>Small correction. Since humans are diploid and contain two copies of each
>gene, the mutation rate per progeny for that gene is TWO in 10000 (not one
>in 10000, as Glenn calculated).
Shouldn't it be two in 20,000? i.e. 1/10,000 for each copy?
>Glenn speaks of "six substitutions". WHAT six substitutions? He never
>showed ANY DATA on humans showing that modern alleles typically differ by
>six nucleotides. The data he offered (the "59 alleles of MHC genes") lacks
>this necessary information. Glenn ASSUMED (out of thin air) that SIX
>substitutions are necessary. He is wrong for doing that. That data for
>typical genes shows no such thing.
Walter, what does the data show?
>In addition, Glenn model of the how genetic variation accummulates in a
>population is wrong. It does not correctly model
>the way human populations accumulate genetic variation. A) Humans are
>diploid. B) Human populations have been in the millions for most (if not
>all) recorded history. Those two factors were left out of Glenn's model.
I don't think either of these factors affect the statistics of the mutated
gene *frequency*.
>I also point out (once again) that Glenn SELECTED the MHC genes because they
>have the highest number of alleles. In other words, he SELECTED those
>particular genes that most favored his point of view. But MHC genes are
>distinctly UNTYPICAL, they do not represent typical genes. As Steve Clark
>pointed out, MHC genes -- UNLIKE MOST ALL OTHER GENES -- are subject to gene
>conversion, which injects genetic variation into those genes at a much
>higher rate. Glenn's assumptions about the mutation process and its rate of
>occurrence DO NOT APPLY TO THE MHC GENES.
>
>Sorry for the shouting, but virtually everything I am saying in this post
>Glenn has already heard before. Yet he continues with the same ill-formed
>and false arguments. Most loci of present-day animals contain between 1 and
>5 alleles (Mani 1984, p. 282), so Glenn's selective use of the MHC genes is
>fallacious on several grounds.
On this most crucial point I agree that Glenn has yet to make a decent case.
Jim
Jim Blake
Associate Professor
Department of Electrical Engineering
Texas A&M University
College Station, TX 77843