For all we know it did. We believe that the Earth is 4.5 billion years old but it’s estimated that conditions suitable for life only appeared about 200 million years after that. Since the oldest fossils we’ve found are 3.7 billion years old, there is a 600 million year gap between when we think life could have formed and out earliest records of it.
There is every possibility that life formed multiple times in different environments on Earth in those first few hundred million years and then been wiped out by one of the frequent cataclysms that ravaged the early Earth. We have no way of knowing though. If life formed around a volcanic vent and then got wiped out by a meteor impact there would be no evidence it ever happened. Even if such life was wiped out by a climatic shift or something like that, there still wouldn’t likely be much evidence left if any right now. The Earth’s surface has been changed so much in the last 3.7 billion years, there are very few areas older than that where such fossil records from before that could be found.
And there’s a good chance that other life would be chemically or structurally similar, so without DNA evidence we’d confuse it’s fossils with others (see Prototaxites).
Also, maybe life does reoccur relatively frequently, but is killed by existing bacteria, viruses, bacteriophage… again, for being too chemically/structurally similar to the existing life.
The conditions for deep biosphere life exist throughout the universe. While surface life is apparently very rare, most planetary bodies with a hot core and subsurface moisture should have some layer conducive to this sort of life.
Since we don’t fully how life arises from non-life, it’s speculation as to whether life really is uncommon or not. But deep biosphere life should easily be the most common form in the universe. Estimates for it on Earth put it at about 90% of our biomass of archaea and bacteria.
For all we know it did. We believe that the Earth is 4.5 billion years old but it’s estimated that conditions suitable for life only appeared about 200 million years after that. Since the oldest fossils we’ve found are 3.7 billion years old, there is a 600 million year gap between when we think life could have formed and out earliest records of it.
There is every possibility that life formed multiple times in different environments on Earth in those first few hundred million years and then been wiped out by one of the frequent cataclysms that ravaged the early Earth. We have no way of knowing though. If life formed around a volcanic vent and then got wiped out by a meteor impact there would be no evidence it ever happened. Even if such life was wiped out by a climatic shift or something like that, there still wouldn’t likely be much evidence left if any right now. The Earth’s surface has been changed so much in the last 3.7 billion years, there are very few areas older than that where such fossil records from before that could be found.
And there’s a good chance that other life would be chemically or structurally similar, so without DNA evidence we’d confuse it’s fossils with others (see Prototaxites).
Also, maybe life does reoccur relatively frequently, but is killed by existing bacteria, viruses, bacteriophage… again, for being too chemically/structurally similar to the existing life.
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Life has been found deep in the Earth’s crust. Think about that in this context.
https://en.m.wikipedia.org/wiki/Deep_biosphere
The conditions for deep biosphere life exist throughout the universe. While surface life is apparently very rare, most planetary bodies with a hot core and subsurface moisture should have some layer conducive to this sort of life.
Since we don’t fully how life arises from non-life, it’s speculation as to whether life really is uncommon or not. But deep biosphere life should easily be the most common form in the universe. Estimates for it on Earth put it at about 90% of our biomass of archaea and bacteria.