Did Life Begin in an RNA World?

The big problem I have with the RNA world idea, and its experimental implementation, is that it runs in a soup that doesn't seem plausible.

RNA gets made from pure, energy-rich molecules that themselves are quite complex. This soup of pure monomers isn't something that just arises naturally in the absence of life. Prebiotic chemistry produces a random soup of a wide variety of chemical species, with the abundance of each declining exponentially in its size and complexity.

You see this issue all the time in origin of life claims. For example, that recent result of "all the bases of RNA and DNA were found on this asteroid by the Japanese" tended to slide over the fact that they were there at extremely low levels, mixed with huge numbers of other non-biological organic molecules.

Trying to replicate RNA in a mix of random crap will just give you polymers of crap, if it gave you anything at all.

OoL needs an idea that will work in a soup of junk, not in massively artificial pure soup on a lab bench.

It seems obvious that if replication of elementary particles appears that everything else will be an emerging property given enough time. And if you look at atoms and math there're definite parallels that once atoms can interconnect stronger than everything else (considering the 3d world) and something like Penrose's tiles where you get repeating interconnecting structures that more higher level structures would be possible. And with energy connected to the particles momentum and Heisenberg's uncertainty principle you get fluctuations in the structures that allow for both new structures and enforcing of the construction rules. You also have clear levels between forces that work on different levels that create boundaries to the structures. 3 spacial dimensions give additional directions of interactions between structures. And voila, given conditions, there's a place for emerging properties. Whether it was RNA who knows. It does seem that the search becomes way murkier toward going into the actual mechanism but the ingredients seem to be in place

> There’s scarcely any corner of Earth in which life hasn’t gained a foothold[..]

About that, not that long ago I was entertaining the idea of what environments can be completely devoid of life. I was thinking about examples like a volcano Cauldron, a nuclear reactor or the insides of a particle accelerator.

Is there a reason why the alternative idea of closed autocatalytic sets from Stuart Kauffman doesn't get nearly as much attention or discussion as the RNA origin hypothesis?

Ever since I first learned about it, it seems to me a much more likely origin of life hypothesis, as it doesn't require something to catalyze itself, which causes inevitable problems with mutation causing loss of catalytic efficiency.

Also, it is not incompatible with RNA being one of the early building blocks. It just doesn't require RNA to be where everything started.

When I read about self-replicating RNA I always think about the equivalent in the protein world, the prions. One can make many parallelisms with these scary proteins, responsible of the Creutzfeldt-Jakob disease.

Of course, the are too many limitations for evolving into some more complex, but they can self-replicate and they can infect other organisms. If we could give them an oceanic soup of PrPC and enough time, who knows?

The hardest part of the transition from prebiotic chemistry (assembling the building blocks) to an 'RNA World' is doing so in a way that can support RNA copying. As others have shown the chance of finding one replicator is low - so you need supporting RNA copying chemistry at a pretty substantial level to help that happen.

This is where the hard part of the field is currently: finding chemistry that can support accurate RNA copying that is also both sufficiently high yielding and also compatible with these reactions being inside protocells (fatty acids for example). An RNA genome only really has value when it can be selfish and keep any innovations it makes to itself inside a protocell!

I work in Origins Research - if you have questions please ask and ill try to answer with the current opinions of the field!

I think the biggest unresolved question isn't whether RNA can replicate itself, but how you get from occasional replication to a self-sustaining system

I don’t understand the objections:

Most mutations are negative dead-ends, not unlikely DNA now where most pregnancies spontaneously abort due to errors. But life has many, many chances — especially at the molecular scale. So what’s the actual problem?

Similarly, if you have a soup of 10-15 nucleotide sequences, what are the odds actually that they’d link into larger segments?

Let’s suppose that density is a million times lower than blood, so you have one picogram per gram of water. There are 10^24 grams of water on Earth’s surface and 10 base pairs weighs 10^-20 grams, giving us approximately 10^32 segments of that length.

Feel free to play with my numbers, but I’m supposed to believe that with ~10^30 pieces, we can’t have ten of them form the right sequence?

suddenly, as we enter the realm of nanotechnology ourselves, the speculative possibility of intelligent design becomes more plausible . Who knows how, what, or where life had started, but we might be the second version.

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