COMMENTS:
Ray,
Of course, there would have been “many competing LUCAs” (perhaps thousands or millions), occurring at all places on the planet in which conditions were compatible with “life” at that time. [Either the deep ocean where hydrothermal vents and serpentinization (the process of converting minerals such as olivine, pyroxene, and amphiboles into serpentine minerals (those rich in magnesium and silicate) — through hydrothermal alteration) of the sea-floor — provided a source of H2. Or the ocean surface where the atmosphere would have provided a source of H2 derived from volcanoes and metamorphism (alteration of the composition or structure of a rock by heat, pressure, or other natural phenomenon)]. Ultimately, one genome “was the winner” — although it would be impossible to identify where “the original winner” was located — that resulted in all life on the planet.”
A somewhat similar occurrence happened with the origins of Homo sapiens. From fossil evidence, at least 21 “fits and starts” of sublines have so far been discovered and named (as discussed most recently in the 18 Aug 2024 GEITP email blog) over probably ~5 million years (and there are probably dozens or hundreds of other fossil sublines to be discovered). All this happened — before “the winner” in Africa emerged from Homo heidelbergensis or Homo erectus — which then “won over” the Denisovan and Neanderthal sublines that had become extinct during the most recent Glacial Maximum in the late Pleistocene (129,000 to 11,700 years ago).
And, yes, evolution continues to happen today — even if we cannot appreciate it.
DwN
From: Ray D’Alonzo
Sent: Sunday, August 25, 2024 11:49 PM
Dan,
It seems to me that a single last common ancestor is an assumption. Why couldn’t there have been more than one? Chemistry is chemistry. The same necessary elements could have assembled at different locations on the planet. Furthermore, there is no reason why that process isn’t happening presently right under our nose.
Ray