"Stephen Harris"  wrote 

> > > If the population is defined as the consequence of
> > > some natural process and you observe it at different
> > > epochs of time, you will have selected samples from
> > > that population.
> > >
> > > Example: The process is the use of an old fashioned
> > > well pump to fill a tin cup. Each cupful is a sample
> > > of the water and can be considered a replication of
> > > a measurement process.
> >
> > Let's say the samples indicate that the well is
> > becoming contaminated.  Would you say that the act of
> > sampling the water is causing the well to become
> > contaminated?
> >
> > Jim
> >
> 
> No. 



> You are shooting an an imaginary target . . .

This is my point.

> If you want to argue against genetic drift, then argue
> against what people actually mean, . . . 

How would I, supposedly, know what they mean if they 
don't say what they mean?  

> , the actual claim.
> 
> >From the talk.origin FAQ:
> 
> Another example of genetic drift is known as the founder effect.
> In this case a small group breaks off from a larger population and
> forms a new population. This effect is well known in human populations;
> 
> 
> "The founder effect is probably responsible for the virtually complete
> lack of blood group B in American Indians, whose ancestors arrived in
> very small numbers across the Bering Strait during the end of the last
> Ice Age, about 10,000 years ago. More recent examples are seen in
> religious isolates like the Dunkers and Old Order Amish of North
> America. These sects were founded by small numbers of migrants from
> their much larger congregations in central Europe. They have since
> remained nearly completely closed to immigration from the surrounding
> American population.
> 
> As a result, their blood group gene frequencies are quite different from
> those in the surrounding populations, both in Europe and in North America."
> 
> SH: This does not mean that when they were taking blood samples
> from the Dunkers, there was a mistake in measuring or evaluating
> the sample containing the DNA which was compared to the parent
> population located in Europe.
> 
> Nor does it mean that taking the blood samples containing the DNA
> *caused* the gene frequencies in the two samples,

Why do you assume that it wasn't caused by NS?

> one from Europe
> and one from North America to show different allele frequencies and
> this genetic drift does not make the claim that sampling is the cause.
> Taking the samples caused the discrepancy to become known but
> did not cause the discrepancy. Genetic drift is about there being another
> mechanism to account for gene frequency which is not rule-generated
> like NS which actively selects for an allele rather than by GD happenstance.

Is there such a thing as non-active selection?  Explain.

> 
> > Let's say the samples indicate that the well is
> > becoming contaminated.  Would you say that the act of
> > sampling the water is causing the well to become
> > contaminated?
> >
> > Jim
> >
> 
> No. Your example is about a physical cause contaminating
> the water and sampling is unlikely to cause contamination
> unless you use a dirty cup. Neither is sampling the physical
> cause for genetic drift.

Then you would agree that people that do indicate that 
sampling is the cause of GD are mistaken.  Right?

> The frequency deviation between
> a founder and parent population must occur because it is
> impossible for the smaller population to represent all of the
> genes by containing them phenotypically. The parent deme
> is larger and cannot be fully represented and this does not
> even need to be measured. The idea is somewhat like only
> calling 3 people to get an opinion on the war in Iraq. It is
> not possible to get an evenly divided or representative
> statistical opinion from such a small sample which would
> actually reflect the true content of mass opinion. Your
> question uses a reverse causation which is not going to
> have any analogical connection to describing genetic drift.

IMO, I just shed light on the reverse causation that 
others indicated.

Jim
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