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Comment by dopylitty | Hacker News Reader

It’s amazing how RNA pops up everywhere we look. As our tools get better and better we find simpler and simpler RNA based things floating around, apparently being replicated by some chemical or biological processes.

It’s hard to see the trillions of other planets in the known universe along with its age and apparently limited chemistry and not imagine how similar RNAs should’ve have popped up over and over again.

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"Some chemichal or biological processes" seem to always be living cells, isn't it. So any kind of RNA depends on already existing living cells.

I mean it's a bit more complicated, since ribosomes are themselves mostly made of RNA. Which gives RNA a kind of unique property that it can not only be transcribed into new proteins but also build the machinery to do this transcription.

Given a bath of amino acids you can easily use RNA to bootstrap a whole self-replicating system, which is probably what happened by accident at some point.

"Probably" - yet the real calculations of probability say it is not going to happen at all, ever. And then when we observe the natural world...lets take things that are alive and then die. Well, are they not essentially a soup of everything one would possibly need for life to arise, even with external energy source from the sun (think road kill as an example)...and yet we know of no instance in which life, by chance formed out of it; all the dead bodies seem to degrade into dirt. Of course if it did happen even once - how would we know as we can't possibly observe all occasions of such things. Anyway - just some thoughts I had on the matter.

Calculations don't matter if they are based on faulty premises. There is nothing all that special about earth that what happened here couldn't have happened on trillions of planets across billions of years in the known universe. I think that's why biologists and just generic humans like me posit that there has to be life elsewhere in the universe, no woo woo or gods needed.

Every dead body you've ever seen is teeming with life. Now, it's probably impossible for a novel life form to arise in a dead body, because the existing life (bacteria) that takes over has been optimized by billions of years of evolution to consume the resources around it better than any novel self-replicator possibly could. But that's not really evidence that a self-replicator couldn't get going if there weren't much better ones already around.

I’m curious why you say “easily”. Has this ever been done in a realistic environment? AFAIK it takes over 100 base pairs to produce a single self-replicating RNA, and prior to its ability to self-replicate there is nothing which would favor its creation over other random RNA.

I mean 'easily' is very much relative. It's easier than trying to build a cell from scratch, but much harder than say writing a quine in lisp.

Well you gonna be excited when you learn about proteins.

>we find simpler and simpler RNA based things

>In the early 20th century, plant pathologists came across viroids

>some of the obelisk sequences encoded proteins involved in RNA replication, making them more complex than standard viroids

I don't mean to interrupt your narrative but you seem to be getting information from other sources and I was wondering what they are.

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