Re: [asa] lactose tolerance mutation

From: PvM <>
Date: Wed Dec 13 2006 - 12:12:39 EST

Neutrality drives evolution:

While this may sound somewhat self contradictory, few people have
realized the importance of neutrality in evolution. For instance,
neutrality plays an essential role in RNA evolution and has been shown
to be an essential component in evolvability, the capacity to evolve.

Let me try to explain. If sequence space were islands of functionality
separated by values of low fitness, evolution would indeed be very
difficult. However, in case of RNA, findings show that sequence space
is characterized by few common and many uncommon motifs connected by
extensive pathways of neutrality. In other words, any given motif is
'close' to any other motif in the sense that it can be approached
closely via neutral pathways alone.

Toussaint, in his thesis, has shown how neutrality is an essential
component for evolution's success to evolve and that neutrality itself
is a selectable trait...

Recently, the work by Gavrilets on Holey Landscapes has shown that
also for proteins, the concept of neutral pathways exist,
significantly improving the probabilities of evolution.
 -----Begin quote------
Tellgren wrote:

To summarize, the implications of the assumption of a randomly chosen
fitness function do not just include Wolpert and Macready's NFL
result, but also the results

   1. that the absolute performance of any search for high-fitness
genotypes is fairly good and, importantly, independent of the size of
the genotype space, and
   2. the set of high-fitness genotypes is well-connected and the
connectedness ncreases with increasing dimensionality of the genotype

More metaphorically, the NFL scenario may deny biological evolution a
free lunch, but once the lunch break is over it hands evolution a
large free bowl of noodle soup.
-------end quote-----

And on neutrality

Gavrilets homepage ( has various of
his relevant publications available
On 12/13/06, Randy Isaac <> wrote:
> It's about as close to a quote as I can get. It certainly surprised me when
> I heard it.
> I expected him to throw in a loophole like "well, maybe on very rare
> occasions..." but he didn't.
> Could you explain more what you mean by "neutrality does drive evolution"?
> Randy
> ----- Original Message -----
> From: "PvM" <>
> To: "Randy Isaac" <>
> Cc: <>
> Sent: Tuesday, December 12, 2006 11:02 PM
> Subject: Re: [asa] lactose tolerance mutation
> > Man, if Paul really said this then he seems even more confused about
> > evolutionary science than I had imagined.
> > First of all, there exist good examples of beneficial mutations,
> > second of all, neutrality does drive evolution.
> > Are you sure he said this as this seems to be quite a vacuous and
> > erroneous statement.
> >
> > On 12/12/06, Randy Isaac <> wrote:
> >>
> >>
> >> This afternoon I listened to the radio program "The Bible Answer Man"
> >> sponsored by the Christian Research Institute. Paul Nelson was the guest.
> >> He
> >> is very impressive in his style of communication. It was generally the
> >> standard ID fare but I was surprised at his answer to one of the call-in
> >> questions. The caller asked whether there were any beneficial mutations
> >> or
> >> if they were all harmful. Paul essentially said none was beneficial and
> >> mutations may be neutral at best but neutrality doesn't drive evolution.
> >>
> >> I wish I could have jumped in and asked about the article that Jack Haas
> >> posted on his blog on Dec. 11 (I presume you all regularly check Jack's
> >> blog
> >> at ) on lactose
> >> tolerance. If I understand it correctly this is not only an example of a
> >> positive mutation (assuming it is positive to be tolerant of lactose) but
> >> also one of convergent evolution. I'm not an expert in this field so I
> >> have
> >> some questions for those of you who are. Are they implying that the same
> >> mutation occurred in different populations to achieve convergence in
> >> lactose
> >> tolerance? Or are these different mutations? If so, what are the
> >> characteristics of the mutations causing this change? Is it silencing a
> >> specific protein? Activating a silent one? In general, I would like to
> >> know
> >> what you think is the significance of this finding.
> >>
> >> Randy
> >
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Received on Wed Dec 13 12:13:18 2006

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