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-al

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"