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From: William Hyde <wthyde1953@gmail.com>
Newsgroups: talk.origins
Subject: Re: Las universal common ancestor
Date: Sat, 13 Jul 2024 18:03:52 -0400
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erik simpson wrote:
> The nature of the last universal common ancestor and its impact on the 
> early Earth system
> 
> Abstract
> The nature of the last universal common ancestor (LUCA), its age and its 
> impact on the Earth system have been the subject of vigorous debate 
> across diverse disciplines, often based on disparate data and methods. 
> Age estimates for LUCA are usually based on the fossil record, varying 
> with every reinterpretation. The nature of LUCA’s metabolism has proven 
> equally contentious, with some attributing all core metabolisms to LUCA, 
> whereas others reconstruct a simpler life form dependent on 
> geochemistry. Here we infer that LUCA lived ~4.2 Ga (4.09–4.33 Ga) 
> through divergence time analysis of pre-LUCA gene duplicates, calibrated 
> using microbial fossils and isotope records under a new cross-bracing 
> implementation. Phylogenetic reconciliation suggests that LUCA had a 
> genome of at least 2.5 Mb (2.49–2.99 Mb), encoding around 2,600 
> proteins, comparable to modern prokaryotes. Our results suggest LUCA was 
> a prokaryote-grade anaerobic acetogen that possessed an early immune 
> system. Although LUCA is sometimes perceived as living in isolation, we 
> infer LUCA to have been part of an established ecological system. The 
> metabolism of LUCA would have provided a niche for other microbial 
> community members and hydrogen recycling by atmospheric photochemistry 
> could have supported a modestly productive early ecosystem.
> 
> https://www.nature.com/articles/s41559-024-02461-1

Does not the existence of the immune system itself imply the existence 
of other life forms?  Smaller, parasitic or infectious?  But since this 
is LUCA they themselves cannot have left descendants.


So if they were virus-like they went extinct and the virus form evolved 
again.

Corrections and comment welcome, as ever.

William Hyde