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The Drunken Sailor's Stumble (was Re: March of "progress")



----- Original Message -----
From: "Ken Kinman" <kinman@hotmail.com>
To: <dinosaur@usc.edu>
Sent: Sunday, March 04, 2001 8:50 PM
Subject: March of "progress"


> Tim,
>      The old "march of progress" idea is criticized mainly because
progress
> is such a loaded word (just like "superior" is a loaded word).
>      But it does reflect the directionality of evolution, certainly in the
> time dimension, and often in complexity as well (although the latter is
> somewhat reversible, as in Mesozoans, pentastomid "worm" crustaceans, and
> parasites in general).   Single cells must precede multicellularity.
> Amphibians and reptiles had to precede birds and mammals.  [and I strongly
> believe Eubacteria were around almost a billion years before giving rise
to
> the Metabacteria-Eukaryota clade].

Stephen J. Gould, in his IMHO excellent book "Full House", makes a very good
case against this. He writes that if you plot the complexity of life on the
x axis against the number of species (or, probably, individuals or whatever)
on the y axis, a distorted Gauss curve will emerge; distorted because there
is a "left wall", the minimal complexity of life, to the left of which there
are only viruses, but apparently no "right wall". Life began near or at the
left wall and has been filling all the available space; there is probably an
equal probability that a species will be more vs. less complex than its
ancestor (though there is a selection pressure for decreasing complexity,
the evolution of parasitism, but apparently no such universal one for
increasing complexity, so it might be on the whole more probable that
descendants are less complex). Single cells must indeed precede
multicellularity and so on, but multicellularity etc. _need_ not evolve.

[so all you think is wrong about the 3 domains is the failure to find that
(Eu)bacteria is paraphyletic?]

>      So because of this directionality

which only appears a posteriori, and even then only if one overlooks the
bulk of life, bacteria,

[...]
>      Life on Earth (Geobiota) is optimally divided into a handful of
> Kingdoms (about 4-6),

Optimally? Why?

> and everyone's education should include a basic
> understanding of their relationships.

I agree.

[...]
> The confusion it is generating
> is just a tip of the iceberg, and the now overused crutch of ad hoc
> "horizontal gene transfer" is just sweeping the confusion under the rug.

Horizontal/lateral gene transfer is a real phenomenon, and often it is
detectable. It is probably always tempting to us it as an ad hoc crutch, but
it happens. An hour ago I cited "Natura non facit saltus", but genes can and
do make quite big jumps at times.

>      But just one simple step-----Stop using "Archaea" as outgroup to
> Eubacteria-----would go a long way to mitigating the mess (and the name
> "Archaea" is helping to perpetuate such misrooting).  That has been my
main
> message to bacteriologists all along, whether they believe my other ideas
or
> not.

Erm... are there any bacteriologists on this list?

> Otherwise medicine, agriculture, and other important fields (that
> depend on accurate bacterial phylogenies)

Not being a bacteriologist, I can't imagine... how?

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