r norman  wrote:


> >BA:-
> >In Richard Dawkin's The Ancestor's Tale, he mentions the 50/50 split on
> >Humanity's ability to curl our tongue into a tube.  Might there
> >have been a
> >reason for this trait, or its' absense?  Or is this just likely
> >an example
> >of a minor mutation that is advantageously neutral?  Or
> something else?  TIA
> >Regards, Brett Aubrey.

>RN:-
> There are a number of traits traditionally taught in intro genetics
> classes that similarly seem to have absolutely no function:
>     tongue rolling
>     widow's peak hairline
>     attached vs. free ear lobes
>     hand clasping, right vs. left thumb on top
>     thumb hyperextension  (hitchhiker's thumb)
>     mid-digital hair
>
> There are some illustrations at
> http://scidiv.bcc.ctc.edu/rkr/Biology201/labs/pdfs/HumanInheritance201.pdf
>
> The usual explanation is that these are simply anatomical
> peculiarities that result from developmental processes, perhaps as
> side effects (spandrels?) It is difficult to find a trait dependent
> (or at least largely dependent) on any single gene that can be seen
> easily without doing biochemical or molecular biological studies.  So
> these have been identified as examples.  In teaching, I call them
> silly little examples of genetics.  All  "real" traits involve so many
> alleles at so many loci with so many gene interactions and
> environmental influences that they become too difficult to study in an
> intro class.

JE:-
What these "silly little examples of genetics"
illustrate is the _overpowering_ importance of
the dependency of all genomic genes on just
a single Darwinian fertile organism level
of selection. This very basic fact of biology proves
Hamilton's notion of an independently selectable
genomic gene level of selection to only
constitute a Neo Darwinian act of oversimplified
model misuse.

I would strongly suggest that the discussed phenotypes are
pleiotropic effects, i.e. they probably constitute different
phenotypes coded for by the same gene (the flip side is
genetic epistasis: many genes coding for the one phenotype).
Taken at just face value a single gene that becomes
correlated to one of these apparently neutral phenotypes
but which also codes for something else that is critical
as just an unknown pleiotropic effect of that gene may cause
a common Neo Darwinian error: the quite _unwarranted_ assumption
of just a neutral fitness for single genes.  All genes
are fitness epistatic by default _assumption_ and
not the opposite.  This is because all genomic gene fitnesses
are only selectable as  a "real" fitness, i.e. a gene
fitness epistatic trait which  always "involve so many
alleles at so many loci with so many gene interactions
and environmental influences that they become too difficult
to study". The misused heuristic assumption of an independent
genomic gene fitness level (favoured even today by
a massive Neo Darwinian bias simply because this assumption
allows organism fitness altruism) was never a valid substitute
for "difficult to study" but never the less REAL, genomic
gene fitness _dependence_. Genes are only selectable at a
single Darwinian fertile organism level of selection because
the TOTAL fitness of each Darwinian selectee is entirely
an epistatic fitness when measured at just the gene level.
Deleting gene fitness epistasis for mathematical convenience
is like a biologist deleting the head of an organism because
it became inconvenient within a study on how feet may be
selected ...


Regards,

John Edser
Independent Researcher

PO Box 266
Church Pt
NSW 2105
Australia

edser{at}tpg.com.au
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