LUCA (Introduction)

by dhw, Tuesday, January 21, 2025, 11:26 (22 hours, 20 minutes ago) @ David Turell

GEORGE: I came across this article on the Last Universal Common Ancestor (LUCA)
and thought you might be interested.
https://www.nature.com/articles/s41559-024-02461-1

I’m afraid this huge article is mostly way beyond my range of comprehension. However, I did note a couple of passages which raised questions, but I’ll be quite happy if someone can point out what I’m missing.

QUOTE: By definition, we cannot reconstruct LUCA’s contemporaries using phylogenomics but we can propose hypotheses about their physiologies based on the reconstructed LUCA whose features immediately suggest the potential for interactions with other prokaryotic metabolisms.

If there were other “prokaryotic metabolisms” living at the same time, what is the point of singling out LUCA? If they were all interacting, could LUCA not have been one particular community of prokaryotic metabolisms?

QUOTE: A chemoautotrophic acetogenic LUCA could have occupied two major potential habitats (Fig. 3e): the first is the deep ocean […] The second habitat is the ocean surface […] Another possibility may be that LUCA inhabited a shallow hydrothermal vent or a hot spring.

Back where we started – nobody knows which it was?

QUOTE: 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 (~4.2 Ga) compared with the origin of the Earth and Moon suggests that the process required a surprisingly short interval of geologic time.

DAVID: The article provides a different estimate of LUCA age and size. The striking point is how quickly life appeared after the Earth formed. Strongly supports the concept of a designer at work.

4.2 billion years is “inferred” and approximate. How do you and the authors know the length of time it normally takes for life to appear and complexify?

I’d be interested to hear George’s own views.