4-Billion-Year-Old Fossil Protein Resurrected

First time accepted submitter Zoë Mintz writes "Researchers have 'resurrected' a 4-billion-year-old Precambrian protein and found they resembled those that existed when life began, proving that protein structures have the ability to remain constant over extended periods of time."

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Re:Sorta

[Samantha Wright]

The LUCA dates range from 3.5 to 4 gya, so it's even broader than that. Different estimates come from different sources and with different precision, though, so it's not quite right to give a single symmetrical error measurement. I'd personally vote for saying 3.8 +0.2/-0.3 gya. In the case of this article, however, they chose 4 exactly because of their molecular clock predictions.

The article doesn't clarify between the Archean and Hadean periods, however, and it's probably bad to equate the LUCA with the beginning of life because we have pretty strong evidence that the LUCA was already a very well-developed organism, with a complete central dogma, hundreds of enzymes, and a preference for potassium ions over sodium ones. Wikipedia cites several science journalism pieces that argue for a Palaeoarchaean LUCA.

As for what the LUCA actually looked like, I would say somewhere between Archaea and Bacteria, but defying both categories. Archaeans have a number of later innovations that definitely disqualify them from being good representatives, since they can do sophisticated chromatin modelling (folding DNA to make gene transcription more efficient) and have a unique membrane composition (which I personally like to imagine may be evidence of multiple abiogenesis events, but that's a bit of an uninformed theory.) Bacteria, on the other hand, are known to have a tendency towards simplifying their genomes. If anything the bias seems to be toward Bacteria as the root; no one has recently proposed that Archaeans pre-date Bacteria.