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Tim,
it all depends how does one define "live". Then
again in your consideration(s) the ubiquitous reductionistic-scientific
narrow 'model' definition also fights your more lax Rosennean complexity
view: a sure chance of a clash.
Just for the fun of it:
1.
>"a virus is not alive insofar as an entity
unto itself it cannot 1) reproduce, 2) is not a
true cell, 3) it has no metabolism or internal
processes."<
Are you alive? You, as an entity, cannot reproduce, you may have true
cells among other stuff, but "are" not one, and I would not exclude a virus's
internal processes by timing: that such do occur only after the combination with
other cells.
Of course then you call it a chimera. In the
parlance the 'virus' causes the pneumonia.
Is a sperm a virus? or the "real cell" egg, for
that matter? Is a fetus a parasite?
2.
>"A virus on its
own has no volition, no internal metabolic processes at all. It is inert.
It does not "seek" a host cell; instead, it randomly floats around until it
is in proximity to one. Once in proximity, if the virus and cell are of the
right types, the virus will become attached (chemically bind?) to a receptor
site on the cell."<
If a virus "gets attached" it was not inert. Your 'volition'
includes chemical affinity? in that case an acetic acid molecule has volition?
And the internal (metabolic and other) processes function, once activated, just
as in any other living organism which all require activation by enzymes,
stimuli, heat, etc. for functioning. By 'activation' through the host a virus
reproduces and the transfer of DNA-RNA (and who knows what else) may mean a
(special) metabolic activity.
3.
I did not want to use the word: it anticipates the symbiosis
with a host (or rather a parasitic cohabitation?) I wonder where to draw the
line between such and a chimera-formation (generally speaking, not as one
example). Also: where to draw the line between sickness-causing viruses and
other (viruslike functional) additives which are necessary in our
life-process?
4.
I don't quote, but there is a long line of
arguing how the parts have not identical functions to the assemblage
(complexity). In the eucaryote-evolution the "live" cell penetrating the other
"live cell" as forming later the nucleus is 'not live anymore', just part of the
ensemble tghe live eucaryotic cell, which is not identical anymore with "the
other" procaryote, the citoplasmic originator, or the mitochondrium-originator.
The virus(part) of the (infected?) cell is living within your chimera. The
chimera is live.
I suggest to look at these things with a more
'wholistic' eye and pay less attention to debatable details drawn upon narrowly
cut models of the reductionist science. Rosen could not write a book saying:
Hey, Fellows, you got it all wrong... he had to abide by the language and terms
of the profanum vulgus of scientists, his readers in spe. Even in his
explanations to Judith (Sorry, Judith, there is no put-down in this) he could
not expect his daughter to be at the 'complexiologistic' thinking level what he
attained in his many years of studying. He had to use understandable and
believable metaphors if he wanted to get appreciation and understanding.
Otherwise maybe even Judith would have thought
that he speaks a "different" language.
Tim, your post is interesting and well written,
I think there are more stringent topics to think of. I would not start a debate with the (reductions science)
enemy on their own turf.
At any rate I would not penetrate a field, very
controversial in itself, with my new ideas
controversial enough without the added
excitement of a debated situation in itself.
My negative point may (at least partially) come
from my scanty education in biology.
Best regards
John M
---- Original Message -----
Sent: Tuesday, September 30, 2003 12:33
PM
Subject: Viruses and Chimera
To
all,
Since the recent
discussion regarding the definition of life, I have been thinking some about
this topic. I realized that one useful area to look at might be the
contentiousness in biology surrounding whether or not a virus is
"alive".
I had some offline conversations with Judith on this
topic, and she disagrees with some of my points. It seemed to both of us like
an interesting topic for list discussion.
After reading
some webpages, it seems to me that the common thinking goes roughly this way: a virus is not alive insofar
as an entity unto itself it cannot 1) reproduce, 2) is not a true cell, 3) it has no
metabolism or internal processes. And the
argument on the other side is that once a virus "takes over" a host cell, then
it "controls" that cell and uses the machinery of the cell to perform
processes and reproduce, so in this (extended) sense the virus is
alive.
It strikes me,
though, that this debate is all wrong.
