What does the remarkably early appearance of the Last Universal Common Ancestor tell us about the first days of life on Earth? My article in yesterday's Observer. www.theguardian.com/science/2025... - ThreadSky

philipcball.bsky.social • 33 days ago

What does the remarkably early appearance of the Last Universal Common Ancestor tell us about the first days of life on Earth? My article in yesterday's Observer.
https://www.theguardian.com/science/2025/jan/19/luca-is-the-progenitor-of-all-life-on-earth-but-its-genesis-has-implications-far-beyond-our-planet

Comments

alicerizzardo.bsky.social•33 days ago

If it is "easy" for life to appear, isn't it surprising that a universal common ancestor exists at all? Is the expectation that life appeared on Earth only once, or that all unrelated life forms became extinct?

philipcball.bsky.social•33 days ago

It's a good question. It could be that the spread of life was rapid compared to its origination. Or that indeed alternative biologies began but were out-competed. Would be great to see hints of the latter in the geological record...

lembrando.bsky.social•33 days ago

The difficulty in the problem of estimating the probability of life originating in a presumably hospitable planet like ours lies in the self-sampling assumption. We’re alive! In the absence of solid contradicting evidence, it’s very possible it’s an extremely unlikely event.

philipcball.bsky.social•33 days ago

Another option entirely, not considered here, is panspermia. But that's the boring answer, as it doesn't really answer anything! (Which isn't to say it doesn't remain possible.)

johnnie02661.bsky.social•32 days ago

Thanks for this article! Fascinating. After I read it, I was trying to find out more about horizontal gene transfer aka jumping genes aka transposable elements aka transposons and came across this which (if you don’t already know about it) might be of interest: https://www.quantamagazine.org/dna-jumps-between-animal-species-no-one-knows-how-often-20210609/

profriggsy.bsky.social•33 days ago

Excellent article...

galileasun.bsky.social•32 days ago

As usual, splendid writing. I really believe you’re the only one who could have written about such an intricate subject.

lembrando.bsky.social•33 days ago

‘a 4.2bn-year-old and already rather highly evolved Luca, Lenton says, “tells us that [starting] life is not that hard.’

If it’s not that hard, wouldn’t you think scientists would’ve created life in a lab by now?

popsciencebooks.bsky.social•33 days ago

“Hard” is relative here. The evidence suggests life got started relatively quickly, though. Unlike the origin of cells with nuclei which seemed to be a ‘harder’ process. Also, Abiogenesis may have taken longer than humans have been a species. Not something someone could knock together on a Tuesday.

lembrando.bsky.social•33 days ago

There’s also no evidence that life originated more than once in the 4.5B years of Earth’s history. Sure, you could think that other non-DNA forms existed more than 4.2B years ago but were eaten up by Luca’sancestors. But the possibility that life started as one very rare event is still there.

walker212.bsky.social•33 days ago

Fascinating article!

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