An interesting new theory, for those well versed in organic chemistry.
[Update in the afternoon]
This seems related:
Not content with achieving one hallmark of life in the lab, Joyce and Lincoln sought to evolve their molecule by natural selection. They did this by mutating sequences of the RNA building blocks, so that 288 possible ribozymes could be built by mixing and matching different pairs of shorter RNAs.
What came out bore an eerie resemblance to Darwin’s theory of natural selection: a few sequences proved winners, most losers. The victors emerged because they could replicate fastest while surrounded by competition, Joyce says.
“I wouldn’t call these molecules alive,” he cautions. For one, the molecules can evolve only to replicate better. Reproduction may be the strongest – perhaps only – biological urge, yet even simple organisms go about this by more complex means than breakneck division. Bacteria and humans have both evolved the ability to digest lactose, or milk sugar, to ensure their survival, for instance.
Joyce says his team has endowed its molecule with another function, although he will not say what that might be before his findings are published.
More fundamentally, to mimic biology, a molecule must gain new functions on the fly, without laboratory tinkering. Joyce says he has no idea how to clear this hurdle with his team’s RNA molecule. “It doesn’t have open-ended capacity for Darwinian evolution.”
Not yet.
I’m not sure why chiralty is much of an issue. The rest seems to be guided chemical processes, not something that would happen in a harsh random environment.
The smoking gun might be to find bacteria or whatever on another world that doesn’t have the same chiralty as life on Earth.
Well, I know organic chemistry pretty well, and I’m underwhelmed. This is the same old thing, thinking that the mystery is how you get 6-carbon somewhat-reduced molecules from 2-carbon fully oxidized molecules. This really doesn’t strike me as a mystery every since Stanley Miller. Indeed, I’d call this Stanley Millerism: you fill a flask with primordial (i.e. reducing) atmosphere and supply energy, and b’god, you get reduced carbohydrates!
The real mystery is how you go from “precursors” to actual biopolymers, i.e. from amino acids to proteins, from nucleotides to nucleic acids, and so forth. This is up a huge entropy gradient, i.e. very unlikely. In the complete organism, these large molecules cannot be formed without elaborate coupling of their formation to ATP hydrolysis, and they can’t be kept around without careful sequestration from water, e.g. in the case of nucleic acids being packed around histones, and in the case of proteins folding up into globular forms. We know from our habit of cooking that unfolded proteins are easy to digest into their component amino acids.
So far as I know, no one has a serious clue about how biopolymerization got its start. There’s lots of handwaving about tiny pocket environments of this or that magical sort, but the problem with this is that, evolution being the way it is, these environments needed to be ubiquitous for life to have a chance to get going and if they were once ubiquitous, why are they no longer? In short, the magical conditions for the origin of life have to have been once common (so that life actually emerged against the entropy gradient) but now rare (so that life does not continually re-emerge). A tall order.
Carl, is your comment based on the abstract, or the paper itself?
The former, Rand. If I need to read the paper to understand the main point, then the abstract is appallingly poorly written, which does not bode well for the paper itself, huh?
I, for one, welcome our new RNA overlords.
…then the abstract is appallingly poorly written, which does not bode well for the paper itself, huh?
Not necessarily. You can’t always judge a paper by its abstract, any more than you can judge a book by its cover. I think that there’s more to it than you think there is.
I bet the molecules are already registered to vote in Chicago.
Ken – Perhaps not. There appears to be a small amount of asymmetry in the laws of Nature as a whole. The fact that there is any matter in the Universe at all is evidence of that, as is the rather famous experiment (it got the physicist that performed it a Nobel, after all) that showed asymmetry in the direction in which beta decay electrons travelled when emitted from radiocative cobalt – IIRC.
Similarly, it is quite likely that high-energy ultraviolet and X-rays are circularly polarised, and with a preference for one direction – and one thing that the theory of evolution teaches us is that any advantage, however slight, is hugely magnified over the generations. For example, right-handed amino acids may well be less stable to destruction by UV than left-handed ones.
It’s also quite likely that, if there are lifeforms anywhere else in the Solar System, they will have a common ancestry with life here. There is enough material blasted off planetary surfaces by meteorite impacts to carry bacteria, buried deep inside rocks, from one planet to another. So your idea might require interstellar travel before it can be tested.
Interesting. Funny how this comes on the heels of an article I read on peptid nucleic acid (PNA). Researchers playing around with this material focus on potential applications of PNA, but also pose the hypothesis that PNA may have come before RNA, which in turn came before DNA. I hope to read more on this particular orgin of life concept…