Louis
Posts: 6436
Joined: Jan. 2006
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All, I'm collecting references for Big Post, please bear with me during this busy time!
Skeptic,
There are examples of self replicating non nucleotide, non protein chemical systems and molecules. Check out those Rebek refs I provided right at the start. Also, don't get as hung up on the semantics of "alive" or "life" like you're appearing to. The semantics aren't what's important.
| Quote | | Just a thought and certainly not a popular one but what really got it going for me is the fact that there are no other forms (or never have been as far as we know) of life on the planet. Wouldn't it be reasonable to assume that in the past 3-4 billion years something new would have developed from the DNA, RNA, protein framework and we'd see a branch that was similar but different. Wouldn't evolution and selection nearly guarantee this outcome unless such a configuration just flat out didn't function? |
Not necessarily no. First and foremost the reason abiogenesis is tough to find certain types of "fossil" evidence for, and one reason a plurality of different replicating systems don't exist in other organisms is this: we living organisms have a word for things like that: food.
Second you have it bass ackwards. the nucleotide/protein/carbohydrate (everyone forgets the glycome for some reason. Very silly) system we have now is the most successful one that DID evolve, not the only possible one that could have evolved. One of the things we are trying to find out is what other systems could have developed, mainly because they could give us clues to the precise pathways taken to the current point. Never forget Mother Nature, whilst coy and cunning, is also cheap. If it ain't broke there's no need to fix it. At some point there was a replicating system that worked well, perhaps it was in isolation, perhaps it was first amongst equals, perhaps it was an out an out winner, perhaps it was a lucky underdog, this much we don't know. What we DO know is that it occured way in the past (i.e. it was an early event, possibly one prior to the evolution of more complex organisms), we know this because from the bottom of the ocean to the top of the highest mountain every organism encountered uses the same system of transferring inheritable information to the next generation. There are variations, but the underlying "basic" chemistry is the same. (Obviously this is the shorthand, potted version) We know that the most parsimonious explanation for this is common descent, i.e. that modern organisms have evolved from this Ur-replicator, or various Ur-replicators relatively closely aligned. The problem we have (as has been stated many times on this thread) is that we don;t know what specific path was taken nor which "hurdles" were passed in what order. What we DO know is what the likely hurdles are/were, what some mechanisms and paths that could have been taken are, and roughly what is needed to make those paths. To use a magic analogy it's like the guess the card trick done badly. We know that a card is involved (woohoo! , we even have some idea of whether it's a black card or red card. We're not sure of the suit, but interestingly we know that it's a picture card. See what I mean?
Louis
Louis
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Bye.
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