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I'm vaguely aware of that, but I was thinking about life even earlier. That is, instead of having a single universal common ancestor to all life that currently

I'm vaguely aware of that, but I was thinking about life even earlier. That is, instead of having a single universal common ancestor to all life that currently exists, would it have been possible to have a set of separate strands of life that arose from abiogenesis (or however it started) and later merged? I like the thought, though I'm aware that that alone doesn't make it more likely to be true. I'm just wondering if we know something that rules out the possibility.

tempguy9999 7y ago
> to have a set of separate strands of life that arose from abiogenesis (or however it started) and later merged? Not impossible but likely ever impossible to prove. I have read a theory that in the earliest days before impermeable cell walls formed, all dna (or whatever it was then) was being madly swapped around because horizontal transfer couldn't be stopped. No lineage then, but an amorphous glob of all life. When life got more sophisticated it then differentiated, because it could block horizontal transfer. But again, who knows.
- deleted 7y ago
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- TeMPOraL 7y ago
  'Madly swapping DNA around' happens to this day at the bacterial/archaeal level. The argument against multiple "strands" of life is simple: if abiogenesis of a single replicator is extremely improbable, abiogenesis of multiple such replicators is much less likely still. Plus, almost by definition, the first successful replicator will start replicating and eating all it can around itself, strongly altering environmental conditions and closing the doors for anything that could spontaneously arise after it.
  - tempguy9999 7y ago
    > if abiogenesis of a single replicator is extremely improbable If [0] > the first successful replicator will start replicating and eating all it can around itself Assuming such life looked much like it does now, yes. It may, it may not. I'm not disagreeing with you, these are valid points but we can't know and I am uneasy about speculating in such a case. [0] https://en.wikipedia.org/wiki/Laconic_phrase https://en.wikipedia.org/wiki/Laconic_phrase After invading southern Greece and receiving the submission of other key city-states, he [Philip II of Macedon] turned his attention to Sparta and asked menacingly whether he should come as friend or foe. The reply was "Neither." Losing patience, he sent the message: "You are advised to submit without further delay, for if I bring my army into your land, I will destroy your farms, slay your people, and raze your city" The Spartan ephors again replied with a single word: "If"

tempguy9999 7y ago

> to have a set of separate strands of life that arose from abiogenesis (or however it started) and later merged? Not impossible but likely ever impossible to prove. I have read a theory that in the earliest days before impermeable cell walls formed, all dna (or whatever it was then) was being madly swapped around because horizontal transfer couldn't be stopped. No lineage then, but an amorphous glob of all life. When life got more sophisticated it then differentiated, because it could block horizontal transfer. But again, who knows.

deleted 7y ago
[deleted]
TeMPOraL 7y ago
'Madly swapping DNA around' happens to this day at the bacterial/archaeal level. The argument against multiple "strands" of life is simple: if abiogenesis of a single replicator is extremely improbable, abiogenesis of multiple such replicators is much less likely still. Plus, almost by definition, the first successful replicator will start replicating and eating all it can around itself, strongly altering environmental conditions and closing the doors for anything that could spontaneously arise after it.
- tempguy9999 7y ago
  > if abiogenesis of a single replicator is extremely improbable If [0] > the first successful replicator will start replicating and eating all it can around itself Assuming such life looked much like it does now, yes. It may, it may not. I'm not disagreeing with you, these are valid points but we can't know and I am uneasy about speculating in such a case. [0] https://en.wikipedia.org/wiki/Laconic_phrase https://en.wikipedia.org/wiki/Laconic_phrase After invading southern Greece and receiving the submission of other key city-states, he [Philip II of Macedon] turned his attention to Sparta and asked menacingly whether he should come as friend or foe. The reply was "Neither." Losing patience, he sent the message: "You are advised to submit without further delay, for if I bring my army into your land, I will destroy your farms, slay your people, and raze your city" The Spartan ephors again replied with a single word: "If"