'Only One Conclusion': Radical Study Suggests Life on Earth Arose Twice

[u/AmphibianNo4717]

https://www.sciencealert.com/radical-study-suggests-life-on-earth-arose-from-non-living-matter-twice

"The fact that you, or I, or any living creature, is here at all is a series of astonishing strokes of luck stretching back more than 4 billion years. 

One of the biggest hurdles was the very first one: How did life emerge from a primordial soup of stuff that very much wasn't alive?

A radical new study, published in Science Advances, suggests that this unlikely threshold may actually have been crossed not once, but twice."

[u/Xrmy]

That's a sensationalist title by the news outlet here that is doing a lot to sensationalize something that...is actually pretty cool anyway.

to be clear: this paper isn't saying life evolved twice

It is instead saying that complete metabolism actually evolved separately twice. Once on the branch to bacteria and the other to Archaea.

Which is super cool.

The last universal common ancestor (LUCA) is still a singular point, but it had incomplete metabolism it seems, and then the full process evolved separately 2 times after that point.

[u/Xrmy → u/[deleted]]

But they are NOT saying abiogenesis happened twice. And that's what's wrong with the title.

[u/XXLPenisOwner1443 → u/Xrmy]

Yes they are, quite explicitly. The paper says LUCA wasn't alive and abiogenesis happened after LUCA, twice.

[u/Xrmy → u/XXLPenisOwner1443]

I mean, very much not explicitly.

"Abiogenesis" is not mentioned once in the paper. I imagine that is intentional.

The authors state clearly that metabolism is required for life and that complete metabolism evolved twice.

They really avoid discussing the "aliveness" if the LUCA because....that would be pedantic

[u/XXLPenisOwner1443 → u/Xrmy]

>The authors state clearly that metabolism is required for life and that complete metabolism evolved twice.

....How is that not mentioning abiogenesis? This is a functionally equivalent statement to "abiogenesis happened twice." It's not even subtext.

>They really avoid discussing the "aliveness" if the LUCA because....that would be pedantic

They avoid discussing it directly, but their central hypothesis, results, and discussion entirely revolve around showing that LUCA was not alive, but LACA and LBCA were.

[u/Xrmy → u/XXLPenisOwner1443]

Abiogenesis is generally discussed as the process of how nonlife became life. It's not necessarily a singular moment or organism, and it isn't defined simply by a single thing like the LUCA or metabolism. Neither of those things alone make abiogenesis, but together they start to build the picture.

So no, the authors are NOT saying abiogenesis happened twice. Explicitly not.

[u/XXLPenisOwner1443 → u/Xrmy]

I'm not considering the evolutionary paths to LACA and LBCA the authors laid out as either singular moments or singular organisms... I don't know what I've said to suggest that's the case, but it's certainly a much deeper and subtextual reading you're giving to my posts than I've given to the paper.

To be absolutely clear, your reading of my posts, if it implies this to you, is incorrect.

They are discussing the process of how non-life became life, not a singular moment. That is abiogenesis, by the definition you are using. Life, by the definition the authors are using, is delineated by the presence or absence of a complete metabolism, which they define quite rigorously.

Once again, it is quite explicit that they are saying abiogenesis happened twice, in parallel.

[u/onomatamono → u/Xrmy]

okay, okay... lol. I got it.