop. Somewhere in there is a transition. But it’s poorly defined, and so the argument can be there was a bifurcation of sorts.
  - snovv_crash 2mo ago
    People love to put things into neat boxes so that we can somehow reduce them to a single concept. Unfortunately the real world is usually a bit more messy than that. This is one example that makes it pretty obvious that our model is a little bit overly reductive, and at least to me the "Is this life?" question seems to have an answer that is on a spectrum rather than binary.
    - Y_Y 2mo ago
      [flagged]
  - scotty79 2mo ago
    > A closed loop metabolism is indeed a good boundary marker. Presence of metallic catalysts is just an environmental factor. Not counting the organisms that can't live without them as life would be as not counting as life something that can't do metabolism without liquid water. Life at time of LUCA just had a bit stricter environment requirements, but it should still be counted as life. So I wouldn't read this as discovering that life evolved twice. Life just evolved a hack for dealing with environments without metallic catalysts twice.
nativeit 2mo ago
> …one of them at the other, The origin of life is as romantic as I’d hoped.
- DonHopkins 2mo ago
  Procedural Mating to a Sexy Soundtrack https://youtu.be/ofA6YWVTURU?t=1222 https://youtu.be/ofA6YWVTURU?t=1222 https://youtu.be/Dfc-DQorohc?t=2617 https://youtu.be/Dfc-DQorohc?t=2617

ck2 2mo ago

the Great Oxidation Event caused all kinds of crazy stress = crazy mutations/adaptations where one eventually started our path * https://en.wikipedia.org/wiki/Great_Oxidation_Event https://en.wikipedia.org/wiki/Great_Oxidation_Event one of my absolute favorite PBS Space Time on the subject * https://www.youtube.com/watch?v=abvzkSJEhKk https://www.youtube.com/watch?v=abvzkSJEhKk

mycall 2mo ago

You would think there would be some isolated places where proto-life still exists for this to be true.

Drakim 2mo ago
Hash competition from life might cause them to go extinct, and even if it happens again it just gets out-competed to extinction fast.
- giantrobot 2mo ago
  It could be happening on my kitchen counter right this very second. But my kitchen counter, despite a recent cleaning, is absolutely lousy with microorganisms. So the new proto-life is immediately starved or more likely eaten by existing life. There's very few places on Earth that has not been colonized by some sort of life so there's very few places a new form of life could form and succeed long enough to itself grow and spread without being starved or eaten.
binaryturtle 2mo ago
I always found it odd that there's only one single origin of life point or even just a single common ancestor considered in history. Shouldn't entirely new life develop all the time on earth? I mean the ingredients and building blocks are still there, the environmental situation still should work out, like availability of water, temperatures, etc. We should see a constant emergence of new life all the time. Why would that process stop, just because some other life already exists? Maybe we just can't detect this, because whatever new life happens to appear —more or less— resembles life that's already there.
- altcognito 2mo ago
  It has to survive though in the sense that it has to live long enough for us to see it. If we think of life as "spontaneously" (roughly speaking) emerging from the right conditions reasonably rarely, it has to outcompete other existing life for some time. And then there's the chance that we might not recognize it as "new" at all.
  - tejtm 2mo ago
    A step further "novel" life (hence still simpler) made from the same raw materials as existing life would look exactly like decomposing existing life and be routinely scavenged for material.
- Asraelite 2mo ago
  > Shouldn't entirely new life develop all the time on earth? The fact that it doesn't is a pretty simple solution to the Fermi Paradox.
  - antonvs 2mo ago
    It's probably unrelated to the Fermi Paradox. Life doesn't develop all the time on Earth largely because it's already developed. The conditions for that development are largely gone now, plus existing life easily outcompetes new life in general. This tells us nothing about the probability of the development of new life in an environment that doesn't already have life.
randomImmigrant 2mo ago
No, because conditions have changed markedly. For metals to act as catalysts, and replace some metabolic enzymes, they need to be in highly reduced conditions. This was true in early Earth, but about 2.5 billion years ago, we had the great oxygenation event, and over the next billion years free oxygen has gone up enough that you won’t find the reduced conditions where metal can take over the job of metabolic enzymes in much of Earth anymore. That is, what sustains today’s life prevents new proto-life for forming. You need to have the fancy gadgets life has today to continue to survive and replicate on Earth. Note though, it was other life forms that contributed to the great oxygenation event, too. This is all a continuous web.
- foota 2mo ago
  Just curious, are there lifeforms today that rely on these metals to live in anaerobic environments? Maybe the hydrothermal vents that are talked about? Do you think complex life could develop (perhaps by moving backwards) in a way that they rely on an anaerobic metal-rich environment? I guess the oxidation event maybe was necessary for life to develop enzymes (since there wasn't sufficient evolutionary advantage for it to develop in an anaerobic environment?) but maybe something could go backwards? I'm just curious if there might be advantages for live in that sort of environment.
  - randomImmigrant 2mo ago
    There could be deep subsurface microbes that are exposed to both pure metal and anoxic conditions that are similar, but note, it’s not “metal or protein” for catalysis. Many protein catalysts have metals incorporated. What proto life did, it seems, was completely depend on metal surfaces to speed up some reactions. But that’s messy. The same metal can’t distinguish different components, so there would be competition for these surfaces, even within the same “cell”. That’s not ideal. Enzymes are much more specific. You can actually sequester different reactions. And once you have life that’s learned to do that, it will out compete any proto life like matter that may access such environments. Anaerobic microbes have enzymes also. So don’t think that reducing conditions mean no enzymes. It’s merely that in reduced conditions, you have metal that’s not oxidized available for early life -like goo to make use of. Over time, once this life learns to make newer and newer enzymes, the need to be metal dependent went away. Somewhat separately, you also had some of this lineage learn to photosynthesize, and that lead to bulk oxygen in the atmosphere, and that was initially catastrophic, then highly beneficial because oxygen based chemistry is way more energetic than anaerobic chemistry. It would be wrong to think of either condition as “better” though. They’re different. They force different tradeoffs. And both demand fine balance and dependence on the environment, eventually.
wwarner 2mo ago
Maybe, or maybe it was eaten into extinction.
EA-3167 2mo ago
Geology over large time-scales is profoundly unforgiving.
culi 2mo ago
Coacervates, liposomes, acetogenic precursors, etc are all commonplace and could be considered proto-life. Some scientists have even argued that viruses are proto life. Prions (misfolded proteins that can self-replicate) and plasmids (non-chromosomal DNA strands that play a major role in horizontal gene transfer) are also candidates for proto-life that blur the line between living and non-living
andrewflnr 2mo ago
For what it's worth, metals are still critical catalysts all over biology, they just tend to be encapsulated in biomolecules.

