Readers will recall Australian paleontologist Charles Marshall’s argument for horizontal gene transfer between protocells as sparking the origin of life. Anyway, here’s the contradiction, as it appears to Paul Nelson:
Marshall argues (40:10) that the universality of the genetic code, the protein translation machinery (the ribosome, etc.), and other apparently universally shared features of cells, support a scenario in which these features arose within “the same chimney” in an alkaline hydrothermal vent. In other words, we’re back to the single theater model of OOL.
But if the main explanatory attraction of the alkaline vent story is the “massively parallel process” of “hundreds of thousands or millions” (44:00 and following) of OOL theaters in which the RNA World began independently in various localities, then one sacrifices all that probabilistic advantage, and the benefits of horizontal transfer, by reverting to a single chimney to explain the genetic code. “We don’t have to rely on a ‘freak environment’” Marshall says (44:45) “to explain the origin of life.”
Here’s an imaginary dialogue:
Marshall: The universality of the genetic code points unmistakably to a single chimney — one locality where the code first arose.
Skeptic: Why a single chimney?
Marshall: The 64 codon assignments are “ridiculous details” (40:09) — chemically arbitrary.
Skeptic: So these codon assignments would not have happened more than once? Looks like one chimney got lucky.
Thus, unless I misunderstand (always a live possibility), we’re back to postulating a “freak environment,” meaning the OOL explanation is a one-off event after all. The chemical determinism of hundreds of thousands, or millions of alkaline chimneys operating in parallel disappears, and we’re back to one very lucky setting.Paul Nelson, “Charles Marshall: Origin of Life Could Have Happened “Millions of Times”” at Evolution News and Science Today
Horizontal gene transfer will do a lot but not everything. 64 codons? A lot of freak in thatenvironment.
Meanwhile, the smokers again:
See also: New origin of life thesis: Last Universal Common Ancestor (LUCA) wasn’t actually a cell. Marshall favors horizontal gene transfer as a key method of early development because ancestor–descendant evolution is a “very slow” (42:25) evolutionary process. HGT among multiple independent lineages, by contrast, allows a “vast exchange of information,” thus sharing innovations and leading to faster development. Okay. And in the midst of all that, Dawkins’s Selfish Gene got lost in a crowd somewhere and was never heard from again.