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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].
So because of this directionality and the natural preoccupation of humans with their own ancestry, we have unfortunately shown these biases with unfortunate words like "progress" and "superior". And the poorly known bacteria and protists were unduly neglected in our classifications and studies for a long time.
But let's not get carried away in trying mitigate those errors, swinging the taxonomic pendulum too far the other way----which is what Three Domains (and a preoccupation with a few select genes) is doing. This was an overreaction and we are now facing a taxonomic arms race (although that's the least of the problems it is causing).
Life on Earth (Geobiota) is optimally divided into a handful of Kingdoms (about 4-6), and everyone's education should include a basic understanding of their relationships. On the surface, a cladified Three Domain system seems even simpler, but there is not a doubt in my mind that it is simplistic, erroneous, and damaging. 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.
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. Otherwise medicine, agriculture, and other important fields (that depend on accurate bacterial phylogenies) will suffer as a result. That is why I am so critical of Woese's "paradigm". And I also worry that cladistic "analysis" will get a lot of the blame, even though any good tool will cause damage when used inappropriately.
----Gotta run, Ken
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