The metabolic science is really cool. The conclusion that life arose twice requires you to buy that proto-cells that grew on these vents and needed those metallic surfaces to survive didn’t count as “life”.
Then, free living cells, bacteria and archea, could maybe be argued as having independent paths as they plugged the gaps in their metabolism independently. Same DNA/RNA, same proteins. Same broad rules of metabolism. Just some alternate paths through chemical space to plug in the metabolic gaps and get free from metal surfaces.
To me, these are clearly not independent paths, but rather the branching of proto-life into two of the great kingdoms of life. It’s a stretch to call this two origins rather than a branching.
Then a couple billion years later, one of em ate the other, and rather than destroy it, they both started a symbiotic relationship, and we were off to the eukaryotic race. This is all the same web of life. Not two independent streams.
Should be "Life left mineral substrate at least twice" or some such. The research is interesting, but they're playing word games in the telling of it by saying the most recent common ancestor of all life wasn't alive (because it was dependent on a mineral surface), but two of it's children gave rise to lineages that were.
The headline is a little confusing. They're still talking about a "split" between bacteria and archaea, so even under this theory, the very roots of metabolism and (I'm guessing) genetic code etc still have a single origin.
Anyway, it does provide a nice reason that bacterial and archaeal cell membranes are different.
The "life arose twice" makes for a sensational headline.
Free-living cells arose twice would be more accurate.
I heard a good way to describe LUCA is "half-alive", with about 40% of its metabolic reactions driven by the mineral substrates in the pores it lived in, and lacking a complete cell membrane.
I can't help but speculate LUCA would have some simple membranes to cover the "windows" of the mineral pores and keep vital molecules inside - a tiny pore-dwelling metabolic network.
The question of "how much independent metabolism counts as life" is looking a lot more like the question of "how many facial hairs make a beard"
Life may have arisen loads of times but life as we know it out competed the other forms. It's still a bit unknown how rare or common abiogenesis is. It'd be interesting to check out Mars more to see if there's any underground there.
I find this fascinating. LUCA clearly predates some pretty core, basic metabolic capabilities, and yet nucleotide metabolism is complete. This seems to indicate that LUCA and its progenitors were confined to their hydrothermal vents and that the cells could not survive beyond due to the missing metabolic networks.
I wonder if LUCA was not a single cell, but many different populations in different hydrothermal vents, exchanging genetic material wrapped by accident in the remains of the cell membranes as the host cells die and are ejected from their vents.
Perhaps the missing post-LUCA metabolic enzymes evolved by accident from proteins recruited simply to concentrate the required metal ions that are scarcer and ever more diluted the farther from the black smokers you get. Free living was merely a happy bonus effect.
Many essential metabolic enzymes require metal ions for catalysis, structure, or substrate binding. So in some sense the dependence is still there, we just learned to take bits of substrate with us while travelling.
I was already under the impression that life on Earth has had several "Game Over -Play Again?" periods.
I assume that the difference here, is that it went completely to zero, before restarting. The other times, there was a bit clinging on, that seeded the restart.
unfortunately the field of abiogenesis, just like extraterrestrial life, is a lost cause.
The reality we will never be able to replicate creation of life nor find life on other planets (except via contamination). it's why we've never gotten any closer. and i'm not even religious
what's really going to blow your mind is our solar system looked completely different several times with different proto-planets and Earth/Moon is likely made from remnants of those other planets
If life could arise once, why would the conditions not be amenable to it arising more than once? Sure, life tends to pollute-terraform for itself, but it's a big planet, with more than enough distance between the first occurrence and pristine environment for it to happen several more times.
Radical Study Suggests Life on Earth Arose Twice
(sciencealert.com)189 points by jnord 7 August 2026 | 114 comments
Comments
To me, these are clearly not independent paths, but rather the branching of proto-life into two of the great kingdoms of life. It’s a stretch to call this two origins rather than a branching.
Then a couple billion years later, one of em ate the other, and rather than destroy it, they both started a symbiotic relationship, and we were off to the eukaryotic race. This is all the same web of life. Not two independent streams.
Should be "Life left mineral substrate at least twice" or some such. The research is interesting, but they're playing word games in the telling of it by saying the most recent common ancestor of all life wasn't alive (because it was dependent on a mineral surface), but two of it's children gave rise to lineages that were.
https://www.eurekalert.org/news-releases/1138775
Anyway, it does provide a nice reason that bacterial and archaeal cell membranes are different.
Free-living cells arose twice would be more accurate.
I heard a good way to describe LUCA is "half-alive", with about 40% of its metabolic reactions driven by the mineral substrates in the pores it lived in, and lacking a complete cell membrane.
I can't help but speculate LUCA would have some simple membranes to cover the "windows" of the mineral pores and keep vital molecules inside - a tiny pore-dwelling metabolic network.
The question of "how much independent metabolism counts as life" is looking a lot more like the question of "how many facial hairs make a beard"
I wonder if LUCA was not a single cell, but many different populations in different hydrothermal vents, exchanging genetic material wrapped by accident in the remains of the cell membranes as the host cells die and are ejected from their vents.
Perhaps the missing post-LUCA metabolic enzymes evolved by accident from proteins recruited simply to concentrate the required metal ions that are scarcer and ever more diluted the farther from the black smokers you get. Free living was merely a happy bonus effect.
I assume that the difference here, is that it went completely to zero, before restarting. The other times, there was a bit clinging on, that seeded the restart.
I'm your distant ancestooor
I have some news for you
Yes, they think life came once before
The reality we will never be able to replicate creation of life nor find life on other planets (except via contamination). it's why we've never gotten any closer. and i'm not even religious
* https://en.wikipedia.org/wiki/Formation_and_evolution_of_the...