VLM 2mo ago

"proto-cells that grew on these vents and needed those metallic surfaces to survive didn’t count as “life”" What makes that argument extremely weak is analogies with contemporary obviously living animals. For example, humans are not alive, because we get 100% of our vitamin D ascorbic acid by scavenging from the environment, along with a handful of other animals that presumably evolved in an extremely vitamin C rich environment. If any animal, including humans, ever evolve a new ability to internally synthesize vitamin C from glucose like every other animal, then given that there were non-synthesizer animals in their ancestry who we arbitrarily define as not-alive aka dead, then we could say that life evolved twice. Note that humans could be defined as dead because we can't synthesize our own oxygen and have to scavenge 100% of it from the environment using lungs and so forth. If you pencil whip the English language hard enough, anything with lungs or stomachs is not alive. A similar line of argument would lead to all saprophytes not being alive, which is pretty ridiculous. Wood eating mushrooms are not alive because they rely on the environment to provide all their wood dietary needs. Yeah OK whatever.

randomImmigrant 2mo ago
No it’s not that simple. We don’t fall dead the moment we don’t get vitamin D. We can stay alive long enough to get more. That wouldn’t have been the case in these early beings, that were simply not capable of doing anything without these metals.

tshaddox 2mo ago

> The conclusion that life arose twice requires you to buy that proto-cells that grew on these vents and needed those metallic surfaces to survive didn’t count as “life”. Well, sure. For it to ever be possible to say "life arose more than once," one must decide where the boundary between life and non-life is. After all, every precursor of life arose all at once, in the Big Bang!

randomImmigrant 2mo ago
Hardly. There are nucleic and amino acids pretty much in every star system, we now know. But not during the big bang. Theres a lot of intermediate stages before stars are young enough to have the mix of chemicals to give rise to these precursor chemicals to life. Its stages, but it’s a bit hard to say “early stage was a single origin, then we count each bifurcated radiation as a separate start point”. Why not call it convergent evolution, which it would be, over a very long time period?
- cubefox 2mo ago
  The Big Bang is the precursor to everything, including to nucleic and amino acids.

neuralkoi 2mo ago

The paper claims LUCA doesn't count as life because it still depended on its environment to metabolize. It's kind of interesting that there's parasites that arguably don't meet this definition either. Looking it up: Chlamydia can't reproduce independently; relies on its host's metabolism. Microsporidia can't make ATP on its own. Are these "life"?

randomImmigrant 2mo ago
The difference is more on survival. A closed loop metabolism is indeed a good boundary marker. Viruses would fail this. But many have “closed but for a few critical dependencies”, and the argument here is that when life depended on metals like this, it’s more critical dependencies than closed loop. Somewhere in there is a transition. But it’s poorly defined, and so the argument can be there was a bifurcation of sorts.
- snovv_crash 2mo ago
  People love to put things into neat boxes so that we can somehow reduce them to a single concept. Unfortunately the real world is usually a bit more messy than that. This is one example that makes it pretty obvious that our model is a little bit overly reductive, and at least to me the "Is this life?" question seems to have an answer that is on a spectrum rather than binary.
  - Y_Y 2mo ago
    [flagged]
- scotty79 2mo ago
  > A closed loop metabolism is indeed a good boundary marker. Presence of metallic catalysts is just an environmental factor. Not counting the organisms that can't live without them as life would be as not counting as life something that can't do metabolism without liquid water. Life at time of LUCA just had a bit stricter environment requirements, but it should still be counted as life. So I wouldn't read this as discovering that life evolved twice. Life just evolved a hack for dealing with environments without metallic catalysts twice.

nativeit 2mo ago

> …one of them at the other, The origin of life is as romantic as I’d hoped.

DonHopkins 2mo ago
Procedural Mating to a Sexy Soundtrack https://youtu.be/ofA6YWVTURU?t=1222 https://youtu.be/ofA6YWVTURU?t=1222 https://youtu.be/Dfc-DQorohc?t=2617 https://youtu.be/Dfc-DQorohc?t=2617