Reclassifying Viruses as Living?
wboeger at UFPR.BR
Tue Mar 14 21:00:21 CST 2006
Here is my reasoning: the information used by viruses for its replication
is kept in the same type of molecules as "living" cells, correct (DNA and
RNA)? (1)This sharing of character, found nowhere else (as far as we know)
supports the hypothesis that viruses and "living" cells share a common
ancestor (the one that first used these molecules for replication). (2)
Since viruses do not self-replicate on their own, it would not be possible
for them to have originated before "life". If (1) and (2) are acceptable
hypothesis, viruses originated after "life", from "LIFE". Now, if the
concept one uses for LIFE imposes that virus is NOT alive (ex. metabolism,
ability to self-replicate), we still have to assume that the viruses
originated from a LIVING ancestral organism (assuming a monophyletic
origin)! This is an awkward idea to me: NON-LIFE originating from LIFE!
As many other parasites (I will use only parasites as example but this will
hold for many other associations), viruses have "transferred" some or many
of its functions to its hosts and this has allowed the simplification in its
morphology, physiology, and so on. There is nothing strange about this.
Some parasites are "allowed" (i.e. there is a relaxed selection pressure for
the retention of the character) to loose their intestines, for example,
because the digestive process of their hosts is capable of supplying all the
energy and matter they need to survive! Viruses, just went farther in this
pathway of specialization and simplification.
Finally, the concept of life, in my opinion, must be associated to evolution
..if it evolves, it is alive! Virus. in my opinion are alive and I have not
yet seem any argument to convince me of the contrary! Even if one shows
that the rationale presented in the first paragraph is wrong it would be
hard to consider viruses simply as particles that are capable of
self-replication (even if it uses the machinery of another organism). But
this will always depend on the chosen definition of LIFE and this changes
from one person to another.
From: Thomas Lammers
Date: 03/14/06 19:40:13
To: TAXACOM at LISTSERV.NHM.KU.EDU
Subject: Re: [TAXACOM] Reclassifying Viruses as Living?
----- Original Message -----From: Robin Leech Date: Tuesday, March 14, 2006
Subject: Reclassifying Viruses as Living?
To: TAXACOM at LISTSERV.NHM.KU.EDU>
>Hi Taxacomers, If an "thing" can replicate itself by some means, or if we
can kill that "thing" by heat, pressure, chemical or oher means, then surely
we have to classify that "thing" as a form of life?<
The later is only "killing" if we judge the thing to be "living." Many
things can be *destroyed* -- doesn't mean they are alive. Don't get caught
in semantic circularity.
I think a key criterion of life is metabolism and the ability to use energy.
Viruses can't do that.
Besides, they make problems for Cell Theory.
Nope. To me, they'll always just be runamuck nucleic acids ...
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