Re: failure

On 6 Oct 2005 10:07:49 +0200, David Brown
<david@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:

>John Larkin wrote:
>> On 5 Oct 2005 12:43:30 +0200, David Brown
>> <david@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>>
>>>Of course it has to repair mutations -
>>
>>
>> Great- we agree on a meta-machanism, a means by which DNA tunes its
>> own evolutionary process. The natural mutation rate is way too high,
>> so DNA evolved multiple repair mechanisms to undo external damage to
>> itself.
>>
>
>We fully agree that there are mechanisms controlling the rate of
>evolution. We agree that these mechanisms evolved. All we disagree
>with is your implication that DNA controls these mechanisms actively (or
>should be able to control them, or at least *would* be able to control
>them if *you* were DNA). If you didn't actually mean that, and it was
>just a matter of the words you choose, then we've agreed here all along.
>
>>
>>>evolution requires slow, rare
>>>mutations.
>>
>> Or, at this stage, maybe none at all.
>>
>
>Some new features can be made by recombining existing genetic sequences,
>others require entirely new ones. But anyway, the sequence
>rearrangements you are so fond of are just another type of random
>mutation - they are part of what make offspring different from their
>parents.
>
>>
>>>If each new generation was born with a different number of
>>>legs, you'd have a hard time producing more than an occasional
>>>individual that would survive. So it is important that there are
>>>mutations, but not too many.
>>
>>
>> Why do we need mutations, a fundamentally destructive, usually
>> damaging process, whan we can transpose genes, and switch them on and
>> off... much more sensible mechanisms. It's not as though DNA is
>> hurting for randomness, in its environment.
>>
>
>There are several reasons. Mutations can't be avoided entirely. They
>are important when evolving to suit radically different environments.
>And they introduce new sequences, which are often harmful, but could be
>beneficial, and could not occur by just swapping around genes (which in
>itself can be equally harmful). But it is certainly true that swapping
>around genes is a very powerful mechanism, giving better chances of
>benefits for lower risks than simply bashing bits of genes with UV rays
>or other mutations - as shown by the fact that most "highly evolved"
>lifeforms reproduce sexually.
>
>
>

At least gene swapping (an no doubt other fancy mechanisms) can be
targeted. Olde Reliable sequences, the device-driver level so to
speak, can be redundant and heavily defended/repaired against
mutation. The higher-level stuff in the heirarchy, the bits that
determine behavior or structure or immunology, can be carefully
fiddled for advantage.

Just like we compile code.

John


.

Relevant Pages

  • DNA and Alleles
    ... One article on population genetics states, ... natural selection, genetic drift, mutation, migration and nonrandom ... What is the relationship between genes and a ... subset of a cell's DNA. ...
    (sci.bio.evolution)
  • Re: Exactly what are "recessive genes"?
    ... >>the mutation would be dominant. ... mechanisms for these phenomenon are extremely varied. ... >>for recessive mutations to be limited to enzymatic genes, ... > pretty closely to the two fundamental categories of proteins: ...
    (sci.bio.evolution)
  • Re: Darwin, Evolution, the Animal Kingdom, and Man
    ... >> mechanisms other than random mutation mechanisms of natural selection? ... > genes" may become active when the environment changes. ... > complicated than random genetic mutation. ...
    (sci.cognitive)
  • Re: toldya so
    ... random errors in the amino acid sequences and launch the consequent ... Genes come in pairs. ... may hang around in low numbers until either a new mutation or a new ... DNA repair ...
    (sci.electronics.design)
  • Re: failure
    ... The natural mutation rate is way too high, so DNA evolved multiple repair mechanisms to undo external damage to itself. ... All we disagree with is your implication that DNA controls these mechanisms actively. ... So it is important that there are mutations, ... And they introduce new sequences, which are often harmful, but could be beneficial, and could not occur by just swapping around genes. ...
    (sci.electronics.design)