On 8/8/2013 8:10 PM, chris peck wrote:
Hi Prof. Standish
Thanks so much for the offer. I actually hunted the paper down from a link in the
original springer resource you posted. Some of it flies over my head, but not all of it,
so I'll persevere...
"ISTM that you are implicitly assuming that these replicating
hypercycles only emerged once, whereas I would think that replicating
RNA probably arose many times quite easily when life wasn't around to
gobble them up."
Not really, but re-reading your original post I'm actually quite persuaded by the idea
that even if these replicating mechanisms emerged very rarely it would be possible and
enough to invoke the anthropic principle. After all, it only had to emerge once in the
whole universe for these questions to get asked...
Whats niggling me though is something else. Dawkins sometimes intimates that the current
code was something that itself evolved from low to high fidelity. For reasons I've made
I can't see how that can be so. Evolution is a process where beneficial but random
changes accumulate and are passed on through successive generations. But if a random
mutation in the code results in catastrophe as Dawkins acknowledges then that can't happen.
But random mutations *don't* result in catastrophe. Your body has hundreds of cells with
copying errors in their DNA. Of course only those in gametes can get passed to progeny.
But even gamete DNA can have copying errors without catastrophic results.
This is to say that if the code evolved then that evolution could not be Darwinian in
nature.
Sure it could. Random mutations, most of which are bad, many of which are neutral, and a
few of which are beneficial relative to subsequent natural selection. If DNA copying were
perfect there could be no evolution, so if some organisms developed with perfect (or just,
"too good") error correcting codes, they almost certainly got left behind in the
evolutionary arms race and have left no descendants.
Brent
I find it reassuring that there is research underway addressing this issue. I found this
paper over my lunch break:
http://www.pnas.org/content/103/28/10696.full
They emphasize ambiguity over error in early coding mechanisms and suggest a kind of
Lamarkian evolutionary dynamic that existed prior to and eventually gave way to
Darwinian evolutionary dynamics. Horizontal vs. vertical heredity etc. In many ways that
might be seen as heresy by the biological community but laymen like me don't mind a
little heresy here and there. We don't know any better. :)
Anyway, it seems to offer the following response to Statham. His argument is underpinned
by the assumption that all evolution is Darwinian. If one sheds that assumption then the
code could evolve without the consequent catastrophe.
--
You received this message because you are subscribed to the Google Groups
"Everything List" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to everything-list+unsubscr...@googlegroups.com.
To post to this group, send email to everything-list@googlegroups.com.
Visit this group at http://groups.google.com/group/everything-list.
For more options, visit https://groups.google.com/groups/opt_out.
