I had no idea

[james_davis_nicoll]

As pointed out in email, JEP on evolution.

Comments

[carloshasanax.livejournal.com]

What tandw said. That sort of system will look like food to modern life.

I don't think there's that much of a gap. Working from the top down, catalytic RNA has been known for over thirty years. Working from the bottom up, ribose forms in condensation reactions from formaldehyde; adenine forms in condensation reactions from hydrogen cyanide. The bottleneck step, to my mind, would be the formation of reaction conditions which favor the nucleoside linkage.

The pairing of replication with metabolism and membrane division are separate things, of course, but there are signs of early lock-in.

[neowolf2.livejournal.com]

That might work if you have pure ribose, and pure bases. I doubt such things can work at all in the more random glop formed by condensation reactions,without enzymes to catalyse precisely the ones you want.

The scam in origin-of-life research is to show you can make chemical X at some low concentration in some mixture with other stuff, and then start the next round of experiments with pure X purchased from a supply house.

[carloshasanax.livejournal.com]

Actually, not so much. There's a lot more possibility in chemical replication than what we see today, because modern life has converged on a highly efficient solution. You don't need exactly ribose -- DNA is conclusive evidence of that -- and the sugars that work are thermodynamically preferred in Butlerov-style synthesis. Even more obviously, you don't need exactly adenine. There are five big bases that are used in the current set-up, but there are dozens which have been identified as occurring.

There are also plausible natural circumstances which concentrate organic compounds with different properties, in processes roughly analogous to ore formation, or the separation procedures undergraduates perform in chemistry lab.

It's the specific problems -- nucleoside linkage, the origin of chirality, the coupling to phosphate energetics, etc -- that are the real pain in the ass. The "random glop" argument is a red herring.