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>"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

>"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?

lend000 9y ago
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. https://en.wikipedia.org/wiki/Abiogenesis https://en.wikipedia.org/wiki/Abiogenesis
- hetman 9y ago
  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.
  - jessaustin 9y ago
    Yes, I immediately thought of the final scene of Anathem, when I read GP comment.
  - gnaritas 9y ago
    > 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.
    - didgeoridoo 9y ago
      > 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.
      - gnaritas 9y ago
        Agreed.
  - didgeoridoo 9y ago
    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?
  - Retra 9y ago
    They don't have to eat each other. https://en.wikipedia.org/wiki/Great_Oxygenation_Event 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.
EGreg 9y ago
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?
- api 9y ago
  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.
  - EGreg 9y ago
    That's a wishful explanation. So everywhere and in every instance, DNA-based life went and devoured all other life? Really? OK, so what about on Mars?
    - xenadu02 9y ago
      You misunderstand. 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.
api 9y ago
> 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.
- roywiggins 9y ago
  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.
chongli 9y ago
appears to descend from a single common ancestor 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 https://en.wikipedia.org/wiki/Mitochondrial_Eve

lend000 9y ago

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

hetman 9y ago
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.
- jessaustin 9y ago
  Yes, I immediately thought of the final scene of Anathem, when I read GP comment.
- gnaritas 9y ago
  > 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.
  - didgeoridoo 9y ago
    > 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.
    - gnaritas 9y ago
      Agreed.
- didgeoridoo 9y ago
  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?
- Retra 9y ago
  They don't have to eat each other. https://en.wikipedia.org/wiki/Great_Oxygenation_Event 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.

EGreg 9y ago

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?

api 9y ago
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.
- EGreg 9y ago
  That's a wishful explanation. So everywhere and in every instance, DNA-based life went and devoured all other life? Really? OK, so what about on Mars?
  - xenadu02 9y ago
    You misunderstand. 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.

api 9y ago

> 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.

roywiggins 9y ago
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.

chongli 9y ago

appears to descend from a single common ancestor 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 https://en.wikipedia.org/wiki/Mitochondrial_Eve