From: Eliezer S. Yudkowsky (sentience@pobox.com)
Date: Thu Feb 23 2006 - 09:37:10 MST
Eliezer S. Yudkowsky wrote:
> Alejandro Dubrovsky wrote:
>>
>> Someone could claim that the optional methylation of the C base is
>> another state, ie each base pair having 5 options. Then you can
>> multiply by 3 to tell whether the stretch of DNA is in A-DNA, B-DNA or
>> Z-DNA form (obvious overestimation there since the stretches cannot be
>> one base long, and not all stretches can form Z-DNA). Then you can add 3
>> to that multiplier to tell whether the DNA is hanging loose, it's
>> wrapped around a histone, it's hanging between histones, or are more
>> tightly packed (the tightness of the packing depends on the acethylation
>> of the histones, but past some level of packing i'm assuming they are
>> just not read at all, so there's probably no need to make the multiplier
>> acethylation-level dependent) (again, gross overestimation since minimum
>> size for each of these stretches is >> 1) (also, add, not multiply to
>> the multiplier since these states afaik do not get a choice of whether
>> they are in A-,B- or Z-). That'd be 5 x 6 = 30 choices per base. So
>> that would be lg(30) x 3 billion about 15 billion bits, slightly under 2
>> gigabytes as upper limit.
>
> Heh. Unfortunately, this potential extra data storage buys you nothing
> whatsoever in the way of information.
>
> Natural selection pressure on mammals maxes out at O(1) bits (of Shannon
> information) per generation. See
> http://dspace.dial.pipex.com/jcollie/sle/, though the argument is older
> than that - it appears for example in George Williams's "Adaptation and
> Natural Selection".
>
> Bases mutate at a rate of 1e-8 per base per generation.
>
> Thus natural selection cannot maintain more than 1e8 bits of information
> against the pressure of degenerative mutation.
Wait, I take that back. Now that I think about it, packing more
information into one base might increase the total information that can
be maintained against degenerative mutation.
However, it still won't be anything remotely on the order of a gigabyte.
-- Eliezer S. Yudkowsky http://intelligence.org/ Research Fellow, Singularity Institute for Artificial Intelligence
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