A virus on its own has no volition, no internal
metabolic processes at all. It is inert. It does not "seek" a host cell;
instead, it randomly floats around until it is in proximity to one. Once
in proximity, if the virus and cell are of the right types, the virus will
become attached (chemically bind?) to a receptor site on the cell. In
response, the virus then apparently initiates a fixed routine to inject
its DNA/RNA into the cell's cytoplasm.
To speak of this sequence in active volitional language, such
as "the virus seeks out a
host cell, uses its DNA/RNA
to take control of the host cell", seems to me entirely inappropriate, and assigns
volitional capabilities to a structure that has no such
capabilities.
I would argue that, on this level of description, a
virus is a Rosennean mechanism, not a complex system. The virus on its
own has no internal processes, much less any internal causal closed
loops of processes. Its one process of injecting DNA/RNA into a cell
is in reaction to the successful binding to the host. Crudely, it is
like a spring-loaded clamp and
hypodermic attached to a balloon. It floats around randomly until it comes in
contact with something (say, some organism) that trips the spring
clamp, which then causes the hypodermic plunger to move. This is an
entirely fixed and mechanical sequence.
Also, regarding viruses as
"evolving" entities. I think the idea that the "evolution" of viruses is
evidence that viruses are alive somehow is very weak. Prions (so-called
"misfolded" proteins) replicate and apparently also evolve (which may be what
allows them to sometimes pass between species), but no one (to my knowledge)
suggests that this indicates that prions are
alive.
So, the notion that once the virus is attached to the
cell, that the virus "takes the cell over" is erroneous. Just as it would be
erroneous to say that the balloon-clamp-hypodermic mechanism "takes over" an
organism it attaches to and injects with something that alters the processes
in the organism. Similarly, it would be erroneous to conclude that the
balloon-clamp-hypodermic is therefore now properly called "alive" because it
has attached itself to a living organism and has altered what the
organism does.
Instead, I think
the correct view is that the combining
of the virus and the host cell form a chimeric
relationship: the combination becomes a new creature. This new creature has, as one of its functions, to
generate new copies of the virus. Depending on the type of virus, this
creature may then dissolve, turn cancerous, or continue to persist.
Rosen talked about hermit crabs in ch. 18 of
Essays and the way in which the crab adopts a snail shell and
collects sea anemones and becomes a new chimeric organism with a new set of behaviors.
It seems to me that this is exactly the type of case that is occurring in the
virus-host situation. However, I think
this has been historically misinterpreted perhaps because of the apparent similarity of the symptoms arising from
viral infections to
bacterial ones, and probably moreso
because a virus has RNA/DNA, which is taken as putative evidence of life. So,
the virus has been incorrectly seen as purposively usurping
control of the host, leading to the supposition that a virus is alive
somehow.
But the virus by
itself is much like the snail
shell by itself: it is inert and not
alive. When it has become combined with the crab, one cannot ask: is the
shell now alive or not by virtue of this
combining? The question is improper, since the shell is not now a thing by itself, but is now a
part of this larger organism, the chimera, and
that chimera is what is alive. Similarly, the virus does not become
alive by virtue of combining with the host cell; instead, both are
subsumed into this new larger chimera organism.
I hate to use the old saw, but a chimera is a case where
one must adhere to the principle "the whole is greater than the parts". Once
combined, the virus and cell cannot continue to be thought of as distinct
entities or parts if we want to explain and understand the behaviors
of the result of this combining. Otherwise, I think this only
leads to the confused thinking that perpetuates the virus live-or-dead
debate.
The tendency
toward reductionist thinking, and of thinking of the virus as a volitional creature, leads to one attempting to mentally
maintain the virus and host as distinct and separable entities, even after
they have combined. The generation or replication of copies of the initial
virus also seems to support this view. But I think that this is simply trying
to make the situation appear other than it actually is, which is that the
(virus + host) once joined are a new creature with new
functionality (just as the
(hermit crab + shell + anemone) is a new chimeric creature). One of those functions is to process raw materials
into copies of the original virus. And the question of "what is alive?"
at that point is answered by: "this new creature, the chimera, is what is
alive".
Regards,
Tim
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