Reclassifying Viruses as Living?

B.J.Tindall bti at DSMZ.DE
Fri Mar 17 07:57:50 CST 2006

At 16:20 16.03.06 -0600, you wrote:
>Three (at least) trains of thought have gone through my mind in response to
>this thread:
>(1) in trying to determine the "validity" of human-created boxes, one could
>start with an essentially phenetic approach:  How many attributes
>distinguish the contents of one "box" from another?  The particular thing I
>have thought of before seeing this discussion is that maybe we could
>exclude prokaryotes from life.  The differences between them and eukaryotes
>sometimes seem to exceed the similarities.  Would it be valid to count up
>the ways in which Bacteria differ from eukaryotes, on the one hand, and
>viruses in the other direction, and draw a line one way or the other based
>on the results, and, for lumpers, place the prokaryotes with the viruses in
>one large group and eukaryotes in another?  (I have not attempted to list
>the features systematically so genuinely don't know how it would come out).

mmmm..... most eukaryotes actually depend on prokaryotes to survive
(mitochondria and chloroplasts are considered to have their origins in free
living prokaryotes). There are indeed differences between the euakyrotes
and prokaryotes, but both clearly fall under all definitions of life.
Viruses are generally not capable of replicating without a host and they
also do not appear to be able to generate their own energy, they also do
not appear to have a classical "unit membrane". I would not include viruses
as prokaryotes.

>(2) I am fascinated in that every Biology text I have ever used is
>unequivocal in drawing a line excluding viruses from life and including all
>prokaryotes and eukaryotes, and I have willingly followed this custom with
>only minor qualms.
>(3) I think sometimes we underestimate the importance of the specific types
>of "flow" mentioned earlier that are usually lumped together under the
>concept of "energy".  As I may have said much earlier in a different
>context, I tend to think broadly of evolution, for example, as a biological
>expression of the second law of thermodynamics (leading toward the cliche
>that all biology can be reduced to chemistry and all chemistry to physics -
>or perhaps at least part of biology can be reduced directly to physics
>without yet another "box" which we usually call Chemistry.

Sounds like reductionism. I agree that the underlying process in a cell
have a physical-chemical basis, but I don't think that an organism is alone
the sum of those features. Certainly one key element is the
physical-chemistry argument is that biology is the envy of every chemist
who tries to make a biological moleculae. The stereo specificity of
biolology is something which chemists find difficult to reproduce in vitro,
unless one is starting with stereo isomers.


>For what it is worth, and cheers,
>( (At 08:12 AM 3/16/2006 -1000, Richard Pyle wrote:
>>Dick beat me to the punch.  I'm not sure if I would be better placed in the
>>"systematist" box or the "taxonomist" box, but whichever I am, I don't think
>>in terms of natural vs. artificial taxa.  Ultimately, they are all
>>artificial, because they are all boxes.  And I believe that all boxes are
>>ultimately artificial (except, perhaps, at sub-atomic scales).  Of course,
>>there is variation among boxes as to the "fuzziness" of their walls --
>>meaning the extent to which certain properties consistently apply in most of
>>the cases, most of the time.
>>But that doesn't mean that creating artificial boxes is a bad thing.  The
>>point of my original respose to Gordon is that we need these boxes to
>>effectively communicate with each other.  It's why Linnaeus' system of
>>nomenclature beat out the prior system of describing groups of organisms
>>with a long series of adjectives.  Language is pretty severely crippled as a
>>tool without nouns.  The danger, I think, comes when we fall into the trap
>>of seeing these boxes as "real" ("natural") -- which I believe was Gordon's
>> > -----Original Message-----
>> > From: Taxacom Discussion List [mailto:TAXACOM at LISTSERV.NHM.KU.EDU]On
>> > Behalf Of John Grehan
>> > Sent: Thursday, March 16, 2006 4:43 AM
>> > Subject: Re: Reclassifying Viruses as Living?
>> >
>> >
>> > And I will duck. I have no universal recipe for natural vs non natural.
>> > But systematists don't let that stop them from arguing natural vs
>> > artificial taxa. In biogeography it is popular to draw geographic areas
>> > and call them natural. In once sense they are, since they exist with
>> > respect to whatever criterion one uses, but in another they are
>> > artifacts of current patterns rather than any uniquely shared origin.
>> > Others might argue otherwise I expect.
>> >
>> > John
>> >
>> > > -----Original Message-----
>> > > From: Taxacom Discussion List [mailto:TAXACOM at LISTSERV.NHM.KU.EDU] On
>> > > Behalf Of Richard Jensen
>> > > Sent: Thursday, March 16, 2006 9:26 AM
>> > > Subject: Re: [TAXACOM] Reclassifying Viruses as Living?
>> > >
>> > > OK, I'll bite - how do we determine whether a box is natural as
>> > opposed to
>> > > artificial?
>> > >
>> > > Dick J
>> > >
>> > > ----- Original Message -----
>> > > From: John Grehan <jgrehan at SCIENCEBUFF.ORG>
>> > > Date: Thursday, March 16, 2006 8:14 am
>> > > Subject: Re: Reclassifying Viruses as Living?
>> > >
>> > > > > But....if we didn't classify things into boxes to which we apply
>> > > > labels,
>> > > > > what would we talk about?
>> > > > >
>> > > > > Aloha,
>> > > > > Rich
>> > > >
>> > > > Maybe we would talk about non-boxes. Biogeography, for example, is
>> > > > rifewith schemes to put geographic boxes around life. Croizat
>> > > > showed that it
>> > > > was possible to do biogeography without the boxes, and that approach
>> > > > sure generated a lot of talk (or non-talk for those who chose
>> > > > suppression). Perhaps it is a matter of whether the boxes or
>> > > > boundariesare "natural" or artificial.
>> > > >
>> > > > John
>> > > >
>Dr. Steve Manning
>Arkansas State University--Beebe
>Mathematics and Science
>Professor of Biology
>P.O. Box 1000
>Beebe, AR  72012
>Phone: 501-882-8203
>Fax: 501-882-4437

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