Re: bacteria evolution

[Adrian Teo <Adrianteo@mailhost.net>]

McCarrick, Allan wrote:
> 
> Bacteria due seem to be the best examples of "microevolution."  But the

> thrust of the C&EN article was that a simple change in a cell wall
> protein required specific changes in 9 genes !  One might have been
> tempted to say a priori that 9 genes could not mutate in concert.
> Therefore that could never occur by chance.  But it did !
> 
> No information was given whether any of the 9 mutations alone would 
have
> been beneficial, harmful, or neutral.  If they were individually 
harmful,
> then they probably could not have accumulated one by one.  If they were

> neutral, it would be statistically unlikely that they would accumulate
> because of reverse mutations.  The only alternative would be 
individually
> beneficial mutations accumulating until a greater benefit results from
> their mutual interaction.
> 
>      My impression is that the 9 genes were altered simultaneously.  Is

> this good news or bad news for Behe's irreducably complex barrier for
> evolution ?  These bacteria changed only one cell wall protein.  Behe
> talks about cilia and blood clotting mechanisms - much more complex.  
If
> 9 genes can be changed in concert to produce an effective adaptation
> couldn't 10 or 11 or 100 ?

Nine mutations occuring in concert seems pretty amazing. But to further
suggest that since 9 together is apparently possible, then why not ten
or more, does not follow. More accurately, it is possible, but the
probability significantly reduces as we require more genes to change
simulataneously. As the probability of the event reduces (9 must be
pretty unlikely already), it certainly does increase our willingness to
concede that some external forces must be at work (divine and
intelligent perhaps).