Radical Study Suggests Life on Earth Arose Twice
A new study on the origin of life proposes that early “proto-cells” dependent on mineral surfaces in hydrothermal vents later gave rise to two independent lineages of fully free-living cells, leading some to frame this as life on Earth having effectively arisen twice. Commenters examine how strong that claim really is—since both branches still share a common genetic and metabolic root—and explore its implications for abiogenesis research, the Drake equation, and the apparent rarity of life in the universe. They also debate why new forms of life don’t seem to emerge today and whether current Earth conditions and existing organisms would suppress or outcompete any fresh origins.
Headline & framing
- Many see the “life arose twice” title as clickbait or misleading.
- Commenters stress the paper is really about free-living cells arising twice from a mineral‑dependent “proto-life,” not two completely independent origins of life.
- Better framing suggested: life left mineral substrates twice, or free-living cells evolved twice from a shared proto-cell lineage.
What “twice” means & role of LUCA
- LUCA is described as “half‑alive”: incomplete metabolism, strongly dependent on metal-rich hydrothermal vent minerals.
- Bacteria and archaea are argued to have independently filled in missing metabolic pathways and become free-living.
- Critics say this is more like a branching of one web of life than two true origins, since DNA/RNA, proteins, and core genetic machinery are shared.
Definition of life & gray areas
- Debate over whether dependence on mineral catalysts disqualifies LUCA as “life.”
- Comparisons to parasites, viruses, and organisms with strong environmental dependencies highlight that “what counts as life” is fuzzy and likely on a spectrum.
Abiogenesis difficulty & prospects
- Some dismiss abiogenesis and extraterrestrial-life studies as hopeless, arguing we will never replicate life’s origin or find independent life elsewhere.
- Others counter with recent experimental progress (self-replicating RNA, simple synthetic cells, metal-driven phosphorylation) and argue gradual advances are happening.
Extraterrestrial life, Drake equation & Great Filter
- If life (or free-living cells) can emerge more than once on one planet, some suggest this boosts the probability term for life in the Drake equation.
- Others invoke the Fermi paradox and Great Filter: finding a second independent biosphere might imply the real barrier is later (e.g., technological survival), which could be bad news for us.
- There is disagreement over whether simple life is likely common or potentially unique in the visible universe.
Why new life doesn’t keep arising now
- Multiple arguments:
- Modern Earth’s chemistry and atmosphere differ greatly from primordial conditions (e.g., Great Oxidation Event).
- Existing life rapidly consumes or outcompetes any nascent proto-life.
- Origin-of-life steps may be extremely rare, so repeating them is unlikely.