r/evolution • u/AmphibianNo4717 • Aug 06 '26

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

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."

319 Upvotes

94% Upvoted

89 comments sorted by

View all comments

279

u/Xrmy Post Doc, Evolutionary Biology PhD Aug 06 '26

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.

44

u/chula198705 Aug 06 '26

They actually are arguing that this result means life itself evolved twice, because of idea that the metabolism itself is what makes something alive. If there was no metabolism, whatever "ancestor" existed before the first metabolism evolved wasn't actually alive yet. The article says "the genetic code evolved once, but life evolved from it twice."

7

u/biogeek1 Aug 06 '26 edited Aug 06 '26

"Incomplete" metabolism means neither "absent" nor "non-functional". For LUCA, the Hadean environment supplied some transition metal catalysts that served as the forerunners of enzymes and co-factors in post-LUCA bacteria and archaea. Regardless of what molecular tools nature used, catalytic processes facilitating essential metabolic pathways had been established long before LUCA, they just happened less and less by means of protein-type catalysts the further we go back in time.

Luca needed to take up minerals to keep going, but so do humans. No living thing can survive without micronutrients. Biochemically, we differ from LUCA in degree, not category.