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- Hacker News
- If true, fl in the Drake equation just got much bigger.by pingou
- 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.by tim333
- 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.
by Rigdanir - 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"
by merogran - 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.
by andrewflnr - The link the site points to seems like a better source (no ads, cites DOI etc, affiliated with AAAS rather than random aggregator website):by gyomu
- Clickbait headline.
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.
by MarkusQ - 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.