[Taxacom] More "Martian" fossils?

Kenneth Kinman kennethkinman at webtv.net
Mon Mar 7 21:10:09 CST 2011


Dear All,
       The Journal of Cosmology (apparently an online journal only) has
apparently published a recent paper by a Dr. Hoover with similar claims
(like those of NASA scientists back in the 1990s that Martian meteorites
from Antarctica contain microbial fossils similar to cyanobacteria on
Earth).  Those claims were highly criticized and these recent claims
seem even MORE doubtful (if they were not from more contaminatable sites
than the frozen Antarcitic).   My view continues to be that positive
proof of ancient Martian microbes wlll probably ultimately require
collection of rocks on Mars itself (not meteorites).  The less frozen
such meteorites are, the more likely they are prone to terrestrial
contamination.     
        In any case, I proposed the taxonomic category
Cosmogenre back in 1994, Cosmogenre Geobiota for Earth-based life, and
Cosmogenre Exobiota as an umbrella-term for any extra-terrestial life
forms that might be discovered. When the Martian "fossils" were soon
after published (later in the1990s), I suggested that if such life-forms
could be confirmed and named, that they be classified in Cosmogenre
Martiobiota. [If they had been found on Jupiter, I suppose you could
classify them as Cosmogenre Joviobiota]. 
         Anyway, you can see other various comments I
have made online about Cosmogenre Martiobiota by doing a Google search
for "Martiobiota" (especially on the Dinosaur Mailing List back around
2001).   I also mentioned Cosmogenre Martiobiota in a Taxacom posting
last April (see below).  But I seriously doubt that the recently
published article provides any new relevant information.    
            ---------Cheers,
                              Ken 
---------------------------------------------- 
[Taxacom] Classification of ALL life forms? Kenneth Kinman kennethkinman
at webtv.net Wed Apr 21 21:57:26 CDT 2010 
Dear All, 
         The relatively new overall classification of
life (2005) by Peter Ward has apparently not attracted a lot of
attention or support, which is a very good thing in my opinion, because
I don't think the newly proposed taxa are particularly natural or
useful. Actually I only stumbled across it today for the first time. 
              I do agree with him that RNA
life preceded present-day DNA-based life, and also agree with him that
viruses should be classified as "life", even if all present-day viruses
are probably parasitic. However, his classification has a lot of
problems: 
    (1) There is no evidence that cellular RNA forms (his Domain
Ribosea) ever existed. Seems more likely that a precellular RNA world
evolved into a precellular RNA-DNA world before becoming cellularized
into the obcells (of Cavalier-Smith) or other kinds of protocells. We
may be able to synthesize cellular RNA forms in the future, but giving
such freaks of nature a separate Domain is based on the totally
unsubstantiated assumption that DNA evolved after cellularization of
primitive life. 
    (2) I also see no advantage in dividing viruses between two
high-level taxa (his Dominions Ribosa and Terroa). Some present-day,
non-cellular RNA viruses may well be just as derived as non-cellular DNA
viruses). All types of viruses may have been popping in and out of
genomes for billions of years, so whether you regard viruses as living
or not, it is a polyphyletic grouping no matter how you classify them. 
(3) Most importantly, if the RNA world preceded the DNA world, and Peter
Ward and agree on that, his Dominion Ribosa is not only paraphyletic,
but paraphyletic in a highly asymmetric (and unuseful) way.   So I see
this new high-level classification as overly asymmetric, unuseful, and
as discussed above, probably unnatural. Therefore the new taxonomic
category Dominion seems both unnecessary and extremely problematic. 
      Finally, his proposal that Dominions Ribosa and Terroa
be combined into a single taxonomic category (Arborea) for earth-based
life is unneeded. He not only failed to name the earth-based taxon of
rank Arborea, I proposed a same taxonomic category back in 1994, named
Cosmogenre, and gave earth-based life the specific name Cosmogenre
Geobiota. I also proposed calling all non-Earth-based life under the
umbrella term Cosmogenre Exobiota until specific such life forms were
discovered and described. If you regard the supposed Martian "fossils"
found in Antarctica as independently evolved forms of life, I suggested
that you could perhaps call them Cosmogenre Martiobiota, but I am
skeptical about these supposed "fossils", so perhaps it is best to wait
until paleontologists find fossils on Mars (in situ on that planet), a
couple of decades from now. 
              In any case, I still prefer
classifying viruses and progenotes in taxon Parabacteria. Whether you
want to call it a separate Domain or Kingdom is one thing, but I find
the new higher-level taxonomic category (Dominion) neither natural nor
useful. Instead it seems even more unnatural and problematic than
Woese's Domains. In both cases, there seems to be an implication that
they reflect holophyletic taxa (clades) when there is no credible
evidence to back it up. Such cladification at the highest level is more
harmful than helpful. Frankly, I see them as simplistic, deadend,
classifications which divert us from a true understanding of the early
evolution of life. It is strict cladification prematurely run amok
(amuck) and is not only unhelpful, but harmful in the long run. I think
Peter Ward should be more skeptical of Woese's views. It is best to
recognize paraphyly where it clearly exists (and is extremely useful)
and stop pretending (and simplistically ignoring) that such paraphyly is
not only useful, but a fundamental expression of how the true Tree of
Life actually evolved. Even if you don't buy this at the species level,
it is abundantly clear at broader (especially Kingdom) levels. 
              ------------Ken Kinman 

Ward's overall classification of earth-based life:    Dominion Ribosa
(RNA life) 
      Domain Viroea (non-cellular RNA viruses)
      Domain Ribosea (theoretical, cellular RNA forms) 
  Dominion Terroa (RNA-DNA life) 
            most Earth life (including some
viruses) 

          NOTE: It is unclear to me if he would put
such Terroa viruses in a separate Domain from Woese's Three Domains. In
any case, the basal Domains of Terroa are almost certainly paraphyletic,
not holophyletic (strictly cladistic). The only Domain that is clearly
holophyletic is Eukaryota. I don't find either the proposed phylogeny or
the name "Terroa" (a real clade??) particularly helpful. Paraphyletic
taxa are clearly useful in my opinion, but pretending that such
paraphyletic taxa are holophyletic (strictly monophyletic) is extremely
problematic, especially at such high levels of biological
classifications. 




More information about the Taxacom mailing list