15 July 2023

Abiogenetic origin of life-- Metabolism First?

I am reading a truly interesting book, called Spontaneous Order and the Origin of Life (Steven Bratman), on the biochemistry of the origin of life (for nonscientists, although conceptually it does get a teeny bit hairy here and there). The simplest gist: spontaneous (abiogenetic) chemistry precedes actual life: Metabolism First. I feel that this idea is essentially correct (and I use the word "feel" rather than "think" to denote a partially intuitive response). And here's the interesting part: if this is right, then the chemistry of life actually precedes Darwinian evolution and operates more like a non-equilibrium phase shift. Which, if true, for reasons I could almost explain, in turn means that at its metabolic core, life probably really is more or less inevitable if the conditions for it exist. And, according to most planetary formation theories, it should. Not everywhere, but lots of wheres. 

Parenthetically, the sine qua non "conditions" include the functional equivalent of "white smoker" hydrothermal vents, which were present on Earth within 300-500 mA after the inception, and are likely present on at least some substantial percentage of aqueous lithic planets literally everywhere in the universe. By "substantial" I mean, say more than half a percent or so, since there probably are many, many ways for things to go wrong. I like the term "aqueous lithic" better than "terrestroid" or "earthlike," which are somewhat inaccurate in their implications. Most such planets are likely actually quite unlike Earth, since there seems to be growing evidence that Earth is close to the lower mass threshold for such essential qualities as plate tectonics and moderately deep oceans-- most planets that have these features are probably so-called "Superearths," with masses between 1.0 and 2.0 Earth masses, or so. The larger range of Superearths, which by definition are up to the mass of Neptunelike planets able to hold onto hydrogen in their atmospheres, around 3.0+, are almost certainly uninhabitable for other reasons. 

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