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.
Isn’t there evidence mitochondria took a different evolutionary path before they were captured by cells?
There are also a few other really weird cellular-scale life forms I forget the names of that could be different evolutionary paths. Though I’d think the seeming hegemony of life comes from life competing in the same environments and either killing off or adapting to/with other evolutionary chains like with mitochondria. It surely wouldn’t take billions or even millions of years for microscopic life to spread across Earth, so there’s been plenty of time for any different upstarts to mix or kill off each other.
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.
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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.
Isn’t there evidence mitochondria took a different evolutionary path before they were captured by cells?
There are also a few other really weird cellular-scale life forms I forget the names of that could be different evolutionary paths. Though I’d think the seeming hegemony of life comes from life competing in the same environments and either killing off or adapting to/with other evolutionary chains like with mitochondria. It surely wouldn’t take billions or even millions of years for microscopic life to spread across Earth, so there’s been plenty of time for any different upstarts to mix or kill off each other.
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.