A new study suggests it might have been:
In simulated ancient seawater, clay forms a hydrogel — a mass of microscopic spaces capable of soaking up liquids like a sponge. Over billions of years, chemicals confined in those spaces could have carried out the complex reactions that formed proteins, DNA and eventually all the machinery that makes a living cell work. Clay hydrogels could have confined and protected those chemical processes until the membrane that surrounds living cells developed.
…
Scientists previously suggested that tiny balloons of fat or polymers might have served as precursors of cell membranes. Clay is a promising possibility because biomolecules tend to attach to its surface, and theorists have shown that cytoplasm—the interior environment of a cell—behaves much like a hydrogel. And, Luo said, a clay hydrogel better protects its contents from damaging enzymes (called “nucleases”) that might dismantle DNA and other biomolecules.
(Colour emphasis added to signify certainty.)
Clay isn’t a new origin of life idea. It has been championed by origin of life (OOL) researcher A. G. Cairns-Smith, as a rival to “RNA world” (RNA, they claim, happened to evolve before DNA), which he labelled “absurd to imagine” because there are “14 major chemical/molecular hurdles”against more primitive nucleotides like RNA.[1] Remember this; you won’t hear it from tax-funded textbooks introducing RNA world.
Information theorist Hubert Yockey dismisses clay world because clay crystals offer very little information. A crystal structure repeats the same information indefinitely, whereas life’s minimum information density is somewhere around the level of DNA.[2] And OOL theorist Leslie Orgel (1927–2007), who championed RNA world, noted that if clay had the structural irregularities needed to enable RNA to emerge, it probably wouldn’t reproduce it accurately. [3]
But these guys wrote this stuff a while back, so it is doubtless time to throw some clay again. The hydrogel thing sounds new; let’s see what RNA world supporters (and others) say about that.
[1]A. G. Cairns-Smith, Seven Clues to the Origin of Life: A Scientific Detective Story, [1985], Cambridge University Press: Cambridge UK, 1993, reprint, pp.46-48.
[2] Hubert Yockey, “Self Organization Origin of Life Scenarios and Information Theory,” Journal of Theoretical Biology, Vol. 91, 1981, p. 14.
[3] Leslie Orgel (1927–2007), “Origin of Life on the Earth,” Scientific American, vol. 271, October 1994, p. 78.