h a l f b a k e r yVeni, vidi, teenie weenie yellow polka dot bikini.
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Possibly, we are the adaptation of life's earlier forms, which began not in water, but earlier, in volcanic or lava environments, or at the boundaries of water formation in extra-hot environments, while the world was cooling down, during some period of darkness after a volcanic eruption, or in what was
then the north or south poles.
It is commonly accepted that life most probably started with thermophiles and that chemosynthesis is what started it all.
This not-completely-thought-through hypothesis, which I am proposing, says that in fact, it may have happened earlier than previously thought, getting energy from the existing hydrogen gas, hydrogen sulfide or ferrous ions which were abundant, and interacting with thermodynamically favorable premordial co2 to create organic chains with carbon.
Perhaps ATP/ADP, and amino acids preceded the C chains as organic matter, then when water came around, bingo! We got life as we know it?
4.2 Billion Years ago - slap-bang in the middle of the Hadean Eon
https://www.nature..../s41559-024-02461-1
"By treating gene presence probabilistically, our reconstruction maps many more genes (2,657) to LUCA than previous analyses and results in an estimate of LUCA’s genome size (2.75Mb) that is within the range of modern prokaryotes. The result is a picture of a cellular organism that was prokaryote grade rather than progenotic and that probably existed as a component of an ecosystem, using the WLP for acetogenic growth and carbon fixation. We cannot use phylogenetics to reconstruct other members of this early ecosystem but we can infer their physiologies based on the metabolic inputs and outputs of LUCA. How evolution proceeded from the origin of life to early communities at the time of LUCA remains an open question, but the inferred age of LUCA (~4.2Ga) compared with the origin of the Earth and Moon suggests that the process required a surprisingly short interval of geologic time." This dates LUCA (but not earliest life) at ~4.2 billion years ago, in a no-oxygen environment, but one that likely had abundant water - likely habitats being H2 rich deep-ocean hydrothermal vents, or at the interface on the surface of (hot) oceans and a H2-rich atmosphere. Note the Earth-melting, moon-forming, (likely) life-extinguishing impact is dated 4.5 billion years ago, so life managed to bootstrap itself in a time period of less than 300 million years. Is there a different view that places the formation of life later than this? [zen_tom, Sep 06 2025]
The Hadean Eon
https://en.wikipedia.org/wiki/Hadean
"The Hadean is the first and oldest of the four geologic eons of Earth's history, starting with the planet's formation about 4.6 Ga" [zen_tom, Sep 06 2025]
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[+] for opening this sort of discussion. |
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I may be telling you things you already know but there has been an hypothesis that life first formed when organic molecules accumulated on the surface of clays. Another hypothesis, less popular, is that in the early Universe there was a phase during which molecules formed into microörganisms when the Universe was much smaller, the ideal temperature for the origin of life and contained more concentrated matter than it now does. According to that hypothesis, all life of the kind familiar here was distributed throughout space and later settled on various hospitable bodies, including Earth. If that's so, the kind of life in question would be similar to life today in that it uses water. The molecular clock hypothesis also seems to show that life using DNA, I think (possibly RNA if the RNA world hypothesis is also accepted), is older than Earth. |
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I tend to believe in panspermia because it gives a larger volume and more arbitrary reactions for abiogenesis than just the Earth's surface or oceans, or smaller regions such as geothermal vents or carbonate-rich lakes. |
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