Re: Rapid genetic variation

Walter ReMine (wjremine@mmm.com)
Sat, 19 Aug 1995 20:15:30 -0500

Abstract: This continues the (now getting tedious) debate with Glenn Morton
over the rapid generation of genetic variation. Glenn is now wandering
around, trying to find an argument that sticks. Population genetics is not
his field, so his tenacity is to be admired. But his persistence in holding
to a bad argument is not. Is Glenn really making an argument? Or is he on
an exploratory mission? He (partially) makes one new argument (about
racially distinctive sets of alleles) and it is refuted here. (Jump to that
section by searching for "Racially distinctive".)

Glenn writes:
>No, Walter, this is not a different argument. Perhaps you misunderstood. This
>has always been the point. At each given location on the genome there is
>more variability than we should expect if there was a ...
>genetic bottleneck anytime in the past 200,000 years.

Glenn argued that there exists TOO MUCH genetic variation (more than can be
provided rapidly). How much? In the case of humans he said 59 versions of
a given gene could not be provided in 200 generations. I showed him it
could easily be accomplished in ONE generation -- and 200 generations would
provide lots of room to spare.

> Now, the point is that a lot of the traits which make Africans, Africans
>and Europeans, Europeans are due to the different alleles we are dealt.

Glenn originally made his argument in terms of ONE gene, he said 59 versions
was too much genetic variation for one gene. He emphasized that his
argument was precisely about the variation at ONE gene site, and even
protested when I showed that a population can easily receive 700 MILLION new
mutations (which means MANY new versions of MANY genes) in ONE GENERATION.
He seems to have forgotten that now, and is talking about SETS of genes for
Africans and SETS of genes for Europeans. His argument is a traveling
target, he is now wandering around trying to make it work. Let me say it
again? 700 million new mutations is a whopping lot for creating many sets
of variant genes, and it can plausibly be accomplished in one generation.

******
Racially distinctive sets of genes ----

>it gives you 2500 years in which to develop all those
>alleles that Africans and Europeans do not share.

Glenn says, "all those alleles" All WHAT alleles? He has not identified
the alleles that are distinctly unique to all Africans or all Europeans.
What set of alleles is sufficient and necessary to make you African? Or
European? Is it one allele? Or five? Or 100? Glenn hasn't even discussed
this yet.

>First there is a [problem] of collecting all those mutations into one
>segment of the population. ....
>It matters not that some guy in Siberia gets a gene for kinky
>hair, someone in South America gets a gene for Steatopygy, and some guy in
>Europe gets a gene for a broad nose. If they are not collected together, you
>do not have an african (or at least one among many types of africans).

And,

>But Noah and his family did not start with two million copies of a gene at
>least as far as reproduction is concerned. They started with 10 alleles max
>at each location ...

Fine, for the sake of discussion let's freeze the genetics right there --
and allow NO MORE MUTATIONS. Glenn allows that the population contains 10
alleles maximum for a given gene. How many genes are in the human genome?
Here I will use the evolutionists' figure of 100,000 genes to code for the
human body. (I think it a serious underestimate on their part, it amounts
to merely 2.9 percent of the DNA in a human sperm.) Thus, that small
population contains roughly 10 x 100,000 = ONE MILLION different alleles.
Suppose the (male/female) couples go in different directions and thus are
the genetic founders of different groups, (such as Africans and Europeans).
Is ONE MILLION different alleles enough to form various racially distinctive
SETS of alleles? Glenn hasn't even begun to discuss this matter, much less
show any problem. If it's many racially distinctive sets of alleles that
you want, then there isn't any problem even if we allow ZERO mutations. Goo
gobs of genetic variation are already present, and the founder effect does
the work.

******

> Secondly, you are avoiding the issue of how multiple mutations can be
>accumulated in the same 1000-unit long string of DNA. Alleles are not always
>simply a 1 position change in the sequence.

I haven't "avoided" that issue. And it doesn't save Glenn's argument
either. When the number of alleles for a given gene is small, then, to a
good approximation, each new mutation creates a unique new allele (even if
the new mutation occurs in an allele that has already suffered previous
mutations). On the other hand, when the number of alleles is high, then
there is already a lot of genetic variation, and Glenn's argument fails by
definition. Moreover, I pointed out that sexual reproduction is a mechanism
for mixing separate alleles together and creating new unique alleles. Glenn
is just kicking up dust. He hasn't said anything that can save his argument.

>Six hundred thousand, one-locus
>mutations to a genetic code do not make for 600,000 alleles. They might just
>as well make for 600,000 fetus's which failed to develop. And it is a well
>known fact that large numbers of fertilized eggs spontaneously miscarry or
>fail to implant.

Glenn forgot that my analysis ALREADY deducted (and disallowed) those
mutations which fail to grow to sexual maturity and reproduce into the
following generation. It counted only those mutations that make it through
a complete generation cycle. My argument began with an effective population
size of reproducing adults, and assumes the population size remains roughly
constant generation to generation. Thus, all the miscarriages, the failures
of eggs to implant, etcetera, are not counted in the population size and so
not counted in my calculations. Glenn's point is empty.

> Third, I do not think ... that we
>see the type of genetic variation which you envision here in molecular
>studies of various animals. Your model of allele formation would require
>massive, massive numbers of alleles. I just don't think we see that. Can you
>provide documentation?

Yes, I can provide documentation. The best kind ... from Glenn. My
argument used his figures for mutation rate, etcetera. (It set aside and
ignored the factor of 50. It used his measures of genetic variation -- the
MHC, with 59 alleles. It showed every step in the math.) He now complains
that I can provide TOO MUCH genetic variation -- which is the exact opposite
of his original argument.

Walter ReMine
P.O. Box 28006
Saint Paul, MN 55128