Every Living Thing May Trace Back to Something That Wasn't Quite Alive

The ancestor of every living thing may have needed a rock to finish being alive.

LUCA, the last universal common ancestor, sits near the root of the family tree connecting bacteria, plants, animals and everything else alive today. It is usually treated as an early organism. Research suggests that description may be doing more work than the biology can support.

Researchers reconstructed ancient metabolism by comparing enzymes across bacteria and archaea. Their results suggest LUCA possessed genes for only about half of the enzymatic machinery needed for the metabolic network they studied.

But missing enzymes do not necessarily mean missing chemistry.

At hydrothermal vents, metals such as iron, nickel, cobalt and palladium can act as catalysts. The researchers propose that these metals carried out reactions LUCA could not yet perform with enzymes of its own. In laboratory experiments, palladium also helped phosphite drive phosphorylation reactions, showing that at least part of the proposed chemistry can work.

That creates a deeply inconvenient organism, definitionally speaking. LUCA may have had a genetic code, made proteins and conducted part of its own metabolism while still depending on the rocks around it for essential reactions.

Bacteria and archaea later developed different enzymes for some of those missing jobs. If the reconstruction is right, the two lineages may have independently completed the transition to fully autonomous cellular life.

Life may not have arrived all at once. It may have gradually become harder to call chemistry.

Read the full story at Scientific American, August 20, 2026

Hot Take: Biology keeps drawing bright lines around processes that spent billions of years refusing to respect them. "Alive" may be one more category that looks cleaner in a textbook than it ever did in nature.